iOMiaiOQMaiWiMMW 11 .-^ZtSHsSMtMM LHIHWn M UB I I HMW i n i LP I 1037 '7 §mmll mmrmitg \ §\imx^ THE GIFT OF .. J'^i.e.^. .J5... ..Gf. ..*^^ K.\^\1Z^ •S%\iDioo Cornell University Library LD1 037.7 1899 Decennial celebration, 1889-1899. 3 1924 030 630 598 oiin Overs "^^-^^--^ C C^-^-'^^^^rt. The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924030630598 Clark University 1889-1899 Decennial Celebration Worcester, Mass. Printed for the University 1899 3i Copyright, 18B9, By CLAKK university. WortooB 3Jrc8a J. S. Gushing & Co. — Berwick & Smith Norwood, Mass. U. S. A. Or PREFACE. This volume is intended not only to commemorate the Decen- nial Anniversary of Clark University, but also to make the Public acquainted with its aims and ideals, and with the character, scope, and amount of the work it has already done. Ever since it opened its doors to students it has confined itself to truly post- graduate work in a few departments, and has admitted such students only as gave promise of the ability not only to pursue the courses here offered with advantage to themselves, but to benefit the world by advancing science along the lines here repre- sented. It has thus taken a distinct position as a training school for college professors and scientific investigators. Such a policy is conducive neither to large numbers of students nor to popular appreciation. But, small as the university is and few as are its departments, it takes great satisfaction in pointing to this volume as, in some sense, a record of its work and its methods. The list of titles of the publications of its past and present members is a witness of the quality and quantity of what it has accom- plished. We beheve that Clark University, opening, as it did, at the beginning of a new university epoch in this country, has had some special influence in suggesting new lines of scientific research. The five foreign professors who took part in the Decennial Celebration were selected as the most eminent available scientific men in their respective lines in Europe ; this was the first visit of each to America, and four of them came here solely for this anni- iv PrefcLce. versary. Their lectures are here reproduced m extenso and have not been published elsewhere. The lectures of Professors Picard and Boltzmann are given in the languages in which they were delivered, and those of Professors Ramdn y Cajal, Mosso, and Forel in translations made by members of the Faculty and revised by representatives of the departments to which they severally belong. For these laborious services the editors desire to extend their very particular thanks to the individuals who have rendered them. The reports of departments were prepared especially for this occasion, and include not only an account of the work actually done during the decade, but also a statement by the officer in charge of each department of its aims and ideals and the lines along which it hopes to advance. The responsibility for the content and form of each report rests with the individual in whose name it is published; all modifications by the editors hav- ing been made in the form of suggestions to the writers and adopted only with their consent. It is perhaps unnecessary to say that no attempt has been made to secure uniformity in the various articles, excepting in the titles and in rainor details of arrangement. The editors extend their hearty thanks to the authors of the several portions of the volume for their cordial cooperation and for the friendly spirit in which suggestions have been received, and to all members of the Faculty for assistance in reading the proof-sheets. WILLIAM E. STORY, LOUIS N. WILSON, Editors. TABLE OF COJ^TEJN^TS PAGE HISTOEICAL SKETCH 1 THE DECENNIAL CELEBEATION 13 EXTEACTS FEOM CONGEATULATOEY LETTEES ... 25 DECENNIAL ADDEESS 45 By G. Stanley Hall, President of the University. EEPORTS OF DEPARTMENTS THE DEPAETMENT OF MATHEMATICS 61 By William Edward Stokt. THE DEPAETMENT OF PHYSICS 85 By Akthur Gordon Webster. THE DEPAETMENT OF BIOLOGY 99 By Clifton F. Hodge. THE DEPAETMENT' OF PSYCHOLOGY 119 General Psychology 122 By Edmund C. Sanpord. Pstcho-Pathology 144 By Adolf Meter. Anthropology 148 By Alexander F. Chamberlain. Pedagogy 161 By William H. Bitrnham. Philosophy 177 By G. Stanley Hall. THE LIBEAEY 187 By Louis N. Wilson. EEPOET OF THE TEEASUEEE 199 By Thomas H. Gage. V vi Table of Contents SCIENTIFIC LECTURES DELIVERED IN CONNECTION WITH THE DECENNIAL CELEBRATION PAGE i^MiLE PicARD, Professor of Mathemaiics at the University of Paris. 1. Sur I'Extension de quelques Notions Mathematiques, et en parti- culier de I'ld^e de Fonction depuis un Si^cle .... 207 2. Quelques Vues Generales sur la Theorie des Equations Differentielles 224 3. Sur la Theorie des Eonctions Analytiques et sur quelques Eonc- tions Speciales 241 LuDWiG BoLTZMANN, ProfessoT of Theoretical Physics at the University of Vienna. Ueber die Grundprincipien und Grundgleichimgen der Mechanik. (Four Lectures) 261 Santiago Ramon y Cajal, Professor of Histology and Rector of the Xiniversity of Madrid. 1. Comparative Study of the Sensory Areas of the Human Cortex . 311 2. Layer of the Large Stellate Cells 336 3. The Sensori-Motor Cortex 360 Angelo Mosso, Professor of Physiology and Rector of the University of Turin. 1. Psychic Processes and Muscular Exercise 383 2. The Mechanism of the Emotions 396 August Foeel, Late Professor of Psychiatry at the University of Zilrich ' and Director of the Burgholzli Asylum. 1. Hypnotism and Cerebral Activity 409 2. A Sketch of the Biology of Ants 433 DEGREES CONFERRED, 1889-1899 453 TITLES OF PUBLISHED PAPERS 459 SPECIAL STUDENTS 665 HISTORICAL SKETCH. HISTORICAL SKETCH. Clark University was founded by the munificence of Jonas G. Clark, a native of "Worcester County, whose plans, conceived more than twenty years before, had gradually grown with his fortune. His affairs had been so arranged as to allow long intervals for travel and study. During eight years thus spent, the leading foreign institutions of learning, old and new, were visited, and their records gathered and read. These studies centred about the means by which the highest culture of one generation is best transmitted to the ablest youths of the next, and especially about the external conditions most favorable for increasing the sum of human knowledge. To the improvement of these means and the enlargement of these conditions, the new University was devoted. It was the strong and express desire of the founder that the highest possible academic standards be here forever maintained ; that special opportunities and inducements be offered to research ; that to this end the instructors be not overburdened with teaching and examinations ; that all available experience, both of older countries and our own, be freely utilized ; and that new measures, and even innovations, if really helpful to the highest needs of modern science and culture, be no less freely adopted ; in fine, that the great opportunities of a new foundation in this land and age be diligently explored and improved. He chose Worcester as the seat of the new foundation after mature deliberation, — first, Because its location is central among the best colleges of the East, and by supplementing rather than duplicating their work, he hoped to ad- vance all their interests and to secure their good will and active support, that together they might take further steps in the development of superior education in New England ; and secondly, Because he believed the culture of this city would insure that en- lightened public opinion indispensable in maintaining these educational 2 Historical Sketch. standards at their highest, and that its wealth would insure the perpetual increase of revenue required by the rapid progress of science. As the first positive step toward the realization of these long-formed plans, Mr. Clark invited the following gentlemen to constitute with himself a Board of Trustees : — Stephen Salisbury, A.B., Harvard, 1856; Universities of Paris and Berlin, 1856-58; LL.B., Harvard, 1861; President Antiquarian Society since 1887; State Senator, 1892-95. Chakies Devens, A.B., Harvard, 1838 ; LL.B., Harvard, 1840 ; Major-General, 1863 ; Associate Justice of the Massachusetts Superior Court, 1867-73 ; Associate Justice of the Massachusetts Supreme Judicial Court, 1873-77, and again, 1881-91; Attorney-General of the United States, 1877-81; LL.D., Columbia and Harvard, 1877; Died January 7, 1891. GBOKaE F. Hoar, A.B., Harvard, 1846 ; LL.B., Harvard, 1849 ; United States House of Eepresentatives, 1869-77 ; Member Electoral Commission, 1876 ; United States Senate since 1877 ; Chairman of Judiciary Committee, 1891 — ; LL.D., William and Mary, Amherst, Harvard, and Tale. "William W. Eice, A.B., Bowdoin, 1846 ; admitted to Bar, 1854 ; United States House of Eepresentatives, 1876-86; LL.D., Bowdoin, 1886. Died March 1, 1896. Joseph Sakgent, A.B., Harvard, 1834 ; M.D., Harvard, 1837 ; London and Paris Hospitals, 1838^0. Died October 13, 1888. John D. Washburn, A.B., Harvard, 1853 ; LL.B., Harvard, 1856 ; Eepresenta- tive, 1876-79 ; State Senate, 1884 ; United States Minister to Switzerland, 1889-92. Frank P. Goulding, A.B., Dartmouth, 1863 ; Harvard Law School, 1866 ; City Solicitor, 1881-93. George Swan, A.B., Amherst, 1847; admitted to Bar, 1848; Member of Worcester School Board, 1879-90; Chairman of High School Committee, 1887-90. The following gentlemen have been added to the Board since to fill vacancies caused by death. In place of Dr. Sargent : — Edward Cowles, A.B., Dartmouth, 1859; M.D., Dartmouth, 1862, and Col- lege of Physicians and Surgeons, N. Y., 1863 ; Assistant Surgeon, U. S. A., 1863-72; Eesident Physician and Superintendent Boston City Hospital, 1872-79 ; Medical Superintendent McLean Asylum since 1879 ; Professor of Mental Diseases, Dartmouth Medical School, since 1885 ; Clinical Instructor in Mental Diseases, Harvard Medical School, since 1888. In place of General Devens: Thomas H. Gage, M.D., Harvard, 1852; President Massachusetts Medical Society, 1886-88. Historical Sketch. 3 On petition of this Board, the Legislature passed the following Act of Incokporation. Chaptek 133. commonwealth of massachusetts, in the year one thousand eight hun- dred and bightt-seten. an act to incorporate the trustees of clark university in worcester. Be it enacted by the Senate and House of Eepresentatives in General Court assembled, and by authority of the same, as follows : — Section 1. Jonas G. Clark, Stephen Salisbury, Charles Devens, George F. Hoar, William W. Eice, Joseph Sargent, John D. "Washburn, Frank P. Gould- ing and George Swan, all of the city of Worcester, in the Commonwealth of Massachusetts, and their successors, are hereby made a corporation by the name of the Trustees of Clark University, to be located in said Worcester, for the purpose of establishing and maintaining in said city of Worcester an institu- tion for the promotion of education and investigation in science, literature and art, to be called Clark University. Section 2. Said corporation may receive and hold real or personal estate by gift, grant, devise, bequest or otherwise, for the purpose aforesaid, and shall have all the rights, privileges, immunities, and powers, including the conferring of degrees, which similar incorporated institutions have in this Commonwealth. Section 3. Said corporation shall have the power to organize said Univer- sity in all its departments, to manage and control the same, to appoint its ofB.cers, who shall not be members of said corporation, and to fix their com- pensation and their tenure of office ; and said corporation may provide for the appointment of an advisory board and for the election by the Alumni of said University to fill any vacancies in said board. Section 4. The number of members of said corporation shall not be less than seven nor more than nine, and any vacancy therein may be filled by the remaining members at a meeting duly called and notified therefor ; and when any member thereof shall, by reason of infirmity or otherwise, become incapable, in the judgment of the remaining members, of discharging the duties of his office, or shall neglect or refuse to perform the same, he may be removed and another be elected to fill his place, by the remaining members, at a meeting duly called and notified for that purpose. Section 5. This Act shall take effect upon its passage. House of Eepresentatives, March 30, 1887, Passed to be Enacted. Charles J. Notes, Speaker. Senate, March 31, 1887, Passed to be Enacted. Halset J. BoARDMAN, President. During the previous five years, Mr. Clark had gradually acquired a tract of land, comprising over eight acres, located on Main Street, about 4 Historical Sketch. a mile from the heart of the city, with additional tracts near by.. This land has considerable elevation above that part of the city, is a watershed sloping to the southeast, insuring sanitary excellence and a wide and picturesque view. A park reservation of about 25 acres, directly oppo- site, has been set apart by the city, and named University Park. Plans for a main building were submitted to the Board by Mr. Clark, which were approved, and its erection was at once begun. The corner- stone was laid with impressive ceremonies, October 22, 1887. This build- ing is plain, substantial, and well appointed, 204 x 114 feet, four stories high and five in the centre, with superior facilities for heating, lighting, and ventilation, and has been constructed of brick and granite, and finished throughout in oak. On the whole it is a model of stability and solid work- manship. It contains a total of 90 rooms, and in its tower is a clock with three six-foot illuminated dials, which was presented by the citizens of Worcester. The elevations and ground plan are published, and the heat- ing, lighting, ventilation, walls, floors, etc., etc., are described in detail in the Third Official Announcement. On April 3, 1888, G. Stanley Hall, then a professor at Johns Hopkins University, was invited to the presidency. The official letter conveying the invitation to the president contained the following well-con- sidered and significant expression of the spirit animating the trustees : — " They desire to impose on you no trammels ; they have no friends for whom they wish to provide at the expense of the interests of the institution ; no pet theories to press upon you in derogation of your judgment ; no sectarian tests to apply ; no guarantees to require, save such as are implied by your acceptance of this trust. Their single desire is to fit men for the highest duties of life, and to that end, that this institution, in whatever branches of sound learning it may find itself engaged, may be a leader and a light." This invitation was accepted May 1, and the president was at once granted one year's leave of absence, with full salary, to visit universities in Europe. This year was diligently improved in gathering educational literature and collecting information and advice from leading authorities. Many reports based upon this work have already been made in the Peda- gogical Seminary and more are in course of preparation. During the absence of the president a Chemical Laboratory was begun. This building in its main body has three stories, in its eastern wing four, in its southwestern two. It contains 68 rooms. The outer walls are 2 feet in thickness and the partition walls from 12 to 16 inches. All par- Historical Sketch. 5 titions are of brick, so that the building is nearly fireproof. The two large laboratories are 24x58 feet and 22 feet high. This building is also described with plans in the Third Official Announcement. The opening exercises were held in a hall of the University, seating 1500 people, on "Wednesday, October 2, 1889. The late General Charles Devens presided, and made an opening address. Addresses were made by Senator George F. Hoar and the president. The founder of the University stated his purpose as follows : — " When we first entered upon our work it was with a well-defined plan and purpose, in whicli plan and purpose we have steadily persevered, turning neither to the right nor to the left. We have wrought upon no vague concep- tions nor suffered ourselves to be borne upon the fluctuating and unstable current of public opinion or public suggestions. We started upon our career with the determinate view of giving to the public all the benefits and advan- tages of a university, comprehending full ^ell what that implies, and feeling the full force of the general understanding, that a imiversity must, to a large degree, be a creation of time and experience. We have, however, boldly assumed as the foundation of our institution the principles, the tests, and the responsibilities of universities as they are everywhere recognized — but with- out making any claim for the prestige or flavor which age imparts to all things. It has therefore been our purpose to lay our foundation broad and strong and deep. In this we must necessarily lack the simple element of years. We have what we believe to be more valuable — the vast storehouse of the knowl- edge and learning which has been accumulating for the centuries that have gone before us, availing ourselves of the privilege of drawing from this source, open to all alike. We propose to go on to further and higher achievements. We propose to put into the hands of those who are members of the University, engaged in its several departments, every facility which money can command — to the extent of our ability — in the way of apparatus and appliances that can in any way promote our object in this direction. To our present depart- ments we propose to add others from time to time, as our means shall warrant and the exigencies of the University shall seem to demand, always taking those first whose domain lies nearest to those already established, until the full scope and purpose of the University shall have been accomplished. " These benefits and advantages thus briefly outlined, we propose placing at the service of those who from time to time seek, in good faith and honesty of purpose, to pursue the study of science in its purity, and to engage in scientific research and investigation — to such they are offered as far as possible free from all trammels and hindrances, without any religious, political, or social tests. All that will be required of any applicant will be evidence, disclosed by examinations or otherwise, that his attainments are such as to qualify him for the position that he seeks." 6 Historical Sketch. After careful consideration it was decided to begin with graduate work only and in the following five departments : I. Mathematics. II. Physics, Experimental and Theoretical. III. Chemistry, Organic, Inorganic, Physical, and Crystallography. IV. Biology, including Anatomy, Physiology, and Paleontology. V. Psychology, including Neurology, Anthropology, and Education. Mathematics is sometimes called the queen of all the sciences. As the latter become exact, they approximate it, and are fructified by its spirit and its methods. Its antiquity, its disciplinary value, its rapid and recent development, make it obviously indispensable. Physics is the field of the most immediate application of mathematics, and deals with the fundamental forces of the material universe, — heat, sound, light, electricity, — and the underlying problems of form and motion generally, with their vast field of application in such sciences as astronomy and dynamic geology. Chemistry, with its great and sudden development, revealing marvellous order and harmony in the constitution of matter, is rapidly extending its dominion over industrial processes. Biology, which seeks to fathom the laws of life, death, reproduction, and disease, that underlies all the medical sciences, in its broader aspects has taught man in recent decades far more concerning his origin and nature than all that was known before. Psychology, or the study of man's faculties and their education, is a new field into which all the sciences are bringing so many of their richest and best ideas, which is now so full of promise for the life of man. A sub-department of Education was established in 1892, and the department of Chemistry was temporarily discontinued in 1894. To express more explicitly the character and policy of the institution, the Trustees voted to approve and publish the following statement : — "As the -work of the University increases, its settled policy shall be always to first strengthen departments already established, until they are as thorough, as advanced, as special, and as eflcient as possible, before proceeding to the establishment of new ones. "When this is done and new departments are established, those shall always be chosen first which are scientifically most closely related to departments already established ; that the body of sciences here represented may be kept vigorous and compact, and that the strength of the University may always rest, not upon the number of subjects, nor the breadth or length of its cur- riculum, but upon its thoroughness and its unity. Historical Sketch. 7 " This shall in no wise hinder the establishment, by other donors than the founder, of other and more independent departments if approved by the Trustees. " While ability in teaching shall be held of great importance, the leading consideration in all engagements, reappointments, and promotions shall be the quality and quantity of successful investigation." By thus limiting the work of the University in the beginning to five departments, it appeals only to advanced men who desire to specialize in one or more of these fundamental sciences, leaving college students who require a larger range of studies, as well as those who desire to devote themselves to language and literature, historical, technical, or pro- fessional studies, to go elsewhere. Hence our work must be post- graduate. This requires the best professors and apparatus, more books and journals, and necessitates a system of fellowships, scholarships, and provisions for original research. It thus becomes a training-school for professors. This is the most expensive of all educational work, seeks the fewest but the best men from the widest area, and to succeed must be helpful in elevating the academic standards of the coimtry to a higher plane. It requires the highest degree of wisdom and foresight on the part of the Founder and the Trustees, and possibly some sacrifices of local sympathy and support at first, till the nature of the work is well understood. It requires the greatest effort and devotion to work on the part of the Faculty and students. But the cause is itself an inspira- tion. It appeals to the future, the country, and to the world, and seeks quality more than numbers. It is in the current of all the best tenden- cies in the best lands, and is now the ideal of perhaps every eminent man of science everywhere. The inauguration and steady maintenance of this clear and simple policy gives the University a reason for being, and a distinct individuality it could not otherwise have, and also a real leadership in this epoch of awakening and transition, which is the golden time of opportunity for new institutions, and brings them to the front. Such a period as the present gives the latter even greater relative influ- ence and prominence than would be possible in periods of less public interest in education. New institutions can and should lead, set new fashions, and be the first upon the higher planes. Older institutions are retarded by conservatism and must advance more slowly, but when they move they carry great momentum. This condition makes the present a moment of perhaps unprecedented opportunity, which 8 Historical Sketch. has been long looked for and long delayed, and which renders both funds and labor in this field more precious than they have been, or will be when it is past. We may all be content if our Uni- versity can transmit to future generations by means of its organization, plan, and methods the best and highest educational tendencies and move- ments now stirring the souls of the best men of the world, and uniting men of all lands, races, creeds, and stations in a larger if not also a deeper consensus of belief than history has ever known before. Our University does not draw its chief earnings from, or do most of its teaching for, undergraduates, and our so-called graduate students do not take undergraduate courses. This makes the proportion of expendi- ture to income very high here, and indeed we can admit and do justice to but comparatively few students. Most of those who come here have spent one or more years after graduation in teaching, or in study in Europe or elsewhere. Most of those who have been members here have already obtained professorships or other academic positions elsewhere. The proportion of such is hardly excelled by the Ecole Normale of Paris, the special function of which is to train professors from other collegiate institutions. Every student who obtains original results is expected to present theipi in the form of lectures to his department, and thus to acquire experience in teaching under criticism. The work of the educa- tional department deals with problems and history of higher educational institutions, and is adapted to all the body of fellows and scholars, and seeks to increase the efficiency of every man both as a teacher of his own specialty and in general helpfulness to the institution with which he is to be connected. Since the opening of the University not less than five hundred books, memoirs, theses, or articles ^ have been published by members of the Uni- versity, which attempt to make additions to the sum of human knowledge. These contributions are of very different orders of value, but together they constitute a body of knowledge in which the institution takes special pride. Every member of the University is expected to make at least one long and serious effort of this kind. Indeed, had its publications no value as contri- butions to knowledge, its educational value is the highest for mature men. Such effort gets minds into independent action, gives a sense of authority and of true mental freedom, which no amount of acquisition can bring. It brings out new powers of mind and of will, and, while one of the chief I A list of these publications will be found at the end of this volume. Historical Sketch. 9 marks by which true University work is distinguished from that of lower grades, is in the line of all present tendencies to place doing above know- ing from the kindergarten up. Work that is published enlarges the sphere of interests of the author, subjects him to the higher test of being judged by his peers elsewhere, and brings in the potent and salutary stimulus of wider competition. This baptism of ink has often marked a new birth of ideals and ability in young men. Modern as distinct from earlier culture culminates in the man-making training of will and judg- ment thus given. Such work, too, gives teaching a new power and zest. Instruction to a fit few by an investigator who stands on the frontier and has once felt the light and heat in which discovery is wrought out is inspiring, and is very difFerent from information imparted at lower levels by teachers further removed from the work of discovery and creation. Clark University is exclusively what is called in Europe a Philo- sophical Faculty, or a part of one so far as yet developed, devoted to a group of the pure sciences which underlie technology and medicine, but does not yet apply its work to these professional fields. These or a college course could be added with relatively less expense. Our method has brought us face to face with many new problems. Our efforts at solving some of these are described in the department reports which follow. Like all new institutions, we have not entirely escaped trials, but we trust we have learned their lesson, and shall be the better and stronger for them. Instead of dispersing our energies in university extensions, we have followed the opposite course of university concentra- tion, like the Ecole Pratique of France. Accepting the plain lesson of history that the best educational influences work from above downward, that universities create the material of culture, while lower institutions are the canals for its distribution, we have sought aid for the latter work by an educational sub-department and summer school. We are not like the Smithsonian Institute, the Naples school, the Reichsanstalt, academies of science, etc., devoted solely to research, but have to make our lectures more condensed and fewer than usual, because addressed to advanced men, and to devise ways of making seminary and laboratory, two of the noblest words in the vocabulary of higher education, more effective. We have tried to effect systematic exchanges with foreign institutions, — and our library has profited largely from this source, — and have sought by all the above means to aid in giving to universities and to professors the position due them in a time when sciences have come to underlie all the 10 Historical Sketch. arts of peace and war, and when the world, in all its activities, industry and trade, professions, legislation, is coming to be more and more con- trolled by experts, thus trained to the frontier of their specialties. The degree of Doctor of Philosophy has been conferred upon can- didates, whose names, together with the dates of their final examinations and the subjects of their dissertations, are given later in this volume. Other historical facts are given in the President's Address at the Decennial Celebration. REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY. At least two years, and in most cases three years, of graduate work will be necessary for this degree. Examinations for it, however, may be taken at any time during the academic year when, in the judgment of the University authorities, the candidate is prepared. A prearranged period of serious work at the University itself is indispensable. For this degree the first requirement is a dissertation upon an approved subject, to which it must be an original contribution of value. To this capital importance is attached. It must be reported on in writing by the chief instructor before the examination, printed at the expense of the candidate, and at least one hundred copies given to the University. In case, however, of dissertations of very unusual length, or containing very expensive plates, the Faculty shall have power, at the request of the candidate, to reduce this number of presen- tation copies to fifty. Such formal or informal tests as the Faculty shall determine, shall mark the acceptance of each student or fellow as a candidate for this degree. One object of this preliminary test shall be to insure a good reading knowledge of French and German. Such formal candidature shall precede by at least one academic year the examination itself. (See special rules below.) The fee for the doctor's degree is |25, and in every case it must be paid and the presentation copies of the dissertation must be in the hands of the Librarian before the diploma is given. In exceptional cases, however, and by special action of the Faculty, the ceremony of promotion may precede the presentation of the printed copies of Historical Sketch. 11 the dissertation. The latter, however, must always precede the actual presentation of the diploma. An oral but not a written examination is required upon at least one minor subject in addition to the major, before an examination jury composed of at least four members, including the head of the department and the President of the University, who is authorized to invite any person from within or without the University to be present and to ask questions. The jury shall report the results of the examination to the Faculty, which, if it is also satisfied, may recommend the candidate for the degree. For the bestowal of this degree, the approbation of the Board of Trustees must in each case be obtained. They desire that the standard of requirements for it be kept the highest practicable, that it be reserved for men of superior ability and attainment only, and that its value here be never suffered to depreciate. It is to the needs of these students that the lectures, seminaries, laboratories, collections of books, apparatus, etc., are specially shaped, and no pains will be spared to afford them every needed stimulus and opportunity. It is for them that the Fellowships and Scholarships are primarily intended, although any of these honors may be awarded to others. SPECIAL JRULJES. I. Residence. — No candidate shall receive the degree of Doctor of Philosophy without at least one year's previous residence. II. Gandidatwre for the Doctor' a Degree. — Every applicant for the doctor's degree shall fill out before October 15th the regular appli- cation blank provided at the office. This schedule shall be submitted to the head of the department and the instructor in the major subject. Before affixing their signatures they shall satisfy themselves, in such manner as they may desire, as to the fitness of the applicant. III. When countersigned, this schedule shall be filed with the President, who will appoint an examiner to serve with a representative of the major subject as a committee to determine the proficiency of the applicant in French and German. IV. In case of a favorable report by this committee the applicant shall be a regular candidate for the degree. V. Candidates complying with all preliminary conditions, including 12 Historical Sketch. the examinations in French and German, before November 1st, will be allowed to proceed to the doctor's examination at any time between May 15th following and the end of the academic year. VI. Dissertation. — The dissertation must be presented to the in- structor under whose direction it was before written, and reported upon by him before the final examination. In every case the dissertation shall be laid before the jury of examination, at the time of examination, in form suitable for publication. This provision shall not, however, preclude the making of such minor changes later as the chief instructor may approve. VII. The dissertation shall be printed at the expense of the can- didate, and the required copies deposited with the Librarian within one calendar year from the 1st of October following the examination. The candidate alone will be held responsible for the fulfilment of these conditions. VIII. The favorable report of the chief instructor, filed in writing with the Clerk of the University, shall be a sufficient imprimatur or authorization for printing as a dissertation. The printed copies shall bear upon the cover the statement of approval in the following words, over the name of the chief instructor : — A Dissertation submitted to the Faculty of Clark University, Wor- cester, Mass., in partial fulfilment of the requirements for the degree of Doctor of Philosophy, and accepted on the recommendation of (name of the chief instructor). IX. Examinations for the Doctor's Degree. — The examinations for the doctor's degree may be held at any time during the academic year, provided that at least one academic year has elapsed since the completion of the preliminaries of candidature, except in the case of fulfilment of these conditions between the beginning of any academic year and November 1st of that year, to which case Rule V. applies. The examinations shall be held at such hours and places as the President may appoint. X. Examinations may also be held during the regular vacations of the University, but for these an additional fee of five dollars to each examiner, and the reasonable travelling expenses of any examiners who are out of town, all payable in advance, will be required. XI. All these special rules shall go into force immediately as far as practicable, and shaU govern all applicants for degrees in the academic year 1899-1900. THE DECENNIAL CELEBRATION. The work of Clark University is so technical and special that it is necessarily more or less withdrawn from popular interest. It has no commencements, and comes in very little contact with the public or the press in Worcester, or indeed with collegiate institutions in other parts of the country. This is a disadvantage so far as local or general public interest in its work is concerned, but the fact that it does not exercise many of the usual functions of a college is also a distinct advantage to its scientific work. The close of the tenth year of its existence presented an opportunity to bring before the public, in a simple way, befitting at once its size and its quality, a presentation of the work it has accomplished in the past and of its hopes and needs for the future. Early last winter the President began to consider plans of marking this anniversary, and, with the efficient aid of the Faculty, they gradually took definite shape. A personal appeal was then made to a number of public-spirited and wealthy citizens of Worcester, and the scheme was rendered feasible by the gen- erosity of the following gentlemen, who donated the sums affixed to their names: — Mr. Stephen Salisbury, $1000 Mr. Philip W. Moen, 500 Mr. Thomas H. Dodge, 200 Mr. Edward D. Thayer, Jr., 200 Mr. Charles S. Barton, 100 Mr. John H. Goes, 100 Mr. Andrew H. Green, 100 Mr. Arthur M. Stone, 100 John 0. Marble, M.D., 50 Mr. C. Henry Hutchins, $500 Mr. William E. Eice, 500 Mr. Orlando W. ISTorcross, 200 Mr. Matthew J. Whittall, 150 Mr. A. Swan Brown, 100 Mr. Loring Goes, 100 Mr. James Logan, 100 Mr. Joseph H. Walker, 100 Mr. Erederick L. Goes, 25 Charles L. Nichols, M.D., $25. 13 14 Decennial It was decided that the close of the tenth academic year should be celebrated (1) by courses of lectures delivered by distinguished foreign scientific men, (2) by public exercises, and (3) by an evening reception. A conference was then held concerning the most prominent leaders in Europe in branches especially cultivated at the University, and after some correspondence the following persons were invited to give from two to four lectures each: — Emile Picakd, Professor of Mathematics at the University of Paris. LuDwiG BoLTZMAiiTN-, Profcssor of Theoretical Physics at the University of Vienna. Angelo Mosso, Professor of Physiology and Eector of the University of Turin. Sajstiago Ram6n t Cajai, Professor of Histology and Eector of the Univer- sity of Madrid. August Fokel, late Professor of Psychiatry at the University of Ziirich and Director of the Burgholzli Asylum. Under the direction of a committee consisting of Assistant Professor A. G. Webster and Professor W. E. Story, the following forms of invitation to the various parts of the programme were prepared: — Celebration. 15 CiyAe- (jl-€U'C^^ -o^ 'T^yM/^^d^ty^ ■t'l^ iyO'n' •o^ ^n^ J^ iU^j tz^n^ -e^^^^i^^j -^^44^1^. ^t&aAe> i^&jilAf. 16 Decennial C^ /^ ^ (C/i^u-d^eed-j €i/n€!^ O^ -i^e^^u^ed^ €^i^ Ju^n^i^L -o^ '^^txM- ri4^ed€^f'i'€>e- o^n- ■d^ S'te,aA& itjil^. Celebration. 17 C^ J^ m^ y (^■Utd^e^edj tZ'H^ d/^. tz^ ^^-^^md^ lU^x^t^^ ^^'^Ji^ u> e^Cmpe/f^ ■o- -oui^cS. Maa^e/ ve/fd^. 18 Decennial The invitations to the lectures were sent to such persons as were con- sidered to be particularly interested in the subjects in question, of whom over one hundred accepted. Many declinations were inevitable and expected, owing to the unfavorable season of the year and, perhaps in part, to the somewhat too short notice given. The lecturers all arrived in due season, and were entertained as follows : — Professor Emile Picard, by Professor W. E. Story. Professor Ludwig Boltzmann, by Assistant Professor A. G. Webster. Professor Angelo Mosso, by President G. Stanley Hall. Professor S. Eamdn y Cajal, by Hon. Stephen Salisbury. Professor August Eorel, by Dr. Adolf Meyer. The lectures were held in the large lecture-room on the first floor, and were well attended. Professors Picard and Cajal lectured in French, and Professors Boltzmann, Mosso, and Forel in German. Their lectures are printed in full elsewhere in this volume. Many social functions occurred during the week ending July 8. On Wednesday evening, Professor Story received informally the attendants on the lectures of Professors Picard and Boltzmann ; on Thursday evening President Hall gave a reception to all the visitors ; and on Friday after- noon and evening the whole company was entertained by Hon. Stephen Salisbury at the Quinsigamond Boat Club house. The second part of the celebration occurred on Monday morning, July 10, beginning at 10.30, in the University. The professors had adopted academic costume, and many distinguished guests were seated upon the platform. The exercises opened with prayer by the Rev. Alex- ander H. Vinton, Rector of All Saints' Church. A few extracts from congratulatory letters were read by Professor Story, which are printed elsewhere in this volume. Brief congratulatory addresses were made by President Faunce, of Brown University, repre- senting the New England college presidents ; and Professor Bowditch of the Harvard Medical School, representing the higher scientific institutions of the state. President Faunce said : — " I count it a very happy fact that the first occasion on which I am to officially speak, representing Brown University, is at this anniversary at Clark University. I bring you to-day greetings from an institution of the higher learning founded in 1764 to a university founded in 1887. It is Celebration. 19 safe to say that Clark University has done more to widen the confines of human knowledge than any other American college in one hundred and fifty years. " When Professor J. P. Cooke, of Harvard, applied to the Faculty for chemicals and apparatus for experiment, he was told he must secure the materials at his own expense, and that he must be responsible for any explosions or damage in consequence of his experiments. From that day to this is a long step. Our method of applying nature has been trans- formed within a very few years. The distance between Achilles' coach and the English stage-coach is not the same as that between the stage- coach and the Empire State express. The difference between the Phoeni- cian galleys and the Bon Homme Richard is not the difference between the Bon Somme Richard and the modern battleship. The little world of Shakespeare has become one vast universe of learning, and the field has broadened almost infinitely in all directions, and the goal is the far-off divine event toward which the whole creation moves. "In this movement of scholarship the enrichment of one institution is the enrichment of all, the enfeeblement of one is the enfeeblement of all. You have received at this celebration, almost Spartan-like in its sim- plicity, the congratulations not alone of America, but of Berlin and Munich and Vienna, because your advance and success is the advance of all. Only geographically and superficially are the leaders of modern scholarship divided, and so we congratulate you, not because you have duplicated existing plants, but that you have filled a place hitherto unfilled and have broken new ground. " Here among all the institutions of learning you have not detracted from the success of other institutions, you have placed fresh laurels on the heads of each. All of us feel a warm interest and admiration for this University because of the simple, quiet, and noble work done within these walls." Dr. Bowditch said that he was quite unprepared to say much, and he thought it just as weU, for he belonged, in the words of Dr. Holmes, to the "silent profession." He paid a tribute to the felicitous speech of Dr. Faunce, which left him little to say. Dr. Bowditch spoke of the great work in scientific research being conducted by the institution, and, after some wishes for its prosperity, congratulated the youngest college in the name of the oldest college in Massachusetts. 20 Decennial Then followed the address by President Hall, printed elsewhere in this volume. The honorary degree of Doctor op Laws, honoris causd, was then con- ferred, for the first time, upon the five foreign professors in the following terms : — " By virtue of the authority vested by the Commonwealth of Massachu- setts in the Board of Trustees of Clark University, and by them dele- gated to me, I now create you Doctor of Laws, honoris causd, and by this token [presenting diploma] invest you with all the dignities thereunto appertaining." Brief responses were made, of which translations follow. Lttdwig Boltzmann. The problem of science is a twofold one: first, to advance our knowledge of nature independently of any practical application ; and second, to make practical applications of the knowledge gained. Although to a superficial observer it may seem that the latter is of greater importance, the develop- ment of humanity has shown in the most convincing way that the first kind of activity is not only of paramount importance, but that the leading role belongs to it. In fact, it is only thanks to the pioneers of science who, laying aside all practical applications, penetrate deeper and deeper into the essence and arrangement of the forces of nature, that humanity has obtained that sway over the laws of nature which makes possible the present practical achievements. The German universities have devoted themselves at all times to the nurture of pure science apart from its practical applications, although but one of the four university faculties is consecrated to it, and that one not entirely. It must be considered as a good omen, therefore, that here in America, which is usually taken to be the land of practical men, the ideal of a place entirely consecrated to the service of pure science, unattainable in Germany, has found its realization, so that I, who am body and soul a German professor, deem it a great honor to have conferred on me in this place, the greatest distinction which the University can grant. While desiring Clark University to flourish and thrive in the intimate conviction that the whole scientific world is interested in her prosperity, I express my thanks to the President and all its members for the high honor bestowed upon me to-day. Celebration. 21 Santiago Ramon y Cajal. I OFFER my most cordial thanks to Clark University for the honorable distinction she has bestowed upon me in spite of my small deserts by granting to me the degree of doctor of laws by this learned body, the remembrance of which wiU never fade from my memory. This honor I deem to be the prize of the greatest value which my modest researches have procured for me, and the one which will encourage me most in my worship of the laboratory tasks and of the study of nature. This honorary distinction, as weU as the invitation which Clark University condescended to make me to take part in the conferences for solemnizing the tenth anniversary of its foundation, shows once more that the men of science know of no frontiers, and that they form a universal family, whose solidarity and fellow-feeling place them high above the wrangle of mate- rial interests and selfish struggles of nationalities. It was truly a happy idea to create in America a university of higher studies, devoted not only to the labor of teaching, but also very especially to giving impulse to pure science. It has been said many times, but never enough, that there is no lasting industrial progress if it is not connected, as a brook with its source, with the creation of original science. No matter how great the practical genius of a nation, it is impossible for it to preserve its political, commercial, and industrial hegemony, unless it comes out intellectually superior to other nations, unless it attends with equal care to the laboratory and to the mill, to the ideas as well as to the inventions, to the philosophy and to the science which guide as well as to the art which carries out. This happy alliance between theory and practice is what places Ger- many to-day at the head of civilization. It would be easy to adduce num- berless examples of the supremacy which industry, founded on science, holds over empirical industry created at haphazard according to the inventive character of each nation. I will quote only two — the chemical industry of the aniline dyes created chiefly in Germany, which assures to that nation an immense wealth ; and the optical industry representing all kinds of apparatus (microscopes, photographical and astronomical object-glasses) which sprung up under the inspiration of the great mathematicians. Abbe, Rudolph, Goertz, and others, and which by its manifest superiority over that of other nations procures to Prussia a monopoly which makes the whole world her tributary. 22 Decennial That is tlie right way, the only one which leads to glory, wealth, and power. I trust that the creation of Clark University may give the signal for founding in America other similar institutions embracing a still larger number of branches of science, and having as their primary object the wresting of secrets from nature, supplying industry and arts with principles and facts capable of fruitful applications, forming the research spirit of the new generation, freeing it from the clogs of routine and imitation, and finally forming the foundation of a splendid civilization superior in groundwork, as well as in form, to that of the European nations. August Foeel. I THANK you heartily for the great honor you have bestowed upon me by conferring upon me the degree of doctor of laws, honoris causd, of Clark University. But I accept this honor less in my own person than as a representative of Switzerland at your celebration — in the name of my little fatherland. Although nowadays the Swiss Federation disap- pears beside the powerful republic of the United States, yet she prides herself still on being the little old mother of democracy, which has fought for her free rights for centuries, and has maintained them up to the present day. I offer my heartiest congratulations for the brilliant success which Clark University has achieved during the short time of its exis- tence in the high domains of philosophy, pedagogy, and of many a scientific foundation of social questions. But we must also offer our heartiest thanks and congratulations for the generous and magnificent gifts of American citizens for the furtherance of scientific and social progress. Allow me to add a wish. Let Clark University continue to pursue — under the successful guidance of her excellent President, Professor G. Stanley Hall — her researches in the regions of psychology and pedagogy together with those on the brain and its life, and thus to further the investigation and the building up of truth in the teeth of all prejudices. Let her help to bury the old roads of barren metaphysical dogmas and speculations, and thus develop in its entirety the only fruitful ethically built-up progressive method of scientific investigation in these domains, as a blessing to our posterity and for the good of a better and happier humanity. Celebration. 23 Angelo Mosso. I OFFER my thanks to Clark University for the honor bestowed upon me. I shall carry with me to Italy a happy remembrance of the many proofs of sympathy and friendship which I have received in the Uni- versity and the city of Worcester. It is not only the expression of my gratitude that I offer you, but also my great admiration for all that I saw in your University, and especially the development in experimental psychology under the happy impulse which the President has given to this branch of science. It is not only on my own account that I offer you my thanks, it is also because, on my return to Italy, I hope to found in the University of Turin a school of experimental psychology. Emile Pioaed. I offer my heartiest thanks to the President and Professors of Clark University for the degree just conferred upon me. I have been also greatly touched by the honor you bestowed upon me by inviting me to give a few lectures during this academic celebration. Your desire was thus to bear witness to your sympathy with men of science in France. "We follow on our side, in France, with great interest the American scientific movement, and we rejoice in seeing closer relations established between our universi- ties and those of this country. Science treads its ascending march on different roads, and research work requires to-day the most varied apti- tudes. The initiative and the energy which are prevalent in this country will not be wanting in occasions for displaying themselves, and, in all branches of studies, the American scientists will be able to erect some- thing equivalent to those large telescopes by means of which your astrono- mers have made such beautiful discoveries. It is in the universities which, like this one, are devoted to research, that the scientific movement is bound to have its origin. From everything I have seen and heard for the last few days, I am certain that the eminent professors of this University devote themselves with success to this noble task, and I beg to offer my most sincere wishes for the continuance of the brilliant development of Clark University. The exercises concluded with prayer by Dr. Vinton. The closing exercise of the decennial was a reception which was attended by between five hundred and six hundred ladies and gentlemen 24 Decennial Celebration. of Worcester. The arrangements had been made under the direction of Assistant Professor Henry Taber and Professor William E. Story. The large lecture-room and corridors were decorated with festoons of green and white, the flags of the United States and of the native countries of the foreign guests, and with potted plants. A collation was served in the library, and many pieces of apparatus were exhibited in operation in the physical and psychological laboratories. The following persons received : President G. Stanley Hall, Miss Florence E. Smith of Newton Centre, Mass., Mrs. A. W. Beals of Stam- ford, Conn., Hon. Stephen Salisbury, Dr. Edward Cowles, Miss Gage, Professor and Mrs. William E. Story, Assistant Professor and Mrs. Arthur G. Webster, Assistant Professor and Mrs. Clifton F. Hodge, Assistant Professor Edmund C. Sanford, Miss Sanford, Assistant Professor Henry Taber, Dr. and Mrs. A. F. Chamberlain, the foreign lecturers, Sefiora Ramon y Cajal, and Frau Boltzmann. The press of Worcester gave very full and detailed accounts of all that transpired during the week except the scientific lectures, all of which were in foreign languages and upon very technical subjects. The following original documents have been bound and filed in the University library : — (1) The congratulatory letters, telegrams, etc. (2) The correspondence with the foreign lecturers, and the letters of acceptance and declination from American professors. (3) The letters of acceptance and declination to the reception in the evening. The weather was somewhat warm during the first few days, but was clear and cool on Saturday, Sunday, and Monday. The hospitality of Worcester people was all that could be desired. CONGEATULATIONS. The following extracts are taken from many hundred congratulatory letters, personal, official, and from institutions and educators of all grades and many lands. Congratulations on the conclusion of the University's first decade, and best wishes for the successful continuance of the work it has undertaken. William McKinlbt, Washington, D.C., Fresident of the United States. The attraction will be strong to all who are interested in the great subjects which these distinguished men will discuss, or in intellectual eminence for its own sake. Your occasion will be the most distinguished gathering that will occur in all New England this summer. . . . The high plane of the work done at Clark University, the only institution in our country exclusively devoted to original research and the instruction of advanced investigators, so far as I am aware, is well known to all who have followed the course of the University. Modestly, and without ostentation, it has pursued its noble ideals. If, under your able direction, its means were more extensive, the University would, doubtless, become the centre of a still larger circle of influence in the training of men for the prosecution of original research and the conduct of similar work in other institutions. I trust that your own large plans and those of the founder of the University may enjoy a complete realization, and that its future may be crowned with the high success which so great an enterprise rightly deserves. Felicitating the honored founder, yourself, the trustees, and your colleagues in the faculty upon the great occasion you are soon to celebrate, David J. Hill, Washington, D.C., Assistant Secretary of State. It is one of the chief regrets of my life that I cannot attend the celebration of Clark University. Be assured that no reason personal to myself has pre- vented my attendance. I have seriously considered the question of crossing the Atlantic for the purpose, and coming back here immediately afterward. But that seems impracticable. 26 26 Extracts from We have to congratulate the University upon ten years of success. It was not to be expected that an institution whose aim is to lift the university educa- tion, not only of this country, but of the world, to a higher plane, and to break out a new and untrodden path, should command popularity in the beginning, or that its success should at once be recognized by the general public. But we have no cause for regret or for discouragement. Teachers whom we have edu- cated are found in institutions of the first class in all parts of the country, and all parts of the world have sent representatives to receive our instruction. This is largely due to the wise and far-sighted intelligence of the founder, and, next, to your own constant and self-sacrificing labors. There have been times during these ten years when we have been tempted to think that the people of Worcester have been cold, and have been lacking in the liberality which we had hoped from them when we started. But in looking at the history of other institutions which are now useful and flourishing, it will be seen that they had in the beginning a like experience. I remember well a time when it almost seemed impossible to get the people of Worcester to endow a public library. But the hour came and the man came, and our public library is now munificently endowed and is a model of library administration. The Polytechnic Institute had its day of small things. But the liberality of two citizens of Worcester of the same name and race, whose two lives seem almost like the prolonged life of one individual, came to its aid, and it is now doing its work with large endowments, and its scheme has been copied by other institu- tions all over the country. I do not for a moment doubt that the time will come when our endowments will enable us to maintain in the entire circle of univer- sity education the position which we have taken and hold with regard to a few subjects. Already an eloquent orator, formerly head of the National Catholic University at Washington, has referred to Clark as " that little institution in Worcester which has added a new story to university education, and ' Which allures to brighter worlds and leads the way.' " An eminent professor of science from the English Cambridge declared at a meeting in the British Association, in the presence of famous scholars from aU parts of the world, that there is one thing that England envies America, and that is Clark University. There is nothing except the country itself which ought to inspire a deeper devotion in its children than a university. As time goes on this feeling, made up of love and gratitude, will be found in fullest measure among the alumni of Clark. As they go out to reap the harvests of success in life, they vnll repay to their alma mater, in their own way, the great debt they owe her. When that time comes I have no fear that her endowments will not be ample to accomplish the work she has undertaken. In the meantime those of us to whom the con- fidence of the founder has committed a share ia her administration must renew our own vows of fidelity to her service. Among the many public honors which the undeserved kindness of my fellow- Congratulatory Letters. 27 citizens has bestowed upon me, I count none higher than my selection as one of the first board of trustees of this institution. I trust that your celebration wUl be full of delight for those who gather there, that they will look forward with bright hopes to the future, and that an immortality of fame and usefulness may await the institution which now celebrates its tenth birthday. George E. Hoar, United States Senator. I learn from your formal letters of invitation that you are to celebrate the close of the first decade of Clark University. It is one of the most wonderful careers to be chronicled in the history of American education. I congratulate you on your eminent success in conducting your University in so efficient a manner toward the improvement and elevation of pedagogy in the United States. Your movement is all the more valuable because it challenges the aims and purposes of the present existing education. It is an elementary force in making the American teachers circumspect and reflective, and causing them to seek deeper principles on which to ground their practice and on which to im- prove it. Hoping that there will be a long series of equally useful decades in the history of Clark University and in your own successful directorship of that institution, "W. T. Harris, Washington, B.C., Commissioner of Education. I cannot refrain from offering my congratulations to the President, Trustees, and Faculty for securing the services of such distinguished lecturers, as well as for the marked success that has attended Clark University during the first decade of its existence. Willis L. Mooke, Washington, B.C., Chief of Weather Bureau. I must add my profound appreciation of the great work for the highest science that is being accomplished by you. The solid knowledge that Consti- tutes " Science" is a rather slow growth — it can only advance in proportion as man frees himself from ancient errors and evolves higher powers of observation and reason. The fine work done at Clark, the excellent memoirs published by its professors, and now these attractive lectures, give us all the assurance that your labors for the highest attainments in the study and teaching of science will be abundantly rewarded. Cleveland ABBi, Washington, D.C., Weather Bureau. Congratulating you on the successful rounding out of the first decade of the University, and with best wishes for the success of the institution in the future, ' W. J. McGee, Washington, B.C., Smithsonian Institution. 28 Extracts from I send you most cordial greetings on the interesting occasion, and liope the future of Clark will be as successful as the past, and that your plans for scien- tific research may be realized va. the fullest degree. Cabboll D. Wbight, Washington, D.C., Commissioner of Labor. One may well be enTious of the gratification that the generous founder of Clark University must feel at the world-wide recognition of its achievements during the very first decade of its existence. To have established a just claim upon the regard of foremost men associ- ated with educational establishments in this country and in Europe is of great significance. The work that the University has done and is doing will continue to attract to its halls those rare geniuses who, impressed with the transcendent importance of the science of Pedagogy, of Physiology and Psychology, seek with unfailing diligence to penetrate their inmost depth. This work can scarcely fail to exer- cise a beneficial influence upon the schools of the country, and become a distin- guished attraction to the city which is fortunately the home of the University, whose citizens will give it welcome and encouragement and markedly recognize the munificence of its founder, as well as the labors of those who have in so brief a time established it among the foremost seats of learning. Andbew H. Green, 214 Broadway, New Tork City. As I shall not be able to be present during the exercises on Monday, July 10, celebrating the completion of the tenth academic year of Clark University, I desire to express in writing my feelings of sympathy and my strong desire for the success of the University, and also to extend to you and your co-workers my sincere congratulations on this auspicious occasion. It is probably true that the initiative step of the institution was not fully understood or appreciated by the public, but during the past ten years it has, under your able and judicious direction, steadily pursued a course well calcu- lated to win its way to public confidence and to an abiding position among the most eminent and distinguished institutions of learning in the civilized world. The entire exercises attending the celebration are calculated to draw aside the mystic veil, and when the occasion shall have been numbered among past events, the general public will be led to see and know Clark University iu the future as it has been seen and known in the past by distinguished foreign scien- tists and educators. Yes, rest assured, President Hall, that before the last hour of the present century has been struck by the unerring and mighty hand of time, Clark Uni- versity, the far-seeing, noble, and generous founder, together with the Univer- sity's learned and distinguished first president, will have been crowned by Congratulatory Letters. 29 truth and justice with the laurel wreath of victory, exalted merit, and uni- versal appreciation. Thomas H. Dodge, Esq., Worcester. James Brice begs to be permitted to offer his congratulations upon that occasion. Will you please convey to them my best wishes for the continued prosperity of Clark University. It has a high mission ; for gathering in new knowledge is a much nobler task than distributing that which is known, useful as the latter may be. I feel confident that when your present age is lengthened tenfold and your successors celebrate the centenary, they will hold up a great record of influence for good in the States and in the world. Professor Michael Foster, University of Cambridge, England. Though thus tardily, it is none the less heartily, that I congratulate you and your colleagues and fellow-citizens in this celebration — and this not simply on reaching your first natural period of retrospect, but on the worthy manner of the celebration also. You are certainly setting forth a feast of rare and varied intellectual fare, and thereby also giving a great lesson to us in the Old World of that return to the international unity of universities, which it is fitting that you in America should lead. Again accept these my best wishes for the cele- bration, with hearty congratulations upon your vigorous and productive youth — with confident hope also of your yet more productive maturity. Professor T. W. Geddbs, University of Edinburgh, Scotland. Aethuk Bibnaxme (Toulon, France) addresses to the President his most sincere prayers for the prosperity of the University. I address my wishes for the brilliant future of your University. Professor Alfred Binbt, Paris, France. I find it unfortunately impossible to avail myself of your invitation, for I certainly would have desired to enter into personal relations with men who join to their high science a largeness of view seldom to be met with. Professor Jules Tannery, Paris, France. 30 Extracts from My congiatulations on the completion of the tenth academic year of the Uni- versity, with my best wishes for its increase and prosperity. Pbopessor Adolf Baginskt, University of Berlin, Germany. I avail myself of this occasion to express my heartiest wishes for the further prosperity of your University. I rejoice at the admirable way in which you are to celebrate the foundation of your institution, thereby showing that it is to remain what it has hitherto been: the home of scientific investigation and culture. Fbofessob Max Dessoir, Berlin, Germany. I express my heartiest wishes for the prosperity of your University, whose scientific activity has so soon won for it a high place among the universities of your country. Pbopessor Benno Erdmann, Bonn, Germany. In your effort to unite the nations under the banner of unselfish science, accept my most cordial congratulations and wishes for prosperity. Pbopessor Paul Flechsig, University of Leipzig, Germany. I request you to receive my sincerest congratulations to this academical solemnity, and the expression of my hope, that your institution, highly ad- vanced through many difficulties and sacrifices, may enjoy the most splendid prosperity for many secula. Pbopessor Eenst Haeckel, University of Jena, Germany. I send to you and Clark University best wishes for success. Professor Peux Klein, University of Gottingen, Germany. Permit me to express my warmest wishes for the future prosperity of your University, which, called to life ten years ago, has already won such deserved success. Professor KShne, University of Heidelberg, Germany. Accept my heartiest congratulations on your approaching celebration, and may it be the dawn of a still more momentous era than the preceding one has already been. Pbofessok Oswald Kulpe, University of Wurzburg, Germany. Congratulatory Letters. 31 May the following decennium of Clark University be prosperous in its development and ricli in scientific results. Fboi'essob Lindemank, University of Munchen, Germany. I express my good wishes on the occasion of the celehration. Peopessok Max Noethbe, University of Hrlangen, Cfermany. I do not want to let slip the opportunity of expressing my best wishes for the University which has done so much for science, and is spoken of, particu- larly in Germany, with the highest respect and esteem. Peofessoe Eanke, University of Munchen, Germany. With the best wishes for the growth and success of your University, Peopbssoe W. Rein, University of Jena, Germany. I offer my best wishes for the welfare and progress of the University. Pkopessoe C. Eungb, Mannover, Germany. Permit me to send my heartiest congratulations on this celebration. Under your guidance Clark University has, in the ten years of its existence, already won for itself a high reputation in the whole scientific world. May the second decennium continue like the first to advance and increase science^ and may it be granted to you, Mr. President, for many years to come to be the standard- bearer of the scientific labors of Clark University. Peoeessoe Hekmann Schillee, University of Giessen, Germany. Wishing the University further prosperity and progress, Peoeessoe p. Schue, Karlsruhe, Germany. I remember my sojourn in America and the kind reception which I met with in Worcester. I should rejoice to have the opportunity to renew the hospitality shown me by yourself and by your colleagues. Peoeessoe E. Stodt, University of Greifswald, Germany. May the young University, which has already developed so auspiciously, continue according to the old saying: Vivat, floreat, crescat! Peopessoe Waldetee, University of Berlin, Germany. 32 Extracts from I slioiild have also been especially desirous of bringing to you my own recognition of wiiat has hitherto been accomplished and my cordial wishes for the future. I follow with great interest particularly the psychological works which proceed from your University and are published in the American Journal of Psychology. I have always received from them the impression that the psychological and pedagogical departments of your University belonged to the most important institutions of their kind. May Clark University complete the second decennium of its existence with like, and where possible, increasing glory! PEOFESSOK W. "WtTNDT, University of Leipzig, Germany. Accept my warmest wishes for the development of the University. Pbofessok Ed. Wetk, University of Prague, Austria. I feel a great pleasure in congratulating your Clark University on the cele- bration of the festival ; and allow me to express the hope that your University may extend its activity with every year to the honor of its President, its Trustees, and all its Members. Pkofessor S. E. Henschen, University of Upsala, Sweden. I beg you to receive my cordial congratulations on the occasion of the beautiful decennium which your University has completed. I hope that this seat of learning shall have a future correspondingly to the excellent manner in which it has begun its life. Pkofessor H. Hopfding, University of Copenhagen, Denmark. I beg to present my sincere congratulations upon the erection of a scientific centre, the decennium of which you are to celebrate in so fitting a manner. Pbofessok Zeuthen, University of Copenhagen, Denmark. I send you the best wishes for the success of your celebrated University, Peofessok Vito Voltebra, University of Turin, Italy. Eternal prosperity to the vigorous propagator of light. Pbofessok Stephanos, University of Athens, Qreece. De. Wesley Mills (McGill University, Montreal, Canada) wishes the Uni- versity every success in the future. Congratulatory Letters. 33 With best wishes for the continued prosperity of Clark University, Professor J. Squair, University of Toronto, Canada. Peesident Angell (University of Michigan) congratulates them on the useful -work which the University has already accomplished. With hearty congratulations for what you have already achieved as President of Clark University, and in full assurance of a great future before you, Henst Barnard, Hartford, Conn., Ex-U. 8. Commissioner of Education. William W. Bikdsall (President Swarthmore College) desires to extend congratulations upon the completion of the tenth year of Clark University. I congratulate you most heartily on the splendid work which Clark Uni- versity has accomplished during the ten years of its existence. Nothing in our educational work has reflected greater honor upon the American system than the high ideals so successfully maintained at Clark University. President John E. Bradley, Illinois College. Good wishes to the University in all its undertakings, and congratulations to President, Trustees, and Faculty upon the completion of ten years of distin- guished usefulness. Professor C. L. Bristol, New York University. My deepest wish is that Clark may do as much more for the advancement of science and the deepening of the true university spirit in the next decennium as it has in the one now closing. Professor Edward E. Bucknbr, Teachers^ College, New York City. I beg leave to extend to you my most sincere congratulations on the work that Clark University has accomplished under your guidance, since the time of its founding, ten years ago. As a Fellow of the University, I enjoyed opportunities for work that other institutions could not afford, and I found your efforts to provide books, instru- ments, and material as effectual as they were untiring. As a Graduate I have found inspiration in your zeal for the furtherance of all that can advance education and science. I have followed the development of the University with pride. The first high ideals have not been lowered, and Clark remains, as it was at its founda- tion, a University for Universities. Professor H. C. Bumpus, Brown University. 34 Extracts from No undertaking nor movement has made so clear and definite impress upon the educational thought of America nor established guiding lines of control so distinctly in pedagogical and psychological progress as the suggestions and tendencies which have emanated from Clark University. Though the institu- tion is yet in its infancy, though the students in point of numbers have been limited, yet its influence has penetrated every state in the Union, has entered practically every educational institution of the land, from university to kinder- garten, and has quickened the spirit of educational conferences, from those of national repute to those of the little teachers' meetings of the village school. Granting the truth of the educational view for which Clark University stands, and allowing for the singularly forceful methods of instruction by the President and Faculty within the institution, and the energy with which its mission has been prosecuted, it is nevertheless still a marvel that its influence should have become, in this brief space, so widespread and vigorous. The facts which stand prove the wisdom of the plan of an institution which should be exclusively graduate, selecting as its students a limited number of mature thinkers who should be inspired by the power which ever comes from the con- tact with original investigation and a faculty of original investigators. Frederick Burk, President State Normal School, San Francisco, and President Clark University Alumni Association of California. I send my best wishes for the success of the anniversary exercises and for the continued and enlarged prosperity of the University. President Nathaniel Butler, Colby University. Kindly accept my congratulations upon the completion of your tenth aca- demic year. Propesboe R. H. Chittenden, Director Sheffield Scientific School. I desire to congratulate the Faculty of the University on the great work accomplished within a comparatively short period. Brother Chrtsostom, Manhattan College. We rejoice with your many friends in the successful rounding out of Clark University's first decade. It is a consolation to the generous benefactor that the world recognizes the merit of the Institution, which his munificence estab- lished and maintains. Coming into existence the same year, holding similar views as to the place of graduate work, having the highest ideals of university endeavor, striving earnestly to realize them in spite of all difllculty, our two Universities have always felt strong attachments for one another, and a more than ordinary interest in one another's success. The Catholic University ten- Congratulatory Letters. 35 ders you its most cordial greeting on this the day of your rejoicing. It bids me extend to you and through you to the University its most sincere wishes for still higher and greater success in its chosen fields. Thos. J. CoNATT, ■Washington, D. C, Rector Catholic University. With many congratulations on the past ten years' work of the University, PKOrESSOR Charles R. Cross, Massachusetts Institute of Technology. Professor C. B. Davenport (Harvard University) desires to express his appreciation of the brilliant example of research as a primary university func- tion which Clark University has for a decade set. The University and all connected with it are to be congratulated. PROrEssoE Ellert W. Davis, University of Nebraska. I desire to express my appreciation of the splendid work done by Clark University during these ten years. Professor Nathaniel F. Davis, Brown University. I must content myself with rejoicing over the unique intellectual enterprise you are carrying out. I may not be informed regarding such matters, but it seems to me you have accomplished a sort of scientific coup d'itat in getting such a group of scholars to come to America upon the occasion of your anniver- sary. As a disciple of Clark University, and an admirer of everything it stands for, I take pride in the impression that must necessarily be made upon Ameri- can scholarship by the visit of such men. I congratulate all of you, and hope that everything you desire in connection with the series of lectures may be realized. Professor George E. Dawson, Bible Normal College, Springfield, Mass. President Drown of Lehigh University begs for his colleagues and for himself, to offer his hearty congratulations to the President, Trustees, and Faculty of Clark University on the completion of a decade of usefulness in the higher education, marked by distinguished services in many lines of original research. Permit me to express my admiration of the work you have done and are doing. Professor William P. Durfee, Mobart College. 36 Extracts from Let me assure you that we are all grateful for what Clark University is do- ing for sound education in this country, and I can only hope that you may have many successful years in the development of the work which you are doing. S. T. DuTTON, Brookline, Mass., Superintendent of Schools. In the opinion of many who have studied there, the peculiar advantage of Clark University is mainly attributable to the close and personal relations between professors and students under which the work is conducted. The formal lecture delivered to a body of men in the class-room has but little of the stimulative force imparted by a conversational discussion with the man alone in the lecturer's private study, and too great praise can hardly be given to the members of the faculty of Clark for their constant and generous sacrifice of time to this most helpful method of instruction. The frequent assignment through- out the course of problems involving research leads to the best of training for the later performance of original work, and the presentation in the lecture-room of the results thus obtained gives experience in the work of the lecturer. In perhaps no other institution are these methods of the personal conference and the " colloquium " so constantly applied ; no doubt such methods are impossible in most larger universities at present ; and one can hardly imagine such a course followed with more kindness and devotion at any time than is now the case at Clark. Peofessoe Prbdbrick C. Feeet, Williams College. I take this means of expressing my interest in the noble success of the University, and of wishing it continuance and increase. Rabbi Charles Fleischbe, Boston, Mass. Congratulating you and the University upon these years of achievement, Alice C. Pletchbh, Washington, D.G. I rejoice in the prosperity of your institution because it is one which sends forth its light, not only for the few, but for the many. Peesidbnt Wm. Goodell Fkost, Berea College. Though my stay with you was short, yet it meant the inspiration that took me abroad and pushed me on to undertake important work. Peofebsob John P. Fbuit, William Jewell College. Congratulatory Letters. 37 The Johns Hopkins University sends its cordial greetings to the President, the Trustees, and the Faculty of Clark University, on the completion of its first decennium, with congratulations upon its successful maintenance of high ideals, and with best wishes for its continued prosperity and power. President Daniel C. Oilman. I must add my congratulations on the success of your work, and my good wishes for its continuance on even a larger scale. Professos George L. Goosale, Sarvard University. Every educator especially owes a debt of gratitude to Clark for the fearless work it has done in breaking down blind prejudice and advancing the truth. Professor John Y. Graham, University of Alabama. Ton have certainly arranged a most dignified and impressive series of lectures — wholly congruous with the work which you have been doing during the decade. Professor Edward H. Griffin, Johns Hopkins University. You will please accept the assurance that I am very glad indeed that your institution, which has already done so much for the cause of progressive educa- tion, has thus shown its vitality and power of endurance. No doubt these ten years have meant much struggle and anxiety on the part of those whose heart was in the work. Others may be able to express their appreciation of this work with greater eloquence, but none can be more sincere and thankful than I am. Truly, if there is such a thing as a science of education in this country now, Clark University . . . (has) contributed the largest share toward this accom- plishment. To me (its) work has meant an awakening and uplifting hardly equalled by any other influences that have worked upon my soul. May your anniversary week be a thorough success. Professor M. P. E. Gkossmann, Milwaukee, Wis. Allow me to extend cordial congratulations on the auspicious event. Professor Charles W. Hargitt, Syracuse University. I extend for the University of Maine hearty congratulations, and wish con- tinued prosperity for the future. President A. W. Harris, University of Maine. 38 Extracts from I send you my hearty congratulations on your decennial celebration. Pebbidbnt Walter L. Hebvet, Teachers' College, New York City. I congratulate you and the Trustees and Faculty upon these successful years of your University work, and upon this most appropriate mode of celebratiag the anniversary. It is a mode worthy of universal following, and will, without doubt, be more and more adopted by our institutions of higher learning. Professor 6. H. Howison, University of California. Allow me to offer my congratulations to you especially, and to your associ- ates, for the marked success which has attended the career of Clark University. We have felt that it not only increases the resources of high education for youth, but it stands for progress and enlightenment in the commonwealth and the country at large. There is a justifiable pride on the part of those who love earnestness and progress in educational matters, as they review the past of this institution, into whose good name and wide scope of influence you have thrown so much of your personal enthusiasm as well as your scholarly abUity. Rev. Edward A. Hortok, Boston, Mass. I have many pleasant memories of a year's profitable work at Clark, and rejoice in the conttaued success of Clark Umversity. Professor lu. S. HtnLBimT, Johns SopMns University, The programme presented is most attractive and inspiring. I congratulate you upon the successful work of the past ten years. Dr. Henrt M. Hued, Baltimore, Md., Superintendent Johns Hopkins Hospttal. I can't help expressing to you my feeling of satisfaction, and repeating the satisfaction I heard such men as Cattell, Eoyce, Van Gieson, Milnsterberg, and Putnam express, with the excellent good taste and refinement of your little celebration. All the refinements of the world seem now to take refuge in the smaller things ; the bigger ones are getting too big for any virtue to remain with them. You have done something original and succeeded perfectly, from the point of view of the passive " assistant." Professor William James, Saroard University. I beg you to accept my heartiest congratulations. Each year, I sincerely believe, finds me more gratefxd and appreciative of the privileges I enjoyed at Congratulatory Letters. 39 Clark, and especially do I realize more and more what you yourself did for me. I trust you may be spared health and vigor many years to come in your labor, for you are doing a great work. Gbokge E. Johnsok, Andover, Mass., Superintendent of Schools. I have been very deeply interested in the work of Clark University, and in the way it has held to its high purposes regardless of pressure of all sorts in other directions. . . . Stanford congratulates Clark on ten years' noble work for high thought and accurate investigation. Peesident David S. Jokdan, Leland Stanford Jr. Vhwersity. For myself and all the stafE of the University of California, I send you hearty congratulations and good wishes. You have not attempted to do as many things as some other universities, but what you have attempted you have done exceedingly well. If excellent work is the standard of true success, you have been successful among the foremost. May your achievements and your reputation gain still greater lustre, and your educational work confer still larger benefits on succeeding generations. Pbesident Maktin Kellogg, University of Galifornia. May I say that I think you have taken a most admirable course in the char- acter of this celebration, and that I wish you every success, not only on this occasion, but in all the future years of the University. PrOFESSOK J. S. KiNGSLET, Tufts College. I regret more than I can express my inability to be present at the decennial celebration of your noble institution, and to hear the splendid series of lectures which you have provided. Pbofessor Joseph LeConte, University of California. It is a pleasure to me to ]oin in the celebration of the first decade of Clark University. The method of celebrating the event is, I think, exceedingly fit- ting. I enjoyed several of the most interesting years of my life in the lecture- rooms and laboratories of Clark, and always recall them with great satisfaction. Pbotessok J. S. Lemon, ■Washington, D.C, Columbian University. Clark University stands unique among the universities of this country in the work which it is attempting to do. Ko other institution has done more in the 40 Extracts from line of original investigation, nor given during the same period greater inspira- tion to the educators of the country. Pkofessob G. "W. a. Ltjcket, University of Nebraska. Permit me to congratulate heartily the President, Trustees, and the Paculty of Clark University upon the completion of the tenth academic year of the University. Peesident George E. MacLean, University of Nebraska. We appreciate the great work done by Clark University, and send every best •wish for the future. President Jambs G. K. McCluee, Lake Forest University. I have the highest feelings of regard for Clark University, for I feel that I owe much to it. Its conception is the broadest and best of all our institutions, and I hope the time will come when it can broaden out, and, all obstacles being removed, go on to its full completeness. Peofessoe William S. Millee, University of Wisconsin. When one thinks of the amount of light that has spread from Clark Univer- sity and of the place that it fills in American education to-day, it is hard to realize that no such institution was in existence ten years ago. Please accept my most sincere congratulations to this auspicious event, with the hope that a long series of years of vigorous activity may be granted to you, so that you may lead the University to ever new achievements, and continue to benefit the cause of education in the future, as you have so splendidly done in the past. Vivat, floreat, crescat. Peofessok F. Montesee, New York University. It is with very great regret that I find it impossible to attend the rich cele- bration you have prepared for the friends of Clark University and of all the forward movements in science for which you have made Clark University stand, and wish the University long-continued and increasing prosperity. Peofessoe E. H. Moore, University of Chicago. My participation in the treasures you offered was thus limited to one day — but this one day, with the three lectures I listened to, and the very interesting men I met, was so agreeable and valuable that I feel the desire to thank you warmly for the distinguished and exquisite pleasure. I take special pleasure in combining with my personal thanks my congratulations to the high success Congratulatory Letters. 41 of the celebration and my very best wislies for the next ten years in the life of Clark University. FsorESSOB Hugo MSnsteebeeg, Haroard University. Permit me to express here my sincere admiration and respect for the aims, ideals, and plans of Clark University ; these are of such an ideal character that they are bound to interest profoundly every man who loves science for its own sake. Professor J. TJ. Nef, University of Chicago. Permit me to offer my hearty congratulations on the work done and the progress made in the ten years of Clark's existence, to express the hope that the future may be marked by even greater achievements. President Ctkus Northrop, University of Minnesota. Clark University does well to celebrate in such a becoming manner the noble service which she has rendered to higher education in this country. May the next ten years be no less fruitful and helpful to those who have become accustomed to look to Clark University for inspiration and guidance. Professor F. W. Oseorn, AdelpM College, Brooklyn, N. T. I write to congratulate you most cordially upon your celebration of the com- pletion of the tenth academic year of Clark University. Professor Henet F. Osborn, Columbia University. Allow me to congratulate you upon these lectures, and also upon the remark- able results which you have been able to accomplish in ten years in connection with Clark University. Professor G. T. W. Patrick, University of Iowa. The Provost, Trustees, and Faculty of the University of Pennsylvania present their cordial congratulations to the President, Trustees, and Faculty of Clark University on the happy completion of the tenth academic year of the University. The President, Trustees, and Faculty of Clark University certainly deserve the thanks of all those interested in the cause of education. Professor George H. Price, Vanderbilt University. 42 Extracts from Pray accept congratulations on the completion of a decade of grand work, and on the prospects of even better work for the future. John T. Prince, West Newton, Mass., Agent State Board of Education. I send my heartiest congratulations on the great achievements of Clark University during its first decade, and express my sincerest desire that its use- fulness may continue and expand for many centuries to come. Pkofessor Eknst Bichabd, New Torh City. Pbesidbnt H. W. Eogees (North-western University) desires to extend the congratulations of ISTorthwestern University, as -well as his own, upon the great success of Clark University and the distinction it has attained in the academic world. James E. Extssell (Dean, Teachers' College, New York) wishes to convey to the President of the University his best wishes for the continued success and prosperity of the institution. Pkesident L. Clakk Seelvb (Smith College) offers his hearty congratula- tions on the important educational work it has already accomplished. With sincere thanks and hearty congratulations on the auspicious occasion. Professor James Seth, Columbia University. Meanwhile I wish to join in the many congratulations I am sure you will receive upon the quiet and dignified, but none the less eminent, manner in which Clark University has carried on the work of the past decade, and upon the manner in which it has reflected honor upon American scholarship in science and philosophy. Albert Shaw, New York, N. Y., Editor Meview of Beviews. We shall always be grateful for the work that has already been accomplished by the University, and especially for the ideals which it has brought to the colleges and universities of the West. With high personal regard and warmest congratulations from our faculty. President 'William F. Slocum, Colorado College. With best wishes for the success of the celebration and for the continued prosperity of your institution, President F. H. Snow, University of Kansas. Congratulatory Letters. 43 Allow me to congratulate the University upon its happy completion of ten years' life and work, and to wish it a long and prosperous future. Professor Frederick Starr, University of Chicago. I wish to send my cordial congratulations and my wish that the next ten years may witness the coming to the University of such ample endowments as will enable it to accomplish its high ideals. President James M. Tatloe, Vassar College. Please accept my best wishes for continued prosperity. President W. O. Thompson, Ohio State University. I do not like to let the present occasion pass without intimating to you my appreciation and admiration of the methods and aims of imiversity work for which Clark University has stood in the past, and will, I hope, stand in a long and prosperous future. My recent visit to Worcester merely confirmed a belief which I have long held, — that the type of man that Clark University calls to its professorial chairs, and the type of man that it sends into active life at the close of its three or four years of graduate study, are types that represent the highest ideal of scholarship, and are the very salt of American society. I hope, most sincerely, that the coming celebration will prove to be the door through which you and the University pass to greatly extended activity upon your own high level. Professor E. B. Titohener, Cornell University. I wish to express my sincere appreciation of the service to education and investigation which Clark University is thus undertaking, a service which is eminently in harmony with the work of Clark University from the beginning. Professor James H. Tufts, University of Chicago. I wish to extend my hearty congratulations on the successful work of the University during the last ten years, and my best and most hearty good wishes. Professor John M. Ttler, Amherst College. Peofbssok Henry B. Waed (University of Nebraska) extends to the President, Trustees, and Faculty his congratulations upon the occasion, and best wishes for the continued success of the institution. 44 Extracts from Congratulatory Letters. I express my sincere congratulations, Professok Sho Watase. University of Chicago. With best wishes for the success of the University, Pbopessok J. B. Webms, Iowa State College. Please accept congratulations upon the honorable record of these ten com- pleted years. The distinguished service of yourself and the University have made the whole world your debtor. Pbesident B. L. Whitman, iWasMngton, D. C, Columbian University. The Clark University ideal as I understood it, when connected with its early work, is the ideal which I place above any others thus far proposed, and I hope that it may find strong friends to help it forward. Pboeessok Charles O. Whitman, University of Chicago. Pbofessok a. W. Weight (Yale University) sends congratulations and best wishes for the prosperity of the University. DECENNIAL ADDEESS. By G. Stanley Hall, President of the University. It has been said that decades are the best periods for studying historic tendencies because they are long enough to contain a rich array of facts and events, and short enough to be grasped by a single mind in the stage of its prime. The ten years since Clark University was opened, the close of which, by the cooperation of a few beneficent public-spirited citizens of Worcester, we have sought to mark in a very quiet but dignified way that should befit at once its size and its quality, constitute distinctly the most important decade in the educational history of this country. The mere index of a few of the well-known and accomplished facts of these years has an eloquence beyond all words. They have witnessed the establish- ment of the Catholic University at Washington, with its strong faculty and its handful of picked graduates from the seventy Catholic colleges of the country, the only university in the land besides Clark devoted solely to graduate work, an institution related to us, not only by a strong tie of sympathy in the struggle and sacrifice for ideals and high standards, but by my own long and personal friendship with the first rector, and by the fact that its present head was our Worcester neighbor and kindly friend. The Leland Stanford University, now one of the richest in the world, was planned and endowed by a long-time friend of our Founder, and the wife of that founder lately told me that she still counts ours among her wisest and most trusted advisers. The University of Chicago, with possibilities of increase brighter and larger than any other, from the very first the most rapid academic growth in history, has leaped into existence with a Minerva-like completeness, owing in no small part its first impulse to higher creative work in science to the sagacity of the chief trustee of its Ogden Fund, our fellow-townsman, Andrew H. Green, and which is still more closely affiliated to us by the fact that so many of the leading members of its faculty honored us by doing three years of their best work here, and for which we still cherish a little of 45 46 Decennial Address. the feeling of a poor but proud and noble mother for her great son. The new Methodist University at Washington has begun the \infoldment of large and well-matured plans, for the fulfilment of which the vitality of the strong religious body behind it is perhaps the best of guarantees. The millions already provided and about to be expended at the State University of California which will involve transformation and enlarge- ment perhaps greater than all that has hitherto been done there, very comprehensive and valuable as that is ; the magnificent new architectural installation at Columbia and the federation of so many other affiliated institutions about it, with all the possibilities of our greatest metropolis open before it ; the steady development, whether for good or for ill, of the plan of a great national university, to which at least all state, if not private, colleges and universities may be tributary as feeders, and which shall command all the vast resources of science in Washington, unify them, and add the new vitalizing function of research and perhaps teach- ing, a scheme that has enlisted most of the educational leaders of the land and is sure of eventual fulfilment, — such are some of the events which have seemed to many to threaten the academic preeminence of New England, and even of the East, in the future ; that have stirred to their very foundations the older and more conservative institutions, and caused transformations not all apparent from the outside, but which involve hardly less than an ultimate revolution of academic sentiments, methods, and ideals. Fellowships, not for the indigent who need support while preparing for the professions, but to give leisure, opportunity, and incentive for full development to talent, the choicest of all national prod- ucts ; research, with books, apparatus, above all, leaders competent to guide and inspire ; new post-graduate departments for non-professional specialization, with their own laboratories and libraries ; seminaries where experts discuss the latest literature, best methods, instruments, and results of investigation ; new journals devoted to the speedy publication of such studies ; new chairs and topics ; a growing and ever widening distinction between receptive learning and active creation, — these and the gradual completion of a system that is truly national, and has not its apex in Europe, where hundreds of our graduates still go yearly to get what it should be a matter of simple patriotism to supply at home, must suffice to mark the direction and progress of these years in which institu- tions and work alike are becoming more and more plastic to the changing and ever more imperative needs of learning and science which have them- Decennial Address. 47 selves celebrated triumplis during the decade which could not even be enumerated within the hour. It is no wonder that many old academic problems have become obsolete and new ones have arisen, and that pres- ent demands in men, methods, and instruments have changed from those of ten years ago. Again, within this time a wave of doubt and opposition to the public support of intermediate education passed over the country, but the reac- tion against that tendency has made the last few years preeminently the age of high schools. More and statelier buildings than ever before, longer courses and more of them, many modifications suggested by committees and others, great increase in the number of students, rich and well-planned departures like the Tome Institute, Mrs. Emmons Blaine's new normal foundation, and several others contemplated or assured but not yet established, the new associations of high schools and colleges covering now all sections of the country, the ever increas- ing collegiate character of the work done in such institutions, and the consequent development of a distinct, and in some places urgent, small college problem, — all this shows that even secondary education, the last stage to be reached by reforms, has here been stirred and quickened as never before. If we extend our view to lower grades, we find all plastic and chang- ing. This stronghold of conservatism is invaded by the spirit of reform, often revolution, and sometimes even of rather wild experimentation. New journals, pedagogical chairs, new methods, the new school hygiene, broader views that relate teaching to all the great problems of science, statescraft, and religion, have arisen, which have brought the university and kindergarten and all between them into an organic unity, yet fitting all features of the system to the vast variety of individual differences of character, temperament, and ability. In this field, I think, the closing decade has witnessed a change greater than the preceding quarter of a century. New and better minds are enlisted, educational topics are of increasingly central interest in the press and more dominant in the church and pulpit, education is becoming more professional and scientific, recognizing the necessity of expert leadership and mastery, and is at last assuming its rightful and larger power, and its normal basal all-condition- ing place as at bottom a biological science, revealing to us how state, church, home, literature, science, art, and all else have their ultimate justification only in so far as they are effective in bringing human beings 48 Decennial Address. to the ever fuller maturity of mind and body on which civilization de- pends, and which it is the work of education to accomplish in the world. This is increasingly necessary as our country grows in population and in territorial expansion, and educational progress is coming to be recognized by history as the chief standard by which to test all other advancement. Europe has progressed during this decade, although with less rapidity, along nearly all these lines, and the next decennial promises not less, but more advance. In such a time it is, indeed, glorious to be alive, and to be young is heaven, for hope is even brighter than memory. No time in the history of the country could have been more favorable than the beginning of this period for a great and new imiversity founda- tion. The epoch-making work of the Johns Hopkins University, which for the preceding decade had made Baltimore the brightest spot on the educational map of the country, and was the pioneer in the upward move- ment, had leavened the colleges and roused them from the life of mo- notony and routine which then prevailed, and kindled a strong and widespread desire for better things. The significance of the work of that institution can hardly be overestimated. But financial clouds had already begun to threaten this great Southern luminary, and there were indications that, if the great work it had begun was to be carried on, parts of it, at least, must be transplanted to new fields. It was at this crisis that our munificent Founder entered the field with the largest single gift ever made to education in New England, and one of the largest in the world, and with the offer of more to come, if suffi- cient cooperation was forthcoming. He selected Worcester as the site of his great enterprise with a piety to the region of his nativity worthy of the greatest respect and emulation, and in addition to the fulfilment of his pledges gave it the benefit of his own previous wide studies of educa- tion in Europe, and contributed wisely matured plans and constant per- sonal oversight and labor for years. It is as strenuously engaged in this highest of all human endeavors that the world knows him, and that we shall remember him, and I am sure that we all unite to-day first of all in sending him in the retirement his health demands (although it cannot assuage his interest to see the work of his hands prosper) our most cordial greetings and our most hearty congratulations. With a dozen colleges within a radius of one hundred miles doing graduate work, the plainest logic of events suggested at once a policy of transplanting to this new field part of the spirit of the Johns Hopkins Decennial Address. 49 University, and taking here the obvious and almost inevitable next step by- eliminating college work, although the chief source of income by fees was thereby also sacrificed, and thus avoiding the hot and sometimes bitter competition for students, waiving the test of numbers, and being the first upon the higher plane of purely graduate work, selecting rigorously the best students, seeking to train leaders only, educating professors, and ad- vancing science by new discoveries. It was indeed a new field wide open and inviting, the cultivation of which was needed to complete our national life ; the preliminary stages of its occupancy all finished, yes, necessary almost as a work of rescue for the few elite graduates who wished to go beyond college but not into any of the three professions, and who had had hitherto a pathetically hard time. The call to the President gave assurance of the highest aims and of perfect academic freedom, a pledge that has been absolutely kept. He was sent to Europe a year on full pay to learn the best its institutions could teach, and the Faculty that first fore-gathered here has never been excelled in strength, if indeed it has ever been equalled anywhere for its size. Story, an instructor at Harvard, colleague and friend of Sylvester, formerly acting editor of the chief mathematical journal of the country and co-head of his department at Baltimore, founder of another journal here, who has enriched his department by contributions, the list of which printed else- where in this volume tells its own story ; Michelson, who while here accepted an invitation of the French Government to demonstrate in Paris his epoch-making discoveries in the field of light, which he did while on our pay-roll — lately especially honored by learned societies at home and abroad, now head of one of the best-equipped and largest laboratories in the world, and still continuing his brilliant contributions to the sum of human knowledge ; Whitman, now head of another great university laboratory, trainer of many young professors, founder and editor of the best and most expensive biological journal, head of Woods HoU marine laboratory and summer school, one of the best of its kind in the world, himself a contributor to his science ; Michael, than whom America had not produced a more promising or talented chemist, the list of whose published works would be far too long to read here ; Nef , perhaps our most brilliant young chemist, and now head of one of the largest and best-equipped laboratories in the world, and with a power of sus- tained original work rarely excelled; Mall, now full professor at the Johns Hopkins University, and head of the great new anatomical labora- 50 Decennial Address. tory and musemn there, whose published contributions are admirable illustrations of both the great caution and boldness needed by a student in his field ; Boas, the leading American in physical anthropology, now a professor at Columbia ; Loeb, almost the first expert that this country could boast in the new physical chemistry in the sense of Ostwald, now head of his department in the University of the city of New York; Bolza, an almost ideal teacher, suggesting the great Kirchoff in the per- fection of his demonstrations; the brilliant and lamented Baur, leader of the expedition to the Galapagos Islands made possible by the gift of Worcester's patron saint of so many good enterprises, Mr. Salisbury; Donaldson, now dean of the graduate school of the University of Chicago, author of the best handbook in English on the brain, with a caution, poise, and diligence befitting the successful investigator in that dangerous but fascinating field ; MuUiken, suddenly placed in a position of great difficulty, discharged its duties with rare ability and discretion for one so young ; Lombard, now professor in Michigan, genial, assiduous, a gifted teacher and enthusiastic student ; White, scholarly, able, a born teacher and student ; McMurrich, an untiring investigator and a lucid inquirer after knowledge ; those now here, who have since become so well-known, Burnham, Chamberlain, Hodge, Perott, Sanford, Taber, and Webster ; these, not to mention many others, then only fellows, but who have achieved so much in their work and positions since, — these are the men and others whose presence on this spot, whose high intercourse and whose stimulating personal contact with each other, whose ardor and devo- tion in the pursuit of knowledge, whose healthful emulation in achieve- ment, made this almost classic ground and the cynosure of the eyes of all those in this country who love science for its own sake. With the wealth, wisdom, and interest of our Founder, with the high character and culture of our Board of Trustees, with the intelligence of such a community of old New England, with an atmosphere of intellectual free- dom, with unique and precious exemption from the drudgery of excessive teaching and examinations, with the youth of the Faculty, none of whom had reached the zenith of their maturity, with substantial and ample buildings, abundant and forthcoming funds for equipment, few rules and almost no discipline or routine of faculty meetings, the motto on our seal, fiat lux, our university color white, — is it any wonder if some of our young men saw visions and dreamed dreams, or perhaps in some cases fell in love with the highest ideals, or that the very memory of the first stage Decennial Address. 51 of our history is to-day, as it has been in darker hours, a most precious memory and a basis of an all-sustaining hope ? To these days of our prime to which our former students and profess- ors recur with joy, and in whose breasts the processes of idealization of them have already begun, days which were pervaded by sentiments of joy and hope very like those which animated the best years of the Johns Hopkins University, we have often reverted since in soberer hours with longing thoughts of what might have been had the University continued in all its pristine strength. Not one weak, dull, or bad man in our Faculty, all given not only leisure, but every possible incentive to do the very best work of which they were capable, with a Founder and a board of control who realized that a new endowment should do new things, and that the best use of money is to help the best men, we entered a field very largely new and with as bright prospects as we could wish. But life has its contrasts and competitions. The reductions of our force, which occurred at the end of the third year, sad to us almost beyond precedent, although helpful elsewhere, may be ascribed to fate, disease, or to the very envy of the gods. Some incidents should remain unwritten, but it should be known that our Trustees foresaw from the beginning of the year one of the gravest of crises, and met it with an unanimity, a wisdom, and a firmness which even in the light of all that has transpired since, I think, could not be improved on. The pain of it all has faded, the glad hand has been extended and accepted by nearly if not quite all who left us ; the lessons of adversity have been learned and laid well to heart, and we hope and believe that these and all their attendant incidents may be considered closed. Although nearly half our Faculty and students left us in the hegira, and our income had dropped in almost the same proportion, and only the departments of psychology and mathematics remained nearly intact, we fortunately had left in every department young men as promising as any in the land. They needed simply to grow, and never has there been such an environment for a faculty to develop as in this "paradise of young professors," as a leading college president has called this University. To Darwin the greatest joy of life was to see growth ; and to see the unfold- ment of these youthful, intellectual elite, and to feel the sense of growth with them as all near them must, is a satisfaction almost akin to the rapture of discovery itself. Now the years have done their work, and our Faculty, although smaller, was never stronger, never more prolific. 52 Decennial Address. stimulating, and attractive to students, in proportion to its size, than it is to-day. There has never been such loyalty to the institution and its ideals, such readiness to endure the petty and the great economies now necessary, such prompt and frequent refusals of larger salaries elsewhere, and so strong a sentiment that, so long as a man has growth in him, our incentive, opportunity, and plan of work are of more value than a large increase of salary. These changes involved, however, but little reduction of the number of instructors or of students, but materially decreased for a time the effi- ciency of the University. Since the end of the third year the President, who was not required to teach, has done full professorial duty in addition to that of administration, has established a seminary at his house three hours each week through the entire academic year, and founded and con- ducted at his own expense a new educational journal. The income-bear- ing summer school has been organized and conducted during the past seven years with the active and efficient cooperation of a large local advisory board under the direction of Colonel E. B. Stoddard and Charles M. Thayer, Esq., by which its social character, that has contributed much to its success, has been established on a high plane. The summer school represents only the departments of biology, psychology, and peda- gogy, is open to every one of either sex on the payment of a small fee, is popular rather than technical in its scientific character, has been numer- ously attended, and in all ways is directly in contrast with the work of the year. Hardly a ripple has marred the harmony within the Univer- sity during these last seven years, and every man, student and instructor alike, has been hard at work and enthusiastic for our own unique and individual method and plan. This institution must be judged from within and by educational and scientific experts, and the commendations which we have lately received from leading specialists, some of which are printed elsewhere in this volume, have been so numerous, spontaneous, and hearty in response to our invitation to be present, as almost to rival in cordiality and loyalty to the now so definitely developed Clark idea and Clark spirit that of our three alumni associations of the Pacific Coast, Illinois, and Indiana organized during the present year. Scientific work must be weighed and not measured, so that numbers tell but little. Clark University has been instrumental in training weU- nigh three hundred professors or special academic instructors, has numbered Decennial Address. 53 over twelve hundred different persons enrolled in its summer school, not counting the hundreds who have attended more than one session. These, especially the former, are in a sense our epistles known and read of all men. The other output of a university like ours is its scientific work, and here we have five hundred publications based upon work done here, of which twenty-five are books. The University now publishes three journals, with hope of a fourth as a more permanent way of marking the beginning of its second decade. Small as we are, if our departments and students are measured by the significant criterion of the number of the doctorates annually conferred here, we rank among the best and largest institutions of the land. Al- though our fellowship funds have declined, and that, too, in the midst of a competition, which never existed or was hitherto dreamed of, our numbers of late years have slightly but steadily increased, although at the same time we could go on forever and do invaluable work of research and publication like the French Ecole des Hautes Etudes, or a few other Old World institutions, even if we had no students ; and, indeed, America may need in the future, if, indeed, she does not already, at least, one such academic endowment for research only. One thing, at least, is true so far, hardship has no whit lowered our aims or diluted our quality, but if anything has had the reverse infiuence ; and I fervently trust (and think I can speak on this point with confidence for the entire Faculty) that this may be the case throughout all the infinite future that endowments like this in a country like ours have a right to expect. Although influences are too subtly psychological to be traced, I am writing our history, and find it a most inspiring theme, and I believe it adds already a very bright and, hopeful page to the records of higher education in the country, and one which history will brighten to epochal significance. It has, on the whole, in it one clear note, not of discouragement, but of hope and confidence. Have we duly considered, even the best of us, what a real university is and means, how widely it differs from a college, and what a wealth of vast, new, and in themselves most educative problems it opens? A college is for general, the university for special, culture. The former develops a wide basis of training and information, while the latter brings to a definite apex. One makes broad men, the other sharpens them to a point. The college digests and impresses second-hand knowledge as highly vitalized as good pedagogy can make it, while the university, 54 Decennial Address. as one of its choicest functions, creates new knowledge by research and discovery. The well-furnished bachelor of arts, on turning from the receptivity of knowing to creative research, is at first helpless as a new-born babe, and needs abundant and personal direction and encour- agement before he can walk alone ; but when the new powers are once acquired they are veritable regeneration. He scorns the mere luxury of knowing, and wishes to achieve, to become an authority and not an echo. His ambition is to know how it looks near and beyond the frontier of knowledge, and to wrest if possible a new inch of territory from the nescient realm of chaos and old night, and this becomes a new and consuming passion which makes him feel a certain kinship with the great creative minds of all ages, and having contributed ever so little, he realizes for the first time what true intellectual freedom is, and attains intellectual manhood and maturity. This thrill of discovery, once felt, is the royal accolade of science, which says to the novice, stand erect, look about you, that henceforth you may light your own way with independent knowledge. This higher educational realm is full of new " phenomena of altitude." Faculties, instead of discussing and elaborating plans for commencement ceremonies, hearing recitations, preparing and then reading the results of examination papers, and carefully marking each individual exercise, grinding in the old mills of parietal regulations, discipline, and the rules of conduct needful to civilize the adolescent homo sapiens ferns, revising requirements for admission, tacking and shaping the policy to gather in more students and keep ahead of others in the struggle to get the best connections with high and fitting schools, are occupied with far different problems wherever the university spirit has a true and real embodiment. Here first of all men must be discriminated, and great issues hang upon the success in differentiating superior from indifferent young men. To detect the early manifestations of talent and genius in the different fields of intellectual endeavor, which some presidents and professors can, and others so eminently lack the power to do, is the crucial doorkeeping problem, where great privileges are to be awarded to great promise. This is almost a life and career saving function for not only the young professors and students, but for the university. Men are not equal, and there must be a touchstone of mental aristocracy to discriminate $500 from 110,000 men. Second, having selected these, the university should bestow freely its Decennial Address. 55 needed aid and equipment, and the professor his choicest time and knowledge, to perfect the precious environment by which the later stages of growth, so liable to be lost, but on the fuU development of which civilization itself hangs, and perfected. How to select the best, ripest, and most fruitful topics for investigation requires an almost prophetic ken in which differences in individual professors are immense. To study individuals enough to adapt each theme to each personality is another problem as new as it is delicate and difficult. The right solution of both these is the large half of the work. The professor should give his best suggestion, with no reservation for himself, and the able student should not be an apprentice to serve his master, but should be distinctly educated toward leadership himself from the first. Having thus sown fit seed in fit soil, it must be watched and watered with constant suggestion. The best and newest literature ; the most effective and original apparatus that can be devised and if possible made on the spot ; how to insure in the best form and place the speedy publication of work and to bring it under the eye of all experts ; how to avoid conflict and duplication ; how general or how special thesis sub- jects and work should be to best combine the two sometimes more or less divergent ends of discovery and education ; the requirements for perhaps the choicest of all degrees, the doctorate of philosophy ; the best modes of individual examination for it ; the number and relation of subjects required ; the migration of students so as to insure not only the best environment for each, but to give to professors not only in the same department, but in different institutions, the same stimulus that was felt when the elective system aroused the dry-as-dust professors to unwonted effort lest their class-rooms be left vacant ; the kindred ques- tion of the relative value of graduate work at home and abroad for each student and for each department ; the fit federation of graduate clubs and their thirty-five hundred members in the twenty-three Ameri- can institutions now recognized in the yearbook ; the great problem of printing and special journals together with interchange of monographs ; the vast new library problems of purveying for highly specialized, but very voracious, appetites which make the true university librarian a man of far different order from others, and gives him a wealth of new prob- lems of exchange, foraging, etc. ; to maintain the true relations between lecture work and individual guidance while duly emancipating the pro- fessors from the drudgery of elementary teaching and mass treatment 56 Decennial Address. of great' bodies of students ; the many and wide-reaching differences between pure and applied science, and the practical methods by which this distinction is maintained ; the danger of great aggregations of students and the advantages of few ; the wide differences between the new kind of professor needed in the university and those in the college, where no provision is made for the advancement of learning, and the tests are mainly pedagogic ; the even greater contrasts between scholar- ship funds for the aid of poverty to professional careers, which are a doubtful advantage even in colleges where they belong, and the true university fellowship as above described ; the growing dominance and need of expertness in all fields for which graduate departments must prepare as well as for professorship alone, — these and many great ques- tions like them, destined more and more to eclipse all others which are just looming up, and for the irrigation and ventilation of which we hope to establish here soon a new educational journal — such questions con- stitute this opening field of what may be called the higher educational statesmanship. The hastiest glance at the situation on an anniversary like this would be incomplete unless we turned toward the future. Our own needs here are many and our wants urgent, but our faith is firm that in a community like this the time will soon come when no wills will be drawn by wealthy people without carefully considering the conclusion of the largest parlia- mentary report ever made, which fills near a score of volumes, was many years in the making, and describes all the public bequests ever made in England. The substance of the conclusion of that most competent tribu- nal that has ever spoken upon this subject is that the best of all uses of public benefactions is, not for charity to the poor or even the sick and de- fective, noble and Christlike as those charities are, not for lower education or religion, beneficient as these are, but rather for affording the very best opportunities for the highest possible training of the very best minds in universities, because in training these the whole work of church, state, school, and charity is not only made more efficient, but raised to a higher level, and in this service all other causes are at the same time best advanced. I beg respectfully, but with all my heart and mind, to urge this conclusion by the highest human authority upon all those contemplating the bestow- ment of funds where they will accomplish most for the good of man. Our very best department is the library, which is so well endowed that we do not at present need to expend the income of the fund. In this Decennial Address. 57 respect the sagacity and benevolence of our Founder has been more than sufficient for our needs up to the present time, and our most efficient and courteous librarian has found many means and devices, new to the most advanced library science, of bringing out its utmost efficiency for our work, and of making it in all the pregnant sense of that word attractive to all who once come within the sphere of its influence. His work amply merits all the growing recognition that it and his rare personnel are so steadily gaining. His special report contains new suggestions and experiences. The large and new demands upon the Public Library caused by the presence of an university for research which involved a material addition to its work, which is likely to increase in proportion to our growth, should be distinctly recognized. The special privileges needed by investigators have often been a strain upon the capacity of both its officers, its methods of administration and service, and the resources of its alcoves. The Public Library has on the whole well met the test, and I desire here to express, not only for myself personally, but for the other members of the University our gratitude to the city, the Trustees, and particularly to the accomplished head of the library itself, whose cooperation, with his able corps of assistants, has been a factor in an important part of our work. Our two strongest departments are mathematics and psychology. These two, as has been often said, are the root and heart of all other branches. Mathematics is the grammar of all the sciences that deal with inanimate nature, and the study of the human mind and soul opens the field where all animate nature celebrates her highest triumph and which underlies all the humanities. While we could expend with profit much more than at present, perhaps the entire resources of the University, upon these departments, or perhaps, even upon each of them, they are best equipped and least in immediate need. We have books, journals, pro- fessors, means of speedy publication, and well-developed traditions, and can claim, we think with modesty, to be doing creditable work. Our greatest and most pressing need, according to the policy first formulated of strengthening the departments already established before founding new ones, is to enlarge the biology to an independent position, with due provision for botany and the related subject of paleontology. The foundations of a building for this group of studies is already laid on the grounds, and its completion, with an endowment of $150,000 or $200,000 with what we now have, would give us a strong department able 58 Decennial Address. to compete successfully with the best ; perhaps we may sometime dedi- cate such a building and department to the name of some honored public- spirited citizen of Worcester. Physics, like biology, now represented by a single able and promising man, needs enlargement to the same degree, with an annex department of astronomy and astrophysics, and for the same sum could, in addition to what we now have, be put upon a creditable footing. The chemical building, admirably planned after careful studies of all the best in Europe, and well equipped, especially for organic work, has no endowment, and needs for its full development the income of at least a quarter of a million of dollars. Anthropology, so greatly needed in this land, but so lacking in academic installation and tradition here, is already a precious germ with one worthy representative, has been cherished from the first with us, and it, too, needs enlargement and independence. If we pass over into the humanities, there are, of course, the two great groups of philology and literature, ancient and modern, and a historical group culminating in political economy, sociology, and a grand department of international law, nowhere adequately represented in this country, and for the establishment of which somewhere Senator Hoar, acting president of the Board of Trustees, the first citizen of Massachu- setts, competent to-day to fill any one of four professional chairs in any university, in learning, experience, character, and position more nearly the American Gladstone than any other, has been so distinguished an advocate. Education, now coming to be the largest philosophy of life and the natural field of applied psychology, needs a more adequate representa- tion, and with a quarter of a million of dollars for an ideal university school for children, we would almost guarantee in five years to make this place an educational Mecca, by short circuit methods now well demonstrated but nowhere embodied, which would greatly increase the efficacy and reduce the expense and ease the labor of the lower grades of education in this country. Our summer school has become one of the largest and highest grade institutions of its kind in the country, and appeals especially to heads of fitting schools, with whom it would be important for us to be en rapport if we had a college ; to normal schools, whose faculties are a growing field for the employment of our pedagogical graduates ; to Decennial Address. 59 young instructors in colleges, superintendents, parents, etc. If our two weeks could become a summer quarter counting toward a degree, and if the summer school could be adequately endowed and furnished, with the interest which one department of our work has already enlisted among the teachers of our country, the best of whom could spend their summer here in work, this, too, could be made an institution of which any city or university might well be proud. We urgently need without delay the means for establishing a univer- sity printing office, where we can publish our journals at less expense and do our own printing ; and if this should grow to larger dimensions and develop a life of its own, that, too, might be welcomed. These needs are all on the university plane, where the beginnings already made are precious beyond words, wrought out as they have been with so much pain and labor, and the highest effort of so many choice spirits. May the day never dawn when this in our country most sorely needed and prayerfully cherished academic tradition shall fade or be broken. The investments of wealth and effort already made are too great, and achievements already attained and future promise too bright, to permit this ever to be an open question here. Satisfied, yes proud, as we are to-day to submit to Worcester, to sister institutions, and the country, the records of our work when compared with our means, we have lived, and even now live and walk, let us confess it, to a great extent in faith and hope, looking confidently to a future larger than our past has been, with steadfast and immovable conviction that our cause is the very highest of all the causes of humanity, but ready even ourselves, if need be, to labor on yet longer in the captivity of straitened resources, being fully persuaded that our redeemer liveth and that in due time he shall appear. THE DEPARTMENT OF MATHEMATICS. By William Edward Story. PAST AND PRESENT STAFF. William Edward Story, Ph.D., Professor of Mathematics since 1889. OsKAE BoLZA, Ph.D., Associate in Mathematics, 1889-92. Henry Taber, Ph.D., Docent in Mathematics, 1889-92; Assistant Professor of Mathematics since 1892. Joseph de Perott, Docent in Mathematics since 1890. Henry S. White, Ph.D., Assistant in Mathematics, 1890-92. FELLOWS AND SCHOLARS. Henry Benner, Fellow in Mathematics, 1889-90. L. P. Cravens, Scholar in Mathematics, 1889-90. EoLLiN A. Harris, Ph.D., Pellow in Mathematics, 1889-90. J. P. McCuLLOCH, Fellow in Mathematics, 1889-90. William H. Metzler, Fellow in Mathematics, 1889-92. J. W. A. Young, Fellow in Mathematics, 1889-92. Levi L. Conant, Scholar in Mathematics, 1890-91. Alfred T. Db Lury, Fellow in Mathematics, 1890-91. Jambs N. Hart, Scholar in Mathematics, 1890-91. Thomas F. Holgatb, Fellow in Mathematics, 1890-93. John I. Hutchinson, Scholar in Mathematics, 1890-91; Fellow in Mathe- matics, 1891-92. Frank H. Loud, Scholar in Mathematics, 1890-91. N. B. Hellbb, Scholar in Mathematics, 1891-92. LoRRAiN S. HuLBURT, Fellow in Mathematics, 1891-92. John McGowan, Scholar in Mathematics, 1891-92. Ernest B. Skinner, Scholar in Mathematics, 1891-92. L. Waylajstd Dowling, Scholar in Mathematics, 1892-93; Fellow in Mathe- matics, 1893-95. John E. Hill, Fellow in Mathematics, 1892-95. Herbert G. Keppbl, Scholar in Mathematics, 1892-93; Fellow in Mathe- matics, 1893-95. 61 62 Department of Thomas P. Nichols, Scholar in Mathematics, 1892-93 ; Fellow in Mathematics, 1893-95. P. E. Stinson, Scholar in Mathematics, 1892-93; TelloTv in Mathematics, 1893-95. W. J. Waggenee, Scholar in Mathematics and Physics, 1892-93. Waeeen G. Bullaed, Scholar in Mathematics, 1893-96. ScHUTLBE C. Davisson, Pellow in Mathematics, 1895-96. Febdeeick C. Feeey, Fellow in Mathematics, 1895-98. John S. Feench, Scholar in Mathematics, 1895-96 ; Fellow in Mathematics, 1896-98. E. W. Ebttgee, Fellow in Mathematics, 1895-98. tS. Edwaed Eteeson, Fellow in Mathematics, 1895-96. Died March 25, 1896. Hugh A. Snepp, Scholar in Mathematics, 1895-96. Jambs W. Botcb, Fellow in Mathematics, 1896-99. Heebbet 0. Clough, Scholar in Mathematics, 1896-97. A. Haeey Wheblek, Scholar in Mathematics, 1896-99. Lindsay Duncan, Scholar in Mathematics, 1897-99. Febdeeick H. Hodge, Scholar in Mathematics, 1897-98; Fellow in Mathe- matics, 1898-99. Halcott C. Moebno, Scjiolar in Mathematics, 1897-98; Fellow in Mathe- matics, 1898-. Stephen E. Slocum, Scholar in Mathematics, 1897-98 ; Fellow in Mathematics, 1898-. John N. Van dee Veies, Scholar in Mathematics, 1897-98 ; Fellow in Mathe- matics, 1898-. Feank B. Williams, Scholar in Mathematics, 1897-98; Fellow in Mathe- matics, 1898-. Elwin N. Lovewell, Scholar in Mathematics, 1898-99. Louis Sipp, Scholar in Mathematics, 1898-99. Oelando S. Stetson, Scholar in Mathematics, 1898-99. SPECIAL STUDENTS. Gboege F. Metzlbe, Ph.D., Honorary Fellow in Psychology, 1891-92. Calvin H. Andeews, Mathematics and Pedagogy, 1894-95. Waltee E. Andeews, Mathematics and Pedagogy, 1894-95. Whole number of students in mathematics in 10 years 44 Aggregate attendance (including 4 who remain in 1899-1900) ... 83 years. Average number of students per year 8 Average attendance per student , 2 years. Mathematics. 63 Mathematics occupies a peculiar position relatively to the arts and sciences. It is, par excellence, an art, inasmuch as its chief function is to solve problems, — not such examples as are given in the text-books, and which serve only as exercises in the application of methods, but any problems that may arise in human experience and for whose correct solu- tion sufficient data are at hand. When any line of investigation, to whatever subject it may refer, has been carried so far that exact reason- ing may be applied to it, mathematics is the authority to which the results of observation are submitted for the final determination of their consistency and the conclusions that may be drawn from them, and fur- nishes the means of appljdng these conclusions to the prediction of phe- nomena not yet observed. No science and no branch of technology is exact, that is, capable of predicting with certainty what will happen under given conditions, unless it rests upon a mathematical foundation. Astronomy, physics, and applied mechanics already have this foundation to a considerable extent, while the other sciences are still in the inductive stage, in which material is being collected with which, it is to be hoped, such foundation will ultimately be laid. Mathematics is also a science, inasmuch as it has accumulated a large body of systematic knowledge involving and leading to the methods that it employs in its solutions. These methods are of such a peculiar nature, differing so widely from other methods, that a special course of training is requisite if any one would learn to use them, and their number and variety have become so great that a lifetime would not sufiice to acquire familiarity with them all. But new problems are continually arising and demanding new methods, and we need, therefore, a body of men who shall devote them- selves especially to the task of supplying this demand. While the col- leges are engaged in general liberal education, teaching a variety of subjects that develop the mental faculties (and no subject is more effi- cient than mathematics for this purpose) and make the student acquainted with his own tastes and powers, thus enabling him to determine the life- work for which he is best fitted, it is the special function of the university to extend the limits of human knowledge, and to train those who have unusual intellectual talents to employ them to the best advantage. We believe this object is best accomplished by an institution devoted solely to it, and whose teachers' energies are not diverted by the lower, though no less important, aims of the college. When the policy that should characterize this University was under 64 Department of discussion, the first point decided was that its work should be strictly- post-graduate, and that it should not compete with other institutions in the work that is generally recognized as undergraduate. . In accordance with this principle, the mathematical department fixed its standard of admission so as to require such a knowledge of mathematics as can be obtained in the average American college, and laid out upon this foun- dation a curriculum of its own, as extensive and as thorough as circum- stances allowed. In elaborating the details of this curriculum, we have kept in mind the fact that those who pursue post-graduate studies in pure mathematics almost always look forward to careers as professors in colleges or other higher institutions of learning ; and we have taken the view that, other things being equal, the ideal teacher is a master of his subject, not only conversant with the general principles of all its more important branches, the problems that have arisen in each, the methods that have been devised for the solution of these problems, and the results that have been obtained, but also unbiassed, ready and sound in judgment, and actively engaged in scientific research. We believe that the training that is best adapted to produce efficient specialists is also the training that is best adapted to produce efficient teachers of specialties. While desirous of supplying all possible facilities to those who wish to pursue studies in special branches, and to those who, already occupying permanent positions, have but a limited leave of absence, we have made it our chief object to provide a thorough training for those who, having just completed a college course, have not yet entered upon their life-work. This provision consists of such courses of lectures, seminaries, and indi- vidual assistance as should enable a faithful student endowed with the proper natural ability to satisfy the requirements for the degree of Doctor of Philosophy at the end of his third year with us. The requirements for this degree have been determined by our conception of the ideal teacher, as already stated. To acquire the necessary breadth of knowl- edge of mathematics as a whole, the candidate is expected to attend, during his first two years, specified courses of lectures on the general principles, methods, and results of all the more important branches of pure mathematics, to supplement these lectures by private reading, and to take an active part in the seminary. In the seminary, a special topic, more or less directly connected with the subject of some lecture, is as- signed, from time to time, to each student, who is required to read it up Mathematics. 65 and make an oral report upon it before the class. Advanced courses of lectures on special subjects that vary from year to year are also given, and each candidate for the degree is expected to attend a number of such courses. The student spends the greater part of his third year in the original investigation, under the constant personal guidance of one of the instructors, of a topic of his own selection. In preparing for this inves- tigation, he is required to make a practically complete bibliography of the subject, and to read all the more important available articles that have been written on it. The results of the investigation, embodied in a dis- sertation suitable for printing, must be submitted to the instructor under whose direction the work was done, and must receive his approval before the candidate will be admitted to the final examination for the degree. This approval will not be given unless the dissertation is satisfactory in form and completeness and the results are sufficiently novel and impor- tant to constitute a real contribution to science. The dissertation is, in fact, the main criterion by which the candidate is judged, and no amount of other work will compensate for its defects. The ability of our grad- uates to carry on research and the excellence of the work actually done is assured by the regulation that each dissertation accepted by us as worthy of the degree shall be printed with the explicit approval of a member of our Faculty. It is evident that, whereas any one that has the necessary preparation and taste for mathematics may profit by the advan- tages here afforded, only those who have a certain amount of mathematical genius can secure the degree. In making appointments to fellowships and scholarships we have endeavored to maintain the same high standard. We are on the lookout for mathematical geniuses ; but it is difficult to determine frpm the evi- dence of others whether candidates come up to our standard or not ; so that we have adopted the general policy of giving the best appointments to those only that have been with us for at least one year, and about whom we are in position to judge for ourselves. Of course, this policy could not be carried out during the earlier years of the University, and its effect is apparent in the fact that, whereas seventy-five per cent of the students that entered the mathematical department during the first three years remained with us but one year, only twenty per cent of those that have been admitted during the last seven years left at the end of their first year. I do not mean to imply that those who left before completing our course were inferior in ability to those who remained three years, but 66 Department of we desire particularly to encourage men who can and will go forward to the degree. Nearly all of those who have studied mathematics with us have adopted teaching as a profession, two-thirds are now members of college faculties, and one-third are engaged in higher school work. Those who have received the doctor's degree have generally secured at once desir- able positions in which to begin their life-work, and most of them have already acquired for themselves, by distinguished ability, very decided influence in the institutions with which they are connected. Of those who have left without the degree fully one-half ought to have continued, and would have done so but for want of pecuniary means ; and we have been obliged to turn away many men of very great promise on account of our inability to assist them in providing the means of subsistence during the unproductive period of student life. We could employ for fellow- ships, with decided advantage, ten times the amount now at our disposal. Although, as I believe, students will find here a broader post-graduate curriculum in mathematics and greater personal attention from the in- structors than at any other university in the country, we need greater facilities to make our course what it ought to be. Four-fifths of the in- struction in the department is now given by two men, and we are com- pelled to give in alternate years lectures on fundamental subjects that ought to be given every year. As I have said, we lay great stress upon the ability of our students to investigate ; but this faculty can be fully developed only under the personal guidance of one who is himseK in the habit of investigating and who has the facilities and opportunities neces- sary for such work. A teacher's usefulness is greatly increased by the inspiration .that comes from a personal identification with his subject, from the fact that he has ideas of his own about it, and that he has ex- tended it by his individual exertions ; and the investigator can have no greater incentive to search for new results than the opportunity to pre- sent his thoughts and discoveries to an intelligent and appreciative class in the lecture-room. But the necessity of teaching many subjects simul- taneously distracts the mind and is fatal to research. The ideal condi- tions for an instructor in an institution like this would be those under which he could teach one subject at a time, and that a subject that he was himself developing, and follow this subject with his class to such a point as to bring into evidence the scope and importance of his own work. To apply this method to the courses that are actually given here Mathematics. 67 would require the services of three additional instructors in mathematics. We are actually laboring under the disadvantage that some of the im- portant branches novr taught by us are not of such paramount interest to any one of our instructors as to be the subject of his personal investi- gation. We are compelled to restrict ourselves to elementary courses in many branches that ought to be carried to a much higher point, and to omit altogether from our consideration applications of mathematics to statistics, to the arts, and to other sciences. Applications to physics re- ceive the attention of the physical department, to be sure, but the mathe- matical department ought to do much more than it is at present able to do in preparing students for higher work in physics. The number of instructors necessary for such advanced work as we do is not to be deter- mined by the number of our students, but by the mmiber of subjects taught. Again, every expert investigator finds himself continually obliged to spend much time in details that could just as well be worked out by a younger man, to whom such work would be of immense advantage, not only as an exercise in the practical application of methods, but also as furnishing the opportunity for a prolonged study of the workings of an investigator's mind ; and example is worth more than precept in the development of the faculty of investigation. We ought to have the means of retaining our best graduates for a year or two as personal assist- ants to the instructors, during which period they might also be gaining experience in the class-room by teaching a few hours a week under the supervision of one of the regular instructors. Such work is not drudgery, and would be, I think, sufficiently attractive to an ambitious young man to induce him to remain with us on a moderate stipend while he is wait- ing for such appointment as may seem to him desirable. It is almost universally assumed that a mathematician needs no mate- rial equipment other than brains, with, possibly, a few books. However true this assumption may have been some decades ago, — and I fancy that its truth then rested solely upon the difficulty of procuring such equip- ment, — it is not true now, as must be apparent to any one who studied carefully the German educational exhibit at the World's Fair in Chicago. Ten years ago our department started out with a fair nucleus for a mathematical library and a moderate collection of models, to which we have not been able to make many additions. We have very few of the older mathematical works that illustrate the history of the subject, and 68 Department of we need particularly complete sets of many important mathematical jour- nals and the transactions of learned societies. In these journals and transactions have appeared most of the original investigations to which, as investigators ourselves, we have continual occasion to refer, both for suggestions and to avoid apparent plagiarism and the unnecessary dupli- cation of research. We should also be greatly assisted in our class-work by a more complete collection of models. In short, what I have in mind as a model mathematical department for post-graduate work would have, say, four professors and assistant professors, each having his personal assistant, and at least two instructors of lower grade for the more elementary work, and would be provided with a complete mathematical library and with all the apparatus that it is now possible to procure, with suitable provision for the purchase of new books and apparatus as they appear in the market. These schemes are not incapable of realization, although, perhaps, opposed to the traditions of education in this country. This University has never had any traditions excepting such as were based upon high ideals. Its mathematical department was not modelled after that of any other institution, but was determined by the conception of what would constitute perfection in such a department. We have always lived up to our ideals, in so far as we have done anything, without regard to consid- erations of material interest. We are not here to do what is done else- where, and we do not acknowledge that it would be best for us to do what other institutions, in their experience, have thought wisest. We propose to adopt no temporary policy that we shall sometime want to abandon, confident that the ideal university of the future will be ideal from the very root and not a graft upon inferior stock. When the doors of the Universty were first opened to students, in the fall of 1889, the mathematical staff consisted of WiUiam E. Story, Pro- fessor, Oskar Bolza, Associate, and Henry Taber, Docent ; a year later it was increased by the appointment of Joseph de Perott, Docent, and Henry S. White, Assistant ; and in 1892 Drs. Bolza and White resigned their positions to accept Associate Professorships in the University of Chicago and Northwestern University, respectively, and Dr. Taber was promoted to an Assistant Professorship, thus leaving the department with practically the same teaching force as it had during the first year. The instruction has been given by lectures, seminaries, and individual conferences. The number of lectures (of fifty minutes each) was sixteen Mathematics. 69 a week the first year, nineteen and twenty a week in the second and third years, respectively, and about fourteen a week, on the average, each year since. In some years courses of lectures on certain mathematical subjects having important physical applications have been given by Assistant Professor Webster of the Department of Physics. The subjects of the lecture courses given during the ten years include the following : — 1. The History of Arithmetic and Algebra among various peoples from the earliest times to 1650 a.d. 2. Theory of Numbers (introductory). 3. Theory of Numbers (advanced). 4. Numerical Computations. 5. Theory of Quadratic Forms. 6. Fiuite Differences. 7. Probabilities. 8. Theory of Errors and the Method of Least Squares. 9. Theory of Functions of a Real Variable. 10. Linear Transformations and Algebraic Invariants (introductory). 11. Theory of Substitutions, with applications to algebraic equations (intro- ductory). 12. Theory of Transformation Groups. 13. The Application of Transformation Groups to Differential Equations. 14. Finite Continuous Groups. 15. Klein's Icosahedron Theory. 16. Simultaneous Equations, including Restricted Systems. 17. Theory of Functions of a Complex Variable, according to Cauchy, Rie- mann, and Weierstrass (introductory). 18. Definite Integrals and Fourier's Series (introductory). 19. Ordinary Differential Equations (introductory). 20. Ordinary Differential Equations (advanced). 21. Partial Differential Equations (introductory). 22. Elliptic Functions, according to Legendre and Jacobi (introductory). 23. Weierstrass's Theory of Elliptic Functions. 24. Elliptic Modular Functions. 25. Abelian Functions and Integrals. 2Q. Theta-Fimctions of Three and Four Variables. 27. Riemann's Theory of Hyperelliptic Integrals. 28. Riemann's Surfaces and Abelian Integrals. 29. Conic Sections by modern analytic methods (introductory). 30. Quadric Surfaces by modern analytic methods (introductory). 31. General Theory of Higher Plane Curves (introductory). 32. Plane Curves of the Third and Fourth Orders. 70 Department of 33. General Theory of Surfaces and Twisted Curves (introductory). 34. Surfaces of the Third and Fourth Orders. 36. Twisted Curves and Developable Surfaces (advanced). 36. Applications of the Infinitesimal Calculus to the Theory of Surfaces. 37. Eational and Uniform Transformations of Curves and Surfaces. 38. Enumerative Geometry. 39. Analysis Situs. 40. Hyperspace and Non-Euclidean Geometry. 41. Modern Synthetic Geometry (introductory). 42. Quaternions, with applications to geometry and mechanics. 43. Multiple Algebra, including matrices, quaternions, " Ausdehnungslehre," and extensive algebra in general. 44. Symbolic Logic. Courses designated as " introductory " are given at least as often as every other year, and attendance on them is required of all candidates for the degree of Doctor of Philosophy that take mathematics as their principal subject. The other courses, intended primarily for the more advanced students, have been given less frequently and vrith particular reference to the suggestion of topics for original investigation. In connection with his lectures. Assistant Professor Taber has con- ducted a weekly seminary for students in their first or second year, for the purpose of cultivating in them an active attitude toward the subjects treated, instead of the passive attitude usually resulting from hearing lectures. Topics related to those of the lectures have been discussed by the students, and their work has been criticised both with reference to rigor of demonstration and manner of presentation. In this way some of the advantages of the laboratory and the practice school are brought into the field of mathematics. Professor Story, with the assistance of the other instructors, has directed the more advanced students individ- ually in the systematic investigation of special topics that promised to afford opportunity for the discovery of new results and methods, — a task that has sometimes required the professor to hold weekly three-hour conferences with each of four students during nearly the entire academic year ; but we believe the results have justified this unusual expenditure of energy. The average annual number of students taking mathematics as their chief study has been about eight, the average duration of their residence was about two years, and more than one-third of them have received (or will undoubtedly receive) the Doctor's degree, which is a decided improve- Mathematics. 71 ment in every respect over the record of the first three years. The pub- lished investigations of these students are enumerated in the Bibliography at the end of this volume. The researches of an instructor in an institution of this kind are not to be judged solely by the number and magnitude of his printed papers, as many of them are naturally turned over, in a more or less incom- plete form, to his pupils for further investigation and more adequate presentation ; at least it seems most natural and desirable that an in- structor should suggest to his pupils subjects for investigation on which he has himself worked, and for whose treatment he has found adequate methods. My chief subjects of investigation have been : — 1. Hyperspaee and Non-Euclidean Geometry. 2. Algebraic Invariants. 3. Curves on Ruled Surfaces, and Restricted Equations. 4. The History of Mathematics prior to the invention of the infinitesimal calculus, and 5. A Mathematical Curriculum for Primary and Secondary Schools. I have developed systematically the general theory of space of any number of dimensions from assumptions that are precisely analogous to those on which the scientific treatment of threefold space is usually based, and which we recognize as the results of experience. In accordance with this general theory, I have thoroughly investigated the properties of loci of the first and second orders and some special loci of higher orders. The introduction of the most general kind of measurement has then led me to an equally thorough study of parallel and perpendicular loci, the curvature of loci, areas, and volumes in the most extended sense. The first part of these results has already appeared in the Mathematical Review, and I hope to publish the remainder within a short time. Ever since the appearance of Clebsch's "Theorie der binaeren alge- braischen Formen," toward the end of the year 1871, when I was study- ing in Berlin, I have taken a lively interest in the theory of algebraic invariants, — an interest that was greatly augmented by my association with Sylvester at the Johns Hopkins University in 1876. I had thought all along that there ought to be a direct process by which all such invar 72 Department of riants could be obtained, but my efforts to find it had failed. A course of lectures on invariants that I have given every year or two since the opening of Clark University caused me to renew my attempts, and the classic paper of Hilbert in the 36th volume of the Mathematisehe Annalen, in which a process devised by Mertens (and which I regarded as indirect, inasmuch as it involved quantities extraneous to the matter in question) suggested a new line of research, which happily led at length to the long-sought direct process. I then applied this process, as Hilbert had applied Mertens's process, to the proof of Gordon's theorem that aU the invariants of any finite system of quantics of finite orders can be expressed rationally in terms of a finite number of such invariants. These results were published in the Mathematisehe Annalen and in the Proceedings of the London Mathematical Society, I have spent much time in trying to find, by means of the process, an extension of Cayley's for- mula for the number of linearly independent ground-forms of a single binary quantic (extended by Sylvester to any system of binary quantics) to the case of quantics involving three or more variables, but so far with- out success. In my lectures on surfaces of higher orders and twisted curves I have paid particular attention to the algebraic curves that lie upon a given algebraic surface. If the given surface is ruled, the curves on it can be classified in such a way that certain problems relating to a curve can be solved when the class of the curve is known. My investigations in this direction have been communicated to my students, some of whom have already solved such problems. In connection with my investigations on twisted curves, I have also made a systematic study of restricted equa- tions, and have carried the determination of the orders of such systems much farther than had been done before. I have lectured at various times on the early history of mathematics, with special reference to the development of arithmetical and algebraic symbolism, and have collected a large number of systems of such symbols, which I hope sometime to utilize for a monograph on the subject. In connection with a course of lectures delivered for two years at the Summer School, I arranged a mathematical curriculum for primary and secondary schools, which will be published when I can find the leisure necessary to prepare the explanatory text. At my request. Assistant Professor Taber has furnished the material for an account of his personal researches, which involves such a complete Mathematics. 73 and excellent history of the theory of matrices that it seems to me inad- visable to abbreviate it ; I therefore append it to this report at length, for the benefit of those readers who may be interested in the subject. Dr. Taber's researches have been devoted to the development of the theory of matrices, and its application to bilinear forms, multiple algebra, and theory of finite continuous groups. The calculus or theory of matrices was invented by Professor Cayley (see his " Memoir on the Theory of Matrices," Phil. Trans.., 1858), and has proved an instrument of great power in the theory of linear transformation, bilinear forms, and for the investigation, generally, of the projective group.i In order to explain the work done by Dr. Taber in this direction, a few words of explanation will be necessary to describe the work done by Cayley and others. Associated with any linear substitution n x! = y a^fij (i = 1, 2, — w) is the bilinear form -^ = / / (^a^il/ji which may be regarded as repre- senting this substitution, or vice versa; and, in the theory of matrices, we do not need to distinguish between this linear substitution and the asso- ciated bilinear form, or between either and the matrix (.'"'' | \i,j = l, 2,...nJ n n common to both. If now B denotes the bilinear form y y i^'^iy,-, or 1 ' 1 ■* its associated linear substitution, A±B will denote the bilinear form n n / / (j^v + ^^^iVji or its associated linear transformation ; and AB will denote the bilinear form /,./,.(/, f^ik^^^pi^p or its associated linear substitution (obtained by the composition of the linear substitutions A and B^. Equivalence between two bilinear forms or linear substitu- 1 By means of this calculus very Important results have been obtained by Cayley himself, by Sylvester, Frobenius, Foss, Weyer, Study, and others ; and, by methods essentially simi- lar, Kronecker obtained important theorems on the orthogonal group to which reference is made below. 74 DepartTTient of tions, A and B, is denoted by writing A = B. Further, in what f oUows, I will denote the identical transformation, represented by 2^^^'' ^^^ 1 J.-1 the form, or substitution, satisfying the symbolic equation AA-^ n n = A-^A = I; A will denote the bilinear iorvaS^y\ajiXiyj, transverse or conjugate to A =y^ y^ a^-x^i/j, and \A\ will denote the determinant 1 ' 1 of the matrix A. A is said to be symmetric if A = A, and alternate, or skew symmetric, if A = — A.^ Cayley was, perhaps, led to the invention of this calculus by his researches upon orthogonal substitution, Orelle (1846), Vol. 32. For in Crelle, Vol. 60, three years before the publication of his memoir on matrices, he expressed the results of these researches in the notation of matrices. Thus Cayley showed that the general expression for the proper orthogonal substitution in n variables is (/— 5) (7+ B^-\ where B denotes an arbitrary alternate, or skew symmetric, linear substitution; and this expression gives Cayley's determination of the coefficients of a proper orthogonal substitution in n variables as rational functions of the essential parameters, J n(n — 1) in number. Again, in his " Memoir on the Automorphic Linear Transformation of a Bipartite Quadrate Function" (PM. Trans., 1858), Cayley showed that the general automorphic linear transformation (linear transformation into n n itself) of a symmetric (alternate) bilinear form A=y y o-if^iVj with cogredient variables and of non-zero determinant, may be represented by (J. + X)"'(J. — X), where X is an arbitrary alternate (symmetric) bi- linear form. This expression gives in the first case (when A is symmet- ric) Hermite's determination of the general proper automorphic linear transformation of a symmetric bilinear form, and, in the second case (when A is alternate), Cayley's determination of the transformation into itself of an alternate bilinear form. Further, in this same memoir Cay- ley showed how to reduce, to the solution of a system of w^ linear equa- tions, the rational determination of the tfi coefficients of the automorphic linear transformation of a general bilinear form A (neither symmetric nor alternate) with cogredient variables and of non-zero determinant. Namely, he showed that the general formula for such a substitution is 1 In the first case a^ = ay, in the second ujt = — cuj(i,j = l, 2, ... ?i). Mathematics. 75 iA + JT)-! (^A-X), where X satisfies the condition (Ay^X+A-^X= 0. This result includes the determination of the general automorphic trans- formation of A, when A is symmetric and when A is alternate. It also includes Cayley's determination of the coefficients of an orthogonal substi- tution to which it reduces when A = I. In what follows G- will denote the group of proper automorphic linear transformations of A (the a;'s and y's being cogredient), and 6r' the proper orthogonal group. A transformation T oi Q- (or of (?') is termed singular if —1 is a root of its characteristic equation (namely, ] T— pl\ =0); otherwise, non-singular. Every non-singular transformation of group Q- (or 6r') is given by Cayley's formula, and may be termed a Cayleyan transformation of the group. ^ No singular transformation of group G is given by Cayley's expression or determination. But for A alternate, also when A is neither symmetric nor alternate provided | J[ ± J. | =?t= 0, Dr. Taber showed in 1894 (Proc. Am. Acad. Arts and Sciences, Vol. 29) that group G- is generated by the Cayleyan transformations of the group, — each transformation T of this group being obtained by the composition of a finite number of Cayleyan transformations. In the same paper Dr. Taber also showed that the sub-group of orthogonal transformations of G is, similarly, generated by the non-singular orthogonal transformations of this sub-group, when A is alternate, and when A =^ ± A provided I i± ^ I # 0. This theorem is similar to a theorem relating to the orthogonal group (group G') established by Kronecker in 1890 (" Ueber orthogonale Sys- teme," Sitzungsberich. d. Preuss. Akad.'), who showed that this group is generated by the Cayleyan transformations of the group, each trans- formation T of this group being obtained by the composition of two Cayleyan transformations, — the coefficients of each of the Cayleyan transformations being rational functions of the coefficients of T. In 1895 (Math. Ann., Vol. 46) Dr. Taber showed that, if A is real and alternate, every real transformation T oi G can be obtained by the com- position of two real Cayleyan transformations of this group. This theorem was obtained independently and extended widely by Dr. Loewy, who in 1896 (Math. Ann., Vol. 48) showed that, if J. is irreducible 1 Por the case in whioh A is symmetric, the determination of the coefficients of T, given by Cayley's formula, is properly Hermite's ; but it is not convenient to distinguish here between this case and the other two oases, namely, when A is alternate, or is neither symmetric nor alternate, when the determination is Cayley's. 76 Department of (which case includes that in which A is alternate), every transformation of Q; real or imaginary, can be obtained by the composition of two Cayleyan transformations of the group, and that, therefore, when A is irreducible, there is no transformation of the kind termed by Foss essentially singular} that is to say, which cannot be obtained by the com- position of two non-singular, or Cayleyan, transformations. For a reducible form A not every singular transformation of Cr can be obtained by the composition of two Cayleyan transformations of this group. Nevertheless, Dr. Taber showed in 1897 (^Mdth. Review, Vol. 1) that in every case the Cayleyan transformations of Gr form a group by themselves ; that the composition of any number of Cayleyan transforma- tions of G- results in a transformation that can be obtained by the composition of two Cayleyan transformations of this group; and that thus the composition of Cayleyan transformations never gives rise to an essentially singular transformation. It is to be noted that from Cayley's formula for a transformation T of Gr, namely, T= iA + X)-i (JL - X) = (7- A-^XXI+ A-^Xy\ we derive X=A(1 - T')(l + T)-^; and, therefore, the parameters, namely, the coefficients of X, which enter into the determination of T, can be expressed rationally in the coefficients of T and of A.^ Similarly, in the memoir by Kronecker mentioned above, he has shown that the coefficients of the two Cayleyan transformations, whose composition gives the general transformation T of group (r', can be expressed rationally in the coefficients of T. For A real, alternate, and orthogonal, Dr. Taber gave, in the paper in the Mathematische Annalen mentioned above, the determination of the coefficients of the two Cayleyan transformations Cj and C^, whose composition gives any real transforma- tion T of G, as rational functions of the coefficients of T and of A. This determination of Cj and C^ he has since extended to the case in which T is imaginary, and A any alternate bilinear form.^ Dr. Taber has pointed out that the transformations of Q; both when A is irreducible and when A is reducible, are in general of two essentially 1 Abhand. d. k. Bayer. Akad. d. Wiss., II. CI., XVII. Bd., II. Abth. 1890, p. 77. ^ Between these parameters when A is neither symmetric nor alternate n^ equations persist. = See papers to appear in Froc. Am. Acad, of Arts and Sciences, Vol. 35. Mathematics. 77 different kinds. The difference between the two, kinds of transformations of G- is given by the following theorem : — (I.) If we designate a transformation of group G as of the first or sec- ond hind according as it is or is not the second power of a transformation of the group, then every transformation of the first hind is the mth power of a transformation of the group, for any positive integer m, and can he generated hy the repetition of an infinitesimal transformation of the group. A transformation of the second hind, hy definition not an even power of any transformation of the group, is always the (2m + 1)'* power of a transforma- tion of the group for any odd exponent 2m + 1. But no transformation of the second hind can he generated hy an infinitesimal transformation of the group. (II.) Every Oayleyan transformation of group G is a transformation of the first hind ; whereas, a non- Oayleyan transformation is, in general, of the second hind?- Dr. Taber has also given the conditions necessary and sufficient that a transformation T of group Q- may be of the first kind for the case in which A is symmetric (which includes the case when J. = Z, in which case 6r becomes G"), and for the case when A is alternate.^ Dr. Taber has shown that, if A is neither symmetric nor alternate and iThis was proved for the orthogonal group in 1894, Bull. Am. Math. Sac, Vol. 3. At the conclusion of this paper it was stated that a precisely similar theorem held for what is here designated as group G. In the Math. Ann., 1895, Vol. 46, the theorem was proved for group G- when A is alternate; for the case in which A is symmetric, in the Proc. Land. Math. Soc, 1895, Vol. 26; and for the general case, in the Math. Beview, 1897, Vol. 1. ' For the orthogonal group, to which O reduces when A=:I, the conditions necessary and suf&cient that a transformation shall be of the first kind were given hy Dr. Taber in a com- munication to the American Academy of Arts and Sciences, March, 1895. (See Proceedings, Vol. 30, p. 551.) The necessity and sufflciency of these conditions was afterwards shown in Free. Land. Math. Soc, 1895, Vol. 26, and the theory for the orthogonal group extended to group G for A symmetric. It was not explicitly stated in this paper that the conditions given for the orthogonal group hold for & when A is symmetric, being so obvious a conse- quence of the considerations adduced. This does not seem to have been recognized by Dr. liOewy, who refers to this paper but gives the necessary and sufficient conditions, Math. Ann., Vol. 48, when A is symmetric as an extension of Dr. Taber's theorem for group G'. Tor A alternate the necessary and sufficient conditions were given by Dr. Taber in a communication to the American Academy of Arts and Sciences, January, 1896. (See Pro- ceedings, Vol. 31, p. 349.) The necessity of these conditions has previously been shown by Dr. Taber in the Math. Ann., Vol. 46. In Vol. 49 (1897), Dr. Loewy gave the conditions as sufficient, undoubtedly without knowledge of Dr. Taber's priority in the statement of this theorem. 78 Department of I Jl ± ^|:^ 0, group Q contains no transformation of the second kind. Thia theorem leads, for the case mentioned, to the following rational represen- tation of any transformation of this group, namely, where (A')~^i+A~^X= 0. Moreover, Dr. Taber has shown that the sub-group of orthogonal transformations of Q- contains no transformation of the second kind when A is alternate.^ The determination of the congruent transformations between two bi- linear forms is the natural generalization of the problem to determine the automorphic linear transformations of A. A determination of the trans- formations between A and B depending on the solution of a single equa- tion of degree n has been given by Dr. Taber (Mathematical Review, Vol. 1, 1897), which holds for any case whatever in which A and B are both symmetric or both alternate. The theory of matrices, or bilinear forms, is closely related to the theory of Hamilton's linear vector functions. In the American Journal of Mathematics, Vol. 12, Dr. Taber has given a development of the theory of matrices, proving many of the fundamental theorems, from the point of view of Hamilton's theory. One of Sylvester's most important contributions to the theory of matrices was a general formula, given in the Oomptes Rendus, Vol. 94, 1882, expressing any power, integral or fractional, of the bUinear form or matrix .4 as a polynomial in A of degree w — 1. Thus, if jB = J. ^ where /n is any fraction, and if py, p^, . . . p„ are the roots of the characteristic equation of A, we have (Pl - P2)(Pl - Ps) - (Pl - P») By means of this theorem the determination of a matrix or linear substi- tution whose jitth power is equivalent to A is reduced to the solution of a single algebraic equation of degree n. This formula was afterwards ex- tended by Sylvester to any function of the matrix A.^ Thus we have /(^) = 2/(p,) CA-p,IXA-p,iy..CA~ pJ^^ (Pi - P2)(Pi - Pa) - (Pi - P») 1 See Suit. Am. Math. Soc, Series 2, Vol. 2, pp. 5 and 161. ' Johns Hopkins Univ. Circulars, No. 28, Vol. 3, p. 34. Mathematics. 79 Neither of these formulae applies unless the roots of the characteristic equation of A are all distinct. For the general case, in which the roots of the characteristic equation have any given multiplicities, a formula for f(A) has been given by Dr. Taber.i Thus, if the distinct roots of the characteristic equation are /Sp pj, ... p„ respectively of multiplicity m^, m^ - m„ and if ^« = ^^w ... ^,_i('M,^i« ...^^(*>, where 4« denotes KA - pj:yi - (pj - ft.)™*/]-,- : [( - i)- t^® quadrate of n^ units is a compound of /ij quadrates each with B-^ units, fi^ quadrates each with B^ units, etc. The general projective group holds a position of special importance in Lie's theory of finite continuous groups. For the adjoined group T of any finite continuous group G, by means of which the sub-groups of G are determined, wiU, if the equations of transformation of this group are properly chosen, appear as a sub-group of the general projective group. Thus the theory of matrices is of importance in the investigation of certain problems of Lie's theory, since this calculus furnishes a convenient instrument for the treatment of the general projective group. The chief theorem of Lie's theory states that if a system of infinitesi- mal transformations satisfies certain conditions, they generate a group with continuous parameters, each of whose finite transformations can be generated by an infinitesimal transformation of the group.^ In 1892 Professor Study made the extremely important discovery that this theorem is subject to certain limitations, — showing that an exception to this theorem existed in the case of the special linear homogeneous group in 1 Am. Jour. Math., Vol. 12, p. 391. * Ibid. This theorem was obtained independently, but subsequently, by Professor Study. See " Math. Papers of Internat. Math. Congress of 1893," p. 378. " Transformationsgruppen, Vol. 1, pp. 75, 158 ; Continuierliche Cfruppen, p. 390. Lie originally defined a finite continuous group, substantially (Trans. Grp., p. 3), as a group with continuous parameters. Ultimately, he assumed that in a continuous group as thus defined each transformation can be generated by an infinitesimal transformation of the group (Con- tin. Grp., p. 879). Mathematics. 81 two variables, namely, that not every transformation of tMs group can be generated by an infinitesimal transformation of the group.^ Subsequently, in 1893 (Am. Jour. Math.., Vol. 16), Dr. Taber showed that the orthogonal group in n variables (for w S 4) also presents an exception to Lie's theorem; and in 1895 gave, in a communication to the American Academy of Arts and Sciences, the conditions necessary and sufficient that a proper orthogonal substitution may be generated by an infinitesimal orthogonal substitution.^ For n> 2 also, the special linear homogeneous group in n variables is continuous only in the neighborhood of the identical transformations. For two variables, Study gave the conditions necessary and sufficient that a transformation of this group may be generated by an infinitesimal trans- formation of this group. Dr. Taber gave, in 1896 (Bull. Am. Math. Soc, Series 2, Vol. 2, p. 231), these conditions for n variables ; also the conditions necessary and sufficient that a transformation of the special linear homo- geneous group may be the mth power of a transformation of this group. From these conditions it appears that the mth power of any transforma- tion of this group can be generated by an infinitesimal transformation of this group; and that the transformations of this group can be divided into as many genera as there are prime factors of n. Thus, if S is a prime factor of n, there are transformations of this group whose w/Sth power, but no lower power, can be generated thus.^ Dr. Taber has shown that the following groups are not continuous, except in the neighborhood of the identical transformations, namely, the group G-, mentioned above, for A symmetric or alternate, and in general when A is neither symmetric nor alternate, provided either | ^ -f- .4 1 or \A — A\ is equal to zero.* For all these groups the infinitesimal trans- formations satisfy Lie's criterion. Dr. Taber has also shown that the following groups are continuous, namely, group Cr when \A±A\4=(i, the sub-group of orthogonal trans- formations of Q-, for A alternate, and the group of automorphic linear n n transformations of a bilinear form J. = \ ^ a^a;,yj-, of non-zero deter- minant, the a;'s and y's being contra-gredient.^ 1 Leipsige Beriehte, 1892. ' See Proc, Vol. 30, p. 551. This result is referred to above on p. 77. » See Sull. Am. Math. Soc, Series 2, Vol. 3, p. 9. * See p. 77, note 1. * See p. 77 above, also Proc. Am. Acad. Arts and Sciences, Vol. 31, p. 181. 82 Department of Investigations upon the continuity of the groups in two and three variables have been carried on under Dr. Taber's supervision by certain of the students in the mathematical department. Dr. E. G. Rettger has investigated the continuity of all the two and three fold groups, fifty-nine in number, enumerated by Lie, Continuierliche G^ruppen, pp. 288 and 519 ; and shown that twenty-one of these groups are discontinuous.^ Mr. F. P. Williams has investigated the continuity of certain groups of the plane, not treated by Mr. Rettger; and Mr. S. E. Slocum has pointed out the nature of Lie's error in his demonstration of the fundamental theorem referred to above. ^ If a system of real infinitesimal transformations satisfy a modification of the Lieschen criterion, Lie states that they generate a real continuous group, that is, a group with continuous parameters, each transformation of which can be generated by an infinitesimal transformation of the group. But this theorem is subject to certain modifications. Dr. Taber has shown that the group of real proper orthogonal trans- formations is continuous; 3 also that in the groups of real transforma- tions enumerated below not every transformation can be generated by an infinitesimal transformation of the group, namely, — the real projective group,* the general and special real linear groups, the general and the special real linear homogeneous groups, the sub-group of real transformations of G, for A real and either alternate or symmetric. Further, that if G denotes either of the groups just enumerated, the first part (I) of the theorem of p. 77 holds. And he has given the con- ditions necessary and sufficient, for each of the first three of the groups just eniunerated, that a transformation of this group may be generated by an infinitesimal transformation of this group.^ Let G denote a group generated by the composition of r one-fold ^ Proc. Am. Acad, of Arts and Sciences, Vol. 33. 2 See papers to appear in Vol. 35 of the Proc. Am. Acad, of Arts and Sciences. » Bull. Am. Math. Soc. for July, 1894. See also Froc. Am. Acad, of Arts and Sciences, Vol. 27, p. 163. ^ For the real projective group this was first pointed out by Professor H. B. Newson, Kansas Univ. Quart., 1896. ' Bull. Am. Math. Soc, Series 2, Vol. 2, p. 228 et seq. Also Proc. Am. Acad, of Arts and Sciences, Vol. 31, p. 336, and Vol. 32, p. 77. MaihematiGS. 83 groups (each containing the identical transformation), namely, Gi^^^ Gi<^\ •••Gi"'\ whose infinitesimal transformations satisfy Lie's criterion. It may happen that a transformation T of one (or more) of these one-fold groups, as Gi*''', combined with any transformation of another of the one- fold sub-groups, as Gi'"' (in particular with the infinitesimal transforma- tion of Gi'"'), results in a transformation that cannot be generated by an infinitesimal transformation of G. Any such transformation T, together with any transformation T of G that cannot be generated by an infinitesi- mal transformation of this group, may be termed singular; all other transformations of G will then be non-singular. In a paper, of which an abstract was read at the February meeting of the American Mathematical Society, 1899, Dr. Taber showed that, if G is a sub-group of the projective group, any singular transformation of G can always be obtained by the composition of two non-singular transformations of G ; and moreover that, if T is any singular transformation of G not generated by an infini- tesimal transformation of G, a transformation Tp, generated by an infini- tesimal transformation of G, can always be found which can be made to approach as nearly as we please to T by taking p sufficiently small, so that limp^o T^ = T. DEPAETMENT OF PHYSICS. By Arthur Gordon Webster. STAFF. Albert Abraham Michblson, Ph.D., Professor of Physics, 1889-92. Arthur Gordon Webster, Ph.D., Docent in Mathematical Physics, 1890-92 ; Assistant Professor of Physics, 1892-. FELLOWS AND SCHOLARS. Louis W. Austin, Scholar in Physics, 1890-91; Fellow, 1891-92. Frank K. Bailey, Scholar in Physics, 1898-99. William P. Boynton, Scholar in Physics, 1894^-95 ; Fellow, 1895-97. Arthur L. Clark, Scholar in Physics, 1896-97; Fellow, 1897-98. D. Ellis Douty, Scholar in Physics, 1898-99. William F. Durand, Scholar in Physics, !Nov.-Dec., 1889. Thomas W. Edmondson, Fellow in Physics, 1894-96. Benjamin F. Ellis, Scholar in Physics, 1892-93. T. Proctor Hall, Scholar in Physics, 1890-91; Fellow, 1891-93. fBENjAMiN C. HiNDB, FcUow and Assistant in Physics, 1892-93. Died Feb. 6, 1894. Richard J. Holland, Ph.D., Honorary Fellow in Physics, 1893-94. James Edmund Ives, Scholar in Physics, 1897-98 ; Fellow, 1898-. Sidney J. Lochnbr, Scholar in Physics, 1892-93. Alexander McAdie, Fellow in Physics, 1889-90. Alfred G. Mayer, Assistant in Physics, 1889-90. EoLLA R. Ramsey, Scholar in Physics, 1898-99. Stanley H. Rood, Scholar in Physics, 1893-94. tCLARENCB A. Saunders, Fellow in Physics, 1892-95. Died Dec. 19, 1898. Benjamin F. Sharps, Fellow in Physics, 1894r-96 ; 1897-98. Robert R. Tatnall, Ph.D., Honorary Fellow in Physics, 1897-98. Samuel K Taylor, Fellow in Physics, 1893-96. Frank L. 0. Wadsworth, Fellow in Physics, 1889-90; Assistant, 1890-92. Arthur J. Warner, Scholar in Physics, 1889-90. Albert P. Wills, Scholar in Physics, 1894-95 ; Fellow, 1895-97. 85 86 Department of SPECIAL STUDENTS. Eevin W. Howard, 1892-93. Albert B. Kimball, 1893-94. William Nelson, 1892-93. Joseph 0. Phblok, 1892-93. Aethue L. Eige, 1892-93. Stanley H. Kood, 1892-93. Claxton 0. Smith, 1892-93. Hugh M. Southgate, 1892-93. The work of a Department of Physics in a university at the present time may be best understood after a brief survey t)f some of the chief achievements of the science during the present century. As we in this country have our attention called more frequently to the achievements of applied than to those of pure science, it is worth while to dwell somewhat upon the influence of pure science upon applied, and upon its contribution to the progress of civilization. At the beginning of the century, the various subjects that together make up the science of Physics were in a very imperfect state. Of heat, light, sound, electricity, and magnetism, little that we now accept was known, while of that little still less had been applied to practical matters. The science of mechanics, upon which the whole superstructure of physics must inevitably rest, had indeed been set upon a firm basis by the immortal Newton, while its principles had recently been formulated by the distinguished mathematician Lagrange, in a way so broad and powerful that it has not since been improved upon. The science of pure mathematics had of course arrived at a high degree of perfection, and many of the leading mathematicians had devoted their best efforts to the subject of mechanics. But while a large number of investigators had laid the foundations of our present knowledge by the method of experiment, the habit of questioning nature, instruments in hand, had as yet by no means become general. This habit of direct experimental research is certainly in large degree to be credited to the present century. Without stopping to enumerate the leading achieve- ments of physics during the century, let us take as illustrations a few leading cases. Nothing has, perhaps, done more to change the face of the earth, from the point of view of man, than the invention of the steam- engine and of the railway thereby made possible, of the telegraph and telephone, while the transmission of energy by electricity bids fair to rival them in importance. Let us then briefly consider what led to these Physics. 87 inventions. At the beginning of the century it was universally held that heat was a substance, which could be put into, or removed from, ordinary matter. It is to the experiments of one of our own countrymen, the celebrated Count Rumford, that was due the original assault on this notion, the last blow at which was delivered by the Englishman, James Prescott Joule, in his great discovery of the mutual convertibility of heat and mechanical work, and of the doctrine of the Conservation of Energy. This discovery, so simple that it may be understood by every one, namely, that for whatever we do we get an exact equivalent, neither more nor less, is the fundamental truth of physical science. It is in physics the supreme achievement of the century. Until it was discovered, a true understanding of the principles of the steam-engine could not be arrived at, although the way had been prepared by the theoretical work of a French engineer, the illustrious Sadi Carnot. To Carnot and Joule, then, we owe the two laws of the new science of Thermodynamics, or the relations between heat and work, which lie at the basis of all steam, gas, oil, or other heat engines, as well as of all freezing machines, and of transmission or storage of energy by means of compressed gases. It would be well, therefore, for all intending investors in new and promising compressed or liquid air companies, no matter how attrac- tively advertised, to find out what thermodynamics has to say of the propositions advanced. The foundations having been laid by the experimental work of Joule and the theoretical work of Carnot, the required knowledge of the prop- erties of steam and other vapors used in engines and cooling machines was furnished by a masterly series of experimental researches of the dis- tinguished French physicist, Henri Regnault, who was set at work by the French government, and whose work has ever since been classical. No engineer could to-day design an engine without making use of the data thus furnished. Let us pass on to the telegraph. Here again it was the patient work of our countryman Henry, working quietly with purely scientific aims in his little laboratory in Albany, — it was Henry's investigations on the electromagnet that made feasible the invention by Morse of the recording telegraph, which is still in use more than any other system all over the world. It is, however, when we come to the great question of submarine telegraphy that we see most emphatically the practical contribution of pure science. The problem of telegraphing through an insulated wire 88 Department of immersed in water is totally different from the corresponding one for a land line, and for years seemed hopeless of solution. The construction of a cable reaching from Europe to America was such a costly undertaking as to deter the most venturesome capitalists, unless they could be pre- viously furnished with a reasonable guarantee of success. It was here that the work of William Thomson, to-day known as Lord Kelvin, our greatest living physicist, furnished the necessary assurance. Taking up the purely mathematical problem of the propagation of an electrical impulse in a submarine cable, he for the first time set its mode of work- ing in a clear light, and by means of his solution predicted that the American cable, if constructed in accordance with his specifications, was bound to work. Led by faith in this statement, Cyrus "W. Field col- lected the money, the cable was laid, and the cable worked. That the first cable of 1858 lasted but little more than a month was due to the unfortunate mode of working adopted by the chief electrician, a so-called practical man, who would however have been much better off if he had possessed the theoretical knowledge of Professor Thomson. To-day twelve working cables span the Atlantic, representing an investment of eighty-five million dollars. Is this too large a sum to credit to theoretical physics ? The problem of telegraphy that is to-day most interesting is that of telephoning across the Atlantic, and I feel no hesitation in saying that before this can be accomplished a large amount of theoretical research will be necessary, together with such experimental work as may be car- ried on in laboratories like ours, and is now being carried on by Professor Pupin of Columbia University, before a single dollar is sunk under the sea. The question of electric power transmission is one whose genesis is easy for aU to remember. All do not remember, however, that far from electrical science being, as the newspapers maintain, in its infancy, the laws governing our dynamos and motors were discovered in the first quar- ter of the century, mainly by two princes among workers in physics, the Frenchman Ampere and the Englishman Faraday. The achievement of Ampere in discovering the laws of the action of electrical currents in producing magnetic forces upon each other was, in its combination of mathematical and experimental brilliancy, one of the most remarkable achievements in the annals of science. Still more important practically were the discoveries of Faraday, who deduced unaided aU the laws upon which the working of dynamo-machines depends. Physics. 89 Another illustration of our point is the wireless telegraphy of Mar- coni, of which we hear so much in the newspapers to-day. What the newspapers do not tell us is that the electrical waves made use of in tele- graphing across the English Channel were predicted in a paper published in 1864 by the great English physicist, Clerk-Maxwell, who completely remodelled the theory of electricity as it then existed. Twenty-three years afterward his predictions were experimentally verified by Hein- rich Hertz, who thus rendered the practical results of Marconi possible. These researches, far-reaching as were their practical results, were carried on by purely scientific workers, solely for the interest that they presented by increasing our knowledge. This should always be the posi- tion of the scientist, for, if he turns aside, attracted by the seductive paths of moneymaking, he is almost sure to lose the prize of the great discovery. Let us now turn to the present means of advancing our scientific knowledge. It is not to be overlooked that many of the great discoveries above mentioned were made with very simple apparatus and with very modest facilities. When we see the very primitive instruments of Ampere, Henry, and Faraday, we are led to wonder that they could pro- duce such accurate results. The days of such work are however over. It is now possible to add to the knowledge already so richly harvested only by experiments of the most careful nature and by measurements of great refinement, involving often complicated and expensive apparatus. It is for this reason that the great laboratories have sprung up, which we find in such large numbers both in this country and in Europe. Until about a quarter of a century ago there were none. It had, however, come to be recognized that, in order to make an investigator of a student, it was necessary not only that he should hear lectures, but that he should him- self have practice in experimentation and in the making of exact meas- urements. For these purposes, courses of instruction in physical measure- ments were planned, and laboratories where they might be practically carried on were erected. One of the earliest of these teaching labora- tories was that of the Massachusetts Institute of Technology, presided over by Professor Pickering, now director of the Harvard College Observatory. Later came the laboratories at Yale, Harvard, Cornell, Johns Hopkins, Chicago, and Columbia, costing between one and two hundred thousand dollars each. In each case is to be added the sum of from twenty to fifty thousand dollars for equipment with apparatus. During the same 90 Department of time a large number of physical laboratories have been built in Europe, some of them involving a still larger expenditure of money, notably the one at Zurich, in which the Swiss government invested about a quarter of a million of dollars. At all these laboratories both teaching and the performance of research were contemplated, and an idea of the results achieved may be obtained from the statement that from the Johns Hop- kins laboratory have issued upwards of five hundred papers, and from those of Harvard and Cornell in the neighborhood of one hundred each. Besides these institutions so immediately connected with teaching, another type of laboratory has made its appearance within the last ten years. Of this the most conspicuous example is the German Imperial Physico-technical Institute, which is separated from teaching, and is intended solely for the performance of research, especially for the per- formance of such measurements as would require resources exceeding those possessed by private or university laboratories. The work per- formed in this great institution has been of the highest class, and has drawn the attention of other governments to the desirability of establish- ing such national laboratories, with the result that England has now fol- lowed the example of Germany, though upon a smaller scale. A further example is presented in the Faraday-Davy research laboratory in London, the gift of a private individual, Mr. Ludwig Mond, a successful technical chemist, who in this most appropriate manner recognized the debt of applied to pure science by the foundation of a laboratory devoted espe- cially to the furtherance of research in physical chemistry. What, then, has been the position occupied by Clark University in the ranks of this march of progress? Naturally it has been a modest one. Without a separate laboratory building, with a small equipment, and a staff reduced to the minimum, it has of course not been able to rival in quantity the work of its greater predecessors. It may, however, be re- marked that limitations of size are not necessarily limitations of quality. The relatively small number of students coming here have received greater individual attention than would have been possible at more crowded institutions. In spite of our limited space and equipment, it has always been found possible to put in possession of each student apparatus suitable for the performance of original research, and to give him what is more important, minute personal direction and encouragement. In this manner students coming to us from the colleges, often ill prepared for the severe mathematical work so necessary to the physicist, but to which they have Physics. 91 been little accustomed, are rapidly pushed on, and recover their places in line. The Department of Physics was, during the first three years of the history of the University, under the direction of the distinguished physi- cist, Professor Albert A. Michelson, who was then called from it to take the conduct of the larger department at the University of Chicago. During his stay at Clark Professor Michelson was engaged in research in the field of optics, inventing a method for the study of radiations from both celestial and terrestrial bodies, by means of an instrument devised by him, and depending on the interference of light. By means of this ingenious and elegant method, valuable results in connection with spec- troscopy and the measurement of small astronomical objects were obtained, upon which a number of papers were published. Before the termination of his labors here, Professor Michelson was invited by the International Bureau of Weights and Measures to make, by means of his new apparatus, a comparison between the international standard of length and the length of a certain wave of light, thus establishing a natural unit of length. A new apparatus having been designed and constructed under the direc- tion of Mr. F. L. O. Wadsworth, preliminary observations were made at the University, and, obtaining leave of absence. Professor Michelson and Mr. Wadsworth proceeded to Paris, where the experiment was carried out with marked success, constituting a performance in metrology that will undoubtedly become classical. During his conduct of the department, Professor Michelson delivered usually one lecture a week, on various subjects concerning the Theory of Light, especially connected with his own researches. Upon the be- ginning of the incumbency of the writer, a consecutive course in theoreti- cal or mathematical physics was planned, and has been regularly delivered, the course covering five lectures a week for a term of two years. Per- haps the principal claim that can be made for the department is the stress that has been laid upon the subject of mathematical physics, undoubtedly the most difficult branch for the student, and one which has not yet be- come popular in this country, yet which is of prime importance, and without which none can hope to reach the highest position in the science. A gratifying testimonial to the truth of this contention is furnished by the recent arrival at the University of two students, both doctors of phi- losophy from German universities, who have come here impressed with their need for more study of mathematical physics. 92 Department of In this course tlie several parts of the subject are treated in regular order, as parts of a logically connected whole, starting from the funda- mental basis of dynamics. The course is attended by every student in the department, and he is held responsible for a knowledge of its subject- matter in his examination for the doctor's degree. It is safe to say that in this respect the requirement for the degree is not exceeded at any institution in the country. The regular courses of the cycle are as follows : — 1. Dynamics. — General Methods, Canonical Equations, Methods of Hamil- ton and Jacobi, Systems of Particles, Eigid Bodies. 2. Newtonian and Logarithmic Potential Functions, Attraction of Ellipsoids. 3. Elasticity, Hydrodynamics, Wave and Vortex Motion, Dynamical Basis of Sound and Light. 4. Electricity and Magnetism. 6. Optics, Physical and Geometrical. — Elastic and Electromagnetic Wave- theories. 6. Thermodynamics, Thermo- and Electro-Chemistry, Kinetic Theory of Gases. 7. The Partial Differential Equations of Mathematical Physics. Laplace's Equation, Equation of Thermal and Electrical Conduction, Equation of Wave-motion, Telegrapher's Equation, Developments in Series, Legendre's, Laplace's, Bessel's, and Lame's Functions. Besides these, it has been the practice to deliver each year at least one new course, so that certain courses are delivered occasionally. A num- ber of courses in pure mathematics have also been delivered at various times, supplementing those of the mathematical department. These extra courses have been as follows : — Dynamics of Cyclic and Oscillatory Systems, with applications to the The- ory of Electricity, Sound, and Light. Comparison of the Theories of the Ether. Theory of Functions of Real and Complex Variables. Definite Integrals, Fourier's Series. Ordinary Differential Equations. Linear Differential Equations, particularly of the second order. Elliptic Functions (notation of Weierstrass), with certain physical applica- tions, including the theory of the Top. Orthogonal Surfaces and Curvilinear Coordinates, and their applications. Of the lectures in the above course one volume, on the theory of elec- tricity and magnetism, has been published, and has apparently been of use Physics. 93 to teachers in other institutions. Other volumes are in course of prep- aration. In addition to the lectures, a weekly colloquium or meeting for the discussion of questions in experimental physics has been held. Here reports upon current articles in the leading physical journals are deliv- ered by the students, and the most important classical determinations are also taken up, in order that familiarity may be gained with the methods of the masters of research. These meetings have been of great help to students, and have given them practice in presenting their ideas before an auditory. Beside the work of instruction, research has been carried on in the laboratory by every student and the professor. When a stu- dent arrives at the University he is at first put at work upon a subject designed to test his powers, and to give him familiarity with the princi- ples of exact measurement. When he has shown his ability, he is encour- aged to undertake a research for himself, under the continual guidance of the professor. In this way the undertaking of research before the necessary experience has been gained is prevented, and the publication of trifling or ill-considered articles is discouraged. As a rule a student devotes at least two years to the preparation of a doctor's dissertation. Thus the number of published researches is limited. Six doctor's disser- tations have been published, and another is ready for publication. Be- side these a number of other researches, both theoretical and experimental, have been published, one of which latter was honored by a substantial money prize in an international competition. These researches have not been confined to any one branch of physics, but have dealt with molecular physics, electricity, magnetism, and sound. Most of them have been of such a nature that the student was forced, not to work in a single narrow specialized line, but to gain a large amount of experience in various parts of the subject. A research of this nature is of far more value to the student than one performed simply for the purpose of gaining him a de- gree, and dealing only with a narrow range of ideas. The subjects of the dissertations have been as follows : Mr. T. P. Hall worked out a new method for the determination of the surface tension of liquids, suggested by Professor Michelson, in which the pull upon a film of liquid was directly weighed by a balance. Mr. C. A. Saunders made a determination of the velocity of electric waves in parallel wires, by a direct method, in which the wave-length and period of the waves were measured, the latter by photographing the periodic spark giving 94 Department of rise to the wave by means of a revolving Foucault mirror, the wave- length by measuring the length of the wires, which was made to be a quarter wave-length by means of electrical resonance. This research demanded a large amount of time, and elaborate apparatus. In connec- tion with the revolving mirror a convenient method devised by the writer for maintaining a constant angular velocity was made use of. Mr. T. W. Edmondson determined the distances necessary for the formation of a spark at varying potentials between spheres of different sizes in air and in various insulating liquids, the potentials being measured by means of an absolute attracted disk electrometer. Mr. S. N. Taylor made a com- parison between the important cadmium element devised by Weston with the well-known Latimer Clark standard cell, in which he compared their electromotive forces by means of an electro-dynamometer, obtaining results agreeing remarkably well with those obtained by a quite different method at the German Reichsanstalt. Mr. W. P. Boynton carried out an experimental verification of the theory of the action of the peculiar high-frequency induction coil invented by Elihu Thomson and Tesla, which had never been mathematically treated in detail, not to say experi- mented upon. This work involved a large number of difficult measure- ments, including the currents, potentials, and frequencies of oscillation involved in the working of the apparatus. The results were in excellent agreement with the theory, considering the difficulty of the experiments. Mr. A. P. Wills undertook the development of a new and ingenious method, suggested by the writer, but materially improved by him, for measuring the magnetic permeability of substances, whether magnetic or diamagnetic, differing so little in this respect from air as to be not amenable to the usual methods. By means of a simple arrangement involving the use of a slab of the substance suspended in the field of a powerful electromagnet with peculiarly shaped pole-pieces, the effect was measured by the pull on a sensitive balance, so that accurate results were easily obtained. This work of Mr. Wills resulted in his being received into the laboratory of Professor du Bois, one of the leading authorities in magnetism, in Berlin, where he performed a number of other interesting pieces of research in the same subject. Mr. B. F. Sharpe spent the greater part of three years in developing a method devised by the writer for the measurement of the intensity of sound, a measurement of more than ordinary difficulty. The instrument depends upon the application of Michelson's interference methods to the measurement of the very small Physics. 95 distances involved in the vibration of plates set in motion by sound. The interference bands observed in an interferometer, of which one mova- ble mirror is fixed upon a plate of thin glass forming the back of a reso- nator, are observed through a moving telescope, or have their motion photographically registered. In this manner a very sensitive means of measurement is obtained, and it is possible to measure sound in absolute measure, even when it is rapidly varying in intensity, a result not before attainable. The applications of this method which have been already suggested are very numerous and important. Mention should not be omitted of the labors of Mr. F. L. O. Wads- worth, who, as assistant to Professor Michelson, by his untiring energy and especial skiU in the design and construction of apparatus, contributed in large measure to the success of the researches of the latter. The most important experimental paper published by the writer was a determination of the period of electrical oscillations in a circuit contain- ing a condenser and a coil, the purpose of the investigation being to verify the formula of Lord Kelvin, aU the constants of the apparatus being measured in absolute measure. For the research a new instru- ment was devised capable of breaking two electrical contacts at instants separated by a very small measured interval of time. The instrument was very sensitive, permitting the appreciation of less than a millionth of a second. This research, already begun in the attempt to improve a method for the determination of the ratio of the two units of electricity, was found to correspond to a question proposed by a committee in Paris having in charge the prize established by EUhu Thomson, and being sub- mitted for the competition, was awarded the prize of five thousand francs. During the first year of the history of the University a considerable sum was spent upon a set of meteorological instruments, especially for the study of atmospheric electricity, and research was begun in this subject by Mr. Alexander McAdie, of the Weather Bureau, who has now become a recognized authority upon the subject of lightning discharges. This work came to an end upon the departure of Mr. McAdie from the University, but it might with advantage be resumed, with the addition of observations of phenomena of terrestrial magnetism. In concluding this report, it will not be out of place to speak of the needs and ideals of the department for the future. It is extremely desirable that the courses in mathematical physics be repeated every year. 96 Department of instead of once in two years as at present, this being as often as the time and strength of a single lecturer will allow him to cover the subject. If this were done, students could then begin each year at the most appropri- ate part of the course, without waiting for the natural beginning in their second year, as is now necessary for those students coming in alternate years. Even more desirable than aid in instruction is assistance in experimental work. Research in the laboratory can be carried out much more economically if a number of assistants are available to carry out details, leaving the professor free for the more important work of planning and personally attending to the more difficult parts of the work. One of the most important adjuncts of the department, the workshop, in which a skilled mechanic is constantly employed in the construction of apparatus for research, is capable of great extension of facilities. The absolute necessity of this work cannot be too strongly emphasized, and the department could even at the present moment profitably employ two or three men instead of one. Research in physics demands instruments of great exactness, complication, and cost, so that the maintenance of such a department in which research is done entails more expense than that of any other scientific department, except engineering. Each partic- ular research requires much of the apparatus used in it to be particularly designed, so that in view of the frequent changes necessitated before it exactly fits its purpose, and of the fact that it is impossible as a rule to find it kept in stock by dealers, it is more economical to have apparatus constructed in the workshop of the department under the eye of the professor than to have it made elsewhere. In designing an ideal laboratory, one of the first things to be con- sidered would accordingly be a workshop well equipped with modern machine tools, with an ample and convenient source of power for driving them, and with a large electric storage plant, both as a source of supply for investigations in electricity and magnetism, and for the purpose of furnishing power in smaller quantities than would require the main supply. An optical shop would greatly increase the capability of a laboratory for work in light. That such a suggestion is not extrava- gant is shown by the fact that Professor Michelson's new and ingenious echelon spectroscope was constructed by methods devised by him in the workshop of his laboratory, and could not have been so well constructed anywhere else. The famous diffraction gratings of Professor Rowland Physics. 97 have for years furnished a further striking example, forcing European physicists to send to this country for their supply. A laboratory should be provided with the means for the determina- tion of the important physical constants of nature, such as the velocity of light and of electric waves, of the Newtonian constant of gravitation, of the mechanical equivalent of heat, and of the fundamental relation between electricity and magnetism, the so-called " v " of Maxwell. Thus it would be possible not only to initiate students into the most precise methods, but even to hope to improve upon classical determina- tions. Ample facilities should be always at hand for the comparison and calibration of the important physical standards of measurement, such as those of length, time, mass, of electrical and magnetic quantities. The small facilities in this line possessed even by our national govern- ment are in painful contrast to what is seen in Europe, particularly in the German Imperial Physico-technical Institute, in which a million or more of dollars is invested. Beside the matter of accurate measurements of well-known phe- nomena lies the wider field of research in fields which are sure to prove fertile in new discoveries. The great domain of electrical waves, a creation of the last decade, although already exploited by scores of ob|servers, is still full of interesting problems, that are sure to yield a rich reward to those who shall devise more perfect methods of investiga- tion. The field of spectroscopy, whether in its terrestrial or celestial applications, is an enormous one. To this is to be added the study of radiations in general, of whatever character. The recent discovery of Rontgen was followed quickly by hundreds of researches bearing on the rays discovered by him, resulting in the discovery of several closely allied forms of radiation, and in a greatly increased interest in the phenomena of electrical discharges in vacuum tubes. Here remain a multitude of questions to be decided. The nature of cathode and of Rontgen rays remains to be settled, and will probably be one of the achievements of the early years of the next century. Research on the liquefaction of gases, and on the properties of bodies at temperatures not far removed from the absolute zero, until recently limited to a few observers possessing far more than ordinary facilities, will soon furnish a field for the labors of many, who will undoubtedly be well repaid. The many relations predicted by the recent applications of thermody- namics, especially in the domain of physical chemistry, remain in large 98 Department of Physics. measure to be verified. The science of meteorology, hitherto largely an empirical one, remains to be put upon a satisfactory theoretical basis, and presents many problems for the physicist to attack in his laboratory. The same may be said of geology, which is, for example, vitally con- cerned with the thermal properties of rocks and other materials of the substance of the earth, and with many problems concerning the physics of the earth's crust. The foregoing is but a brief sketch of the field of physical investiga- tion. The enthusiasm of one devoted to the performance of research, and considering it the most attractive form of human endeavor, would enable him to enlarge the subject over many more pages than are here available. The field is enormous, and each new discovery leads to new paths of inquiry. It is obvious that, in order to enter upon these attractive fields of work, one must be provided with large resources. Is it unreasonable to look forward eagerly to the day when Clark University shall possess a well-equipped physical laboratory building, fitted out with the utmost that our knowledge can suggest, in which we may hope to contribute our just share toward the enlargement of the boundaries of science, and thus to the welfare of humanity? DEPAETMENT OF BIOLOGY. By Clifton F. Hodge. PAST AND PRESENT STAFF. Charles 0. WniTMAiir, Ph.D., Professor of Animal Morphology, 1889-92. Teanklin p. Mall, M.D., Adjunct Professor of Anatomy, 1889-92. Heney H. Donaldson, Ph.D., Assistant Professor of Neurology, 1889-92. Waeeen p. Lombaed, M.D., Assistant Professor of Physiology, 1889-92. Clifton V. Hodge, Ph.D., Assistant and Fellow in Neurology, 1889-91; Assistant Professor of Physiology and Neurology, 1892-. J. P. McMuEEiCH, Ph.D., Docent in Morphology, 1889-91; Assistant Pro- fessor of Morphology, 1891-92. Adolf Mbybe, M.D., Docent in Psychiatry, 1895-. fGEOEGE Baue, Ph.D., Docent in Comparative Osteology and Paleontology, 1890-92. Died June 25, 1898. John C. Caedwell, M.D., Assistant in Physiology, 1889-91. Sho Watasb, Ph.D., Lecturer and Assistant in Morphology, 1890-92. FELLOWS AND SCHOLARS. Feanklin W. Baeeo-ws, M.D., Fellow in Physiology, 1893-94. Charles L. Beistol, Fellow in Morphology, 1891-92. Heemon C. Bumpus, Fellow in Biology, 1889-90. Albert C. Eycleshymee, Fellow in Morphology, 1891-92. Charles L. Edwards, Ph.D., Fellow in Morphology, 1890-92. E. E. GuRLBY, M.D., Fellow in Biology, 1895-96. Homer Gage, M.D., Honorary Scholar in Anatomy, 1889-90. Edwin 0. Jordan, Fellow in Morphology, 1890-92. Hbebert p. Johnson, Fellow in Morphology, 1891-92. F. C. Kenyon, Ph.D., Fellow in Biology, 1895-96. tW. E. LocKwooD, M.D., Fellow in Physiology, 1891-92. Died June 23, 1897. Feank R. Lillie, Fellow in Morphology, 1891-92. A. D. Mead, Fellow in Morphology, 1891-92. William S. Miller, M.D., Honorary Scholar, 1889-90; Scholar in Anatomy, 1890-91 ; Fellow in Anatomy, 1891-92. James E. Slonakee, Fellow in Biology, 1893-96. 100 Department of Colin- C. Stbwaet, Scholar in Physiology, 1894-95 ; Fello-w in Physiology, 1895-97. Fbedbeick Tuckebman, M.D., Ph.D., Fellow in Anatomy, 1889-90. William M. Wheeler, Fellow in Morphology, 1890-91 ; Assistant, 1891-92. SPECIAL STUDENTS. James Jenkins, Special Student in Biology, 1894-95. Preston Smith, Special Student in Physiology, 1899. W. Gr. Watts, Laboratory Steward and Special Student, 1889-91. HISTORICAL REVIEW. It will be seen from the above list of appointments that the depart- ment was organized to cover animal biology. Animal morphology, ver- tebrate anatomy, physiology, comparative osteology and paleontology, and neurology, which forms the natural transition to psychology, and has been classed in that department, formed a compact and well-selected group with which to begin work. This organization was still further strengthened by a strong force of organic chemists in this fundamental department. A good share of the equipment necessary for different lines of research work already in progress or planned by the different appointees had been ordered during the previous summer, so that the work of the whole department began practically with the opening of the University. Zeiss microscopes of the most approved patterns and with full complements of apochromatio eye-pieces and objectives, Thoma microtomes, together with those of Minot, the Minot-Zimmerman, Schanze, and others, complete assort- ments of chemical reagents, stains and laboratory tools, apparatus and glassware, all were supplied with liberality. Abundant and suitable rooms were also placed at the department's disposal in the main univer- sity building. Two large rooms and a convenient dark room for photo- graphic purposes on the fourth floor were assigned to physiology and were devoted to laboratory and lecture-room with workshop equipped with lathe and tools for working both wood and metals. Four large rooms on the third floor were arranged to accommodate anatomy and morphology for laboratories, lecture-room and drafting room ; and, in addition, four small rooms adjoining supplied office and library for the head of the depart- Biology. 101 ment, and private laboratories for three of the docents and assistants. Two rooms on the second floor, adjoining the psychological department, ■were assigned to neurology, the one for private laboratory and office of Assistant Professor Donaldson, the other for his general laboratory. All of these rooms were equipped with water and gas, and some with hoods to render them the most convenient and ideal laboratories possible, and the morphological laboratories were furnished with five large aquaria, the largest being eight feet in length, all supplied with running water, and a large number of smaller glass aquaria which made it possible to keep all sorts of aquatic animals both summer and "winter. While the chief emphasis both as to equipment and disposition of the instructor's time was given to research, the side of instruction toward breadth and depth of view, so necessary to the highest type of investiga- tion, was not neglected. Models of the brain (Auzoux, Aeby, Ziegler), as well as Ziegler's models of classic embryological types, and a complete set of Leuckart & Nitche's zoological charts, and an extensive library of wall charts copied from various monographs and text-books, all these, supplemented by anatomical and zoological specimens, gathered as rapidly as possible to form the nucleus of a museum, imparted the best possible quality to the work of instruction. In fact, instruction and research began together and went hand in hand, the one aiding the other. Professor Whitman immediately began courses of lectures funda- mental to the doctrine of evolution. The first of these treated, entirely from original sources, the historical development of Compara- tive Anatomy, beginning with its renaissance in the works of Marco Aurelio Severino (" Zootomia Democritsea, id est Anatome generalis totius animalium opificii libris quinque distincta," 1645), and bringing the sub- ject down to the discussions, just preceding the Darwinian epoch, between Etienne Geoffroy Saint Hilaire and Georges Cuvier (1830). As Professor Whitman himself announced with reference to this early course : " Attention will be directed particularly to the origin and development of historic ideas, tendencies, methods, and schools, as pre- sented in the early iatric and physiological stages of Zootomy ; in the works of Haller, Geoffroy, and Cuvier; in the 'Anatomic Philosophique ' of the French, and the ' Naturphilosophie ' of the Germans ; in the doctrines of the 'Scale of Nature,' 'Unity of Composition,' and of ' Types ' ; in the hypotheses of Evolution and Epigenesis, in Homology 102 Department of and Teleology, etc. The biograpMcal side of the subject -will also receive due consideration, especially in the cases of such representa- tive men as Malpighi, Swammerdam, and Leeuwenhoek of the seven- teenth century, and Haller, BufEon, Daubenton, Linn^, John Hunter, Camper, Vicq-d'Azyr, Kielmeyer, Geoffroy, and Cuvier of the later period." A second and third historical course was devoted respectively to the subjects of Generation and Comparative Embryology. These courses, compactly coordinated, and following logically on the development of comparative anatomy, were likewise worked up from original sources in Aristotle, Harvey, John Hunter, Wolff, Von Baer, and others, and led naturally up to the modern doctrines of heredity as developed by Lamarck, Darwin, Weismann, and their followers. Especially in the course in Comparative Embryology, the present phase of biological work, cytological technique and terminology, were fully treated, together with matters of interest in recent discussions as to origin and maturation of ova and spermatozoa, phenomena of fecundation, cleavage of the ovum, with comparison of different types of cleavage and experimental researches in cleavage, gastrular and pre-gastrular stages, their differ- ent types and derivations, germ layers, the trochosphere, budding and fission, formation of the embryo in invertebrates and vertebrates, to- gether with that of double and multiple monsters, and, finally, the course culminated in a discussion of the origin and significance of metameric segmentation. Simultaneously with these courses Dr. McMurrich lectured on the ccelenterates and platyhelminths, sifting all discoverable evidences for coelenterate ancestry of the worms, the origin of segmentation, and the significance of coelenterate structure in gastrular stages of vertebrate embryos. Dr. Baur on the side of paleontology discussed the osteology of reptiles and mammals, living and extinct. Dr. Bumpus also lectured on the aifinities of the Crustacea. For two years, as a means of uniting still further instruction and research, and of keeping all members of the department in touch with one another, an active biological club was maintained. Monthly meet- ings were held, and at each a carefully prepared lecture was read and discussed. The subjects of these lectures indicate to such an extent the lines of interest developed in the department, that a list for 1890- 92 is given in full. Biology. 103 1. Scope and Aims of the Club. — C. 0. Whitman. 2. Ideas on the Origin of the Galapagos Islands and the Origin of Species. — Geo. Baur. 3. Insect Metamorphosis. — W. M. Wheeler. 4. The Origin and Significance of the Blastopore. — J. P. McMurrich. 6. Nitrification and Nitrifying Organisms. — E. 0. Jordan. 6. The Animal Ovum. — Sho Watase. 1. The Salisbury Expedition to the Galapagos Islands. — Geo. Baux, 2. The Third Eye of Vertebrates. — A. C. Eycleshymer. 3. Some Points in the History of Bacteriology. — E. 0. Jordan. 4. Amphimixia in the Protozoa. — H. P. Johnson. 6. Nervous System of MoUusca. — E. E. Lillie. 6. Germ Cells. — Sho Watase. 7. Mammalian Spermatogenesis. — Sho Watase. 8. Metamerism in Arthropods. — W. M. Wheeler. The scope of work of the morphological section will be seen more fully in the list of investigations which follows, under the heading of Research Work, which has been grouped together for all divisions of the biological department. In Vertebrate Anatomy, Dr. Mall lectured for three successive years on the histology of tissues arising from the mesoderm, on the develop- ment of serous and blood spaces in vertebrates, and on the development, histology, and comparative anatomy of the organs arising from the endoderm. Dr. Tuckerman lectured in connection with his research work, on the gustatory organs of mammals, and Dr. Miller likewise on the lobule of the lung with its blood-vessels. In Physiology Dr. Lombard devoted a series of lectures of a year each, supplemented by numerous demonstrations, to the following sub- jects : — 1. Physiology of Muscle and Nerve. 2. Physiology of Circulation and Kespiration and the Nervous Mechanisms by which they are regulated. 3. Physiology of Muscle, Nerve, and Spinal Cord. Dr. Cardwell gave a number of lectures upon Animal Locomotion and Coordination. And Drs. Hodge and Jordan lectured respectively on the Physiology of Spinal and Peripheral Ganglia, and the Physiology of Leucocytes. 104 Department of A convenient laboratory was fitted up with microscopes, microtomes, and all needed instruments, materials, and reagents for neurology. A number of brain and other neurological specimens were prepared for purposes of instruction and demonstration, and the best neurological models were purchased with this end in view. Dr. Donaldson lectured during 1889-90 on the anatomy of the central nervous system in man ; and in 1890-91 completed the course by treat- ing the peripheral nervous system and discussing at length the various physical measures, so-called, of intelligence as found in the brain, its size, weight, convolution, thickness of cortex, and relative development of lobes, as these have been presented in the history of neurology. The course was repeated in 1891-92, together with a practice course in the laboratory on the histology of the nervous system. A seminary which met once a week was devoted to the reading of papers on neurological topics, both of historical and current interest, and to reports on work in progress in the laboratory. The primary aim of the department, as Professor Whitman expressed it, is to make " research men," men imbued with the spirit and desire for original investigation. This purpose is seen in all the courses of instruc- tion and becomes even more patent in the number of investigations actually in progress in the different laboratories of the department. In fact, the serious work of every member was research, for which lecture and semi- nary combined to form an appropriate historical and philosophical back- ground. During this period. Professor Whitman being in charge of Woods HoU Marine Laboratory, practically all the men in morphology continued their studies there through the summer seasons, taking microscopes, apparatus, and reagents from the University. Lectures were also given at Woods HoU by Professors Donaldson, Lombard, and McMurrich, and Drs. Watase, Wheeler, and Jordan assisted Professor Whitman with the laboratory instruction. The following resume is given to present a general picture of the spirit and scope of the department's work during this three-year period. KESEARCH WORK. Professor Whitman, in addition to editing the Journal of Morphology, equipping and directing a new and complicated laboratory, and giving Biology. 105 regular lectures, spent most of his time investigating the Hirudinea, publishing a series of papers on their classification, with descriptions of new species, on their metamerism, and on their hypodermic impregnation by means of spermatophores. " Specialization and Organization," " The Naturalist's Occupation," and other papers show that he was following lines of more general interest both in scientific work and in public education. Dr. Baur was delving in problems of fundamental importance in com- parative osteology of vertebrates, morphology of the vertebrate skull, carpus, ribs, etc., and working out the descriptions of a number of forms discovered during his successful paleontological expeditions. A good share of his work grouped itself about the plan of his great expedition to the Galapagos Islands, which was finally made possible by the munificence of the Hon. Stephen Salisbury, together with contributions from Pro- fessor H. F. Osbourn and from the Elizabeth Thompson Science Fund. This trip Dr. Baur made (in company with Mr. C. F. Adams) be- tween May and October of 1890, visiting all the islands, excepting Nar- borough, Wenman, and Culypepper. Extensive collections of both flora and fauna were obtained, which were worked up by Dr. Baur himself and by specialists both in this country and in Europe. The main general result of the expedition was a demonstration of the fact that the life on these islands is harmonious, and hence that the islands themselves must be explained on the subsidence theory, rather than on that of emergence as held by Darwin, Wallace, and others. Dr. McMurrich devoted his time chiefly to investigating the morphol- ogy and embryology of the Actinozoa, and from these researches derived his conclusions as to the phylogeny of the group. Dr. Watase was at work on various fundamental problems on the cell, caryokinesis, cleavage of the ovum, spermatogenesis, and sex differentiation. The research work of other members of the department was dis- tributed as follows : Mr. Johnson investigated the morphology and biology of the Stentor. Mr. Lillie studied the embryology of Unio. Dr. Wheeler worked upon the embryology of the Insecta, and in that connec- tion investigated the neuroblasts in the Arthropod embryo. Dr. Bumpus completed his study, already under way, upon the embryology of the American lobster. Dr. Edwards studied the embryology of the Holo- thurians. Dr. Jordan studied the life history and embryology of the common newt ; and Mr. Eycleshymer made a special investigation of the development of the optic vesicle in the amphibian embryo. 106 Department of In the closely allied field of vertebrate anatomy, Dr. Mall was making a minute study of a human embryo, investigating the formation of the lesser peritoneal cavity in birds and mammals, the motor nerves of the portal vein, and also completed his important work on a new connec- tive tissue element, the reticulated connective tissue, with its distribu- tion in the body. Dr. Tuckerman carried on an extended research on the gustatory organs of a series of animals, and their development in man. Dr. MiUer also worked out the minute anatomy of the lung, and by a most exhaustive and varied method succeeded in demonstrating for the first time the manner of ending of the terminal bronchi, together with their relations to the arteries, veins, and capillary system. On the side of practical surgery Dr. Homer Gage conducted a series of experiments on intestinal suture. In physiology Dr. Lombard continued his investigations on effect of fatigue on voluntary muscular contractions and alterations in strength which occur in severe muscular work, and on the conditions, barometric pressure, temperature, sleep, food, alcohol, and tobacco, which effect voluntary effort. Dr. Cardwell investigated the physiology of the cerebellum with relation to animal locomotion and coordination. For neurology Dr. Donaldson was pursuing a similar plan with that followed by Dr. Whitman in morphology, viz., gathering the history of the science from original sources, and reducing to uniform statements, tables, and curves all the data as to size and weight, both relative and absolute, of the brain. In this connection he made an exhaustive study, both gross and microscopical, of the brain of Laura Bridgman. An extended series of observations was also being carried on in the laboratory upon the influence of hardening reagents upon brain weight and specific gravity. Dr. Hodge worked for two years (1889-91) on the physiology of nerve cells, their diurnal fatigue and recovery in sleep, and their recovery from effects of electrical stimulation. Dr. Donaldson, with Dr. Bolton, completed a study of the size of the cranial nerves in man, and Dr. Bolton studied microscopically the spinal cord of a horse affected with spring halt. The above gives, in the main, a picture of the work in progress during the first three years of the department's existence. AU but one or two of the researches mentioned have been published, together with others not cited. For place of publication and the complete record the reader is referred to list of publications by members of the University for the corresponding years. Biology. 107 If one science is entitled to claim the special interest of the founder more than another, biology is that science ; and in the organization of this department, the aim above all else was to make it the most ideal pos- sible place for biological research. Foundations were laid at this time for a special building more adequately to house this flourishing depart- ment. How well the ideal was realized may be seen from the estimate of Professor Whitman, whose experience in the laboratories of three continents entitles him to an opinion. "Writing in 1899, he says, " The Clark University Ideal, as I understood it when connected with its early work, is the ideal which I place above any other thus far proposed, and I hope it may find strong friends to help it forward." Unencumbered by the burden of undergraduate courses, untrammelled by red tape and traditions, the laboratory formed for three brief years a veritable garden spot in the field of biological history in this country. It was a place where each man was free to devote all his best energies to just that which he wanted most to discover; where the best thing a man could possibly do for himself constituted the highest service he could render to the University. A "Flying Squadron," has been suggested as the most fitting defi- nition for a university. Scarcely had this splendid organization been attained than it was carried off bodily, almost, to lay foundations for the biological department in a new university. While no higher tribute could have been paid to Clark University, it has left the department sadly crippled both for men and means for work. Since 1892 biology has been represented by but a single instructor. Dr. Hodge, who was recalled from the University of Wisconsin, with the title of Assistant Professor of Physiology and Neurology. For the first year Dr. Hodge offered only courses on the physiology, anatomy, and embryology of the nervous system. During the succeeding years, owing to the great need of having the subject presented, a course in gen- eral biology has been given, the aim of which is to present the funda- mental principles of the science. A sense of the importance of this course has grown from year to year, with the conviction that the sub- ject finds too little representation in most of our educational institutions ; and it is hoped, as soon as practicable, to develop it into a solid course, historical, philosophical, and practical, to extend through all of two and possibly three years of university study. The main courses offered by Dr. Hodge have related to anatomy and physiology of the nervous sys- 108 Department of tem, botli comparative and human, including the sense organs as well, and to the entire field of physiology and to that of embryology, especially of the nervous system and sense organs. These have been supplemented, wherever possible, by laboratory courses. A seminary meeting, usually one evening weekly, has been maintained, the plan of which has been, in the main, to spend a year upon each of the three following top- ics : 1, history of medicine, with special reference to physiology, epochs, schools, and men ; 2, history of, and present discussion centring about, the doctrine of evolution ; 3, development of neurology. A journal club, meeting weekly, has aided to bring all members of the department together for discussion of articles in current literature. In general, all seminaries and courses of instruction have been given with reference to furnishing aid and stimulus to students in their research work. In addition to the above, on the teaching side. Dr. Hodge has become interested in lines, especially of biological education in ele- mentary schools. A definite standpoint for elementary nature study has been developed, which is a distinct reaction against the tendency toward technicality, classification, and minutiae which have come to constitute so large a part of our elementary science courses. It is planned to include this in the general biology course by way of discussing the question, What aspects of biological science shall be taught in the elementary school ? The kind of physiology which should form a part of elementary education has also been given considerable attention. Both subjects have formed the basis for courses in the summer school. In passing to consider the research work of the department since Dr. Hodge took charge of it, a word as to its general purpose and plan will simplify the discussion. Science, in this country especially, has become unnecessarily arrogant. We hear on all sides such expressions as " pure science," a term which Huxley wished had never been invented, " truth for truth's sake " or " science for the sake of science," and the " uselessness " of science is made a boast. An important truth is stated in these expressions ; for science is of such paramount use and importance to mankind that to discuss this point with one who says it is not, is clearly " casting pearls before swine." Possibly another reason for resorting to these expres- sions is that the human values attaching to knowledge are so enor- mous that we have no measures or terms with which to adequately express them. However this may be, if science have a faith worthy Biology. 109 of respect, it should result in mutual benefit to share it so far as pos- sible with a reasonable and intelligent public. A research laboratory is an institution the business of which is to investigate those problems which have either never been attempted or have hitherto baffled all efforts of the human mind to solve. These problems are not far to seek, but crowd upon our lives at every point. The values attaching to their solutions can be expressed only in terms of human life and happiness, compared with which the output of Klondikes and Cripple Creeks is but the small change of the hour. It is clearly recognized that we may not be able to estimate the value of truth until it be discovered, and that the investigator himself, who is willing to devote his time and energies to the work, should be the one to estimate its values, and that he should have the greatest freedom to select the task for which he knows himself to be best fitted. Still, one must be a man before he can be a scientist, and fundamental human values must be in the main the same for all. And it would seem to be the first duty of a research laboratory to devote its resources to the work of solving those problems which concern human life most closely, and possess the greatest human importance. A laboratory owes no less than this to a community ; or, better stated, a laboratory is that part or organ of a community differ- entiated to perform the special function of discovering and making avail- able whatever truth is of greatest value to its common life. In deciding the directions, therefore, which research work shall take, the above general policy has been followed, and it is a satisfaction to note that the same sentiment was prominently expressed at the founding of the University. On that occasion Mr. Hoar spoke as follows : — " Speaking now for myself alone, I have little sympathy with that arrogant and disdainful spirit with which some men who undertake, with little title, to represent science in this country, sneer at any attempt to make use of the forces she reveals to us for the service of mankind. Some one said the other day that science was becoming a 'hod-carrier.' I do not see why the term ' hod-carrier ' should express the relation rather than the term ' benefactress.' I do not see, either, that there is anything degrading in the thought that the knowledge of the learned man enables him to lift the burden beneath which humanity is bowed and bent. I do not know that science is exempt from the divine law, ' He that is greatest among you, let him be the servant of all.' If the great forces of the universe perform all useful offices for man, if the sun- shine warm and light our dwellings, if gravitation move the world and keep it true to its hour, nay, if it keep the temple or cathedral in its place when the 110 Department of hod-carrier has builded it, I do not see why it shoidd not lend its beneficent aid to him also. Our illustrious philosopher advised his countryman to " hitch his wagon to a star." The star will move no less serenely on its sublime pathway when the wagon is hitched to it. I do not know that any archangel or god- dess, however resplendent the wings, has ever yet been constructed or imag- ined without feet. I do not know that any archangel, however glorious, has ever been created or imagined without sympathy for suffering humanity. " I look for great advantage to the country, both in wealth and power and in the comfort and moral improvement of the people, by the application of science to the useful arts." The manner in which this fundamental purpose has been carried out thus far may now be seen in part in the lines of work which have been carried out, and, more fully, in plans for the future. In this country of, so-called, nervous tension, nervousness and nervous prostration, nothing could be of greater value to the common life than knowledge of the fundamental laws of the working of nerve protoplasm. It is only in discovery and obedience to these laws that we may hope for escape from present evils and possession of sane and permanent national health. Consequently lines of investigation upon the physiology of the nerve cell have been kept open from the beginning. Continuing the studies mentioned in speaking of an earlier period in the history of the laboratory, the nerve cell has been studied during its electrical stimulation and also in connection with changes which occur in the process of aging and in death from old age. Dr. Barrows has investigated its appearance under various kinds of diet and when the body has been deprived of food. Dr. Stewart has studied the effect of alcohol on the cells of the cerebrum, cerebellum, and spinal cord. Drs. Starbuck and Lancaster respectively studied effects on the nerve cell of artificial (by means of electrical stimu- lation) and natural fatigue carried to an extreme degree. Dr. Kenyon devoted a year to a most successful study of the brain of the honey-bee. Dr. Burk devoted considerable time in working out the meduUation of the brain in puppies. Dr. Goddard tested by especially rapid methods of preparation theories as to the possible amoeboid movements of nerve cells in conditions of activity and sleep. Further experiments are now in progress on the influence of alcohol, and work has been begun on the effect of other chemical substances, notably strychnine, morphine, and nicotine on nerve cells. For the purpose of making possible a more prac- tical study of the human brain, a brain microtome has been devised in the laboratory by Dr. Goddard, with suggestions from Dr. Hodge. This Biology. Ill instrument is constructed on principles new to such microtomes thus far made, and has rendered it possible to cut sections of the entire human brain in any desired plane with the ease and uniformity with which smaller sections are cut by the ordinary microtomes. The blade of this microtome was made, and presented to the University, by the firm of Loring, Goes, & Co. of Worcester. A research less closely connected with the general plan, but still es- sentially upon the nervous system, was carried out by Dr. Slonaker upon the eyes of vertebrates. This line of work in the physiology of the nervous system is one which the department proposes to continue, as opportunities and properly prepared men present themselves, imtil, it is hoped, the American public may be able to live on more amicable terms with its "nerves." In order to attack, in a more fundamental manner, problems centring about the nerve cell and its normal activities, it has been necessary to make a wide detour of investigation in two directions. The first of these has consisted in a study of the microscopical appearances of lymph as compared with different special protoplasms under various methods of hardening and staining. This has proved to be a matter of fundamental importance to histology in general, and has demonstrated that, until we are able to gain some definite notion as to the substances in question, it is useless to go on figuring and describing " granulations," and " fibrillse," " alveoli," and the like. The other line of research to which study of the rhythms of the nerve cell has led logically is that of the physiological conditions in general which underlie and determine phases of animal activity. In other words, if we wish to learn the condition of nerve cells in states of rest and fa- tigue, we must study first the normal rhythms of activity and rest of our animal. Knowing this, we may be able to examine the nerve tissues at any desired point in the curve of functional activity. And in order to gain the fundamental laws of nervous activity, we need to study these rhythms of sleep and waking, rest and activity, which make up the normal flow of an animal's life, in a series of animals. This fundamental work has not been done for more than one or two forms as yet, and for those only in a preliminary way. Dr. Aikin's study of vorticella, which showed that a one-celled animal is capable of continuous activity so long as food and environment remain suitable, was the first on the subject. Stewart's experiments on the influence of barometric pressure and diet. 112 Department of including alcohol, on the diurnal activity of rats and mice, together with Dr. Hodge's similar work on dogs and squirrels, serve further to indicate the possibilities in this field. These studies have pointed to the fact that the activity of each animal conforms to a type as to periods and rhythms which is characteristic of the species, and that the total amount of work developed is profoundly influenced by physiological conditions thus far investigated. These researches have been suspended for the present, but it is hoped to push the work in the near future along two main lines. The first of these aims to discover the typical rhjrthms of physio- logical activity for a series of animals, both invertebrate and verte- brate. It would seem that these physiological types are of even greater ultimate interest and philosophical importance than the purely structural and morphological types from which the comparative anatomists have worked out the evolutionary series. When this has been done, we shall be in position for the first time in the history of biological science to study hirtnan rhythms of activity and repose in the light of similar rhythms of the animal series, and to gain, possibly, some notion as to a norm for human work. The second line of study in this field essays to analyze the physiological conditions under which any particular animal is able to develop the greatest possible amount of normal activity. This is no less a problem at bottom than the study of the physiological conditions which underlie the highest possible types of human life and activity. The question naturally arises at this point as to what position the biological department of Clark University assumes upon some of the wider aspects of the science. Since the times when Aristotle employed the armies of Alexander the Great to collect specimens for his museums from all the then known world, the greater portion of biological effort has been directed toward classification and naming of animal and plant species. The uttermost corners of the earth have been searched to the tops of the mountains and dredged to the deepest ocean depths, all to discover some new species of animal or plant, while the common plants and animals of our dooryards are known scarcely more than in name. This classification work, ex- tending from Aristotle in Greece through Linne and Cuvier, Buffon and Brehm, to Agassiz in America, has been in part necessary and impor- tant. But, when it is possible to find single species which have been christened ten or even twenty times, it is safe to insist that the passion for naming things has been carried too far. This passion for names is Biology. 113 characteristic of a certain period in infancy in the individual, and, we may hope, in the growth of a science as well ; and while it gives the best promise for the future, is it not time to hope that this phase of biology may wane, and the maturer work of learning the really important facts concerning animals and plants be seriously undertaken ? These facts of paramount importance have to do with the functions of species, the work species do in the world. As a matter of fact, to work in classification by methods of external characters the monumental work of Darwin and Wallace has long since put a final period. Species are not fixed immu- tably, but are plastic and normally variable! Embryological studies, even by Louis Agassiz himself, proved that animals repeat simpler stages of organization each in its own life history. With the doctrine of evolu- tion the whole method of the science has been changed. Deeper char- acters than those on the surface must be discovered, and only such as reveal blood relationships and indicate the true position of the species in the line of evolutionary descent can be of permanent importance in the new classification. Thus the past two decades have been devoted in biological laboratories largely to tracing most minutely the embryology of different species, and in exhaustive studies into comparative anatomy and embryology combined. There has been a constant gravitation, natu- rally enough, to again consider the findings of the microscope, arrange- ments of cells, and all the infinite variety of granule and rod and fibril as fixed entities, rather than again as plastic and possibly changing with every phase of functional activity. There has thus been no limit to the careful drawing and figuring and coloring of what are supposed to be important structures in living protoplasm. This may all be well enough as pastime. But where the idea of functional changes has been left out of account, the work is builded on the sand. It is like studying and map- ping the positions, forms, and colors of the clouds by means of the nice adjustments of the telescope. Many of the books of the past decade will be museum junk before 1910, if they are not already. We need to real- ize in our modern laboratories that turning the crank of a microtome in .and of itself has no more educational value, possibly not so much, as turning the crank of a grindstone. In fact, our theories of laboratory research and even of laboratory instruction in the brief period in which these have come into prominence have gone far astray. In drifting away from all considerations of human good and even common sense, our modern laboratory work is in the same danger of becoming an end in 114 Department of itself that sunk tlie old classification into a worse than imbecile waste of time. Furthermore, progress is the word which has characterized every expression of the purpose of the biological department. The advance- ment of science has been its fundamental raison d'Stre from the beginning. There is little danger that the world will have too many institutions de- voted to the serious work of advancing science. The great difficulty has been, and, we may add, still is, that, after a period of great achievement, the inevitable tendency asserts itself to spin round and round about it as though there were nothing else ahead worth working for. The endless discussions of the past two decades reminds one of the hollow disputations of the scholastics. The coursing over and over again of the ground covered so well by Darwin and Wallace, and even by Aristotle, in great part, has been enough to raise the shades of some of these good men to urge us to cease hairsplitting and trifling, and go forward into the great field which their works have opened up. Their great contributions have consisted in demonstrating the plas- ticity of living forms, and the field which this presents is that of infinite possibilities of perfection and utilization in the future. It has opened up before us, instead of the dead finality, the idiotic circle with its endless round of " vanity of vanities," of the old philosophy, an infinite future of progress. In this progress Science must worthily lead, but may well hold Art by the hand, lest the doing of science, which is its consummation in virtue, fall behind, and Science, herself, languish for very lack of sustenance. We expect great help for the present status of biological science from Brooks's " Foundations of Zoology." To the question which he imagines Aristotle to ask : " Is not the biological laboratory which leaves out the ocean and the mountains and meadows a monstrous absurdity ? " this department would answer — Yes. And it would add that it is not enough to bring our laboratories to the ocean and make fine trips to the mountains and the ends of the earth, unless these great factors become a real part of the scientific quest. In a word, with the so-called discovery and naming of a species of animal or plant, and even with its embryonic and adult anatomization, biological science has scarcely touched the great problem which the species presents. With the half million species of animals and plants of which Science has told us scarcely more than the names, Art has stumbled Biology, 115 haltingly along, with aU too little help from Science, toward the perfection and utilization of a very few, our domesticated species. Even with these few the scientific biology of no single one has been adequately worked out, and we are practically in the beginnings of scientific studies as to the influence of environment in cultural conditions, and as to the possibilities for improvement in cross fertilization. Biological science owes to the world not only knowledge of the name, form, and structure of a species ; it owes as well a clear statement of what the species does, considered as a force in nature ; and further, the method by which this force can best be utilized. And this is no whit less pure science because incalculable human values attach to the knowledge. Biologically we are now at a stage comparable from the standpoint of physical science with that of the sail-boat and the stage-coach, before science had discovered, and discov- ered a way to utilize, the forces of steam and electricity. And we find, when we study carefully what one animal or a plant can do, and multiply this by the number of individuals in the species, values and magnitudes, which we scarcely possess terms to express. Add to the total amounts of forces which different species represent, the nicety of adjustment, the adaptation of means to ends, the intelligent direction of the forces, which make comparative psychology a part of biology, and we begin to realize the importance of biology as a science. No seed is too small to contain the power, under proper conditions, of covering the world with plants of its kind ; and, not only that, but generation after generation it may be capable of indefinite improvement. The most minute organisms, the bacteria, possess very few interesting features of form or structure that we are able to discover, but they have the power to determine the ultimate food supply of all animal life, on the one hand ; and, on the other, to cause the disease, suffering, and death of untold numbers of animals, and even human beings. Insects, on the one hand, have created fiowers and fruits by their work of cross fertilization, and, on the other, have laid a tax on human industries heavier than that of bad government and even of war. Since the side of function, of the actual work which a species can do, presents the greatest ultimate value connected with knowledge of living things, if modern biology does not go forward into this great field, its whole past history from Aristotle down AviU be an arrested development. The laboratory that undertakes this work must be a unique affair as biological laboratories go now. It should have greenhouses, terraria and 116 Department of aquaria, aviaries and insectories, in order to provide the essential elements of normal environment where the life and work of species may be conven- iently studied in both their daily rhythms and in their larger life cycles. It should especially have easily accessible the actual normal environment of the species under investigation, the pond, ocean, stream, grove, forest, hill, mountain, field, and garden, where results obtained in the laboratory can be readily tested and confirmed in the actual environment of nature. In fact, during favorable seasons much of this line of laboratory work might well be done out of doors. A laboratory of this kind need not be expensive, but should consist largely of rooms adapted for individual investigators, so that researches upon the life and work of a number of different forms may be carried on with the least possible mutual disturb- ance and interference. This is an absolute essential to investigations of this class. It should also be provided with sunny and sanitarily perfect quarters for not only keeping, but rearing and breeding, a con- siderable variety of animals. These and many other considerations render it imperative, if work of the best quality is to be turned out, that a biological laboratory have a building of its own. At present this lack has been one of the chief obstacles to prosecution of the important lines of work indicated. They cannot be successfully studied in rooms used for other purposes, or in a building shaken by the running of powerful dynamos and other heavy machinery. Natural rhythms and periods of rest and activity may be profoundly influenced by these disturbing conditions, and results thus largely vitiated. As already stated, the foundations for a biological laboratory have been laid, and an inexpensive building would greatly facilitate the work of the department. It ought to be erected under the idea, now gaining ground, that a laboratory should be a somewhat temporary building, which could be altered and reconstructed from time to time as new problems arise. The matter of biological nature study has already been referred to, and it is the opinion that such a research laboratory should be in organic relationship with elementary education and the public school. It is believed that this side of nature, the side of movement and activity, is the natural side of approach for the child. It is peculiarly akin to that animism of childliood which projects life and action even into inanimate things. It is this side of living nature, which, from its intrinsic fascinations and varied affinities with the passionate activity Biology. 117 of child life, is calculated to create enduring love" of nature ; and the vast human values and interests connected with it constitute the most natural wellspring for love of science. In line with this idea, two nature-study leaflets have already been printed, upon, respectively, the " Biology of the Common Toad " and the "Biology of Our Common Birds." Both of these were written by Dr. Hodge, and he has thus far assumed all financial responsibility for their publication. He also has in course of preparation similar studies on a series of biological subjects, insects, fishes, and reptiles, flowers, fruit, and forest trees, bacteria and moulds, and a few others, which will provide ample materials for nature study from the standpoint above indicated for the entire school course. On the one hand, such connection between the biological laboratory and the schools will furnish channels for the distribution of information to the public, and, on the other, may be made to supply, not only stimulus, but assistance to its work as well. Bacteriology is a recently created department of biology which has claimed recognition as an independent science by reason of its wonder- ful development since about 1880, when the discoveries of Koch, Pasteur, and Lister revealed the causal relations which exist between these minute organisms and disease. We can express the enormous values of scientific knowledge of these germs only in terms of human life itself. And it is a worthy refutation of the charge sometimes brought against science that it disregards the welfare of humanity that, as Professor Ludwig said, laboratories devoted to other lines of biological work have been depopulated, because their students have flocked into this new and important field. The bacteria are coming to be recognized as one of the most, if not the most, important element in the environment of animal and even plant species ; hence their consideration is essential in such studies as have been outlined above, which aim to determine the influence of environmental conditions upon the activity, health, and vigor of species. Still the pathological side will not be able long to dominate the science of biology ; and even with relation to diseased conditions, the side of normal function, physiology proper, must remain preeminent. In fact, it may even now be stated as the highest contri- bution of bacteriology, that it has revealed the fact that the highest possible health level is the best practical safeguard against inroads of microbic disease. Still the great importance of the subject has made it cause for regret that the resources of the department have not permitted 118 Department of Biology. the establishment of a well-equipped bacteriological laboratory. The next step in the development of the department should be in this direction. The library of the biological department has been selected with a view to making it the best possible working library for those engaged in biological research. THE DEPARTMENT OF PSYCHOLOGY. Bt Edmund Clakk Sanford. PAST AND PRESENT STAFF, i Gr. Stanley Hall, Ph.D., LL.D., President of the University and Professor of Psychology and Education since 1889. Heney H. Donaldson, Ph.D., Assistant Professor of Neurology, 1889-92. Clifton F. Hodge, Ph.D., Assistant in Psychology, 1890-91 ; Assistant Pro- fessor of Physiology and Neurology since 1892. Edmund C. Saneokd, Ph.D., Instructor in Psychology, 1889-92; Assistant Professor of Psychology since 1892. William H. Buknham, Ph.D., Docent in Pedagogy, 1890-92 ; Instructor in Pedagogy since 1892. Benjamin Ives Gilman, Instructor in Psychology, 1892-93. Alexander F. Chamberlain, Ph.D., Lecturer in Anthropology since 1892. Franz Boas, Ph.D., Docent in Anthropology, 1889-92. B. C. Burt, A.M., Docent in Philosophy, 1889-90. Alfred Cook, Ph.D., Docent in Philosophy, 1889-90. Herman T. Lukens, Ph.D., Docent in Pedagogy since 1895. Arthur MacDonald, A.M., Docent in Ethics, 1889-91. Adolf Meter, M.D., Docent in Psychiatry since 1896. Charles A. Strong, Docent in Philosophy, 1890-91. FELLOWS AND SCHOLARS. H. Austin Aikins, Ph.D., Fellow in Psychology, 1892-93 ; Honorary Fellow, 1893-94. Ernest Albee, Scholar in Psychology, 1889-90 ; Fellow, 1890-91. Arthur Allin, Ph.D., Honorary Fellow in Philosophy, 1895-96. N. P. Avert, Scholar in Psychology, 1895-96. Thomas P. Bailet, Jr., Ph.D., Fellow in Psychology, 1892-93. 1 As this list shows, the Department of Psychology has included, Anthropology, Crimin- ology, Neurology, Psychiatry, Education, and Philosophy. The report of work in Neurology has been incorporated by Dr. Hodge with that in Physiology and Biology. 119 120 Department of Henkt E. Bakee, Student in Psychology, 1894-95 ; Fellow, 1895-96 ; Honor- ary Tellow, 1896-97, and 1898-99. John A. Bekgstkom, Fellow in Psychology, 1891-94. Eugene W. Bohanhon, Scholar in Pedagogy, 1895-96 ; Fellow in Psychology, 1896-98. Feederick E. Bolton, Honorary Fellow in Psychology, 1897-98. Thaddeus L. Bolton, Scholar in Psychology, 1890-91 ; Fellow, 1891-93. Eenest N. Beown, Scholar in Psychology, 1891-92. Elmee B. Betan, Scholar in Philosophy, 1898-99. William L. Beyan, Fellow in Psychology, 1891-93. Feedbeio Buek, Scholar in Psychology, 1896-97 ; Honorary Fellow, 1897-98. Will G. Chambees, Scholar in Psychology, 1897-98. Waltbe Channing, Honorary Scholar in Psychology, 1889-90; Honorary Fellow, 1890-92. OscAK Cheisman, Fellow in Pedagogy, 1892-94. EoBEET Claek, Scholar in Pedagogy, Jan., 1898-June, 1899. Chaeles W. Clinton, Fellow in Psychology, 1897-98. Feedeeick W. Colegeove, Honorary Fellow in Psychology, 1896-99. Thomas E. Ceoswell, Scholar in Pedagogy, 1895-97. Hbney S. Cuetis, Fellow in Psychology, 1895-97. Aethue H. Daniels, Fellow in Psychology, 1892-93. Gboege E. Dawson, Fellow in Psychology, 1895-97. Fletchee B. Deesslae, Scholar in Psychology, 1891-93 ; Fellow, 1893-94. Feank Deew, Scholar in Psychology, 1892-93; Fellow, 1893-95. Feedeeick Eby, Scholar in Pedagogy, 1898-99. Stapeoed C. Edwaeds, Scholar in Pedagogy, 1897-98. A. Caswell Ellis, Scholar in Pedagogy, 1894-95; Fellow in Psychology, 1895-97. H. L. Evbeett, Scholar in Psychology, 1896-97 ; Honorary Fellow, 1897-98. Daniel Folkmae, Fellow in Psychology, 1889-90. Clemens J. Feance, Scholar in Psychology, 1898-99. J. Iewin Feance, Scholar in Psychology, 1896-97. Alexander Feasee, Fellow in Psychology, 1891-92. John P. Feuit, Scholar in Psychology, 1891-92. Heney H. Goddaed, Scholar in Psychology, 1896-97 ; Fellow, 1897-99. Cephas Guillet, Scholar in Psychology, 1895-96 ; Fellow, 1896-98. John A. Hancock, Fellow in Pedagogy, 1893-94. S. B. Haslett, Scholar in Psychology, 1898-99. Claek W. Hetheeington, Fellow in Psychology, 1898-99. tE. C. HoLLENBAUGH, Ph.D., Scholar in Psychology, 1892-93. Died July 6, 1893. William A. Hoyt, Scholar in Pedagogy, 1893-94. Edmund B. Huey, Scholar in Psychology, 1897-98; Fellow, 1898-99. D. D. Hugh, Fellow in Psychology, 1895-96. John P. Hylan, Fellow in Psychology, 1895-97. Psychology. 121 TiLMON Jbnkiks, Scholar in Pedagogy, 1897-98. Geobge E. Johnson, Scholar in Pedagogy, 1893-94 ; Fellow, 1894-95. E. A. KiEKPATEicK, Scholar in Psychology, 1889-90; Fellow, 1890-91. Milton S. Kistlek, Scholar in Pedagogy, 1897-98. Linus W. Kline, Scholar in Psychology, 1896-97 ; Eellow, 1897-98 ; Honorary Fellow, 1898-99. William O. Krohn, Ph.D., Fellow in Psychology, March-June, 1892. E. G. Lancaster, Scholar in Psychology, 1895-96 ; Fellow, 1896-97. James S. Lemon, Scholar in Psychology, 1891-93 ; Student, 1893-94. James E. Le Rossignol, Ph.D., Fellow in Psychology, May-July, 1892. James H. Leuba, Scholar in Psychology, 1892-93 ; Fellow, 1893-95 ; Honorary Fellow, 1895-96. Ernest H. Lindley, Fellow in Psychology, 1895-97. George W. A. Luckey, Fellow in Psychology, 1894-95. Frank H. McAssby, Scholar in Psychology, 1898-99. George F. Metzler, Ph.D., Fellow in Psychology, 1891-92. Dickinson S. Miller, Fellow in Psychology, 1889-90. Herbert Nichols, Fellow in Psychology, 1889-91. C. A. Orr, Scholar in Psychology, 1889-90. George E. Partridge, Special Student in Philosophy, 1895-96; Scholar in Psychology, 1896-98 ; Fellow, 1898-99. T.-EicHARD Peede, Special Student in Philosophy and Pedagogy, 1895-96; Honorary Scholar in Philosophy, 1896-97. Daniel E. Phillips, Scholar in Psychology, 1894-March, 95 ; Honorary Scholar, Jan. -June, 97 ; Fellow, 1897-98. Jefferson E. Potter, Scholar in Pedagogy, 1890-91. J. 0. QuANTz, Ph.D., Honorary Fellow in Psychology, 1897-98. J. F. EiEGART, Scholar in Psychology, 1890-91. EoBERT J. EicHARDsoN, FcUow in Psychology, 1898-99. Erwin W. Eunkle, Ph.D., Honorary Fellow in Psychology, Jan.-June, 1899. Albert Schinz, Ph.D., Honorary Fellow in Psychology, 1897-98. Alva E. Scott, Honorary Scholar in Psychology, 1894-95 ; 1896-97. Colin A. Scott, Fellow in Psychology, 1894-96. E. W. Scripture, Ph.D., Fellow in Psychology, Jan.-June, 1891 ; 1891-92. Charles H. Sears, Ph.D., Honorary Fellow in Pedagogy, 1897-99. Albert E. Segsworth, Honorary Fellow in Psychology, 1893-94. John C. Shaw, Scholar in Pedagogy, 1895-96 ; Fellow in Psychology, 1896-97. Henry D. Sheldon, Fellow in Pedagogy, 1897-99. Frederic D. Sherman, Ph.D., Honorary Fellow in Psychology, 1898-99. Toshihide Shinoda, Honorary Scholar in Pedagogy, 1889-90. Maurice H. Small, Scholar in Psychology and Pedagogy, 1895-96 ; Fellow in Psychology, 1896-98. WiLLARD S. Small, Scholar in Psychology, 1897-98 ; Fellow, 1898-99. Frank E. Spaulding, Ph.D., Honorary Fellow in Psychology, 1894-95. 122 Department of Edwin D. Starbuck, Fellow in Psychology, 1895-97. J. EicHARD Street, Scholar in Pedagogy, 1895-96; Fellow in Psychology, 1896-98. Charles H. Thurber, Honorary Fellow in Pedagogy, Jan.-April, 1899. Frederick Tract, Fellow in Psychology, 1892-93. Norman Triplett, Fellow in Psychology, 1898-99. Geraid M. West, Ph.D., Fellow in Anthropology, 1890-91 ; Assistant, 1891-92. Gut M. Whipple, Scholar in Psychology, 1897-98. MiNosuKE Yamaguchi, Scholar in Psychology, 1897-98. Albert H. Yoder, Scholar in Pedagogy, 1893-94. Lewis E. York, Scholar in Pedagogy, 1897-98. HISTORICAL SKETCH OF THE WORK IN GENERAL PSYCHOLOGF. The ten years covered by the history of the Psychological Depart- ment in this University have been eventful in the history of Psycho- logical Science in the country at large. Before 1880 the science was taught as a stepping-stone to metaphysics and ethics ; its method was chiefly introspective ; laboratories were unheard of; and genetic and comparative psychology were a terra incognita. During the early part of the eighties, however, the idea that psychology was an independent science, to be advanced by experi- ment and systematic observation, was gradually taking root, and in 1888 and 1889 began a vigorous growth. New interest was taken in the subject, laboratories began to be opened, and a special journal was started for the publication of psychological investigations (2%e American Journal of Psychology^. Since that time the interest has continued; the laboratories have increased at the rate of three or four a year till they now number between thirty and forty, are found in almost all the leading universities of the country, are often liberally supported, and in some cases surpass the best European laboratories in equipment ; and many workers trained at home and abroad have entered the field. In 1892 the American Psychological Association was started, and now numbers over one hundred members, nearly all actively interested in psychological teaching or investigation. A little later genetic and comparative psychology appeared in an awakened interest in the study of childhood; and more recently still have been extended Psychology. 123 into a new and fruitful study of the mind and habits of animals. Since 1894 a second psychological journal, The Psychological Review, has been published; and many articles of psychological interest appear in the Pedagogical Seminary (especially on Child Study) and in the other educational magazines. It is with such a period of vigorous interest in psychology and of rapid growth in facilities that our own ten years' history coincides. In turning now to this more particularly, I shall speak first of the work in experimental psychology, which, though by no means the whole of the new movement, has been so far rather its centre and characteristic mark, and afterward of that of a more general character. The distinctive feature of American laboratories generally is the extent to which they are used for psychological teaching as distinct from psychological investigation. Both foreign and home laboratories have the double purpose of instruction and research, but in the American laboratories a little greater emphasis seems to be laid on their pedagogical usefulness. This emphasis is doubtless due in part to more deep- seated differences between American and foreign universities, but it has been favored also by the feeling that a general acquaintance with laboratory problems and methods should precede the undertaking of original investigation. In the case of the Clark laboratory, it has been further enforced by the number of students of pedagogy for whom a psychological groundwork must be provided. The advantage of laboratory teaching of psychology is that of all proper laboratory teaching, namely, that the student is brought face to face with that about which he is studying, and knows the thing itself at first hand rather than what some text-book or lecturer may say about it. For those who intend to take up experimental investi- gation later, it is of course the natural apprenticeship. Such elementary laboratory teaching demands some sort of manual or guide that can be put into the hands of the students, a fact that became painfully evident in the first years of the department ; and as at the time none whatever existed, it was necessary to make one. A beginning was made with manuscript sheets struck off on the mimeo- graph. Later these were worked over in part in a series of articles in the Journal of .Psychology, and, finally, again revised and enlarged, this part was regularly published, six chapters in 1894, and the remainder last year, making altogether a volume of about 450 pages covering the topics of 124 Department of sensation and perception. This work seems to have supplied a genuine need — at least, has met with a wide acceptance in American laboratories. Up to the year just passed the laboratory course has not extended beyond the usual laboratory topics of sensation and perception, reaction- times, Weber's law, and the like. But, beginning with the year 1898-99, an important enlargement was made by the addition of laboratory practice in comparative psychology. Under the special guidance of Dr. Kline, opportunities have been given for the study of the habits and mental life of a number of more or less typical animals. Starting with the microscopical amcsba, paramecium, and vorticella, the list has been extended upward to include earthworms, slugs, fish, chickens, white rats, and kittens. Though lectures have been regularly delivered, demonstrations made, and seminaries held in connection with the labora- tory work, the development of this practice course in both experimental and comparative psychology, together with the manual mentioned and the similar though briefer work of Dr. Kline, is regarded as the most important product of the Clark laboratory on its teaching side. The scientific work of the laboratory has resulted in ten or twelve extended researches and in a considerable number of briefer studies. It is not easy in short space to give an intelligible account of studies upon a variety of topics so considerable as these have covered, but it has seemed to the writer that a list of the titles of papers published, with a few lines of explanation where necessary, might serve the purpose. STUDIES FROM THE PSYCHOLOGICAL LABORATORY. Time and Rhythm. Nichols : The Psychology of Time. Am. Jour, of Psy., Vol. 3, pp. 463-529, and Vol. 4, pp. 60-112 (1891). (Dissertation.) Repub- lished in book form by Henry Holt, New York, 1891. A general discussion of the time problem. The experimental portion shows that a period of practice in keeping time at a slow rate tends to slow a quicker rate tried immediately afterward, and vice versa, thus demonstrating a dependence of time judgments upon artificially acquired rhythms. Bolton, T. L. : On the Discrimination of Groups of Rapid Clicks. Ihid., Vol. 5, pp. 294-310 (1893). An indirect determination of the fineness of discrimination for very short periods of filled time. Psychology. 125 Bolton, T. L. : Rhythm. Ibid., Vol. 6, pp. 145-238 (1894). (Dis- sertation.) A general account of the subject. The experimental portion deals with the subjective rhythms observed in uniform series of sounds, and with the structure of the rhythmic feet which result when sounds of different length or intensity are regularly introduced in an otherwise uniform series. Hamlin, Alice J. : On the Least Observable Interval between Stimuli addressed to Disparate Senses and to Different Organs of the Same Sense. Ibid., Vol. 6, pp. 664-575 (1895). Experimental determination of the interval that must separate nearly simultaneous sensations in order that their order may be recognized. Experiments with clicks and flashes, flashes and shocks, separate clicks heard by the two ears, etc., and with indifferent and with specially directed attention. Whipple : On Nearly Simultaneous Clicks and Flashes. Ibid., Vol. 10, pp. 280-286 (1899). A study of the reason for the difference between the results of Dr. Hamlin and of earlier European observers in the matter of which order of stimuli (click-flash or flash-click) could be more readily recog- nized. Dr. Hamlin's results are confirmed and the difference proved not to lie in the fact that the European observers had made use of series of pairs of clicks, which had been supposed a possible cause. Memory. Bolton, T. L. : The Growth of Memory in School Children. Ibid., Vol. 4, pp. 362-380 (1892). A study by the memory-span method on upwards of fifteen hundred children, made in connection with the anthropometric studies of Dr. Boas, together with a theoretical treatment of the statistical curves obtained. Bbrgsteom : Experiments upon Physiological Memory by Means of the Interference of Associations. Ibid., Vol. 5, pp. 356-369 (1893). The Relation of the Interference to the Practice Effect of an Association. Ibid., Vol. 6, pp. 438-442 (1894). An Experimental Study of Some of the Conditions of Mental 126 Department of Activity. Ibid., Vol. 6, pp. 247-274 (1894). (These tliree papers ■were united to form a Dissertation.) A pack of eighty cards (eight cards each of ten different kinds) is sorted according to the kinds, and after an interval re-sorted, but with such an arrangement that each kind occupies a different place on the table. The second sorting takes longer because of interference between the new as- sociations and those formed in the first sorting, and the excess of time required measures indirectly the persistence of the first set of associa- tions. The first paper gives curves showing the rate of falling away of the first associations (curves of forgetting) determined by this method. The second paper, by an ingenious application of the same method, shows that the interference power of any association is practically equal to the fixity given it by practice, — in other words, " that the work of breaking up a habit is roughly proportional to the work of forming it." The third paper gives determinations of the variations in mental abil- ity during the work hours of the day made upon several different sub- jects and with different sorts of tests. Daniels : The Memory After-image and Attention. Ibid., Vol. 6, pp. 558-564 (1895). The aim was to measure the native persistence of bare impressions as distinguished from that which they show when received with atten- tion and held by association. The time was found to be very short, not more than five or ten seconds. Smith, Thbodate L. : On Muscular Memory. Ibid., Vol. 7, pp. 453-490 (1896). A painstaking comparative study of the memory of nonsense syl- lables learned with and (as far as possible) without the cooperation of the vocal mechanism. The memory assisted by even incipient move- ments was, in all cases, distinctly better, — a result further confirmed by a similar study on various combinations of the manual signs of the deaf-mute alphabet learned with and without execution of the hand postures involved. COLEGKOVB : The Time required for Recognition. Ibid., Vol. 10, pp. 286-292 (1899). A chronoscopic study of the time required for deciding whether a picture suddenly presented had been seen before or not. Psychology. 127 Psychology of Movement. Bryan, W. L. : On the Development of Voluntary Motor Ability. Ihid., Vol. 5, pp. 125-204 (1892). (Dissertation.) A study of the rate, precision, and strength of voluntary movements in the case of adults, and of a large number of school children from six to sixteen years old. Differences due to fatigue, to increasing age, to sex, to bilateral asymmetry, and the like, are carefully worked out; the mathematical treatment of the statistics (thanks in part to suggestions from Dr. Boas) is unusually full and rigid. Reigaet and Sanpord: On Reaction-times when the Stimulus is Applied to the Reacting Hand. Ibid., Vol. 5, pp. 351-355 (1893). The experiments bring into question the statement of Exner that reactions are slower when the stimulus is applied to the reacting hand. Hancock: A Preliminary Study of Motor Ability. Pedagogical Seminary, Vol. 8, pp. 9-29 (1894). The Relation of Strength to Flexibility in the Hands of Men and Children. lUd., Vol. 3, pp. 308-318 (1895). The first is a study of the spontaneous movements of school children from five to seven years old, — of the swayings and tremors displayed in efforts to stand still with eyes open or closed, or to hold the hand or forefinger still, — movements analogous to those of nervous disease. The second paper shows for the persons tested (20 men, 22 boys, and 11 girls), greater flexibility in the hands of the men as measured by the extent to which the joints could be flexed voluntarily. Both papers are of avowedly pedagogical interest. Lancaster : Warming Up. Colorado College Studies, Vol. 7, pp. 16-29 (1898). Based upon ergographic experiments. Sensation and Perception. ScRiPTtrRB : Einige Beobachtungen iiber Schwebungen und Differenz- tone. PhUos. Studien, Vol. 7, pp. 630-632 (1892). A brief experimental study of beats and difference tones produced by forks sounding separately on either side of the head. 128 Department of Debsslar: On the Pressure Sense of the Drum of the Ear and "Fa- cial Vision." Am. Jour, of Pay., Vol. 5, pp. 344-350 (1893). The study shows that the faculty of the blind of recognizing the presence or absence of neighboring objects, which has been credited to some sort of obscure visual sensation in the skin of the face, or to sen- sations of pressure mediated by the drum of the ear, is probably a matter of hearing. Kkohn : An Experimental Study of Simultaneous Stimulation of the Sense of Touch. Journal of Nervous and Mental Disease, N. S., Vol. 18, pp. 169-184 (1893). Based chiefly on experiments made in the Clark laboratory. Leuba: a New Instrument for Weber's Law, with Indications of a Law of Sense Memory. Am. Jour, of Psy., Vol. 6, pp. 370-384 (1893). Weber's law demonstrated in the classification of artificial stars. The law of sense memory suggested is that memories of intensities of sensation tend to shift toward the middle of the usual scale of intensities. Dkbsslar : A New Illusion for Touch and an Explanation for the Illusion of Certain Cross Lines in Vision. Ibid., Vol. 6, pp. 275-276 (1894). This illusion is similar to that of the Poggendorff illusion in vision, and the obvious explanation iu the case of the touch illusion is extended to the visual one. Sanfokd: a New Visual Illusion. Science, Feb. 17, 1893. A visual illusion involving false judgments. Debsslak : Studies in the Psychology of Touch. Am. Jour, of Psy., Vol. 6, pp. 313-368 (1894). (Dissertation.) The study is in three sections : 1. On the Education of the Skin with the iEsthesiometer, particularly of its bilateral effects ; 2. Experiments on Filled and Open Space for Touch, showing that filled space seems larger when the finger moves over it, or when the extents compared are moved under the resting finger ; 3. On Apparent Weight as affected by Apparent Size and Shape — tests upon school children and adults. Psychology. 129 Circulation and Respiration. Dawson : Effects of Mental States upon Circulation. (Records in the instructor's hands but not worked up as yet.) Preliminary note in the Proc. of the Am. Psychological Ass'n, Psychological Review, Vol. 4, pp. 119-121 (1897). An extended study made with the plethysmograph applied simultane- ously to the hand and eye. Whipple: The Influence of Forced Respiration on Psychical and Physical Activity. Am. Jour, of Psy., Vol. 9, pp. 560-571 (1898). The effect of very rapid breathing on eight simple tasks involving sensory or motor activities, or both. Effects slight in most cases; physical strength and endurance seem to be increased, while discrimi- native powers seem to be depressed. Comparative Psychology. Kline : Methods in Animal Psychology. Ibid., Vol. 10, pp. 256-279 (1899). Discussion of methods, and presentation of the results of experiments upon vorticellae, wasps, chicks, and white rats. Small, W. S. : Notes on the Psychic Development of the Young White Rat. Hid., Vol. 11, pp. 80-100 (1899). The study consists of a careful record of the bodily and mental development of the white rat from birth onward for a number of weeks. Studies on Miscellaneous Topics. Calkins, Mary Whiton : Statistics of Dreams. Ibid., Vol. 5, pp. 311-343 (1893). A careful analjrtical and statistical study of dreams, recorded immedi- ately after waking by two subjects during a period of six or eight weeks. An effort to get as full a picture as possible of normal dream- life. LuCKEY : Some Recent Studies of Pain. Ibid., Vol. 7, pp. 108-123 (1895). A review of recent literature on the physiology and psychology of pain. 130 Department of Miles, Cakolinb : A Study of Individual Psychology. Ihid., Vol. 6, pp. 534^558 (1895). A questionnaire study of a number of special points, made on one hundred students in Wellesley College. Such topics are considered as : How do you know your right hand from your left ? How do you con- centrate attention ? Fears as children ? Things causing anger ? Favor- ite color? Earliest memories? Early ideals? etc. (This study and the preceding, though not experimental, were made in connection with the work of the laboratory.) Dkew: Attention: Experimental and Critical. Ibid., Vol. 7, pp. 533-576 (1896). (Dissertation.) The experimental portion of this paper consists of three sections: 1. Eeaction and Association Times with Differing Degrees of Distraction ; 2. A Qualitative Study of Associations with Full and with Distracted Attention; 3. A Study of the Apparent Order of nearly Simultaneous Stimuli with variously Directed Attention. Hylan : The Fluctuation of Attention. Psychological Review, Mono- graph Supplement, No. 6, pp. 1-78 (1898). An experimental and expository paper, the experiments approaching the question in several different ways. HiTET : Preliminary Experiments in the Physiology and Psychology of Reading. Am. Jour, of Psy., Vol. 9, pp. 575-586 (1898). Tests of rate of reading in vertical and horizontal directions, of the importance for recognition of the first and last parts of words, and of the actual movements of the eye in reading, determined by apparatus attached to the eye. This study was continued during the year 1898-99, with results that are nearly ready for publication. Technical Matters. The following papers have been chiefly concerned with technical matters and apparatus. ScEiPTURE : Psychological Notes. Ihid., Vol. 4, pp. 577-584 (1892). On the method of regular variation ; The least perceptible variation in pitch; The faintest perceptible sound ; Notation for intensity; A con- stant blast for acoustical purposes ; Some psychological terms. ScEiPTtruB : An Instrument for Mapping Hot and Cold Spots on the Skin. Sdence, Vol. 19, p. 258 (1892). Psychology. 131 Debsslae: a New and Simple Method for comparing the Perception of Rate of Movement in the Direct and Indirect Fields of Vision. Am. Jour, of Psy., Vol. 6, p. 312 (1894). Sanfoed: a Simple and Inexpensive Chronoscope. Ibid., Vol. 3, pp. 174-181 (1890). A New Pendulum Chronograph. Ihid., Vol. 5, pp. 384-389 (1893). Some Practical Suggestions on the Equipment of a Psychologi- cal Laboratory. Ibid., Vol. 5, pp. 429-438 (1893). Notes on New Apparatus. Ibid., Vol. 6, pp. 575-584 (1895). The Vernier Chronoscope. Ibid., Vol. 9, pp. 191-197 (1898). While these studies have been going on in the laboratory, the work in philosophy and education, and in the non-laboratory sections of psychology, has been carried forward with perhaps even greater vigor. President Hall, Dr. Burnham, Dr. Boas, Dr. Chamberlain, Dr. Meyer, Messrs. MacDonald, Strong, Gilman, and others, have lectured on various aspects of the history of philosophy, pedagogy, psychiatry, aesthetics, criminology, and anthropology. Some account of the work in education, anthropology, and psychiatry wiU be found below in the special reports of Drs. Burnham, Chamberlain, and Meyer; the rest wUl be spoken of here. The work of instruction has been carried on by means of seminaries as well as lectures, and to a great extent also in the more informal but most effective way of personal conference with individual students. It is not possible from data now at hand to give a complete list of the courses given by President Hall, but at different times he has lectured upon the History of Philosophy, Ancient, Mediaeval, and Modern (taking philosophy in a sense wide enough to include psychology, education, and medicine) ; on Cosmology, on General Psychology, on Morbid Psychology (with clinics at the Worcester Lunatic Hospital), on Genetic Psychology (both in the animal series and in the child). Educational Philosophy and Practice, Child Study, Adolescence, Curricula, Teaching of Special Sub- jects, and upon other pedagogical topics. In addition to these lectures, 132 Department of President Hall has, almost from the first, conducted a weekly seminary, meeting in the evening at his own house. Here members of the depart- ment have reported on the progress of their investigations and received the benefit of mutual criticism, or have united in the study of some special author or topic. Notes of the discussions of the seminary during a period when chief attention was given to Plato have been published by Dr. H. Austin Aikins in the Atlantic Monthly (September and October, 1894), under the title, "From the Reports of the Plato Club." Presi- dent Hall has also directed the research of the greater part of the men in the department, recommending topics, methods, literature, and lines of thought, and in some cases has gone so far as to enter into joint author- ship with the students, taking their incomplete results and putting them into shape for publication. In the first years after the opening of the University, President Hall was assisted in the philosophical teaching by Dr. Alfred Cook, Dr. B. C. Burt, and Mr. C. A. Strong as Docents. During the year 1889-90, Drs. Burt and Cook gave courses on Greek philosophy and on modern philos- ophy from Locke to Kant; and in 1890-91, Mr. Strong gave a brief course on the history of psychology among the Greeks from Thales to Aristotle, — an abstract of the lectures being later published in the American Jour- nal of Psychology, Vol. 4, pp. 177-197 (1891). During 1892-93, Mr. Ben- jamin Ives Gilman, as Instructor in Psychology, lectured on Pleasure and Pain, and pursued independent investigations on the theory of musical consonance. Abstracts of his lectures are to be found in the American Journal of Psychology, Vol. 6, pp. 1-60 (1893). Mr. Arthur MacDonald, as Decent in Ethics, devoted himself to theoretical and practical studies in criminology, lecturing on that topic during the first year of the University and conducting a seminary, with occasional lectures, during the second. Since 1891 all the philosophical teaching of the department has been done by President Hall himself. The research of this section of the psychological department has been devoted for the most part to questions that are too large and too unman- ageable for successful treatment in the laboratory, — questions of the origin and development of mental life in the race and in the child, of adolescence and sex, of emotion, of religion, and the like. Its scope and nature will be apparent from the following list of studies: — Psychology. 133 Child Study and Psychogenesis. Tracy : The Language of CMldhood. Am. Jour, of Psy., Vol. 6, pp. 107-138 (1893). The Psychology of Childhood. Boston, 1893. 94 pp. (Includes a reprint of the preceding.) (Dissertation.) The first paper is a careful study of extant data on the physiology, phonetics, and psychology of infant language, together with new mate- rial gathered by the author. The second is a similar treatment of sensation, emotion, intellection, and volition as they appear in very young children. Shaw: A Test of Memory in School Children. Pedagogical Semi- nary, Vol. 4, pp. 61-78 (1896). An account of tests made with a carefully prepared story, which was read to the children to test memory and lines of greatest interest. Statistics of about seven hundred papers from children ranging from the third year of school life to those in the higher classes of the high school. Hall and Ellis: A Study of Dolls. Ihid., Vol. 4, pp. 129-175 (1896). A study of the various aspects of the interest in dolls and of ways in which they are used in play, based upon numerous replies to two ques- tionnaires. Small, M. H. : The Suggestibility of Children. Ihid., Vol. 4, pp. 176-220 (1896). A record of experiments both on groups of children and on separate individuals, together with a large number of returns from a question- naire, with pedagogical inferences and applications. CuKTis: Inhibition. J&ic?., Vol. 6, pp. 65-113 (1898). (Dissertation.) The four sections of the paper present: 1. A Summary of Facts and Theories, Psychological, Biological, and Neurological ; 2. An Account of the Influence of Different forms of Activity on one Another ; 3. A Study of Restlessness in Children ; and 4. Pedagogical Inferences from the Fore- going. The third section gives results of experiments and observations by the author together with questionnaire returns. The term " inhibition " is taken in a very wide sense. Paeteidge: Reverie. Ibid., Vol. 5, pp. 445-474 (1898). A study of 337 questionnaire returns on day dreams and related phe- nomena. The physical signs, the subjective state, the causes and condi- 134 Department of tions, the content, and the awakening are considered. An appendix contains records of the efforts of 330 children to describe an imaginary animal, and of an attempt to gather statistics as to hypnagogic images from upward of 800 children. Dawson: A Study of Youthful Degeneracy. lUd., Vol. 4, pp. 221-258 (1896). A careful study of about 60 degenerate youths (including 26 boys and 26 girls from the state reform schools of Massachusetts) as to Vitality, Head and face configuration. Anomalies of physical structure, Keenness of senses, Intellectual ability. Parentage, and EuYironment. Hall: Some Aspects of the Early Sense of Self. Am. Jour, of Psy., Vol. 9, pp. 351-395 (1898). A study of the growth and dcTelopment of self-consciousness based on questionnaire returns. Making acquaintance with hands, feet, and other parts of the body, external and internal ; influence of dress and adornment ; experiences with mirrors ; various pet names ; childish conceptions of the soul ; questionings of children about their own identity, present reality, etc.; the effect of social environment, beginning espe- cially with the mother. Psychology of Religion. Daniels: The New Life: a Study of Regeneration. Ibid., Vol. 6, pp. 61-106 (1893). (Dissertation.) A study of adolescence in its anthropological and psychological as- pects, with special reference to conversion and other religious experi- ences occurring at that period, the whole being an effort to show the means by which the fundamental truths of religion and theology may be restated in accord with science and life. Lbuba : A Study of the Psychology of Religious Phenomena. Ihid., Vol. T, pp. 309-385 (1896). (Dissertation.) Based upon noted cases of conversion found in religious literature, on material gathered by questionnaire and in personal interviews. The headings of the first part are : The religious motive, Analysis of con- version, Sense of sin. Self-surrender, Faith, Justification, Joy, Appear- ance of newness. The second part treats of the current doctrines of justification, faith, will, determinism, and the doctrine of the grace of God as related to the experiences described. An appendix contains a number of the cases in full. Psychology. 135 Staebuck: a Study of Conversion. Ihid., Vol. 8, pp. 268-308 (1897). Contributions to tlie Psycliology of Religion : Some Aspects of Religious Growth. Ihid., Vol. 9, pp. 70-124 (1897). (Dissertation.) The first paper is a study of sudden conversions ; the second of more gradual changes of a similar character. Both are based almost exclu- sively on questionnaire returns ; the first on 137 cases, the second on 195. The topics in the first paper are : Age of conversion, Motives and forces leading to conversions, Experiences preceding conversion, The change itself. Post-conversion phenomena, Other experiences similar to conver- sion, General view of conversion. Those of the second paper are: Statistics of material. Adolescent phenomena. The period of reconstruc- tion. External influences. Cases without marked stages of growth, Adult religious consciousness, Ideals, Significance of the facts. Letjba: The Psycho-physiology of the Moral Imperative. Ihid., Vol. 8, pp. 628-569 (1897). An analysis of the phenomena of conscience, together with argument to show that the " moral imperative " is the psychical correlate of cer- tain activities of the cerebro-spinal system (taken as the neural basis of the life of relation) as opposed to activities of the sympathetic system (taken as the neural basis of the vegetative and emotional life). Philosophy and Criticism. KiEKPATKiCK: Observations on College Seniors and Electives in Psychological Subjects. Ihid., Vol. 3, pp. 168-173 (1890). A study of questionnaire returns from college seniors as to their rea- sons for studying philosophical and psychological subjects, benefit gained, authors most impressive, and special topics found most interesting. Hall: Contemporary Psychologists. I., Prof. EduardZeller. Ihid., Vol. 4, pp. 166-175 (1891). An account of the life and writings of Zeller. Feasee: Visualization as a Chief Source of the Psychology of Hobbes, Locke, Berkeley, and Hume. Ihid., Vol. 4, pp. 230-247 (1891). The Psychological Foundation of Natural Realism. Ihid., Vol. 4, pp. 429-450 (1892). 136 Department of The Psychological Basis of Hegelism. Ibid., Vol. 5, pp. 472- 495 (1893). These papers are the result of an effort toward a "psychology of phi- losophy." The first two trace the influence of concepts derived from vision and from touch on the philosophic schools in question, and the third the influence of those derived from galvanism. Bailey : Ejective Philosophy. Ibid., Vol. 5, pp. 465-471 (1893). An attempt to describe briefly the philosophical "signs of the times." Lbtjba : National Destruction and Construction in France as seen in Modern Literature and in the Neo-Christian Movement. Ibid., Vol. 5, pp. 496-539 (1893). A review of these topics under the following heads : Artist sensual- ists, The quest for new sensations, Nihilism and pessimism. School of the decadents. Literary critics. Chronicles, The tormented. The Neo-Chris- tian movement. Allin : The " Recognition-theory " of Perception. Ibid., Vol. 7, pp. 237-248 (1896). Recognition. Ibid., Vol. 7, pp. 249-273 (1896). The first paper is a critique of a theory of perception widely held in the past and present ; the second is an analytical, critical, and expository account of the mental experience of recognition. Mental and Physical Peculiarities. ScKEPTcrEE : Arithmetical Prodigies. Ibid., Vol. 4, pp. 1-59 (1891). Accounts of a large number of phenomenal calculators collected from widely scattered sources ; analysis and discussion of their mental pecu- liarities, and pedagogical inferences. Krohn : Pseudo-chromsesthesia, or the Association of Colors with Words, Letters, and Sounds. Ibid., Vol. 5, pp. 20-41 (1892). A summary of literature with presentation of several new cases, and a discussion of the theory of the phenomenon, followed by a bibliography. LiNDLBY : A Preliminary Study of some of the Motor Phenomena of Mental Effort. Ibid., Vol. 7, pp. 491-517 (1896). A study, on the basis of a questionnaire and special tests, of the "tricks and peculiarities of movement and posture that accompany mental effort. Psychology. 137 LiNDLEY AND Partbidge : Some Mental Automatisms. Pedagogical Seminary, Vol. 5, pp. 41-60 (1897). A questionnaire study of 495 cases of such mental automatisms as the avoidance of stepping on cracks, counting objects unnecessarily, group- ing objects like small patterns in wall paper into regular figures, and the picking out the middle one of rows of objects. « Phillips : Genesis of Number Forms. Am. Jour, of Psy.-, Vol. 8, pp. 506-52T (1897). A study, based on over 2000 cases (974 school children, and nearly 700 normal school pupils and adults personally questioned), showing the almost universal presence of number forms, though often in very rudi- mentary condition. COLEGEOVE : Individual Memories. Ibid., Vol. 10, pp. 228-255 (1899). (Dissertation.) The paper is a study of some sixteen hundred replies to a question- naire on earliest memories, period of life best remembered, forgetful- ness and false memories, aids to memory, etc. This paper is an extract from a more extended work on memory in general. Emotion. HALL : A Study of Fears. lUd., Vol. 8, pp. 147-249 (1897). Discussion of the chief fears of seventeen hundred people mostly under twenty-three years of age, together with description of methods used in reducing the original reports for general treatment. Fears of high places and falling, of losing orientation, of being shut in, of water, of wind, of celestial objects, of fire, of darkness ; dream fears ; shock ; fears of thunder, of animals, of eyes, of teeth, of fur, of feathers; special fears of persons, of solitude, of death, of diseases ; moral and religious fears; fear of the end of the world, of ghosts; morbid fears; school fears ; and the repression of fears, — are all treated in separate sections. Hall and Allin: The Psychology of Tickling, Laughing, and the Comic. lUd., Vol. 9, pp. 1-41 (1897). A study based upon about seven hundred questionnaire returns. The following rubrics are treated: The Physical act of laughing. Tickling, Animals and their acts, Eecovery from slight fear. Laughter at calamity. Practical jokes, Caricature, Wit, Laughter at what is forbidden or secret, at the naive and unconscious. Animal laughter. Miscellaneous items, and Notes on literature. 138 Department of Hall : A Study of Anger. Ibid., Vol. 10, pp. 516-591 (1899). A general summary of very widely gathered literary material, followed by a discussioa of over two thousand questionnaire returns ; General descriptions of the state, Causes (with many sub-heads). Subjective variations. Physical manifestations (with many sub-heads), Anger at inanimate and insentient objects, Venting anger, Reaction, Control, Treatment, Miscellaneous aspects. Miscellaneous Topics. MacDonald : Ethics as Applied to Criminology. Journal of Mental Science, Vol. 3T, pp. 10-16 (1891). Criminal Aristocracy, or the Maffia. Medico-Legal Journal, Vol. 9, pp. 21-26 (1891). Lb Rossignol : The Training of Animals. Am. Jour, of Psy., Vol. 5, pp. 205-213 (1892). A review of literature on the subject. Keohn: Facilities in Experimental Psychology at Various German Universities. Ibid., Vol. 4, pp. 585-694 (1892); Vol. 5, pp. 282- 284 (1892). Notes on Heidelberg, Strasburg, Zurich, Preiburg, Munich, Prag, Ber- lin, Leipzig, Halle, Jena, Bonn, and Gottingen. Lemon : Psychic Effects of the Weather. Ibid., Vol. 6, pp. 277-279 (1894). A preliminary note on the general question. Scott : Sex and Art. Ibid., Vol. 7, pp. 153-226 (1896). The study traces the higher enthusiasms of art and religion, as well as the passions of sex, to the " fundamental quality of erethism found in every animal cell." Beginning with erethism, the following topics are discussed: Specialization among cells, Separation of the sexes, Eadia- tion. Selection, Combat, Courting, Fear and anger, Sex and care for young. The aesthetic capacity. Courting instinct in the lower races. Tattooing, Clothing, Shame, Jealousy and fear. Symbolism and fetich- ism, Phallicism, Modern phallicism. General features and laws of court- ing. Degeneration, Perversion, Ecstasy, iEsthetics, Conclusion. Scott : Old Age and Death. Ibid., Vol. 8, pp. 67-122 (1896). (Dis- sertation.) Old age and death treated from biological and physiological stand- points, together with discussion of 226 returns to a questionnaire designed Psychology. 139 to bring out the ideas of young people and others with regard to the aged, to death, and to a future life. Partridge : Blushing. Pedagogical Seminary, Vol. 4, pp. 387-394 (1897). A questionnaire study (120 cases, all normal school pupils) : Objective and subjectiye aspects, After-effects, Physiology, Psychology, Blushing and sex. Partridge: Second Breath. Ibid., Vol. 4, pp. 372-381 (1897). A study based upon about two hundred questionnaire returns. The following are the headings: Physical second breath. Mental second breath. Over-play and abandon in children, Eeaction, Physiology of second breath. LiNDLEY: A Study of Puzzles with Special Reference to the Psy- chology of Mental Adaptation. Am. Jour, of Psy., Vol. 8, pp. 431-493 (1897). (Dissertation.) The subject is introduced by a consideration of the biology and psy- chology of play in general, followed by the classification of puzzles. The time and conditions of greatest interest in puzzles are treated on the basis of questionnaire returns. This is followed by a report of extended experiments made upon school children to discover their growth in abil- ity to deal with the difficulties presented by puzzles. Kline : The Migratory Impulse vs. Love of Home. Ibid., Vol. 10, pp. 1-81 (1898). (Dissertation.) A biological and psychological study combining the results of experi- ments upon animals with those of a questionnaire. Such topics as the Influence of temperature, Spring fever. Migrations of wild and domestic animals and of man. Wandering tendency in men, women, and children. Love of home, and homesickness, are treated. QuANTZ : Dendro-psychoses. Ibid., Vol. 9, pp. 449-506 (1898). A study on material gathered from biology, anthropology, and ques- tionnaire returns of the psychic influence of experiences with trees. Biological evidence of man's descent from arboreal ancestors, Psychical reverberations from ancestral experience. Tree worship. The life tree, The tree in folk-medicine. The tree in child life, The tree in poetry. Bolton, F. E. : Hydro-psychoses. Ibid., Vol. 10, pp. 171-227 (1899). (Dissertation.) A study, similar to the last, on the psychic effects of experiences with water : Evidences of man's pelagic ancestry, Origin of animal life, Ani- 140 Department of mal retrogression to aquatic life, Water in primitive conceptions of life, in philosophical speculation, Sacred waters, Water deities. Lustrations and ceremonial purifications by water. Water in literature. Feelings of people at present toward water. GoDDAED : The Effects of Mind on Body as evidenced by Faith Cures. Ihid., Vol. 10, pp. 431-502 (1899). (Dissertation.) " Christian Science," " Divine Healing," hypnotism and other forms of mental treatment of disease are briefly considered ; and " Mental Sci- ence," taken as a type, is treated fully from data gathered by extended correspondence and from hospital records. In the remainder of the paper the following topics appear : Positive testimony of the influence of mind on disease, Failures in the practice of mental therapeutics. Hypnotism as a therapeutic agent. Theory of mental therapeutics. Psy- chological problems suggested, Resume and conclusions. Street : A Genetic Study of Immortality. Pedagogical Seminary, Vol. 6, pp. 267-313 (1899). (Dissertation.) A study of the origin and characteristics of ideas of the soul, im- mortality, heaven, and a future life, made on the basis of the reports of the thoughts of deaf mutes before training, on about five hundred replies to a questionnaire, and on other material. Biological, psychologi- cal, and moral aspects of the belief in immortality are also considered. Besides the studies of these lists, which have been printed, a number more have been made and are in the hands of the instructors practically ready for publication. Others still have been made and the data sub- mitted without complete writing out ; a good part of these will ultimately be made use of either in themselves or as the basis for further research along the same lines. After this outline of work done in the past, a few words may be per- mitted with reference to the future of the department. This, like its past, must be closely connected with the general progress of psychological science, and the question naturally becomes that of the directions in which progress may be most reasonably expected. Let me begin, as before, with the laboratory. It seems to me that the two lines of greatest promise, conceding readily Psychology. 141 the importance of continuing research along lines already undertaken, are those of comparative and of individual psychology. Work has already been begun in both fields. Especially in comparative psychology much has already been done by the biologists, but much remains yet to be done. There is surprisingly little accurate knowledge of the mental life of even the commonest animals ; there are many anecdotes, but not many reliable observations, and very few experiments. In this field lie the questions of instinct and heredity, belonging alike to psychology and biology, to which run back so many of the most fundamental and practical of even strictly psychological questions. Much may also be expected from the full intro- duction into psychology of the comparative method which has so broad- ened and enriched other sciences in which it has been applied. The conception of mind, as of something not narrowly human or confined to a few higher animals, but as in some sort present in all animals, even the lowest, with a history as long as evolution, opens up vistas to which psy- chologists have been too little accustomed. Much surely is to be expected from this closer alliance of psychology with biology. While the theoretical interest of comparative psychology is thus hardly to be overestimated, the practical interest of the efforts toward an individual psychology is hardly less important. We know something about the mental differences of our fellow-men, but we know very little about them in a scientific way. What underlies temperament? What are the laws of the growth of character ? Why do some pupils do well with some teachers and not with others ? What is the best treatment for reform school boys ? How shall one deal with exceptional and peculiar children in the family? Individual psychology ought to answer such questions as these, and many others. It is clear, of course, that many of these questions extend far beyond the possibilities of the laboratory, but the methods and standpoint and training of the laboratory will play no small part in their final solution, and justify attacking them from that side. Closely connected with individual psychology, but lying a little fur- ther from the laboratory, is another field which might be called the " psychology of the permanent apperceptive groups " — the study of the mental attitudes, that is, that result from the fundamental experiences of life, a study of apperception which does not stop at demonstrating the fact of mental habit, but goes on to investigate the effect of one sort of mental habit upon the rest ; how, for example, the fact of fatherhood or 142 Department of a severe sickness may alter character distinctly and permanently. These topics have not been neglected, but many questions remain that would well repay the worker of proper equipment and insight. Coordinate with these are the study of the more complex emotions, of religion and of aesthetics, all of which promise much and should have an important place in a psychological department as a counterweight to the laboratory. It is on the data obtained from the study of these topics and those of the last group, with others like them, that true mental and moral hygiene must rest. Fortunately, here also we have beginnings. Beyond these again, there are topics of great popular interest, like those of Christian science and psychical research, upon which the lay- man has a right to ask an expert opinion from science, and on which psychology, after careful investigation, can and ought to speak. What any particular department of psychology can do in realizing these promises of the future, must depend upon the resources in men and materials that it can command. Work in comparative psychology can be begun at once wherever suitable accommodations can be provided for the animals, — proper housing, cages, aquaria, and such attendance as shall insure the health and happiness of the animals, which are essential factors in any reliable study of their behavior, — and a properly qualified observer can be secured. The first of these requirements is easier to fill at present than the second, for as yet too few persons have equipped themselves both as psychologists and naturalists, but this lack will not long exist if the subject is taken up in earnest. For the portion of individual psychology that comes within the scope of the laboratory, there is need of new instru- ments of at least a relative precision, many of which must yet be devised or slowly perfected by trial and failure, which involves a liberal subsidy. For any of the more general problems mentioned, the first requisite is men of proper natural equipment and training. Not every man of learn- ing is fitted to handle them, and those devoted to them must not be so much taken up with the routine and responsibility of elementary teaching, that they lack the time and spirit for ardent research. And these men, once secured, must be liberally supplied with such help in the way of books and other materials as they need. Of these three things, — quarters for comparative psychology, apparatus for individual psychology, and an enlargement of the staff, — the last is, in all ways, by far the most impor- tant. Competent and enthusiastic investigators can work with inadequate facilities, but no facilities can take the place of the men or of the freedom Psychology. 143 from routine teaching. The Clark department has already made such efforts in all these lines as its opportunities have permitted. Its ten years' history justifies the prophecy that, with enlarged opportunities, it would make more than commensurate return in an increase of the advanced teaching and research for which it was originally organized. PSYCHO-PATHOLOGY. By Adolf Meyee. It is hardly necessary to insist to-day on the remarkably suggestive influence which pathology has had on the biology of man, and especially on psychology. Many of the most fundamental changes in psychology are directly traceable to problems furnished by the study of abnormal life, clinical and post-mortem pathology, and experimental reproduction of diseases and of symptom-complexes. Under these conditions it is evident that the curriculum of a psychologist, and of biologists generally, is quite incomplete without, at least, some touch with results and problems of general pathology, and more especially of neuro- and psycho-pathology. Starting from the experience that certain types of psycho-pathology lead very promptly into paths which have nothing to do with biology, and put themselves directly on pre-biological traditions, it was considered best to develop a course which would begin with the principles of general pathology, the abnormalities of the most general biological factors, i.e. with a chapter properly belonging to any general biology. In this field, the experience in the domain of neurology and of psychiatry would have to be worked up more carefully, as far as possible in constant touch with the broader biological concepts. Medicine, barely deserving the attribute of an applied science, is not rich in literature breathing the biological spirit. To a great extent it stands on a pre-biological, materialistic standpoint, and the orthodox practitioner of medicine is usually anxious to keep to materialism and to profess ignorance of the psychological aspect ; and, again, many of those who look upon the psychological manifestations in their patients very rapidly acquire one of the traditional exclusive standpoints, danger- ously near certain mystical concepts. The psychology of hypnotism, of hysteria, even that of aphasia, give good instances of such tendencies. It is consequently desirable to build up a course from the elementary to the more difficult, and starting from the least contested foundations to proceed to the less comprehensible points. 144 Psycho-Pathology. 145 The plan outlined in the lectures and clinics of the spring of 1897 gives an idea of the work. The course during the year covered the following ground : — 1. Introductory remarks on general biological conceptions. The gen- eral biological principles applied to the study of abnormal life. Relation between neurology and psychology, neuro-pathology and psychiatry, neuro- logical and psychical phenomena from the biological standpoint. Appli- cation of the point of view to alcoholic intoxication and to several forms of mental disease. Demonstration : Cases of Febrile Delirium, General Paralysis, Catatonia, and Idiocy. 2. Review of the general pathology on the ground of the aspect- hypothesis. The terms " disease," " residual," " defective formation," and "defective Anlage." Clinical and post-mortem pathology and their share in general pathology. Only clinical pathology furnishes data on the psy- chological and physiological side. Plan of clinical study. Anatomical study. Our knowledge of the macroscopic and microscopic lesions of the nervous system and the underlying pathological processes, defective growth and nutrition, intoxication, abnormal function. Local disorders : Abnormal circulation, local intoxications, traumatic disorders, over activity, perverted function. Demonstration of abnormal brains and histological changes. 3. The general plan of the nervous system and illustrations of diseases of the various parts (levels). The neural tube; the segmentary arrangement and the elements of the segments within the lowest level. The middle level apparatus — cerebellum, midbrain, and forebrain, and their afferent and efferent connections. Demonstrations : (1) Traumatic paralysis of the nervus peroneus. (2) Infantile paralysis. (3) Cases of hemiplegia. (4) Lead paralysis (Remak type). (5) Alcoholneuritis. (6) Locomotor ataxia. 4. The principles of localization. The meaning of the connections of neurones by numerous collaterals, of the " interruptions of the tracts by gray matter," of the term "centre." Description of the most important "centres," the lesions of the apparatus of mimic movements, the sensorimotor areas, the principal "sensory" projection fields. An outline of the principles of aphasia and its forms, of hemianopsia. Highest level symptoms. Demonstration : Hemiplegia with hemianop- sia; two cases of hemiplegia with motor aphasia; one case of sensory aphasia. Reference to a case of Brown-Sequard paralysis. 146 Psycho-Pathology. 5. General outline of mental diseases. Explanation of Kraepelin's classification. Illustration of a paradigm of mental disease : General Paralysis, its etiology, symptomatology, and principal types. Demonstra- tion of six cases. 6. Toxic psychoses and psychoses of disturbed metabolism. Sum- mary of the data of psycho-physiological study of fatigue and intoxication furnished by the school of Kraepelin. Review of the methods and the results. Application to the clinical problems. Demonstration : Delirium Tremens, Subacute Alcoholic Insanity. Cretinism. Dementia Precox and Catatonia. 7. Periodic Insanity compared with the types of Verbloedungs- processe. Demonstration of further types of Catatonia and of Periodic Insanity; "Acute Mania," "Acute Melancholia." 8. Short sketch of Senile Dementia and demonstration of a case. Constitutional psychoses. Resume of the methods and aims of individual psychology (Cattell, Miinsterberg, Jastrow, Kraepelin, Gilbert, Binet et Henri, Guicciardi and Ferrari). Value of "types" of character or constitution. Their formation. Dominant ideas. Mysophobia as a type of Neurosis of Fear. Development of Paranoia ; cases of Paranoia. In the spring of 1896 a similar course of demonstrations had been given (see the outline, Ameriean Journal of Psychology, April, 1896, Vol. 7, pp. 449-450). In the spring of 1898 only one lecture was possible (on the methods of individual psychology, especially Kraepelin's work) and a short course of four clinics in the spring of 1899. The desire to extend the studies into research work has remained unfulfilled. Several attempts failed because the possibilities for such work were not mature, neither on the side of the hospital nor on the part of the University. The general principles of the work at Clark University tend toward the education of workers. So far the sub-department of psycho-pathology has been purely didactic, covered by the lectures of President Hall, on the topics which have specially attracted psychology, e.g., border-line phenomena, as seen in neurotic people, prodigies, and geniuses; defec- tives, such as the blind, deaf, criminal, idiotic ; mental and nervous diseases, epilepsy, phobias, neurasthenia, hysteria ; morbid modifications of will, personality, emotion, etc., and by the above attempt at giving a course with clinics based on general pathology. The research work along these lines depends on two important condi- tions. For systematic work the organization of a clinic is necessary, Psycho-Pathology. 147 and on the part of the worker a fair knowledge of general and special pathology (in its broadest sense — the knowledge of abnormal life, not merely pathological anatomy and bacteriology) is an absolute pre- requisite. A training in general and special pathology on the ground of a complete course of biology must be regarded as an absolutely necessary pre-requisite for research in psycho-pathology. Whether most courses of medicine offer what is needed, and whether • a medical education should be required, is a matter of some doubt ; since much of the ordinary medical course is business training rather than work in pathology in the true sense of the word, leaving out almost intentionally the broader aspects which we have to require more especially for research in our lines ; and most of the medical courses are so overburdened that the training in the history of human thought and philosophical criticism is completely crowded out, and this important safety-valve and balancing apparatus is almost missing in the medical curriculum. The other point, the creation of clinical possibilities, is not less difficult. Our attempt at the Worcester Insane Hospital has hardly matured sufficiently to allow of much research work. The work which forms the foundation of research must be done first, and the reorganiza- tion begun in 1896 is only just beginning to furnish the material for some studies suggested by Dr. Sanford, and some investigations on more closely psychiatric questions. The study of the most protracted disorders of human life requires such a patient spirit of work and an atmosphere of such tenacious adherence to solid working principles, that the predilection for fads and the haste for results are nowhere more lamentable. Should it be the good fortune of this department to get strengthened by the State, as well as by the University, a psychiatric clinic and research-station might grow up. Efforts of this character are being made in New York by an institute independent of the hospitals. Our plan is rather to develop the research-station on the basis of the clinical work. The constant con- tact with a field of experience such as a clinic offers furnishes the safest working basis and prevents one from running away with hasty specula- tion derived from too limited a number of facts. The best field for getting problems for work is that of actual observation, such as a clinic only can afford. To pick out curiosities merely will never lead to a psycho-pathology worth its name. ANTHEOPOLOGT. By Alexander Fkancis CHAMBERLAm. The history of the Department of Anthropology at Glark University forms an important chapter in the history of the study of anthropology in America, since it was the first educational institution to distinctly recog- nize anthropology as a subject of graduate study leading to the degree of Doctor of Philosophy. The first official announcement of the University, published in May, 1889, included, under the work to be undertaken in the Department of Psychology, the following subjects : " The Psychology of Language ; Myth, Custom, and Belief anthropologically considered." With the opening of the academic year, anthropology was established as Section C of the Department of Psychology, and a laboratory and departmental library provided, with proper facilities for original investigation and research. The laboratory contained crania for practical study, necessary craniographic and oraniometric instruments, together with the usual tools of the anthropologist working in the field. The library of the University, besides a special anthropological collec- tion, contains a very complete selection of the literature on applied ethics (criminology), embracing the chief works of the English, Italian, French, and German writers. In the psychological library will be found also many works relating to the subjects which anthropology and psychology treat of in common. In 1889 Dr. Franz Boas (now Professor of Anthropology at Columbia University, New York), a graduate of the University of Kiel, who was already well known through his researches among the Eskimo of Baffin Land and the Indians of Alaska and British Columbia, was appointed Decent in Anthropology, which position he held until the close of the academic year, 1891-92, when he assumed the duties of director of the sub-department of physical anthropology at the "World's Columbian Exposition, taking with him his fine collection of crania. At the Uni- 148 Anthropology. 149 versity Dr. Boas continued his studies of the anthropology of the Northwest Coast, paying especial attention to a monograph on "The Mythologies of the North Pacific Coast," which he prepared for pub- lication, and to osteological studies of the material collected during his several journeys. In the summer of 1890 Dr. Boas was engaged in investigating the anthropology, ethnology, and linguistics of the Indian tribes of the coast of British Columbia, under the auspices of the British Association for the Advancement of Science. His report, presented to the Leeds meeting in 1891, treated of the customs and beliefs of the Bella Coola, who were shown to be of Salishan stock, besides containing a general review of the physical characteristics of the Indians of the North Pacific coast, with a discussion of the problem of mixed races. Studies of the Chemakum and Chinook languages were also continued and articles prepared for publica- tion. Early in 1890, the approval of the school authorities having been obtained, an extensive series of anthropological measurements was begun in the schools of the city of Worcester, and carried to successful comple- tion. Preparations were also made for the inauguration of similar investigations in other parts of the Union and in Canada. These measurements were undertaken with the object of studying the growth of children as influenced by varying conditions. The investigations in Worcester were carried on by Dr. Boas, with the assistance of the follow- ing members of the University : Dr. G. M. West, Mr. A. F. Chamberlain, Mr. T. L. Bolton, Mr. J. F. Reigart. In the spring of 1891 preparations were made for extensive anthropological measurements of the American Indians, under the auspices of the World's Columbian Exposition, Dr. Boas being placed in charge of the sub-department of physical anthro- pology. In prosecution of these investigations, the following students of the University, trained in the anthropological laboratory,, were engaged during the summer : Dr. G. M. West, in Quebec and the maritime provinces of Canada; Mr. T. F. Holgate, in eastern Ontario; Dr. T. Proctor Hall, in western Ontario ; Mr. T. L. Bolton, in Idaho and Utah. Other observers were similarly employed in Alaska, British Columbia, the northwest territories of Canada, Labrador, Dakota, Wisconsin, Washington, Oregon, New Mexico, Yucatan, etc. The chief object of the extensive investigation thus begun is to show the distribution of types over the American continent, and to settle, if possible, disputed points regarding the physical anthropology of the Indians. In the 150 Anthropology. summer of 1891 Dr. Boas resumed his investigations of the Indians of British Columbia for the British Association, and also visited the last survivor of the Chinook tribe, from whom he obtained very valuable ethnologic and linguistic data. During the academic years, 1889-92, Dr. Walter Channing, of Brook- line, Mass., Honorary Fellow of the University, carried on original investi- gations in the laboratory of the department. In November, 1890, Dr. G. M. West (afterward Instructor in Anthropology in the University of Chicago), a graduate of Columbia College, was appointed Fellow (and afterward Assistant) in Anthro- pology, and devoted himself to the consideration of its physical side, taking a large part in the anthropometric investigations begun in the Worcester schools. During the summer of 1891 Dr. West was engaged in anthropological measurements of the Indian tribes of Quebec and the maritime provinces of Canada. Appointed Assistant in Anthropology in 1891, he continued in that position until the close of the academic year 1891-92, when he became associated with Dr. Boas in the sub-depart- ment of anthropology in the World's Columbian Exposition, having charge of the anthropological investigations during Dr. Boas's absence in Europe. During the Docentship of Dr. Boas the lectures of the department were as follows : — 1. A course of lectures on : Physical Anthropology, Osteology, and particularly Craniology. The Physical Character of the living subject : Anatomy of Races. In connection with these lectures practical work was carried on in the laboratory. 2. A course of lectures on : The Anthropology of Africa, embracing the consideration of the geographical distribution, physical characters, languages, and culture of the native tribes. 3. A course of lectures on: The Application of Statistics to Anthro- pology. In the spring of 1892 Dr. West delivered a course of lectures on The Growth of School Children, based upon the results obtained in the Worcester schools. These lectures have been published in Science and the Archiv fur Anthropologie. In the spring of 1890 Mr. A. F. Chamberlain, a graduate of the University of Toronto, then Fellow in Modern Languages in University College, Toronto, who had been a student in ethnology under the late Sir Anthropology. 151 Daniel Wilson, -was appointed to the first fellowship created in anthro- pology in the University. Previous to entering upon the course of study for the doctorate, Mr. Chamberlain had made special investigations of the Algonkian Indian languages, and these he continued, offering as his thesis an original monograph, "The Language of the Mississagas of Skugog," which was published in 1892. Other briefer essays in the same field have appeared in the Proceedings of the Canadian Institute (Toronto), Canadian Indian, American Anthropologist, Journal of Ameri- can Folk-Lore, Proceedings of the American Association for the Advancement of Science, etc., during the years 1888-99. Time snatched from busy hours from 1891 to 1893 was devoted to original investigations in the language and folk-lore of the Canadian French, some results of which have been published in Modern language Notes (Baltimore), Vols. 6-8. In 1892 was published the result of an extensive investigation of the use of " Diminutives in -ing," in the Platt- Deutsch (Low German) dialects, another study from which field, " Color Comparisons in the Low German Dialects," subsequently appeared. In the spring of 1891 Dr. Chamberlain delivered a brief course of lectures on " The Relationship of Linguistics to Psychology and Anthro- pology." In the fall of the same year he assisted in the anthropometric investigations carried on in the schools of the city of Worcester under the direction of Dr. Boas, and in April-May, 1892, superintended the measurements of some 15,000 school children in Toronto, Canada, the results of which work are being from time to time published (see Report of Commissioner of Uducation, 1896-97, Vol, 2) by Dr. Boas, under whose auspices it was carried out. From June to October, 1891, he was absent among the Kootenay Indians of southeastern British Columbia and Northern Idaho, having been selected by the committee of the British Association for the Ad- vancement of Science to carry on anthropological investigations among the Indian tribes of northwestern Canada. His report (discussing in detail the ethnography, physical anthropology, mythology, and language of this comparatively unknown aboriginal people) was presented at the Edinburgh (1892) meeting of the Association and printed, with an introduction by Horatio Hale, as the " Eighth Report on the Northwestern Tribes of Canada" (London, 1892, 71 pp.). Other briefer studies, botanical, linguistic, mythological, psychological, based upon the material gathered during this expedition, have been published in the American 152 Anthropology. Anthropologist, American Antiquarian,, Journal of American Folh-Lore, Verhandlungen der Berliner anthropologischen Gresellschaft, Arehivio per V Antropologia, Am Ur-Quell, Science, etc. The great mass of material, however, is still in process of preparation for publication, and will, when complete, make some four good-sized treatises or volumes as follows : — 1. Kootenay Indian Art. An Interpretative and Comparative Study of some Three Hundred Drawings of Natural Objects, Human Beings, Animals, etc., made by various Indians of the Upper and Lower Kootenay. 2. Mythology of the Kootenay Indians. A Comparative and Interpretative Study of some Fifty Animal Tales and Legends of the Kootenay Indians. With original Indian Text, Translation, Explanatory Notes, etc. 3-4. Dictionary of the Kootenay Language, with Introduction on Grammar and Morphology. Part I., Kootenay-English ; Part II., English-Kootenay. As much time as could reasonably be spared from other duties has been devoted to the long and difficult task of compUation and revision of these original studies. During his tenure of the Lectureship in Anthropology, Dr. Chamber- lain has lectured twice a week throughout the academic year, the following courses having been delivered: — 1892-93. Mythology of the North American Indians. The syllabus and bibliography of this detailed interpretative study have been published in the " Third Annual Eeport of the President to the Trustees of Clark University," 1893, pp. 123-125, 141-161. Several of the lectures have appeared in full, or in abstract, in the Journal of American FolkrLore. 1893-94. General Course : The Science of Anthropology in its Eelations to Psychology and Pedagogy. Special Courses: (a) Comparative Mythology of Ancient Greece and Italy ; (6) Child Life among Primitive Eaees, the American Indians especially. The introductory lecture of this course, under the title "Anthropology in Universities and Colleges," with brief historical bibliography, has been pub- lished in part in the Pedagogicai Seminary, Vol. 3, pp. 48-60. An abstract of one of the lectures in course (6) has appeared as "Notes on Indian Child Language," in the American Anthropologist, Vol. 3, pp. 237-241 ; Vol. 6, pp. 321-322. 1894-95. Besides the course in General Anthropology, the following brief special courses were delivered : Anthropology and Ethnology of Sex ; The Child amongst Primitive Peoples ; Comparative Mythology of America and Anthropology. 153 the Old World; Psychology of Primitive Languages; The Beginnings of Art and Language ; The ^sthetical Ideas of Primitive Peoples. The lectures on the " Psychology of Primitive Languages" were based upon original investigations among the Algonkian Indians of Canada, and the Koote- nay Indians of British Columbia, and abstracts of several of them have been published in the American Anthropologist, Vol. 7 (1894), pp. 68-69, 186-192 ; Verhandlungen der Berliner anthropologischen Gesellschaft, 1893, pp. 421-425, 1895, pp. 651-556 ; Archivio per V Antropologia e la Etnologia (Firenze), Vol. 23 (1893), pp. 393-399. The lectures on " The Child among Primitive Peoples," delivered also in popular form at the Summer School in July, 1894, have been elaborated and published as a book, -with the title " The Child and Childhood in Polk-Thought " (New York, Macmillan, 1896). 1895-96. Besides the course in General Anthropology, the following special and briefer courses were delivered : Anthropometry of Children and Youth ; The Emotions and their Expression among Primitive Eaces; The Idea of the Soul among Primitive Peoples ; Crime and Degeneracy among the Lower Races of Man; Origin and Development of the Family; Sociological History of Woman. Two of the lectures on "The Emotions and their Expression among Primi- tive Peoples " have appeared in part in the American Journal of Psychology, Vol. 10, pp. 301-305, "Fear," and Vol. 6, pp. 585-592, "Anger." 1896-97. Besides the course in General Anthropology, the following briefer special courses were delivered : The Philosophy of Primitive Mythologies ; Origin and Development of Social Institutions; Eace-Psychology ; The Anthropology of Childhood ; Civilization and Evolution. One of the lectures in the course on "The Philosophy of Primitive My- thology" appears, under the title "Folk-Lore and Mythology of Invention," in the Journal of American Folk-Lore, Vol. 10 (1897), pp. 89-100. 1897-98. Besides the course in General Anthropology, the following briefer special courses were delivered : The Anthropology of Sex ; Primitive Children and Children of Civilized Eaces ; Social Evolution ; Origin and Development of Primitive Eeligions ; Anthropometry. 1898-99. Besides the course in General Anthropology, the following special briefer courses have been delivered : ChUd Study in Italy, Variation and Degeneration, Heredity and Environment. Outside of the academic and summer school courses the following lectures and addresses on topics of general interest have been delivered from time to time in Worcester and elsewhere : — 154 Anthropology. 1892. Aims and Methods of Anthropometry. Principals and Teachers of Grammar Schools, Toronto. 1892. Optimism. Canadian Club, Clark University, Worcester. 1893. Savage Views of Nature. Natural History Society, Worcester. 1893. The American Indian. Men's Association, Pilgrim Church, Worcester, Mass. 1894. Woman's Eole in the Development of Eeligion and Civilization. Fort- nightly Club, Woonsocket, R.I. 1895. The World's Debt to the Eed Man. Natural History Society, Sterling, Mass. 1895. The Mother and the Child in the Story of Eeligion and Civilization. South Unitarian Church, Worcester, Mass. 1896. Childhood. Conference of Lend-a-Hand Clubs, Lowell, Mass. 1896. The American Indian. Universalist Church, New Britain, Conn. 1896. The Making of Abraham Lincoln. South Unitarian Church, Worcester, Mass. 1897. Johanna Ambrosius. Lend-a-Hand Clubs, South Unitarian Church, Worcester, Mass. 1897. Youth. Lend-a^Hand Conference, Boston, Mass. 1897. Lincoln and Darwin. South Unitarian Church, Worcester, Mass. 1897. In Memoriam : Henry George. South Unitarian Church, Worcester, Mass. 1897. The Unitarian Church and Alcoholism. Conference of Unitarian Churches, Barre, Mass. 1898. Primitive Nature Study. Jacob Tome Institute, Port Deposit, Md. 1899. The Child and the Criminal. Monday Morning Club (Universalist Min- isters), Boston, Mass. At the meetings of various scientific societies, 1890-99, the following papers have been presented, those marked * having been published since their delivery: — 1. American Folk-Lore Society : — 1890. *Nanibozhu among the Otcipwe, etc. 1892. *Physiognomy and Physical Characteristics in Folk-Lore and Folk- Speech. 1892. Christ in Folk-Lore. 1893. Mythology of the Columbian Discovery of America. 1896. *Poetical Aspects of American Aboriginal Speech. 1896. *Folk-Lore and Mythology of Invention. 1898. *American Indian Names of White Men and Women. 2. Modern Language Association of America : — 1891. *The Use of Diminutives in -ing by some writers in Low German Dialects. Anthropology. 155 3. American Association for the Advancement of Science : — 1893. Primitive Woman as Poet. 1894. *Translation into Primitive Languages. (Abstract.) 1894. *Incorporation in the Kootenay Language. 1894. *Primitive Anthropometry and its Folk-Lore. (Abstract.) 1895. *Kootenay Indian Personal Names. *Word Formation in the Kootenay Language. 4. British Association for the Advancement of Science : — 1892. *Kootenay Indians. 1897. *Kootenay Indian Drawings. (Abstract.) 1897. *The Kootenays and their Salishan Neighbors. (Abstract.) 6. Berliner Anthropologische Gesellschaft: — 1893. *Wurzeln aus der Sprache der Kitonaqarlndianer. 1895. *Beitrag zur Pflanzenkunde der Naturvolker America's. 6. International Congress of Anthropology (Chicago) : — 1893. *The Coyote and the Owl. (Tales of the Kootenay Indians.) Dr. Chamberlain has been a Councillor of the American Folk-Lore Society (1894), Secretary of the Anthropological Section of the Ameri- can Association for the Advancement of Science (1894), and one of the secretaries of the Anthropological Section of the British Association for the Advancement of Science (1897). Since 1894 anthropology has been represented on the programme of the Summer School of the University, and each year Dr. Chamberlain has delivered a course of twelve daily lectures upon anthropological questions and topics of more or less interest to the teacher and to the general public. These courses have been as follows : — 1894. Anthropology of Childhood. (The Child Among Primitive Peoples.) 1895. Pedagogical and Psychological Aspects of Anthropology. 1896. Anthropology of Childhood. (New Series.) 1897. Anthropological Aspects of Childhood. 1898. The Beginnings of Education and Educational Institutions. — Primitive Pedagogy. 1899. Educational Aspects of Human Evolution. At the various summer schools the following topics have also been popularly treated in evening lectures : — 1896. (a) The Philosophy of Childhood with the Poets. (6) The Genius of Childhood. 156 Anthropology. 1897. (a) The Divinity of Childhood. (6) The Attitude of Primitive Peoples toward Nature. 1898. The Childhood of Genius. 1899. (a) The Prophecy of Childhood. (&) The Making of a Genius. (Abraham Lincoln.) Anthropology, while comparatively a new, is by no means an uncom- mon, subject of academic instruction, and the time has distinctly passed when it should be called upon to plead for its existence, or to make an oratio pro domo. Very many of the great European universities have specifically rec- ognized anthropology as worthy of the highest positions in their gift, and, in this country, institutions like Harvard, Columbia, Chicago, and the University of Pennsylvania have endued this department vrith the full dignity of a professorship. Moreover, nearly twenty other colleges and universities in America now offer instruction in anthropology, as such, while Sociology, one of the most important branches of the science, is to be found on the curriculum of all such institutions as are making any efforts whatsoever to keep abreast of the times. Other branches of anthropology, such as Comparative Philology, Comparative Religion, Race Psychology, Anthropometry, Archaeology, Culture-History, etc., are finding more and more acceptance with the higher institutions of learning. Both with respect to original research and to academic lectures, the representatives of anthropology in American universities have no reason to fear comparison with the professors and instructors in any other branch of science, and their influence in broadening and humanizing some of the more belated and conservative of the kindred brancjies of human knowledge can hardly be overestimated. It is a significant fact that the latest and most complete academic recognition of anthropology, the promotion of Dr. Franz Boas to a profes- sorship in Columbia University, does just honor to one who began his academic career as a Docent in Clark University in 1890. How much of the interest in anthropology in other institutions of learning can be legiti- mately traced to this University, which, in 1892, conferred the first Ph.D. ever granted in America for research and investigation in anthropological science, cannot readily be ascertained, but its influence, both direct and indirect, has been, no doubt, as it still is, very great. Proofs of this are not wanting in the curricula of more than one of the higher institutions of learning, while the course in anthropology in the University of Illinois, Anthropology. 157 offered by Dr. Arthur H. Daniels, a graduate of Clark University, is directly due to the initiative and encouragement of the department of anthropology. Through the lectures delivered at the University and during the Summer School, the anthropological department has exercised an ever increasing influence, which has been added to by the appearance of one series of these lectures in book form. Another point of contact with the teaching profession throughout the country lies in the use of the depart- ment as a sort of bureau of information upon many and varied topics of educational science. During the last year, especially, very many requests for such information have been received and responded to, often in detail and as the result of personal research. To the students of the University the department of anthropology has always emphasized the great value of a bibliographical knowledge of the subject under investigation, and its services have always been at their disposal. In this University anthropology ranks as a branch of psychology, and to promote and advance it as such has been the constant aim and endeavor of its representative on the Faculty. The lectures have been such as to correlate with the instruction given in philosophy, psychology, and peda- gogy, and their object has been to furnish the students in those depart- ments with the most recent results of anthropological investigations, and to imbue them with that wider and deeper thought that comes from the contemplation of the history of individual and of racial man, and to lay firm foundations upon which in years to come may rise a complete and per- fectly equipped department of anthropology. A glance at the theses and essays in the departments of philosophy and psychology will demonstrate the way in which the department has advantaged those who have pro- ceeded to their degrees in this University, such subjects as " Regeneration," "Dolls," "Migration," "Hydro-Psychoses," " Dendro-Psychoses," "Im- mortality," "Teaching Instinct," "Philosophy of Education," "Adoles- cence," "Degeneracy," etc., naturally calling upon anthropology for its quota of fact and information, which has often been quite large and sig- nificant. Especially has this been the case since " Child-study" has loomed up so largely in the field of education, for questions of heredity and environ- ment, recapitulation, atavism and reversion, degeneration, variation, genius, and the like, must receive from anthropology, more or less, their true orientation and interpretation, — the science of the child would be help- less without the science of man, the story of the individual not half 158 Anthropology. understood without the story of the race. The greater prominence now being given to individual psychology, brings psychology also into closer and better touch with anthropology. That the first woman to hold a fellowship in any department in Harvard University was an anthropolo- gist is a fact, which, taken in connection with the great amount of excel- lent original work done in anthropology by women, both in Europe and in America, augurs well for the future advancement of the science, when all institutions offering post-graduate instruction in anthropology and facilities for original investigation shall have been opened to women upon the same terms as to men. The composite character of the population of the United States, the existence within its borders of several entirely dis- tinct races, and the addition to these resulting from the recent acquisition of outlying and distant possessions, must inevitably tend to make anthro- pology more and more a real academic necessity, no less than a constant factor in the determination of national welfare and progress. Unless every sign fails, the history of anthropology in the next quarter century of American university life will compare in brilliancy with that of any other science similiarly stimulated and environed. At this University, anthropology has accomplished, as the record of the publications of the department shows, results out of proportion to its financial resources and the facilities for investigation and research made possible thereby. With other departments in the University it has striven to overcome these serious handicaps as much as might be, and what has already been done must serve to indicate what can be done in the future, if the department is generously and satisfactorily endowed. Nowhere else, perhaps, can the " sinews of science," rightly employed, give ampler or juster returns, if the past foreshadows the years to come. Clark University, the first institution in America to recognize anthro- pology as a fit and proper subject for post-graduate researches and inves- gation leading to the degree of Ph.D., and the first university to confer such a degree, can justly hope for that recognition which comes to the pioneers in all great educational movements. But before the department can labor at its best, it must have the best means of research and investigation, be equipped as well, at least, as any similar department in any other institution in the country. Given these, it can do as good work, or even better. The professorships at Harvard, Columbia, Chicago, and Pennsylvania, the Thaw Fellowship at Harvard, the library of 20,000 books and pam- Anthropology. 159 phlets in a single branch of anthropology at the University of Pennsyl- vania, and the laboratory and museum facilities of aU these institutions ■which have come into such rich fruition during the last ten years, point the way for us, if the good work of the past is to increase and multiply. For comparison with the present state of affairs at this University, the following data from the most recent official publications of the universi- ties concerned, institutions which offer post-graduate courses in anthro- pology and confer the degree of Ph.D. in that department, wiU suffice (sociology, etc., not included): — Harvard: Professor; Instructor; Thaw Fellow ($1050); Hemenway Fellow ($500) ; Winthrop Scholar (f 200). Chicago : Associate Professor ; one Fellow. Columbia : Professor ; two Instructors ; President's University Scholar ($150) ; one Fellow ; two Scholars. One cannot escape seeing the necessity of enlargement and further endowment at this University, if anthropology is to prosper fully. Before the great things of which it is capable can, in all their rounded completeness, be accomplished here, changes and improvements must take place, and the following are among those most needed or most desirable : — (1) The department must ultimately be dignified by the existence of a professorship, if it is to continue to hold its own among the similar departments in other great educational institutions. Anthropology can wait, as it has waited, but it scarcely deserves that refusal of academical advancement, which is, of necessity, bound up with straitened financial conditions. (2) A complete departmental library, which shall include all cur- rent periodicals and journals of anthropological interest and afford imme- diate access to the very latest American and foreign publications in all branches of anthropological science, is an absolute necessity. The ad- vantage of having all these under one roof and procurable immediately after their issuance is inestimable. (3) A thoroughly equipped laboratory, for special researches and investigations, is also among the things first to be desired, and what investigators now, or formerly connected with the University, have done in this field is a full guarantee that such an addition to the facilities of the University would be well utilized and appreciated. 160 Anthropology. (4) A museum, which shall contain materials and specimens illustrating the parallel development of the individual and the race, is also a desidera- tum, for this truly anthropological theory, so fecund for education and psychology, has yet to undergo that stern test which zoology, palseon- tology, and geology have so successfully sustained. (5) Generous endowment of fellowships and scholarships (intra-mural and extra-mural) and other aids in investigation and field work is abso- lutely necessitated by any adequate instalment of anthropology. (6) More, perhaps, than is the case with most other departments, lib- eral allowances for clerical work and for travelling expenses, the lack of which so often delays good studies and inconveniences good men, are nec- essary, and the department must be congratulated on what has been achieved in the absence of all these. Often to be able means to accomplish. Judged both by the work accomplished here and the status of anthro- pology in other universities, the department has every reason to ask and every right to expect such increased endowment as will enable it to make the next ten years of its existence as notable as the same period in the history of anthropology in any of the higher institutions of learning, European or American. PEDAGOGY. By William Hbnkt Burnham. Soon after the opening of the University, President G. Stanley Hall entered upon the duties of Professor of Psychology and Education. During the first academic year no pedagogical courses were given, but toward the close of the year Dr. William H. Burnham, the writer of this report, was appointed Decent in Pedagogy and sent to Europe by the University to study educational institutions, methods, etc. During the year 1890-91, courses of lectures on pedagogy were given in the psycho- logical department by Drs. Hall and Burnham, and a seminary met weekly for the study and discussion of educational subjects. In 1893 the educa- tional courses were designated as a sub-department of psychology offering a minor for the doctor's degree. But the work has remained most inti- mately connected with that in psychology and anthropology. In any natural development of these three subjects, the subject-matter overlaps and is interrelated. In this University no attempt has been made to mark a line of division between them. Specially close has been the connection between psychology and pedsof'sijf *, most of the students in one subject taking courses in the other. Scich vital connection of the two subjects has mutual advantages. Pedagogy is based upon psychology and owes to it the inspiration and stimulus to scientific work, and psy- chology owes to pedagogy the suggestion of some of its most fruitful fields of investigation. With a limited staff no attempt has been made to cover the whole field of pedagogy ; but by choosing specially important parts of the field, and by extending the courses over two or three years, an effort has been made to show how the subject should be studied. By this method lectures have been given on the history of the modern reform movement in educa- tion, begun on the one hand by the early Italian Humanists, and on M 161 162 Pedagogy. the other by Comenius, the present organization of schools in England, France, and Germany, the Evolution of the Teaching Profession, the Historical and Critical Study of Educational Principles, Mental and Physical Development, Educational Psychology, and School Hygiene, including the Hygiene of Instruction. Other courses have been given by Drs. Hall, Burnham, and Lukens on the following among other topics : History of Methods in Reading, Physical Education, Child-study, Adolescence, Ideal School, Herbartian Pedagogy, History of Curricula, and leading present topics in education. A great variety of subjects have been studied in connection with the seminaries, and the results of many of these studies have appeared in the Pedagogical Seminary, an educational journal edited by G. Stanley Hall and published at the University, beginning in 1891. The work of the department is best seen, however, by noting its aims, methods, and concrete results. The aim of the department is twofold : first, to give instruction and training to those who are preparing to be professors of pedagogy, super- intendents, or teachers in higher institutions ; second, to make scientific contributions to education. These two ends are so closely related that the pursuit of one involves much of the work required for the other also. Suitable preparation for the course involves so much of general edu- cation as is usually indicated by the B.A. degree. A good reading knowledge of French and German is of vital importance, and an acquaint- ance with elementary psychology is desirable, it being taken for granted, of course, that those who intend to teach have adequate knowledge in their own special departments. Assuming that a S';i*4ent has adequate preparation, three things are essential for higher peda"^gical training: first, a general knowledge of the organization of education in different countries and of literature in the field of education, including the history of education, psychology in its relation to education, and school hygiene; second, actual experience in teaching, together with observation of good teaching, and some direct study of educational institutions of different character and grade ; third, some experience in independent research, involving not only the thorough study of all authorities upon a subject, and of all work that has been done in the same field in different countries, but also original investigation leading to a scientific contribution. These three kinds of work may be done simultaneously or successively. Pedagogy. 163 In some of the best higher pedagogical seminaries in Germany they are done simultaneously. Students study and report upon educational and psychological literature. They visit classes of different grades, observing the work of regular teachers, and also teach in a practice school. At the same time they endeavor to investigate some special problem. In this University the study of educational literature, by lectures and inde- pendent reading, and the investigation of some problem, are usually car- ried on simultaneously; but practical experience in teaching must be gained before or after the University course. There are some advan- tages in doing actual teaching simultaneously with the study and investi- gation of educational problems. Direct experience in the school makes investigation more vital and practical, and is an important control in scientific research. But, while at present the University has no practice school, as a matter of fact, most of those who have been members of the educational department have had experience in teaching before coming to the University ; and the lack of direct connection with the schools is in part supplied by visits to educational institutions. Moreover, there is no rigid line between instructors and students in the department. Both are teachers and learners in turn. Special emphasis is placed upon the importance of research ; and much of the time of the instructors is spent in consultation with individual students in regard to their investigations. President Hall especially has given a large amount of attention to direct- ing this work. The research undertaken has been largely in the field of genetic psychology and related subjects ; and the students have been assisted by the instructors in psychology, anthropology, and neu- rology. A great variety of topics, however, have been studied; and a large part of the investigations have yielded results for publication. The papers ^ that have already appeared may be roughly classified as follows : — Contributions to the Physiology and Psychology of Development. BOHANNON, E. W. : A Study of Peculiar and Exceptional Children. Pedagogical Seminary, Oct., 1896, Vol. 4, pp. 3-60. Based upon answers to a questionnaire reporting over a thousand cases. 1 Many of the papers mentioned in this list are quite as much products of the department of psychology as of that of pedagogy ; and, on the other hand, the pedagogical department has contributed to many of the psychological studies mentioned above. 164 Pedagogy. BoHANNOsr, E. W. : The Only Child in a Family. Pedagogical Seminary, April, 1898, Vol. 5, pp. 475-496. Prom a study of reports of 381 only children, it appears that only chil- dren are below the average in vitality and unusually subject to mental and physical defects of a grave character, and that, lacking the impor- tant education from the constant companionship of other children, they need special pedagogical care and training. Btjkk, Frederick: Growth of Children in Height and Weight. Am. Jour, of Psy., April, 1898, Vol. 9, pp. 253-326. A comprehensive resum^ of the numerous studies in this field, with a discussion of their pedagogical significance. BuRK, Frederick : From Fundamental to Accessory in the Devel- opment of the Nervous System and of Movements. Pedagogical Seminary, Oct., 1898, Vol. 6, pp. 5-64. A contribution to the physiology of development, especially a study of the evolution of hand movements in the development of the normal child. From a comprehensive review of the various neurological and psychological studies upon this subject, the author makes among others the following conclusion : that there is an early period in the develop- ment of each part or process when the purpose of education must be to follow the fixed innate heredity line of tendency (fundamental educa- tion); that there follows a later period in an activity's development when it passes partially out of the control of racial habit and becomes more plastic to present environment (accessory education). Presented as a dissertation. BuRNHAM, Wm. H. : The Study of Adolescence. Ibid., June, 1891, Vol. 1, pp. 174^195. A brief introduction to the study of the adolescent problem. BuRNHAM, Wm. H. : Individual Differences in the Imaginations of Children. lUd., March, 1893, Vol. 2, pp. 204-225. Based upon literature and reports by students at the Worcester Normal School. Chrisman, Oscar: The Secret Language of Children. Science, Dec. 1, 1893, Vol. 22, p. 308. Pedagogy. 165 Ckoswell, T. R. : Amusements of Worcester School Children. Pedagogical Seminary, Sept., 1899, Vol. 6, pp. 267-371. A study of Jhe amusements of two thousand children based upon reports by the children. A contribution to the problem of variation in play as conditioned by age, sex, nationality, locality, and season. The results indicate as characteristic of the games of adolescence the cooperar tion of a number of individuals to secure a definite end, and the delight in contest in contrast with the individualistic amusements of earlier years. Hall, G. Stanley: Initiations into Adolescence. Proc. Am. Antiq. Soc, Worcester, Mass., Oct. 21, 1898, Vol. 12, pp. 367-400. Includes a detailed account of certain rites of primitive peoples, and discusses the relation of adolescent instincts in religion. Lancaster, E. G. : The Psychology and Pedagogy of Adolescence. Pedagogical Seminary, July, 1897, Vol. 5, pp. 61-128. A comprehensive study by the questionnaire method. With a resum^ of the work of others and practical suggestions. Presented as a disser- tation. YoDEE, A. H. : The Study of the Boyhood of Great Men. Ibid., Oct., 1894, Vol. 3, pp. 134-156. Based upon the study of a large number of biographies. Studies of Special Branches of Education from the Genetic Point of View. Ellis, A. Caswell : Sunday-school work and Bible Study in the Light of Modern Pedagogy. Ibid., June, 1896, Vol. 3, pp. 863- 412. An attempt to suggest the psychological method of religious instruc- tion, together with an historical sketch of the Sunday-school idea. Johnson, G. E. : Education by Plays and Games. Ibid., Oct., 1894, Vol. 3, pp. 97-133. Presents a classified list of about five hundred plays and games with a study of their educational value. HOYT, Wm. a. : The Love of Nature as the Root of teaching and learning the Sciences. Ibid., Oct., 1894, Vol. 3, pp. 61-86. Based chiefly upon literature, with pedagogical suggestions. 166 Pedagogy. Ltjkens, Herman T. : Preliminary Report on the Learning of Lan- guage. Ihid., June, 1896, Vol. 3, pp. 424r460. Traces the stages in a child's learning to talk, and presents much data in regard to pronunciation and the development of the sentence. LuKENS, Heemast T. : A Study of Children's Drawings. Ihid., Oct., 1896, Vol. 4, pp. 79-110. A genetic study based upon original reports and observations. Phillips, D. E. : Number and its Application psychologically con- sidered. Ihid., Oct., 1897, Vol. 5, pp. 221-281. Includes a study of over two thousand arithmetic papers prepared by children in the schools, the results of a questionnaire research, a criti- cal estimate of many text-books, and a discussion of the general sub- ject from the genetic standpoint. Stbeet, J. R. : A Study in Moral Education. Ihid., July, 1897, Vol. 5, pp. 5-40. Based upon the reminiscent answers of adolescents to a questionnaire. The results suggest the great rSle of imitation, instruction, the sentiments, and heredity in. moral action, and emphasize the significance of habit. Street, J. R. : A Study in Language Teaching. Ihid., April, 1897, Vol. 4, pp. 269-293. Studies in School Hygiene. Bfenham, Wm. H. : Outlines of School Hygiene. Ihid., June, 1892, Vol. 2, pp. 9-71. Includes, besides a general survey of school sanitation, brief studies of such topics as fatigue, the period of study, school furniture, the hygiene of writing, etc. Btjrnham, Wm. H. : Bibliography of School Hygiene. Proc. N. U. A., 1898, pp. 505-623. A selected list of 436 titles. Chrisman, Oscar: The Hearing of Children. Pedagogical Semi- nary, Dec, 1893, Vol. 2, pp. 397-441. A resume of the investigations of the hearing of school children in different countries. Practically complete to the date of publication, with practical suggestions collected from different authorities. Pedagogy. 167 Dbesslar, F. B. : Fatigue. Ibid., June, 1892, Vol. 2, pp. 102-106. An introduction to the general subject of mental fatigue. Deesslab, F. B. : a Sketch of Old Schoolhouses. Ibid., June, 1892, Vol. 2, pp. 115-125. A brief historical contribution to school hygiene. Principles, Methods, and Organization of Education. Ckoswell, T. R. : Courses of Study in the Elementary Schools of the United States. Ibid., April, 1897, Vol. 4, pp. 294-335. Devoted especially to state and city courses and legal requirements. Ellis, A. Caswell : Suggestions for a Philosophy of Education. Ibid., Oct., 1897, Vol. 5, pp. 159-201. The closing chapter of an extended historical study of the philosophy of education presented as a dissertation. Hall, G. Stanley: Child Study the Basis of Exact Education. Forum, Dec., 1893, Vol. 16, pp. 429-441. LuKENS, Heeman T. : The Correlation of Studies. Educational Re- view, Nov., 1895, Vol. 10, pp. 364-383. POTTEE, J. R. : History of Methods of Instruction in Geography. Pedagogical Seminary, Dec, 1891, Vol. 1, pp. 415-424. Specially an account of German methods, based upon literature. ScEiPTUEB, E. W. : Education as a Science. Ibid., June, 1892, Vol. 2, pp. 111-114. A plea for experimental education mth report of illustrative experi- ments. Seaes, Charles H. : Home and School Punishments. /6ic?., March, 1899, Vol. 6, pp. 159-187. Based upon literature and the answers to a questionnaire. The Training of Teachers. BuEK, Feedeeick L. : The Training of Teachers. Atlantic Monthly, Oct., 1897, Vol. 80, pp. 547-561, and June, 1898, Vol. 81, pp. 769-779. 168 Pedagogy. Btjbnham, Wm. H. : Higher Pedagogical Seminaries in Germany. Pedagogical Seminary, Dec, 1891, Vol. 1, pp. 390-408. A sketch, of the history and present character of the different kinds of pedagogical seminaries for training teachers for the higher schools in Germany, based on literature and personal observation. BxrBNHAM, Wm. H. : Some Aspects of the Teaching Profession. Forum, June, 1898, Vol. 25, pp. 481-495. Hall, G. Stanley : American Uniyersities and the Training of Teachers. Ihid., April and May, 1894, Vol. IT, pp. 148-159, 297-309. Hall, G. Stanley: The Training of Teachers. JTSic?., Sept., 1890, Vol. 10, pp. 11-22. Hall, G. Stanley : Research the Vital Spirit of Teaching. Ibid., July, 1894, Vol. 17, pp. 558-570. Phillips, D. E. : The Teaching Instinct. Pedagogical Seminary, March, 1899, Vol. 6, pp. 188-245. A study of the phenomena of leadership and teaching among animals and children, of the lives and motives of the great teachers, and of train- ing in relation to the teaching instinct, including a contribution by the questionnaire method. Presented as a dissertation. Rbigart, J. F. : The Training of Teachers in England. Ihid., Dec, 1891, Vol. 1, pp. 409-415. A brief sketch based upon literature. Miscellaneous. BuKK, Fbedekick L. : Teasing and BuUying. Pedagogical Seminary, April, 1897, Vol. 4, pp. 336-371. Based on returns to a questionnaire. Hall, G. Stanley: Boy Life in a Massachusetts Country Town Thirty Years Ago. Proc. Am. Antiq. Soc, Worcester, Mass., Oct. 21, 1890, N. S., Vol. 7, pp. 107-128. An historical contribution showing the many-sidedness of the home education of the New England country boy. Pedagogy. 169 Hall, G. Stanley: The Case of the Public Schools. Atlantie Monthly, March, 1896, Vol. 77, pp. 402-413. Hall, G. Stanley: The Love and Study of Nature: a Part of Education. Agriculture of Massachusetts, 1898, pp. 134-154. Lectures delivered before the Massachusetts State Board of Agri- culture at Amherst, Dec. 6, 1898. Treats of the child's attitude toward nature. Hancock, John A. : An Early Phase of the Manual Training Move- ment. Ibid., Oct., 1897, Vol. 5, pp. 287-292. A brief historical sketch of the old manual labor school. Johnson, G. E. : Contribution to the Psychology and Pedagogy of Feeble-minded Children. Ibid., Oct., 1895, Vol. 3, pp. 246-291. Reports result of tests of memory span, motor ability, and association, in feeble-minded children at the Massachusetts School for the Feeble- minded at Waltham, together with an historical introduction and practi- cal suggestions for their education. KiSTLEE, Milton S. : John Knox's Services to Education. Education, Oct., 1898, Vol. 19, pp. 105-116. Kline, Linus W. : Truancy as Related to the Migratory Instinct. Pedagogical Seminary, Jan., 1898, Vol. 5, pp. 381-420. Includes a comparison of the physical condition of truants as shown by anthropometric tests with that of public school children. Sheldon, Henky D. : The Institutional Activities of American Chil- dren. Am. Jour, of Psy., July, 1898, Vol. 9, pp. 425^48. Based largely on returns to a questionnaire. Small, M. H. : Methods of manifesting the Instinct for Certainty. Pedagogical Seminary, Jan., 1898, Vol. 5, pp. 313-380. A comprehensive study of oaths based upon 2,263 answers to a ques- tionnaire and a vast amount of literature. Such have been the methods of the department, and such in part the work done. The aim has been to treat a few subjects in a broad way, 170 Pedagogy. rather than to exhaust the field of conventional pedagogy. The necessity and the advantages of this method are obvious from a brief consideration of the subject of education, both theoretical and practical. Jean Paul Richter quotes the French artist who required from a good director of the ballet, besides the art of dancing, only geometry, music, poetry, painting, and anatomy. " But," he adds, " to write upon educa- tion means to write upon almost everything at once ; for it has to care for and watch over the development of an entire . . . world in little, — a microcosm of the macrocosm. ... If we carried the subject still fur- ther, every century, every nation, and even every boy and every girl, would require a distinct system of education, a different primer and do- mestic French governess, etc."^ The subject of pedagogy is still more encyclopaedic to-day than when Jean Paul Richter wrote these words. Its foundation involves the whole physiology and psychology of develop- ment in the individual, and the history of culture in the race, and its superstructure includes, not only all the various forms and systems and methods of education, but the study of the influence of environment in the widest sense. The conventional views minimize both the difficulties and the impor- tance of the subject. It is said that pedagogy is applied psychology or applied child study, and again that pedagogy must get its norms from the history of education and from child study. This statement will do if one knows what it involves. The history of education means the history of civilization from its earliest traceable genesis among primitive peoples. It means a study of types of culture and the conditions of their develop- ment. In a word, it is a study of the evolution of education. Child study means, too, the study of the physiology and psychology of develop- ment in man. The science of development aims to give a complete description of all the stages of physical development from infancy to maturity, to show their sequence and their relation to the acquisition of organic, sensory, motor, and psychic processes. As far as psychology goes, it is genetic psychology, which means more than is frequently connoted by child study. Adult psychology is one thing, relatively fixed, except for variations incident to environment or the individual. Child psychol- ogy) even for a single individual and a given environment, varies con- tinually because the individual is in the process of growth and rapid development of function. It is one thing for the infant, a very different 1 Richter, " Levana, or the Doctrine of Education," Author's Preface. Pedagogy. 171 thing for the child who can walk and talk, still another at that plateau in the curve of development that seems to come somewhere between nine and twelve for girls and ten and fourteen for boys, still another for the adolescent. The variation is seen in the period of a single year, almost with the changing moons. This is true, not only on account of the grosser acquisitions, but is seen in the sequence of interests and activities. Child psychology is protean. It varies not only with the individual and the environment, but especially with the stage of development. Further, the science of development includes comparative psychology. Not only must the child mind be compared with the adult mind, but the stages of devel- opment in the child should be compared with the stages of development in animals, the faculties of the child with those in animals, the motor ability and activities of the child with those in animals. And again, the stages of development in the child must be compared with those in the race; ontogenesis in relation to phylogenesis must be studied. All this is scientific study, not directly practical. Before deriving the norms for practical pedagogy, a propsedeutic study must be made. As Professor James has said: " Psychology is a science, and teaching is an art; and sciences never generate arts directly out of themselves. An intermediary inventive mind must make the application by using its originality." This mediating function is represented by two somewhat vaguely defined branches of pedagogy — educational psychology, and the general principles and methods of education. Again, after the general principles of education have been derived from psychology and history, and the theoretical norms established, they must be verified by practical educational experiments. This brings us to the practical side of pedagogy represented by such subjects as the organiza- tion of schools, the art of teaching, and special didactics. And parallel with the art of teaching in its derivation from the science of development is school hygiene, which studies especially the conditions that favor the healthy development of the school child. Thus pedagogy is both theoreti- cal and practical, at once a science (at least potentially) and an art. Such is the subject which, as the Italian proverb runs, is always poor and naked, and, in the words of a German writer, has long sat as a drudge at the academic hearth, and whose highest recognition in the great univer- sities has usually been as the handmaid of philosophy. Everybody believes in education, yet few believe in pedagogy. The reasons for this are obvious. Apart from a few fundamentals that are almost common- 172 Pedagogy. place, pedagogy has lacked a solid body of scientific knowledge and universally accepted principles. Worse than this, it has lacked a definite method and a definite ignorance. Most of the works on the history of education are padded with accounts of second-rate writers and second-rate books that happen to be labelled educational ; while the really great educators have often been neglected, and educational movements have been described as isolated currents in the progress of civilization, without regard to their vital connection with political, social, and industrial movements. The method has been the elementary method of studying and describing isolated facts without regard to historical perspective and causal relations; and even the works of the classic writers have been chiefly the repetition and recasting of a few old truths which had been forgotten or were ignored at the time in which the reformers lived. For example, Comenius two hundred and fifty years ago taught that we must study nature by the inductive method and adapt education to the sequence of the stages of natural development; but his writings were forgotten, and again and again the reformers have had to teach again to a new generation the simplest principles of the Comenian didactic. Most of the books on the educational systems of to-day, in like manner, consist of the barren details of organization and method, and the description often of inferior teachers and schools. The forces that have produced these teachers and schools, the significance of the educational movements, have not been seen; and the philosophical, social, and religious thought that has determined educational ideals has not been studied. These isolated facts are barren. Their real signifi- cance is in their relation to other facts. We cannot, for example, under- stand the educational events in England to-day unless we know something of the wider relations of the school movement. The wrangling over the question whether the parish of Eastbourne shall have a school board, or whether the school education of the parish shall continue to be supplied by voluntary schools, means a great deal more than a difference in taxes of a few pence in the pound. This petty struggle is a part of the great movement for the disestablishment of the Church of England. The com- missioning of a new fellow for university extension work marks another step in the progress of the democratic ideal, which, no longer satisfied with provision for elementary education for every child, now demands also for each individual, according to his ability, a share in higher education. A new endowment for a technical school by the Worshipful Society of Gold- Pedagogy. 173 smiths, or the like, may indicate a new dread of democracy on the part of certain monopolists quite as much as any special interest in industrial education. Oxford itself, with all its marvellous beauty and idealism, the stronghold of conservatism, cannot keep aloof from the great social, indus- trial, and educational movements outside. No better illustration could be chosen to show the progress of the democratic ideal in education. At the beginning of Queen Victoria's reign one could not even study at Oxford without subscribing to the Thirty-nine Articles. A few years ago Jowett advocated opening the university honors and emoluments to the world, admitting anybody to any university examination without restriction of sect, class, race, age, or residence. As was remarked at the time, if fifty or perhaps twenty years ago a radical undergraduate were to have made such suggestions, he would have stood a chance of being expelled from the university, as Shelley was, for blasphemy; now they are the last words of Jowett, quoted with approval before the vice-chancellor. To miss these larger aspects is to miss everything of permanent value. Historical literature in education has relatively little importance for its direct practical teachings ; but the importance of the history of education as a culture subject can hardly be put too high. Education represents one of the deepest human interests, more vital than politics, and well- nigh as universal as religion. The history of education is the history of the development of civilization. It aims at nothing less than the study of the school as a factor in the development of culture in relation to the other factors in education, — the home, the church, the farm, the work- shop, the playground, and the rest. And it aims at the study of educa- tional movements in their genesis, and in relation to political, social, industrial, scientific, and literary movements. This involves not merely the study of educational writers so-called and school systems, but the study of types of culture and the causes that condition them. Likewise in the other parts of the field the failure to recognize the wider significance of the subjects studied, and the attempt to build sys- tems before the foundations were laid, have brought pedagogy into disre- pute. But in recent years the conviction has grown that educational problems must be studied inductively ; and, better still, important contri- butions by the inductive method have actually been made. This has put life into the subject and given hope for the future. Take child study as an illustration. The significance of the modern study of children is not merely the renewed emphasis on the old truth of adapting education to 174 Pedagogy. the stages of development, but the insight that the only way to make this principle vital is concrete inductive study to find out just what are the stages of natural development. Thus every fact in regard to general development or individual variation is deemed significant, and the student is willing to wait for a new science of development before attempting a permanent pedagogical system. During the past ten years the opportunities for truly scientific work in education have been shown as never before, methods of investigation have been demonstrated, and in part the foundations of a science have been laid. The things now needed are trained men and facilities. With them a solid content of scientific knowledge can be acquired that wUl place historical and social pedagogy on as firm a basis as general history and sociology, and genetic pedagogy on a scientific footing comparable to that of psychology. School hygiene has already its methods and a solid body of knowledge, but it needs special laboratories for instruction and research, either independent or in connection with psychology, physiology, and anthropology. The work in pedagogy in this University, although the practical aspects of the subjects studied have not been neglected, has been chiefly in the more scientific and theoretical parts of the field. It is not less important on this account. Pedagogical study, like research in any other field of history or science, is valuable for its own sake without regard primarily to practical results. It is its own justification and its own reward. With the nucleus of solid scientific contributions that now exists, no university can long afford to omit courses in education from its curriculum, whether they have any practical value or not. Such scien- tific studies, however, cannot be divorced from the practical art of educa- tion. The studies of children have emphasized the doctrine that the aim of childhood is its own development, and the best guarantee of normal maturity is normal childhood and immaturity ; in a word, they have emphasized the principles of normal development. But these principles are no longer pedagogical abstractions ; they are greatly modifying the practical work of education, causing greater regard for individual chil- dren rather than uniform classes, for health rather than scholastic prod- ucts, for a psychological order of instruction adapted to the capacity and interests of children rather than logical sequence and articulation of grades. In a word, they are causing courses of study and methods to be reconstructed with regard to the one fundamental principle of fostering Pedagogy. 175 normal growth and development. To mention a few details, ten years ago school baths, adjustable seats and desks, and vertical script, were vagaries of university theorists; to-day they are deemed essentials in the best schools. Ten years ago suggestions of periodic disinfection of school apparatus and school text-books, of investigating pupils' individual capacity and power to resist fatigue, and of adapting education to indi- vidual capacity and interest, in elementary and secondary schools, were likely to be ridiculed ; now their soundness has been demonstrated by practical experiments. What part this University has had in this movement, it is not easy to say ; but it has always advocated such reforms in the regular courses of lectures ; many addresses on topics in school hygiene and pedagogy have been given outside the University before schools and teachers' meetings ; students from this University have become school superintendents, teachers in secondary schools, professors of pedagogy or psychology in normal schools, professors of pedagogy in colleges and universities ; and teachers and educators from all parts of the country have attended lectures on pedagogy during the sessions of the Summer School. To make a department of pedagogy what it should be, it is necessary that the whole field of education be covered by lectures as far as possible, that the more elementary courses be given every year, that research should be extended to the multitude of topics that offer opportunity for study. Nowhere in the world is a complete course in pedagogy covering all the important parts of the field given. Here and there throughout this country and Europe are offered a few truly scientific courses, but the subject will hardly attain its due academic dignity until somewhere in one university are given courses which approximate an adequate treatment of the whole field. That this University might approximate a complete course in the subject are needed an addition to the staff, especially for the study of historical and social pedagogy, the establishment of special fellowships for educational research, a laboratory for school anthropometry and school hygiene, a great enlargement of the educational museum, a pedagogical library like that of the MusSe pSda- gogique in Paris, where educational literature of every kind, both good and bad, may be collected ; and, finally, a model school for the objectifi- cation of ideals, under the direction of competent teachers who should safeguard the interests of the pupils, but offer to university students op- portunities for observation, and in some cases for practice in school work. 176 Pedagogy. The aim of such a course in pedagogy, like that of the more limited course already given in this University, would be twofold : first, to con- tribute something to the body of knowledge in regard to education, the content of pedagogy ; and, second, to give practical training to students preparing to become teachers. These two aims are quite in harmony, for an essential in the training of a teacher is the development of those permanent professional interests and that professional apperception and prevision acquired by the study of the more scientific parts of pedagogy. PHILOSOPHY. By G. Stanley Hall. In addition to my own work in psychology and education, reported in the preceding articles by my colleagues, Drs. Sanford and Burnham, and in editing the American Journal of Psychology and the Pedagogical Seminary, I have lectured during the last eight years on the History of Philosophy. This course is felt to be of cardinal importance for those studying either psychology or education, to give them breadth of view, to teach what great problems have interested the race, and to give a repertory of general ideas that will obviate some of the dangers of specialization. The course begins with a very brief survey of Oriental speculation, treats the pre-Socratio Greek thinkers with considerable detail and with constant reference to their fragmentary texts. Great stress is laid upon Plato, and from a quarter to half of all his works are read aloud by the students in turn from Jowett's translation, and on these dialogues the examination for the doctorate is in some part based. Even for those who read some Greek, the use of the English translation is preferred, because more can be gained from Plato by men of this grade by extensive reading than by intensive and critical study of text. Discussions often arise in this work. Aristotle is treated in the same manner, and selec- tions and sometimes large portions of some of his works are read in English. From twelve to twenty lectures are given on the later schools, ending with Plotenus and Proclus. This usually concludes the work of the first year. Until two years ago the second year began with the rise of scholasti- cism and the third ended with Schopenhauer, Lotze, Hartmann, and con- temporary writers. Special effort has always been made to go considerably outside the stock text-book field and to deal to some extent with the history of science, with some reference to medicine and with very slight reference to literature, art, etc. The texts of Spinoza, Locke, Berkeley, N 177 178 Philosophy. Hume, Kant, Fichte, Schelling, Hegel, Schopenhauer, and Lotze have been used at different times and with very different results. Ethics, logic, metaphysics, and aesthetics are included in this course, and no special courses in any of these subjects have been given, although logical and ethical questions are treated in my psychological course. Considera- ble time is always given to epistemology. Two years ago, after considerable previous preparation, a course in Christology and Patristics was inserted between the ancient and the mod- ern course as above described. The life of Jesus was treated concisely and reverently from the standpoint of psychology, which is felt to be very different from that of the current lives of Jesus. This course, although at present being repeated with amplification, is still too incomplete to warrant any final report upon its utility. On the whole this historic course, which occupies three years, is earnestly recommended to all stu- dents of psychology, religion, education, or any of the humanities, and has generally been taken by all. During the past eight years I have opened my house one evening every week of the academic year to all students in the department of psychology and related themes from seven to ten o'clock. We began by discussing philosophical topics assigned beforehand to leaders in turn. One year most of the time of this seminary was devoted to reading and discussing Jowett's Plato. ^ Schopenhauer, Kant, and Hegel were tried for briefer periods, but gradually, as the numbers have increased and as the rule that each man should devote a portion of his time to some original investigation has prevailed, the evening has been occupied by each student in turn, who presents his thesis or subject, or a part of it, which is then freely discussed by the other members. The debates are often animated, as nearly every standpoint is represented. There are clergymen, young professors from other institutions, Hegelian idealists, Kantian epistemologists, and men of empirical science, and from these various directions nearly every subject is really illuminated. Attendance is never enforced, and the light refreshments served in the middle of the evening have never been an attraction, but only a welcome break from continued tension. The attendance for the last few years has rarely been 1 See a somewhat disguised account of the first semester's work in two articles by H. Austin Ailiins, entitled "From the Eeports of the Plato Club." Atlantic Monthly, Sept. and Oct., 1894, Vol. 74, pp. 359-368, 470-480. Philosophy. 179 under fifteen and rarely over forty, so that the entire freedom and infor- mality of conversation has been the rule. The themes assigned in a way described later have been presented here in so compact and forcible a way, that the seminary has been one of the most effective agents in my own education, and I think all its members share my sentiments in this respect. Here the new work on which each individual is spending so much of his year's time is pooled for the common benefit, the reader has the healthful stimulus of emulation in interesting his audience, acquires valuable practice in the methods of effective presentation, and always receives help in the way of new literature, references, the pointing out of defects in argument or method ; and conflicts are thus most surely avoided. Often other professors from the University attend, and the list of distinguished guests from abroad who have either participated in the discussions or introduced matter of their own is a long and dignified one. There is rarely any lack of interest or reluctance to discuss, and very infrequently is the animation too great for healthful mental circulation. Here nearly everything that has been done by the student members of this department of the University has been carefully wrought over, some of it more than once. Such stimulus I believe to be unsurpassed in educational value. The dialectic give and take of the conversational method, the mental alertness of debate, the charm of friendly intercourse upon high themes, which Lotze, like some of the ancients, thought the highest joy of life and the consummate fruition of friendship, are here combined in judicious propor- tions most favorable to growth. Some European seminaries are devoted to discussions of minute points ; in others the student is simply a literary forager for the professors ; quite frequently some author is read ; but for our American needs, at least for Clark University, I think the method now settled upon is more educative than any other that I have seen. A word should be said concerning student lectures. At various periods during the decade each member of the department has been requested to take his turn in presenting some subject in due form before the class, taking my place at the lecturer's desk, and developing his theme with the aid of charts, blackboard, and specimens if need be; and at the close of the lecture I have a personal interview, stating very frankly any faults of manner, automatism, voice, method of presentation, etc., liable to interfere with his usefulness as instructor or lecturer. More 180 Philosophy. often, in place of an original lecture, each man takes his turn in digesting with extracts some book or chapter of a standard work in the history of philosophy, with the same criticisms. This personal relation together with the many hours spent each week with individuals, elsewhere spoken of, has been, I believe, of great value. At the beginning of the year (or, for those who have already spent a year at the University, near the close of the spring term) careful lists of subjects which seem to the instructors in the department ripe for investi- gation are prepared. Each jots down all suggestions in this direction during the year, and all now meet to compare themes, consider whether they have already been treated, what new books and apparatus each will necessitate, by what paths each can best be approached and which are likely to yield the best and (what for thesis work is of great impor- tance) the most certain results of value. Conferences with each indi- vidual are then held and each is urged to select some theme, either because it is congenial or because it represents a field he desires to enter, and to devote some considerable portion of the year to the effort to master it and to add something new, however small, to the sum of the world's knowledge. A really good subject has aspects or divisions that bring the student into contact with each professor in the department, and each gives everything in the way of information, stimulus, and references that he possibly can. Our plan has always been to allow the student to print such work over his own name and to have full credit, although he usually makes acknowledgements at the close of his paper to his helpers. This plan we have found very congenial and stimulating to students, and it has avoided all questions of ownership rights in intellectual property. Again, a good subject must be midway between a very large and general and a very minutely special standpoint. The student must not waste his energy in vague generalities on the one hand, nor must he be shut up to some petty problem, perhaps fitting into and aiding the professor's special work, being thus unduly subordinated and apprenticed to him, as is so common in Germany. Fitting the problem to the man so that it will enlist all his interest and focus his knowledge and effort is half the work. In beginning more or less independent research like this, our best college graduates are often in a sense suddenly reduced back to infancy and need constant individual help to go alone. For the last ten years Philosophy. 181 most of several afternoons a week of my own time has been given in the laboratory, library, and conference room in trying to assist and direct young men to launch out in some modest yet effective way, as becomes them, on the great life of discovery. Some, often the best scholars, are so tied to authority that it is hard for them to be brought to realize that the best things have neither been done nor said in the world, and that mastery of the text-book is not final. Others are strongly inclined to repeat experiments, multiply observations, and accumulate numbers, and find it hard to make a serious study of the real significance of their data. Some approach subjects with preconceived ideas and speculate in a deductive way, abhorring details which others get lost in. Every type of philosophical opinion and every shade of temperament, every de- gree of intellectual enterprise at almost every rate of progress, is repre- sented. Some are strong in the literary, historical, and antiquarian side of their topic ; others in its experimental technique or in statistical pres- entation and tabulation or in literary form ; some at once tend to lose themselves in aspects of the subject that are so large that, instead of com- ing to a conclusion in an academic year, they begin to anxiously plan a life work and anticipate remote difficulties; while others can see abso- lutely nothing in topics of great range and significance except some over elaborately fortified or proven fact. This form of modern university work is a new kind of high Socratic midwifery, but in my opinion it is the most beneficial of all the points of contact between professor and student. Some must be encouraged; others must be roundly scolded. Some would devote all their time to an interesting work of this kind, while others dawdle with it as a mere side issue of doubtful educational value. A few do not want it, but are con- tented with receptivity of what others have done. Restless ones often seek change of theme, so that great discretion and great patience are needed in this work. Its rewards, however, are incomparably great. Having once discov- ered a fact or made ever so small an original contribution and had the baptism of printer's ink, the novitiate is henceforth a changed man. His ideals of culture, standards of attainment and excellence, and his methods of work are slowly revolutionized from this centre. Instead of being a passive recipient, his mind has tasted a free and creative activity which puts him on his mettle like the first taste of blood to a young tiger. He has learned that achievement and not possession is the end and aim ; his 182 Philosophy. mind has been brought to a focus in such a way that he now knows what real concentration means as never before. He realizes that almost every subject in the universe, if broadly seen, is connected with every other, and that the cosmos, like his own mind, is knit together into a unity of a higher order. In all his works and ways he is more independent and more inclined to seek, do, know, and experience for himself. By such personal conference with individuals at aU stages of their preparation in such a work, which need not be a doctor's dissertation and often is not, I am con- vinced, after a decade of experience here and some years of the same work at the Johns Hopkins, that this is the highest criterion of an academic teacher's real efficiency in his vocation, and that it is as much above the mass teaching of the lecture-room as talent is above mere learning. The necessity of this work is one of the chief reasons why truly university work must always be done, if not at small institutions, at least in squads so small that they can be thus individualized. Having brought this work to some degree of completion, as should be done at the close of each academic year, even at some sacrifice of scientific quality (because educational values should take precedence even over this, where the two conflict), an indispensable requisite is publicity and that without delay. Any institution or department that confers a doc- torate upon the ground of a dissertation that is unpublished conceals that upon which the chief value of the degree rests. The older the student the more stress should be laid upon this part of the work as compared with acquisition. In most departments, science is progressing so rapidly and work is so often duplicated that the necessity of announcing before- hand the theme of each research has often been urged, and any con- siderable interval between the completion of a work and its publication involves danger of anticipation by others, as well as general loss of value from the progress of science, which is always slowly leaving everything behind. Chiefly to avoid this danger the journals of this University were established, in which, without the cost to the students generally insisted upon elsewhere and with the advantage of a more or less extended international circulation among experts, everything can be speedily brought to the knowledge of those most interested and competent. To know that results will thus appear without delay is itself a real stimulus, and it is fortunate that evaluation of such work is coming to be a more and more prominent factor in determining appointments to univei-sity positions. The quality of mind which makes success here is infinitely Philosophy. 183 more inspiring to students, eren of lower grades, than the rehearsal of second-hand knowledge perhaps many removes from its source. Very much might be said upon the effect of research as a stimulant to the teacher, while, from still another point of view, the fact that the instruc- tor has entered the great arena and submitted his productions to the critical estimate of experts, gives his pupils confidence in him as an authority and not a mere echo. The provision of a sufficient number of reprints for circulation among special journals that will notice each work, and for exchange with other productive workers or departments, is another one of the new university problems unknown to the college, to the fuller exploitation of which the new journal here contemplated and elsewhere spoken of wiU be devoted. Great importance has always been attached here to the methods of bringing students into immediate and personal contact with the latest literature, especially upon the topics of their theses or those related to the original researches upon which they may be engaged. The exchanges of the journals constitute a carefully selected list of nearly three score peri- odicals, all of which, besides those regularly subscribed for by the library, are immediately available. Besides these the journals receive a large number of the most important books and pamphlets within their field, especially from American, English, French, and German houses. These works together with the smaller resources of my own library, which mainly supplements that of the University, are at the disposal of students, who are often encouraged to write brief book notices for publication. The frequent personal conferences with each student in the department keeps the instructor's mind alert to find out and bring to the immediate notice of each anything bearing upon his theme. Meetings are occasion- ally held in my library, where I spend the evening going through my shelves, taking out the books that I deem most important and that have helped me most, briefly characterizing each, and passing it around for actual inspection. If I had at my disposal an hour's time of a dozen of the most eminent men to utilize in such a way as would be of greatest benefit to me, I think I should ask them to do precisely this, for they would thus be giving me to some extent a key to their own intellectual activity and direction. Where this method is extended to monographs and pamphlet publications, the collection of which our system of exchanging theses promises to greatly enrich, its value is stUl greater for special students. 184 Philosophy. Genetic psychology, which one sub-department of this University so conspicuously represents, is far larger than the child-study of mothers' clubs or teachers' associations. It is simply the entrance of Darwinism into the field of mind. Underneath it lies the great transforming concep- tion that the soul is as complex, as old, and as gradually unfolded as the body, and like it must be studied comparatively in view of all that the psychic life of the lower or even the lowest organisms can teach us. The new methods cross-section the old classification methods which make memory, wUl, perception, imagination, etc., so many faculties, and seek to trace the origins of the higher mental powers to their faintest beginnings near the dawn of animal life. The most fundamental activities are those whose roots extend lowest down in the scale of existence, and these are also they that send their tops highest. The conception that mind, as we know it in consciousness, has been developed out of something very differ- ent that, like organic forms, tends to vary and change indefinitely is a new conception and is sure eventually to reconstruct out of new and old elements a far larger and more adequate city of Man-sotd with reformed administrative, educational, religious, and other functions. This move- ment appears in biology in the tendency to study psychic phenomena in the most rudimentary and microeosmic organisms. It appears again in the new and careful studies of instinct in the higher animals, where con- ditions can be varied and educational experiments conducted with great precaution and detail. Another root of the genetic movement is in the anthropology of myth, custom and belief among primitive and savage peoples ; another in the studies of degenerative types among the defective classes, where decay has inverted the evolutionary order. It is on this foundation that the child-study movement rests, and its amazing development cannot be adequately explained without a due ap- preciation of this wider field. The minute observation and annotation, the measuring and weighing of a single child, or the collective study of one topic upon the basis of returns from very large numbers of children with the help of questionnaires, anthropometric work with its carefully wrought out averages, — all this appeals to the instinctive love of children; out of it has grown the new conception of childhood as the most generic period of life, wherein the limitations of individuality are not yet so pain- fully apparent as in adults, and it has given us new conceptions concern- ing the nature of genius, the laws of growth, the origin of fear, anger, love, the conditions of health, the nascent periods of maximal interest in Philosophy. 185 special lines and topics, until at last education seems likely to have under it a far more solid and scientific foundation than it has ever yet attained. While this subject has as yet occupied but a slight and recent portion of our curriculum, so much has already been accomplished as to warrant the very fairest hopes for the future. Among the first results likely to be witnessed are the gradual transformation of the methods of teaching and of investigating the problems of the special philosophical disciplines some- what analogous to the transformation of anatomy and morphology under the influence of embryology. How far this movement will extend among the other university studies, and whether with or without any new coor- dination of the successive stages of individual growth with the historic development of different philosophical systems as first presented by Hegel, it is impossible to foretell. THE LIBEART. By Louis N. Wilson, Librarian. From the foundation of the University the library has been consid- ered an important factor and has received a great deal of attention from the Founder, President, and Faculty. Immediately upon his ap- pointment, the President requested each member of the University to draw up a list of books in his special field, laying particular stress upon important serials and special monographs. These lists were carefully collated, duplicates weeded out, and arranged in order for purchase. The total number of items amounted in June, 1889, to upward of fifteen thousand, a very large proportion being books and journals in foreign languages. In order to secure for the University the best possible rates, lists of standard works, both in sets and single volumes, were submitted for competition to a number of well-known booksellers both in this country and in Europe. This necessitated some delay, but it was fully warranted by the resultant saving in cost. To illustrate this point, the figures submitted by five firms for an identical list of 742 items are given here, viz.: 11806.30, $1810.90, I19T1.86, 12038.89, 12166.41, showing a maximum difference of 1360.11. After carefully comparing all the lists sent in, and taking into con- sideration the condition of the books offered, orders were placed with firms in New York, Boston, London, Paris, Berlin, Leipzig, and Vienna. During the past few years, owing to our very peculiar and constantly changing customs and postal regulations, it has become more and more desirable to import from Europe through some responsible bookseller in this country, in order to avoid the frequent and often vexatious annoy- ances consequent upon individual importations. Having decided upon a particular bookseller, orders were freely placed with the understanding that the library should receive the lowest possible rates consistent with good service, and from time to time lists were sent to other firms in order to be assured that the agreement was faithfully carried out. A recent 187 188 The Library. test of this kind showed the following quotations for thirty-five volumes, 1105.26, 1107.57, f 120. 00. In general, the plan has worked exceedingly- well. During the summer of 1889, while these orders were being executed, Mr. Clark placed the first books in the library by donating about thirty- two hundred volumes. A large proportion of these, on history, biogra- phy and travel, were given with the original bookcases as they had stood in his own private library. Another part of the collection con- sisted of the following sets of bound periodicals, almost all complete down to the end of 1883 : Atlantic Monthly, Blackwood's Magazine, Cen- tury Magazine, Cornhill Magazine, Edinburgh Review, Fortnightly Review, Grentleman' s Magazine, Harper's Magazine, LittelVs Living Age, Maemillan's Magazine, North American Review, North British Review, Notes and Queries, Popular Science Monthly, Putnam's Magazine, Quarterly Review, and Scrihner's Monthly, also a set of the Report on the Scientific Results of the Voyage of H. M. S. Challenger, during the years 1872-76. Yet a third part consisted of a large number of rare old books, some of which are fine examples of early printing when there was no title-page, no pagination, date, or printer's name, and where the initial letters were omitted to be inserted later by hand. Of these fine old volumes, the following are mentioned as examples: — Paulus de Sancta Maria Scrutinimn scripturarum. Probably the oldest book in OUT library, with no title-page, colophon, pagination, or signatures. Eubricated throughout. Eationale divinorum o£B.ciorum. Supposed to have been printed at Basle in 1474^75. Astexanis Suma. Libri VIII., de preceptis, de virtutibus et viciis; de sacra- mentis de sacro penitentie, de sacramento ordinis, de excommunicatione ; de matrimonio. Venetiis, 1478. Eoberti Caraczoli de Licio de timore divinorum judiciorum ac de morte. Nuremberge, 1479. Alberti de Padua expositio Evangeliorum dominicalium totius anni et concor- dancia quatuor evangelistarum in passionem dominicam a Nicolao Vinckel- spickel. Ulm, 1480. Sancti Thome de Aquino ordinis predicatorum super quarto libro sententiarum preclarum opus. Venetiis, 1481. Liber moralitatum elegantissimus magnarum rerum naturalium lumen anime dictus. 1482. Sancti Hieronimi Vitse Patrum Sanctorum Egiptiorum. Niirnberg (Koburger) 1483. The Library. 189 Blondi Flavii historiarum ab inolinatione Eomanorum Imperii, libri XI. Venetiis per Octavianum Scotum. 1483. Johannis de Turrecremata questionum dignissimarum cum solutionibus earum- den, etc. Davantriae, 1484. A work of the celebrated Spanish Dominican Juan de Torquemada. Legende de sancti composte per Jacobo de Voragine. Venetia, 1484. An old German almanac beautifully printed in red and black and pasted on one of the covers of Hieronimi Vitce Patrum. It runs from 1486 to 1579, and was probably printed at the earlier date. Summa Eainerij de Pisis. Venetiis, 1486. Liber Cronicarum cum figuris et imaginibus ab initio mundi usque nunc tem- poris Impressum ac finitum in vigilia purificationis Marie in imperiali urbe Augusta a Johanne Schensperger. Anno ab incarnatione domini 1497. The so-called Nuremberg Chronicle, with numerous woodcuts by Wolge- muth, the master of Albrecht Dtirer. Sermones Pomerii de Tempore Hyemales et Estivales et sermones quadragesi- males per Helbartum de Themeswar. Hagenaw, 1502. With rubricated initials. Pauli Jovii elogia virorum bellica virtute illustrium veris imaginibus supposita, quae apud Musseum spectantur. Florentise, 1561. Ramusio, Primo volume, & Terza edizione delle navigationi et viaggi. Vene- tia, Giunti, 1563. The first volume of Eamusio's well-known collection of voyages and travels, containing among other things Pigafetta's log during the first voyage around the world under Magalhaes. Missale Eomanum, ex Decreto Sacrosancti Concilii Tridentini restitutum, Pii V. Pont. Max. jussu editum. Venetiis, apud Juntas, 1602. The Bible : that is the Holy Scriptures contained in the Old and New Testa^ ment. London, 1610. A copy of the so-called Breeches Bible. Missale Eomanum, ex Decreto Sacrosancti concilii Tridentini restitutum, Pii V. Pont. Max. jussu editum et dementis VIII. auctoritate recognitum. Ingol. stadii, 1610. Montanus (Arnoldus) De Nieuwe en Onbekende Weereld of Beschryving van America. Amsterdam, 1671. An old description of America in Dutch. Esquemeling (John) and Eingrose (Basil), History of the Bucaniers of America. London, 1695. Esquemeling, who spent many years at Tortuga, gives here a very graphic account of the buccaneers. Armenian Bible. Venice, 1805. Fleeing from the persecution of their ortho- dox brethren, the Catholic Armenians of the mechitaristic order established themselves at the island of Sau Lazzaro, granted them by the Eepublic of Venice. Many a learned volume issued from their press, of which this is a specimen. New Testament in Lettish language. Mitau, 1816. Select Fables ; with cuts, designed and engraved by Thomas and John Bewick, previous to the year 1784 ; together with a Memoir and a descriptive cata^ 190 The Library. logue of the -works of Messrs. Bewick. Newcastle, 1820, Thomas Bewick is considered the restorer of wood engraving in England. Cookson (Mrs. James). Mowers drawn and painted after nature in India, 1834. In addition to a number of books presented to the library by Presi- dent Hall, we are indebted for gifts to the following citizens of Worces- ter : Hon, George F. Hoar, Mr, Henry J, Howland, Hon, Heni-y L, Parker, Mr, Samuel H. Putnam,^ the late Hon, W, W, Rice, Hon, Stephen Salisbury, Hon. John D. Washburn, and Hon, John E, Russell of Leicester, To receive the books temporary wooden stacks were erected in the main library room, and so substantially were they constructed that they are stUl serviceable. Solid oak shelving was put up on both sides of the reading-room, adjoining the main library room, with a three-foot pro- jecting shelf three and a half feet from the floor, upon which the current numbers of periodicals are displayed. To the problem of cataloguing and classification, always a difficult one, both the President and the members of the Faculty gave a good deal of time and attention. It was felt that the scheme of classification must not be too rigid, and that nothing should be allowed to interfere with the free use of the books by all members of the University, The books were first carefully classified upon the shelves by departments, and marked as follows : — A. Works op Gbneeal Eefekencb. I. PsTCHOiiOOT. B. Journals. J. Philosophy. C. Mathematics. K, Ethics. D. Physics. L. Criminology. E. Chemistry. M. Anthropology. F. Zoology. N. Education. G. Physiology, 0, Botany. H, Pathology. The various subdivisions in each department may be inferred from that of the mathematical department, lA copy of "Justini historici clarissimi in Trogi Pompeii historias Libri XLIIII." Venice, Jenson. 1470. Duke de Noailles' copy of the edAtio princeps. " Virorum Blustrium vitfB ex Plutarcho Groeco in Latinum Versce Solertiqce, cura emendatoe fodiciter explicidt : " per Mcolaum Jensen Gallicum Venetiis Ipressm. 1478, die. II Januarii. 2 vols. "The Scientific Papers of James Clerk Maxwell." Edited by W, D. Mven, F. R. S. The Univer- sity Press, Cambridge, 1890. 2 vols. The Library. 191 C. — Mathematics. In Mathematics, C, the books are grouped in ten divisions, designated by the numerals 1, 2, 3, 4, 5, 6, T, 8, 9, 0, immediately following the let- ter C ; every division is subdivided into sections of which each is desig- nated by a second numeral following that indicating the division. The cipher, 0, always denotes a miscellaneous division or section. The math- ematical worts are arranged on the shelves in accordance with the fol- lowing classification, the subdivisions of which, however, are not all used at present. The italicized part of each title is that printed on the sliding shelf label. C 1. HiSTOET AND PHILOSOPHY. CI. 1. Bibliography. CI. 2. History. CI. 3. Biography. C 1. 4. Philosophy. C 2. Collections. C 2. 1. WorTes, complete and select. C 2. 2. Compendia, Dictionaries. C2. 3. Tables. Formulas. C3. Symbolism and Operation. C 3. L Symbolic Methods. C 3. 2. Operations. C 3. 3. Multiple Algebra (ref. C 9). C 3. 4. Symbolic Logic. C 3. 0. Miscellaneous Symbols. C4. Arithmetic. Elementary Arithmetic. Continued Fractions. Numerical Series. Finite Differences and Sum- mation. C 4. 5. Permutations and Combina- tions. C 4. 6. Probabilities. C4. 7. Theory of Numbers. C5. Algebra. (For Multiple Alge- bra see C 3. 3.) C 5. 1. Elementary Algebra. C5. 2. Determinants. C4. 1. C4. 2. C4. 3. C4. 4. C5. 3. Theory of Eqvtaiions. C 5. 4. Simultaneous Equations. C 5. 5. Transformation. C 5. 6. Invariants. C 6. Infinitesimal Calculus. C 6. 1. Limits and Infinite Series. C6. 2. Functions of a Beal Varia- ble. C 6. 3. Differential Calculus. C 6. 4. Integral Calculus. C6. 5. Total Diffeieuiial Equations. C 6. 6. Partial Dt^rential Equa- tions. C6. 7. Functions Derived from Differential Equations. Spherical Harmonics. C 6. 8. Calculus of Variations. C 7. Theory of Functions. C 7. 1. General TJieory. C 7. 2. Algebraic Functions. C7. 3. Eocponential and Trigono- metric Functions. C 7. 4. Elliptic Functions and In- tegrals. C 7. 5. Hyperelliptic and Abelian Functions and Integrals. C 7. 6. Various Functions (fuch- siennes, etc.). C 7. 7. Functions of Several Varia- bles. 192 The Library. C 8. Geometry. C 8. 1. Elementary Geometry and Trigonometry. C 8. 2. Analysis Situs. G 8. 3. Analytic Geometry in Gen- eral. C8. 4. Projective Geometry. Mod- ern Synthetic Geometry. C8. 5. Special Systems of Geomet- ric Analysis. C 8. 6. Plane Loci in particular. C 8. 7. Loci in S Dimensions in par- ticular. 8. 8. Hyperspace and Non-Eucli- dean Geometry. C 8. 9. Applications of Geometry. As B is the general designation sively devoted to one department letter of the department to which it B C. Mathematical Periodicals, BA. Miscellaneous Periodicals C 9. Extensive Algebra (ref . C 3. 3). C 9. 1. Geometric Bepresentation of the Lnaginary. 9. 2. Quaternions. . 9. 3. Geometric Algebras (Olif- ford). 9. 4. Ausdehnungslehre (Grass- mann). 9. 5. Equipollences (Bellavitis). CO. Miscellaneous. 0. 1. Apparatus. 0. 2. Recreations, Games, Puzzles, etc. 0. 9. Paradoxes and Paradoxers. Oirole-squaring, etc. of periodicals, each periodical exclu- is designated by B, followed by the belongs, thus : Transactions of learned societies, etc. So long as the number of books in any section is very small, they are grouped under the division to which that section belongs, and are desig- nated- only by the number of that division. All books which refer to several divisions are placed in the division C 2 (collections), and all books referring to several sections of any one division are grouped under that division, unless they refer but slightly to more than one division or section. Volumes of a set are not separated, but the whole set is classed as if it were a single volume. Otherwise, every book is placed in the narrowest division or section to which it belongs. The library has two card catalogues : — I. An author's catalogue arranged alphabetically with miscellaneous and anonymous sections, so that nearly all books in the library are represented in it. II. A subject catalogue which is at the same time a shelf and an inventory catalogue. This is arranged as follows : Every volume and every pamphlet has its card, so that each card represents a volume. All the books are classified and arranged upon the shelves according to the departments, divisions, and subdivisions, but under each subdivision The Lih'ary. 193 books are placed alphabetically by authors. While each case, tier, and shelf is permanently labelled, the demarcation between the subdivisions is made by sliding shelf label holders bearing the subject, division, and sub- division. These label holders being movable, the subdivisions can easily be enlarged as new books are added. In mathematics, for instance, C 1, history and philosophy, comes first, with the first subdivision, CI, 1, bibliography. First on the top shelf, and therefore first in the catalogue drawer set apart for these tiers, comes bibliography, beginning with authors in A, and so on through the alphabet to the end of the subject. Then come history, biography, etc., on through mathematics and the other departments, the order of cards being identical with the order of the books upon the shelves, reading down the tiers as down a printed page. In the drawers the book cards are separated by red cards projecting on the right above the others, and on these projections the tier and shelf divisions are marked ; they are also separated by blue cards projecting above the others on the left-hand side, on which the subjects are marked. Whenever the position of any book is changed, it is only necessary to make a corresponding change in the position of its card. The shelf posi- tion of each book is marked in pencil, not upon these cards, but upon each card in the author's catalogue, and in the book itself, in order that it may be readily found and replaced. New books, after being entered in the author's catalogue, are kept in a case reserved for them for a few weeks before being permanently placed on the shelves and entered in the inventory catalogue. A full list of all serial publications taken by the library is kept in a special drawer of the catalogue case, so that a person unfamiliar with the library may ascertain, with very little trouble, what periodical publications are to be found here. Worcester is fortunate in possessing an excellent Public Library of more than 120,000 volumes, and well supplied with serial publications. In the early years of the University, it was the hope of the Founder that we might confine our purchases to such books and journals as were not to be found in the Public Library, and that the two might supplement each other ; this plan was largely carried out in the earlier years, but later the needs of our students demonstrated the necessity of the duplication of the more important scientific publications, though we still depend upon the Public Library for works of a less special character, and our students 194 The Library. have availed themselves of the library privileges thus extended to them to the fullest extent. Besides its indebtedness to the Worcester Public Library the Uni- versity is under great obligations to the following for frequent loans : Library of the Surgeon-General's Office, "Washington, D.C. ; Library of Harvard University; The City Library Association of Springfield, Mass.; Boston Public Library ; Public Library, Cleveland, Ohio ; Trinity College Library and Case Memorial Library, of Hartford, Conn. ; Library of Yale University; Forbes Library, Northampton, Mass.; Library of Vassar College ; and many others. Several of these libraries have freely lent us books and volumes of serial publications, often of the greatest importance to those engaged in research work. No library, however large, can hope or expect to be prepared to meet aU the calls upon it, and a glance at the diverse and advanced character of the publications issued from this University ^ shows how varied and numerous are the demands upon this department. To the Library of the American Antiquarian Society we are especially indebted for the kindly spirit of cooperation invariably shown. While strictly a reference library, its officers have ever been ready and wUling to make reasonable exceptions in aid of the cause of historical and scientific research. The library is a veritable laboratory, and is looked upon as a work- room, and not as a museum with contents too sacred to be profaned by use. It is a favorite meeting-place for professors and students, where the heads of departments meet their men to direct their reading and demonstrate to them how to make the best use of a well-selected collection of scientific books. The books are readily accessible to every member of the University, and there is no limit to the number that may be taken out. Each one enters the volumes he takes out upon a printed form pro- vided for that purpose ; if not returned at the end of ten days, they are renewed by the librarian for another period of ten days, at which time they must be returned, but may be taken out again upon the following day. The library is open to all persons outside the University who are interested in any of its lines, and its books are freely lent to such persons, who are thus placed for the time being upon the same footing as mem- bers of the University ; and, while we borrow during term time an aver- age of fifty volumes a month, we lend as freely. The library is rich in 1 See Bibliography at the end of this volume. The Library. 195 certain special lines, and is often used by experts from other universities, state and national institutions. President Hall has an exceptionally fine private library, especially rich in pamphlets and special monographs in the various fields of philosophy, psychology, and education. During these ten years all students have been permitted to draw upon it as freely as upon the University library, and the efficiency of this department has been largely due to Dr. Hall's broad-minded and liberal conception of the function of the printed vol- ume. In his various courses he frequently gives demonstrations of books, pointing out the best books in each subject, the best to buy, the best to read, emphasizing and explaining the strong points in each, etc. In spite of the absolute freedom of the library, the loss of books has been surprisingly small. Once a year the books are carefully checked by means of the shelf cards, and in very few years have the losses amounted to more than two or three volumes. The missing volumes one year fre- quently turn up later, so that a careful estimate recently made shows the actual money value of the books lost in ten years to be less than fifty dollars. Almost all who are interested in libraries have ideals as to the future development of their special fields, and the librarian has attempted, in the course of the past ten years, to formulate an ideal of an university library. He alone is responsible for his views, and is encouraged to state them here by the fact that the President and Faculty have given him the greatest freedom and their warmest support in aU matters pertaining to his de- partment. The ideal library should be housed in its own building, and not rele- gated to rooms in a building constructed for other purposes. In con- structing such a building, the chief end in view should be to provide every facility for the use of books, and this end should never be sacrificed for architectural features or artistic purposes. Each department in the University should have a working library in its own rooms, but whatever books are placed in these department libraries should be duplicated in the main library. The building should be large enough to allow the book shelves to be arranged around the rooms, leaving the greatest amount of open space in the centre. Movable working desks, liberally supplied with 196 The Lihrary. conveniences for writing, and containing ample drawer space for note-books and papers, are mucli to be preferred to the large fixed tables usually- found in library buildings. The shelving should be of the most approved modern type, insuring economy of space and the proper care of the books, and the highest shelf within easy reach from the floor. The rooms should be provided with every possible convenience, including a sufficient num- ber of comfortable chairs, with cozy nooks and corners inviting to a quiet half -hour with a book, when one would otherwise be disinclined to read. That the light should be good, the ventilation absolutely perfect, and the attendants have but one purpose — the service of the readers — are obvi- ous essentials. In these days of rapid multiplication of new libraries and enlargement of many older ones, there is a great demand for complete sets of serial publications, and many of the important journals are growing rapidly scarce and difficult to obtain. It is, therefore, particularly desirable in an institution of this character to procure, as soon as possible, full sets of all the serial publications in its various departments and on all allied subjects, and every effort should be made, and no expense spared, to procure all the scientific contributions by specialists in the work represented here, or in departments likely to be of service in research work. The current numbers of all these publications should be placed before the members of the University promptly, as it is imperative that those engaged in original investigation be advised of the latest literature on the subject, or of the work others are doing along similar lines. A most important part of a good library is its catalogue. The day has gone by when men can afford to spend hours in hunting among a mass of books to ascertain what the library possesses upon a given subject, or to rely upon the memory of the librarian and attendants, be they ever so erudite. While, therefore, the aim should be to keep in printed and card form a list of all the books and articles that have been written upon a given subject, nothing should be allowed to interfere with the prompt cataloguing under subject headings of everything that the library pos- sesses. Two questions always arise here, first, " Where can I find a list of all printed matter upon my subject ? " and secondly, " How much of that printed matter is to be found in this library ? " A complete card catalogue can be so arranged as to answer perfectly these two questions. In this, as in every well-regulated library, printed forms should be provided to encourage readers to make suggestions and complaints to the The Library. 197 library committee ; the latter, in no case, to pass through the hands of the librarian. The subject of binding is always an important one, and we feel very keenly ^he need of united action on the part of all the libraries of the city in this respect. A careful inquiry has developed the fact that between 14000 and 15000 is expended yearly by the various institutions in this city for this purpose. There are unmistakable signs that the art of book- binding, which has for ages commanded the services of eminent crafts- men, as well as of men and women eminent in art, is receiving increased attention from book lovers here, and the time may not be far distant when this question will be taken up by a committee representing the different libraries. There would seem to be no reason also why the various institutions should not, in the near future, devise a system of cooperation, as is already proposed in Toronto, by means of which the resources of all the libraries in the city could be drawn upon by each. REPOET OF THE TREASURES. At the first meeting of the Trustees of Clark University, May 4, 1887, Mr. Clark proposed to give : — (1) " The sum of f 300,000 (payable as the same shall be needed) to the Gen- eral Working or Construction Pund to be applied in the erection of buildings and equipping them with such appliances and facilities as may be deemed necessary for putting the University in good working order." (2) " The sum of f 100,000, the income of which shall be devoted to the support and maintenance of a University Library." (3) " The sum of $600,000, the income of which is to be devoted to the general ■ uses of the University in its support and management, and which for the sake of convenience may be called the University Endowment Pund." "The Library and the Endowment Funds are never to be diminished, and no part of the principal is in any event ever to be applied to the objects to which the income of each is to be devoted. If by any accident or loss, either of said funds shall at any time become impaired, then the income of each of said funds shall be added to the principal until such impairment is made good and the funds restored to their original amounts." In addition to the foregoing gifts, Mr. Clark then and subsequently conveyed to the Trustees of the University, real estate, the valuation of which on the books of the assessors of the city of Worcester is f 135,600. In the Treasurer's Annual Statement for the year ending August 31, 1899, which follows, is an account of the Library and University Endow- ment Funds. The amounts expended for construction and equipment of buildings under the terms of Mr. Clark's first proposal have been as follows : — 199 200 Report of Construction of the Main University Building . . $159,780.60 Construction of the Chemical Laboratory . . . 56,131.94 Equipment of the Main Building 18,480.28 Equipment of the Chemical Laboratory .... 14,801.47 Apparatus and Supplies 29,082.73 $278,277.02 Additional land was purchased by Mr. Clark for the University at an expense of $12,233.04 The balance to make up the proposed $300,000 . . 9,489.94 was subsequently expended in the additional equip- ment of the different departments. A statement of the expenses of the several departments for the years 1890-98, inclusive, including the amounts expended in the original equip- ment above mentioned, is appended. 1890. 1891. 1892. 1893. 1894. Mathematics . Phvaies . $ 6,664.49 17,214.20 25,334.24 28,083.29 13,604.17 750.00 15,568.04 5,829.00 9,067.48 3,860.00 1 7,235.00 7,320.98 7,491.00 15,429.70 11,400.00 1,550.00 5,733.41 2,900.00 5,162.92 4,560.00 « 7,356.50 6,768.46 6,298.46 12,732.58 7,059.16 1,151.25 1,279.84 3,000.00 4,183.77 7,240.00 % 6,926.40 3,567.78 2,693.26 3,676.47 7,666.08 1,586.13 1,334.45 3,800.00 8,988.01 5,280.00 1 5,905.64 2,880.80 Chemifitry . . 1,337.64 2,066.20 Psychology . Education . . 6,584.00 1,826.87 2,596.33 Administration Expense . . Fellowships . 2,600.00 3,773.51 4,980.00 1125,974.86 $68,788.01 $57,070.02 $45,513.53 $84,000.49 Mathematics . Physics . . . Biology . . . Psychology . . Education . . Libraiy . . . Administration Expense . . . Fellowships 1895. 5,900.00 2,329.07 2,072.74 6,015.46 1,312.29 1,628.72 2,600.00 3,434.18 4,740.00 $30,032.41 1896. 5,900.00 2,398.03 2,200.00 7,010.00 1,250.00 1,740.16 2,800.00 4,319.80 4,620.00 $82,082.99 1897. $ 5,900.00 2,948.73 2,300.00 7,010.00 1,250.00 2,456.00 2,600.00 4,287.82 3,420.00 $32,122.55 1898. 5,900.00 2,173.00 2,054.24 6,676.33 1,250.00 3,508.48 2,600.00 3,190.93 1,500.00 128,852.98 the Treasurer. 201 In addition to tte endowment and gifts, which have already been referred to, Mr. Clark has given to the University for its general purposes : — 1889-90 112,000 1890-91 60,000 1891-92 26,000 1892-93 18,000 $106,000 The University has received from Mrs. Eliza W. Field "a fund of $500 to be called the John White Field Fund, the income of which is to provide for the minor needs of a Scholar or Fellow." There was also presented to the Trustees of the University by Hon. George S. Barton of Worcester $5000, the income of which is to be devoted to the aid of " some one or more worthy native born citizens of the city of Worcester, who may desire to avail themselves of the advan- tages of the institution." Hon. Henry L. Parker, in the summer of 1892, in behalf of many citizens of Worcester, presented the University with a tower clock and the sum of $781.30 to provide for its maintenance, which fund is known as the Clock Fund. KEPORT OF THE TREASURER TO THE TRUSTEES FOR THE YEAR ENDING AUGUST 31, 1899. To THE Trustees op Clark Univbrsitt, G-entlemen, — I have the honor to submit herewith my annual report for the year ending August 31, 1899. The total receipts of the University from Sept. 1, 1898 to Aug. 31, 1899, inclusive, were .... $48,595.53 The total disbursements during the same period were . . . 37,130.27 Leaving a balance on hand Sept. 1, 1899, of $11,465.26 202 Report of (A.) The items of income are as follows : — Gross Income of the TJniTersity Endowment Fund .... $28,407.33 Gross Income of the Library Fund 6,258.46 Gross Income of the University 1,586.00 Gross Income of the Summer School, 1899 1,388.50 Subscriptions to the Fund for the Decennial Celebration . . 4,150.00 From the Field Fund 20.00 Balance from previous year 7,785.24 Total $48,595.63 (B.) The expenditures have been as follows : — For the Department of Mathematics . f 6,300.00 For the Department of Physics 2,641.11 For the Department of Biology 2,012.25 For the Department of Psychology 7,966.82 For the Department of Education 1,250.00 Administration 2,700.00 Expense 4,729.87 Field Scholarship 20.00 Expenses of Summer School 889.85 Expenses of the Decennial Celebration 3,156.85 Library Expenses 3,474.08 Sinking Fund 700.00 Jonas G. Clark on account of premiums 900.00 Accrued interest repaid 389.44 $37,130.27 (C.) The incidental earnings of the University from fees, etc., were . $ 1,586.00 (D.) Account of the Summer School for 1899 : — Eeceipts $ 1,388.50 Expenses . . . , 889.85 Balance carried to University Account $ 498.66 (E.) Subscriptions to the Decennial Celebration : — Eeceipts $ 4,150.00 Expenses 3,156.85 Balance on hand appropriated to the publication of this volume . f 993.16 the Treasurer. 203 (F.) The University Endowment Fund is invested as follows ; Oregon Railway and Navigation Co., 4s . West Shore R. R. Co., 1st Mtg., 4s, 2361 . City of Cambridge, Sewer Loan, 6s, 1905 . Norwich and Worcester R. R. Co., 4s, 1927 Rutland R. R., 1st Mtg., 6s, 1902 . Wilkesbarre and Eastern R. R., 1st Mtg., 5s 1942 Hereford Ry. Co., 4s, 1930 Chicago and Eastern Illinois R. R., 1st Consol Mtg., 6s, 1934 .... 1st Mtg. Sink. F., 6s, 1907 . Wayne Co., Michigan, 4s . Northern Ohio Ry. Co., 1st Mtg., 5s Lowell, Lawrence, and Haverhill St. Ry., 1st Mtg., 5s Worcester and Suburban St. Ry., 1st Mtg., 5s Worcester and Marlboro St. Ry., 1st Mtg., 5s Atchison, Topeka and Santa Fe Ry. Co., . Gen. Mtg., 4s . . . $18,500.00 Adj., 4s .... 10,000.00 Certif. Gen. Mtg., 4s . . 250.00 Second Ave. R. R. Co., New York, 1st Consol Mtg., 5s, 1948 .... 15 shares Worcester National Bank 71 shares Norwich and Worcester R. R. . Deposit in Worcester Co. Inst, for Savings Deposit in Five Cents Savings Bank 100 shares Fitchburg (preferred) 35 shares New York, New Haven, and Hart- ford R. R 100 shares Worcester Traction Co. (preferred) New England Yarn Co., 5s . . . Lake Shore Collaterals, 3^s Invested in premiums .... Cash in Worcester National Bank . Book value. Market value. Sept. 1, 1899. fll0,000.00 $112,750.00 75,000.00 84,750.00 20,000.00 22,600.00 75,000.00 84,000.00 25,000.00 26,500.00 9,800.00 10,600.00 9,350.00 10,000.00 10.000.00 13,700.00 1,000.00 1,145.00 30,000.00 31,200.00 3,000.00 3,180.00 15,000.00 15,750.00 6,000.00 6,240.00 10,000.00 10,400.00 25,000.00 18,500.00 8,800.00 250.00 25,000.00 30,000.00 2,250.00 2,700.00 14,603.50 15,620.00 5,000.00 5,000.00 10,000.00 10,000.00 10,300.00 11,800.00 6,982.50 7,630.00 10,700.00 10,450.00 11,000.00 11,495.00 60,000.00 50,000.00 15,230.00 28,920.25 28,920.25 $614,136.25 $634,480.25 204 Report of The gross income of the University Endowment Fund was There was paid from this : — To Sinking Fund to provide for premiums . To Jonas G. Clark on account of premiums Accrued interest repaid .... $700.00 900.00 389.44 Leaving net income carried to University Account 128,407.33 $1,989.44 $26,417.89 (G.) The Library Fund is invested as follows : — 50 shares Washington National Bank, Boston 25 shares Tremont National Bank, Boston . 50 shares Merchants' National Bank, Boston 50 shares National Bank of Republic, Boston . 50 shares Union National Bank, Boston 50 shares Second National Bank, Boston . 50 shares New England National Bank, Boston 50 shares Atlas National Bank, Boston. 61 shares State National Bank, Boston 15 shares Suffolk National Bank, Boston . 50 shares Eliot National Bank, Boston 50 shares National Bank of Commerce, Boston 50 shares Boylston National Bank, Boston 43 shares Old Boston National Bank, Boston 10 shares City National Bank, Worcester . 15 shares Norwich and Worcester E.. R. stock Northern Ohio R. E. Bonds, 5s . 15 shares New York, New Haven, and Hartford R. R Invested in premiums .... Deposit in Worcester National Bank . The gross income of the Library Fund was : — From dividends and interest .... Rebate on bank tax, Balance carried to Library Expense Account Book value. Market value. Sept. 1, 1899. $ 5,527.00 f 6,000.00 1,766.00 (in liquidation) 7,934.60 8,600.00 7,994.88 8,760.00 6,829.50 7,150.00 9,162.50 8,850.00 8,237.50 7,825.00 6,293.50 5,750.00 6,938.01 7,167.60 1,527.21 1,650.00 6,698.00 7,150.00 5,552.62 5,625.00 6,530.75 5,860.00 4,527.63 5,074.00 1,500.00 1,500.00 3,000.00 3,300.00 4,000.00 4,240.00 2,992.50 3,270.00 150.00 2,273.06 2,273.05 $99,335.25 $100,024.56 $4,085.77 1,172.67 $6,258.44 the Treasurer. 205 (H.) The Library Expense Account : — Unexpended balance from previous years . . . $3,091.18 Credits for books sold 412.38 Income of the Library Fund for 1899 .... 6,258.46 $8,762.02 The expenses, including $900 for administration, heat and light, were 3,886.46 Leaving a balance Sept. 1, 1899, of . . . $4,876.56 The George S. Barton Fund, deposited in the Worces- ter Co. Inst, for Savings, amounts to . . $7,239.24 Income during the year 278.43 (J.) The John White Field Fund, deposited in the Worces- ter Co. Inst, for Savings, amounts to . . . $663.22 Income during the year 25.74 (K.) The Clock Fund, deposited in the Five Cents Savings Bank, amounts to $878.40 Income during the year 33.93 (L.) The Sinking Fund, to provide for premiums, is de- posited in the Worcester Five Cents Savings Bank, and amounts to $2,670.42 (M.) The salaries of the University Faculty were . . $19,990.00 (N.) Fellowships and Scholarships $1,310.00 (0.) Salaries of employees $2,136.00 (P-) Apparatus and supplies $870.18 Respectfully submitted, Thomas H. Gage, Treasurer. 206 Report of the Treasurer. We have examined the books and accounts and securities of Clark UniTcrsity, and find them to be correct and as stated in the foregoing treasurer's report for the year ending August 31, 1899. Jambs P. Hamilton, T. H. Gage, Jr., Auditors. ICC LECTUEES ON MATHEMATICS. By Professor Emile Ficasd. Pkemibeb Configebncb. Sur VExtension de quelques Notions MathSmatiques, et en particidier de VIdSe de Fonction depuis un Siecle, Mes premiers mots seront pour adresser mes remerciments au Conseil de cette Universite qui m'a fait I'honneur de m'inviter a ces fetes et m'a charge de prendre la parole devant quelques mathematiciens americains. C'est un honneur auquel je suis tres sensible, car nous savons en France que les etudes mathematiques se developpent rapidement en Amerique et nous suivons ce mouvement avec une tres vive sympatMe. Votre American Journal of Mathematics compte parmi les journaux periodiques les plus importants et renferme de remarquables memoires, et je lis toujours pour ma part avec grand profit et interet le Bulletin de la Societe mathematique americaine, excellente revue historique et critique qui tient ses lecteurs au courant des travaux les plus recents. J'ai appris aussi que cette Societe allait fonder un nouveau recueil destine a des memoires plus etendus ; je ne doute pas qu'il ne soit appele a un brillant avenir. Dans les trois causeries que nous aUons avoir ensemble, je ne puis songer a aborder un sujet special qui demanderait une pre- paration particuliere. Nous allons rester dans les generalites et jeter un rapide coup d'oeil sur 1' extension de quelques notions mathematiques et en particulier, de I'idee de fonction depuis un siecle. I. Toute la science mathematique repose sur I'idee de fonction c'est a dire de dependance entre deux ou plusieurs grandeurs, dont I'etude con- stitue le principal objet de I'analyse. II a fallu longtemps avant qu'on se rendit compte de I'etendue extraordinaire de cette notion ; c'est la d'ailleurs une circonstance qui a ete tres heureuse pour les progres de la Science. Si Newton et Leibnitz avaient pense que les fonctions continues n'ont pas necessairement une derivee, ce qui est le cas general, le calcul 207 208 Emile Picard: differentiel n'aurait pas pris naissance ; de meme les idees inexactes de Lagrange sur la possibilite des developpements en series de Taylor ont rendu d'immenses services. Sans vouloir trop generaliser, on pent dire que I'erreur est quelquefois utile, et que, dans les epoques vraiment creatrices, une verite incomplete ou approchee peut etre plus feconde que la meme verite accompagnee des restrictions necessaires ; I'histoire de la science confirme plus d'une fois cette remarque et, pour rappeler encore Newton, il est heureux qu'il ait eu au debut de ses recherches pleine confiance dans les lois de Kepler. Les geometres du siecle dernier, sans remonter plus haut, ne raffinaient pas sur I'idee de fonction; pour eux, une fonction d'une variable est une fonction qu'on peut representor par une courbe formant un trait continu ; ce sont ces fonctions qu'Euler appelait funotiones continuce. La question de la representation d'une fonction arbitraire sous une forme analytique dans laquelle interviennent seulement les operations fondamentales de Tarithmetique effectuees un nombre fini ou infini de fois, se posa, semble-t-il pour la premiere fois a propos du probleme des cordes vibrantes. D'Alembert avait donne I'integrale de I'equation sous la forme f(x + at') + (x — at). Daniel Bernoulli montra qu'on pouvait satisfaire a I'equation differentielle et aux conditions aux limites par une serie trigonometrique, et U affirma que cette serie donnait la solution la plus generale. Ce fut I'occasion d'une longue discussion entre Bernoulli, Euler et Lagrange. Pour ces grands geometres, une fonction arbitraire etait toujours la fonction arbitraire susceptible d'etre repre- sentee par un trait continu. En 1807, dans un memoire celebre, et, plus tard, dans sa tlieorie analytique de la cbaleur, Fourier montra I'extreme importance des series trigonometriques ; il a, le premier, ose affirmer que toute fonction pouvait etre representee entre et 2 tt par un developpe- ment de cette nature, et, ce qui est le point capital, qu'un meme de- veloppement pouvait entre ces limites representer des fonctions qu'on considerait comme distinctes, c'est a dire correspondant graphiquement a des arcs de courbes differentes. II est tres instructif d'etudier dans la theorie de la cbaleur de Fourier les voies diverses que le oelebre geo- metre a suivies pour avoir les coefficients du developpement. La determi- nation de ces coefficients a I'aide des integrales classiques ne vient qu'en Premiere Conference. 209 second lieu ; cette determination avait d'aillenrs ete indiquee auparavant, quoique d'une maniere incidente, par Euler. Dans une premiere methods, Fourier obtient les coefficients en envisageant une infinite d'equations du premier degre a une infinite d'inconnues ; c'etait une recherche audacieuse pour I'epoque, et nous ne devons pas nous attendre a trouver dans cette etude toute la rigueur que nous exigeons aujourd'hui. II n'en faut pas moins se souvenir que Fourier eut le premier la hardiesse de resoudre des systemes d'une infinite d'equations lineaires a une infinite d'inconnues. II y a d'ailleurs en analyse plus d'une question ou se presentent de tels systemes. C'est le cas quand on veut chercher le developpement du quo- tient de deux series trigonometriques, et aussi, quand ayant a integrer une equation differentielle lineaire a coefficients periodiques, on veut y satisfaire par une fonction periodique ou au moyen du produit d'une telle f onction par une exponentielle ; ce dernier cas se presente dans plusieurs problemes de mecanique celeste et en particulier dans les beaux travaux de M. Hill sur le mouvement du perigee de la lune. M. Poincare a pose les principes d'une etude rigoureuse des systemes d'equations en nombre infini, specialement dans le cas des systemes homogenes. II introduit dans cette theorie les determinants d'ordre infini, et un fait inattendu ressort de ses recherches, a savoir que des egalites en nombre infini peuvent dans certains cas etre remplacees par une infinite d'inegalites. II y a d'ailleurs en analyse bien d'autres questions ou on se trouve en presence d'une infinite d'equations et il y aura un jour un chapitre interes- sant a ecrire sur I'integration d'un nombre infini d'equations differentielles avec une infinite de fonctions inconnues. Mais revenons aux series trigo- nometriques. En poursuivant rapidement leur histoire, nous arrivons a la periode oii Cauchy, Abel, et Dirichlet soumettent a une revision severe les principes fondamentaux de I'analyse mathematique. Le memoire de Dirichlet sur les series de Fourier est reste un modele de rigueur ; I'illustre auteur precise les conditions pour que Ton puisse affirmer qu'un developpement trigonometrique avec les coefficients de Fourier represente une fonction donnee dans I'intervalle de a 2 tt, et ces conditions sont restees dans la science sous le nom de conditions de Dirichlet. Elles sont seulement suffisantes, mais on ne pent esperer dans cette theorie trouver, sous une forme pratique, des conditions a la fois necessaires et suffisantes. II est certain aujourd'hui, grace surtout aux travaux de Du Bois-Reymond, qu'une fonction continue n'est pas necessairement toujours developpable en serie trigonometrique; la condition suffisante de M. Lipschitz formulee 210 Emile Picard: par I'inegalite [/(a; + A) — /(a;)] 0), en designant par k une constante fixe, a un grand caractere de generalite, et il en est de meme du theoreme de M. Camille Jordan sur la legitimite du developpement pour les fonctions a variation bornee. Le memoire de Riemann sur les series trigonometriques est celebre dans I'histoire de ces series ; on peut dire en deux mots, pour le carac- teriser, qu'il abandonne le point de vue de Dirichlet, et qu'au lieu de chercher des conditions suffisantes, sa principale preoccupation est de trouver des conditions necessaires. A un autre point de vue encore, le memoire de Riemann marque une date parce qu'il continue cette revision des principes du calcul infinitesimal commencee par Abel et Cauchy ; la distinction entre les fonctions integrables et les fonctions non integrables y apparait pour la premiere fois, et on peut dire qu'il resulte des travaux de Riemann qu'D. y a des fonctions continues n'ayant pas de derivees. On doit a M. G. Cantor la reponse a une question importante : une fonction peut-elle etre representee entre et 2 tt de plusieurs manieres par une serie trigonometrique ? En d'autres termes, ziro peut-il etre represente par un developpement trigonometrique ou les coefficients ne soient pas tous nuls ? Independamment du resultat lui-meme, le memoire de M. Cantor est digne d'interet parce que, dans une question depuis longtemps posee, des notions concernant les ensembles de points viennent jouer un role utile. Etant donne un ensemble de points entre et 2 tt, M. Cantor appelle ensemble derive I'ensemble de ses points limites, et on peut deflnir ainsi de procbe en proche les derivees successives d'un ensemble. Si la derivee n^* d'un ensemble se reduit a un nombre limite de points, I'ensemble sera dit de la w^« espece. M. Cantor etablit que si dans I'intervale (0, 2 tt) une serie trigonometrique est nulle pour toutes les valeurs de a; a I'exception de celles qui correspondent aux points d'un ensemble d'espece n, pour lequel on ne salt rien de la serie tous les coefficients seront nuls. 11. J'ai insiste, peut-etre un pen longuement, sur les series trigone metriques. Independamment de leur importance dans les applications et particulierement en physique mathematique, elles ont joue un role considerable dans revolution de la notion de fonction ; c'est leur etude qui a appele I'attention sur des circonstances, qui ne nous etonnent plus aujourd'hui, mais qui paraissaient jadis invraisemblables, comme, par Premiere Conference. 211 exemple, ce fait que la limite vers laquelle tend une serie de fonctions continues peut n'etre pas egale h. la valeur de la serie en ce point. Les precautions a prendre dans la derivation des series ont ete aussi sug- gerees par les series trigonometriques ; on peut faire remonter a cet exemple les nombreuses recherches effectuees depuis Cauchy sur la deri- vation et integration des series, auxquelles M. Osgood ajoutait il y a quelques annees un important complement dans son memoire sur la convergence non-uniforme. Le developpement d'une fonction en serie trigonometrique est aussi le type le plus simple de developpements tres generaux qui se presen- tent dans les applications ; Fourier, ici encore, a ete un precurseur. L'etude du refroidissement d'une sphere, en supposant que la tempera- ture ne depende que du temps et de la distance au centre, I'a conduit a un developpement ou, au lieu des lignes trigonometriques des multiples X, 2x, •••, nx de la variable, figurent les lignes trigonometriques de a^x, a^, ••; a„x, les a designant les racines en nombre infini d'une certaine equation transcendante, et il a esquisse une theorie de ces sortes de developpements. Cette etude a et^ reprise par Cauchy dans plusieurs memoires qui f orment une des applications les plus remarquables de ce que le grand analyste appelait le calcul des residus. Sous des conditions tres generales relatives a I'equation transcendante, Cauchy a demontre en toute rigueur la legitimite des developpements pour une fonction satisfaisant d'ailleurs aux conditions de Dirichlet, et ainsi se sont trouves considerablement generalises les resultats du memoire classique de I'il- lustre geometre allemand. D'autres developpements d'un caractere encore plus general se ren- contrent en physique mathematique, et ont fait I'objet des travaux de Poisson, de Sturm et de Liouville et de bien d'autres, mais ici se pre- sentent, au point de vue de la rigueur complete, des difificultes que I'on y\^ a reussi a surmonter que dans un petit nombre de cas. Je citerai seule- ment I'exemple tres simple du refroidissement d'un mur indefim dont les faces extremes sont maintenues a la temperature zero ; on suppose d'ailleurs que la chaleur specifique soit une fonction de I'abscisse x cor- respondant a chaque tranche, de telle sorte que Ton a pour la tempera- ture V I'equation aux derivees partielles — - = A(x) — , dx^ ^ ^ dt 212 Emile Picard: ok A(x) est une fonction continue et positive de x dans I'intervalle (a, i) de I'epaisseur du mur. Envisageons 1' equation lineaire ordinaire ^, + h.A(x)y = Q et les valeurs positives de k en nombre infini, h■^, k^, ••; k„ •'•, pour les- quelles il existe une integrale de I'equation precedente s'annulant en a et J. A chaque valeur de k^ correspond une integrale ^iQc) de cette equation (determinee a une constante pres), et le probleme qui se pre- sente est de developper une fonction /(x) s'annulant en a et 6 sous la forme La demonstration rigoureuse de ce developpement resulte des der- nieres recherches de M. Stekloff, s'aidant des travaux anterieurs de M. Poincare sur les equations de la physique mathematique. II semble bien qu'il soit indispensable pour I'entiere rigueur de supposer que /(a;) a des derivees des deux premiers ordres ; nous sommes loin d'atteindre ici a la generalite des conditions de Dirichlet pour le developpement en serie trigonometrique qui rentre d'ailleurs comme cas particulier (celui ou A(z^ est une constante) dans le cas precedent. in. L'histoire des developpements en series que je viens de retracer rapide- ment nous donne un remarquable exemple de I'intime solidarite qui unit a certains moments I'analyse pure et les mathematiques appliquees. En plus d'une occasion, ce sont celles-ci qui ont donne I'impulsion en posant les problemes, et c'est un fait assurement remarquable que des questions concernant les cordes vibrantes ou la propagation de la cbaleur aient conduit les geometres a approfondir la notion si complexe de fonction. L'histoire de la science mathematique offrirait d'ailleurs des le debut des exemples analogues ; nos facultes d'abstraction ne trouvent primi- tivement a s'exercer qu'en partant de certains faits concrets, et c'est sans doute en reflechissant aux precedes empiriques des praticiens egyptiens leurs predecesseurs que les premiers geometres grecs creerent la science geometrique. Mais ces vues risquer aient de m'entrainer trop loin. Je tiens seulement a aj outer qu'il ne faudrait pas professer une opinion trop systematique sur cette marche parallele de la theorie pure et des applica- tions, comme le faisait avec Laplace, Fourier, Poisson la brillante ecole Premiere Conference. 213 frangaise de physique mathematique du commencement de ce siecle. Pour eux, I'analyse pure n'etait que I'instrument, et Fourier, en annon- gant a I'Academie des sciences, les travaux de Jacobi, disait que les ques- tions de la philosophie naturelle doivent etre le principal objet des meditations des geometres. " On doit desirer, ajoutait-il, que les personnes les plus propres a perfectionner la science du calcul dirigent leurs tra- vaux vers ces hautes applications si necessaires au progres de I'intelli- gence humaine." Ce desir tres legitime ne doit pas etre exclusif ; ce serait meconnaitre d'abord la valeur philosophique et artistique des matbematiques ; de plus des speculations theoriques sont restees pendant longtemps eloignees de toute application, quand un moment est venu ou elles out pu etre utilisees. On n'en pent pas citer d'exemple plus memorable que le concept des sections coniques elabore par les geometres grecs, qui resta inutilise pendant deux mille ans, jusqu'au jour ou Kepler s'en servit dans I'etude de la planete Mars. Les questions s'epuisent pour un temps, et il n'est pas bon que tous les cberclieurs marcbent dans la meme voie. Peu d'annees apres que Fourier ecrivait les lignes que je viens de rappeler, apparaissait Evariste Galois qui aurait, s'il avait vecu davantage, retabli I'equilibre en ramenant les recherches vers les regions les plus elevees de la theorie pure, et ce fut un malbeur irre- parable pour la science frangaise que la mort de Galois, dont le genie allait exercer una action si profonde sur les parties les plus varices des matbematiques. Avec cette digression, nous semblons etre bien loin, messieurs, de notre promenade a travers I'idee de fonction depuis le commencement de ce siecle. EUe n'etait cependant pas inutile, pour montrer qu'un moment devait arriver ou les speculations sur la theorie des fonctions de variables reelles se poursuivraient sans souci immediat des applications et pren- draient de plus en plus un caractere philosophique. Nous avons deja dit qu'il resultait indirectement des travaux de Riemann qu'une fonction con- tinue n'a pas necessairement une derivee. Weierstrass donna le premier exemple d'une fonction continue n'ayant de derivee pour aucune valeur de la variable, et il fit connaitre au sujet des fonctions continues une proposition qui nous ramene aux developpements en series, mais ici les termes sont des polynomes. D'apres Weierstrass, toute fonction con- tinue dans un intervalle pent etre developpee en une serie de polynomes qui est absolument et uniformement convergente dans cet intervalle. La demonstration de I'illustre geometre est tres compliquee ; elle prend 214 Emile Picard: comme point de depart une integrale consideree par Fourier dans la theorie de la chaleur, qui permet d'obtenir la fonction consideree comme la limite d'une fonction transcendante entiere dependant d'un parametre, quand celui-ci tend vers zero. C'est de la que Weierstrass deduit la possibilite de representer d'une maniere approcliee par un polynome toute fonction continue dans un intervalle fini, d'ou se tire alors de suite le resultat enonce. On peut arriver beaucoup plus rapidement au theoreme de Weierstrass en partant de I'integrale classique de Poisson dans la theorie des series trigonometriques ; elle montre facilement que la fonction, supposee definie dans un intervalle moindre que 2 tt, peut-etre representee avec telle approximation que Ton voudra par une serie limitee de Fourier, et on passe de suite a une representation approchee par un polynome ; celle demonstration s'etend a des f onctions continues d'un nombre quelconque de variables. M. Volterra est arrive aussi tres simplement au theoreme qui nous occupe en remarquant qu'une fonction continue est representable avec telle approximation qu'on voudra par une ligne polygonale convenable ; celle-ci conduit a une serie de Fourier uniformement convergente, et en la reduisant a un nombre suffisamment grand mais limite de termes on retombe sur le resultat indique plus haut. Le theoreme de Weierstrass presente un reel interet philosophique, en meme temps qu'il peut avoir quelque utilite au point de vue du cal- cul pratique ; on en a aussi quelquefois fait usage pour la demonstration de certaines propositions. Les developpements en series de polynomes speciaux sont d'un grand interet, mais ils ne peuvent s'appliquer qu'a des fonctions satisfaisant a des conditions particulieres. Ainsi, dans son memoire sur I'ap- proximation des fonctions de tres grands nombres, M. Darboux a etudie les developpements d'une fonction suivant les polynomes de Jacobi provenant de la serie hypergeometrique. Les conditions sont encore celles de Dirichlet ; pareUlement aussi dans le cas ou la fonction devient infinie, elle doit rester integrable. II y a cependent une difference quand la fonction devient infinie pour les points extremes. Dans le cas des polynomes de Legendre, une fonction qui deviendrait infinie d'un ordre egal ou superieur a ^ pour a; = ± 1 ne serait pas developpable, quoique les coefficients aient un sens. IV. Si nous revenons aux fonctions prises dans toute leur generalite, on reconnait vite la necessite d'etablir avec un soin extreme certaines pro- Premiere Conference. 215 positions que Ton accorde aisement pour les fonctions usuelles. C'est ce qu'avait deja reconnu Cauchy dans son Analyse algebrique ; les travaux de Hankel, le memoire de M. Darboux sur les fonctions discontinues, le beau livre de M, Dini et les etudes plus recentes des geometres italiens montrent bien les precautions necessaires dans ce genre de recherches. Ainsi, une fonction de deux variables reelles pent etre continue par rap- port a a; et par rapport a y sans etre continue par rapport a I'ensemble des deux variables, comme M. Dini en a indique des exemples. Parmi les travaux les plus recents sur ces questions delicates, je m'arreterai un instant sur un memoire de M. Baire qui renferme de curieux resultats. L'auteur a reussi a trouver la condition necessaire et suffisante pour qu'une fonction fQc) d'une variable reelle puisse etre representee par une serie simple de polynomes; I'enonce suppose certaines notions sur la discon- tinuite d'une fonction par rapport a un ensemble de points : une fonction pent etre ponctuellement ou totalement discontinue par rapport a cet ensemble. La condition obtenne est que la fonction soit ponctuellement discontinue par rapport a tout ensemble parfait. M. Baire se pose aussi une question singuliere sur les equations lineaires aux derivees partielles. Envisageons I'equation Si je vous demandais quelles sont les fonctions satisfaisant a cette equation, vous me repondriez sans doute que les fonctions de a; — y repondent seules a la question. M. Baire n'en est pas absolument sur ; il remarque que la theorie du cbangement de variables suppose la con- tinuite des derivees qu'on emploie; si on suppose seulement I'existence des derivees Ji Qt J- Ae, la fonction cherchee /, on ne pent pas faire le dx dy cbangement de variables classique. II faut une analyse delicate pour etablir que la fonction /, supposee continue par rapport a I'ensemble des variables x et y, et satisfaisant a (1) est une fonction A.GX — y; la conclu- sion reste douteuse si / est seulement continue par rapport a a; et par rapport a y. Au point de vue geometrique les recherches generales sur les fonctions ne sont pas non plus sans interet ; elles nous apprennent a nous defier de nos conceptions les plus simples. Quoi de plus simple semble-t-il qu'une courbe dont les coordonnees x sty sont des fonctions continues d'un para- metre t variant entre a et b. M. Peano a cependant montre qu'on peut 216 Emile Picard: choisir ces deux fonctions de telle sorte que, quand t varie entre a et 5, le point (x, y) puisse prendre une position quelconque dans un rectangle. A certains points (x, y) pourront correspondre d'ailleurs, dans I'exemple de M. Peano, deux ou quatre valeurs de t. Ce resultat est au premier abord deconcertant ; il derange nos idees sur les surfaces et sur les courbes. Voici encore un resultat singulier obtenu tout recemment par M. Lebegue ; il y a d'autres surfaces que les surfaces developpables qui sont applicables sur un plan. On pent a I'aide de fonctions continues obtenir des surfaces correspondant a un plan de telle sorte que toute ligne rectifiable du plan ait pour correspondante une ligne rectifiable de la surface, et la surface n'est cependant pas reglee. De tels exemples montrent la subtilite des recherches auxquelles doivent se livrer aujourd'hui ceux qui veulent approfondir la notion de fonction prise dans son extreme generalite. Ces etudes sont en bien des points intimement liees aux speculations sur la notion meme de nombre. Nous rejoignons ici une ecole de philosophic mathematique qui s'est brillamment developpee depuis quelque trente ans, ecole qui se livre a une minutieuse analyse sur la nature du nombre. On ne pent s'empecher d'etre frappe du nombre considerable de publications parues dans ces dernieres annees et se rapportant a cette mathematique philosophique ; elles sont bien en accord avec les tendances generales de I'epoque oti nous vivons, et ou I'esprit humain applique dans des directions varices une critique de plus en plus penetrante. Ces speculations raffinees ont meme penetre dans I'enseignement elementaire, ce qui est a mon avis tres regrettable. Mais il ne s'agit pas ici d'enseignement ; je ne recherche pas non plus I'interet que ces etudes presentent pour le philosophe ; il me parait tres reel, et on doit souhaiter que de jeunes philosophes s'engagent dans cette direction apres s'etre inities serieusement aux mathematiques. Je ne veux me placer qu'au point de vue de la mathematique. De bons esprits contestent que les speculations dont je parle aient quelque impor- tance pour les mathematiques positives et ils craignent de voir beaucoup de talent depense dans des recherches steriles. Je comprends tres bien leurs craintes mais je ne partage pas entierement leur avis. II y a lieu sans doute de faire des distinctions. Certaines questions sont d'un interet purement philosophique et n'auront jamais vraisemblablement la moindre utilite pour les mathematiques, comme, par exemple, de savoir si la priorite appartient au nombre cardinal ou au nombre ordinal, c'est a dire si I'idee de nombre proprement dit est anterieur a celle de rang ou si c'est Premiere Confirence. 217 I'inverse. Mais dans d'autres cas, il n'en est plus de meme ; ainsi il est vraisemblable que la theorie des ensembles de M. Cantor, que nous avons deja rencontree deux fois sur notre chemin, est a la veille de jouer un role utile dans des problemes qui n'ont pas ete poses expres pour etre une application de la theorie. Ne regrettons done pas cet effort hardi sur I'idee de nombre et sur celle de fonction, car la theorie des fonctions de variables reelles est la veritable base de I'analyse mathematique. V. II faut Men, il est vrai, reconnaitre que la notion generale de fonction est tres vague, et nous ne pouvons obtenir des resultats de quelque etendue qu'en faisant des hypotheses particulieres. Qu'est ce qui a guide plus ou moins consciemment dans le choix de ces hypotheses ? II resulte de ce que nous avons dit sur les rapports entre I'analyse et les applica- tions aux phenomenes naturels, que celles-ci ont plus d'une fois guide le mathematicien dans son choix. Une hypothese essentielle a ete celle de la continuite. Suivant le vieil adage "natura non facit saltus" nous avons le sentiment, on pourrait dire la croyance, que dans la nature il n'y a pas de place pour la discontinuite. II est utile quelquefois de conserver le discontinu dans nos calculs, par exemple quand nous regardons comme nuUe la duree du choc en mecanique rationnelle, ou quand nous reduisons a une surface les couches de passage dans plusieurs questions de physique; mais noiis savons que, pour si petite qu'elle soit, les chocs ont une certaine duree et les physiciens nous ont appris a mesurer I'epaisseur des couches ou se produisent dans plusieurs phenomenes des variations tres rapides. L'idee de derivee s'impose deja moins; elle repond cependant au senti- ment confus de la rapidite plus ou moins grande avec laquelle s'accomplit tel ou tel phenomene. L'hypothese relative a la possibilite de la deriva- tion d'une fonction a done une origine analogue a celle de la continuite. Je ne veux pas dire qu'au point de vue du nombre l'idee de continuite soit aussi claire au fond qu'elle en a I'air, mais il ne s'agit ici que de la notion du continu physique tiree des donnees brutes des sens. Dans d'autres cas, on ne voit pas de cause du meme ordre dans la particularite imposee a la fonction ; il en est ainsi, ce me semble, pour la propriete des fonctions dites analytiques c'est a dire des fonctions qui dans le voisinage d'une valeur arbitraire de la variable peuvent etre developpees en series de Taylor. Les fonctions etudiees les premieres, comme les fonctions rationnelles, I'exponentielle, les lignes trigonome- 218 Emile Picard: triques, jouissant de cette propriete, I'attention se sera sans doute trouvee appelee sur elle; et ensuite la facilite aveo laquelle cette hypothese a permis d'aborder certaines questions a fait acquerir aux fonctions analy- tiques une importance considerable. C'est done £i leur commodite dans nos calculs qu'elles doivent le grand role qu'elles jouent. On ne sait pas d'ailleurs, pour une fonction definie seulement pour les valeurs reelles de la variable, quelles sont les conditions de legitimite du developpement en serie de Taylor. Une fonction de x pent avoir des derivees de tout ordre pour toute valeur de la variable, et n'etre cependant pas developpable. On doit a M. Borel un resultat remarquable con- cernant les fonctions d'une variable reelle definie dans un certain inter- valle et ayant dans cet intervalle des derivees de tout ordre. Si I'intervalle est (— TT, +7r), la fonction pent etre representee par un developpement de la forme B=0 (J.„a;" + Bn cos nx + (7„ sin nx'). Ces diverses remarques m'amenent a dire un mot d'une ecole de geo- metres qui ne veulent rien voir en dehors des fonctions analytiques, et d'une maniere plus generale de I'importance, peut-etre exageree, qu'a prise dans les travaux modernes la theorie des fonctions analytiques. C'est mutiler singulierement I'analyse que de vouloir se borner a des deve- loppements aussi particuliers que les series entieres, alors que Ton peut former tant de developpements d'une autre nature qui ne peuvent jamais etre representees par de telles series. Sans doute, les fonctions les plus usuelles sont analytiques, et on pourrait nous demander de citer des examples dans la solution desquels interviennent des fonctions non analy- tiques, tandis que les donnees sont analytiques. lis ne sont pas courants ; ce sont les equations aux derivees partielles qui probablement les four- niront le plus facilement. Le suivant, du a M. Borel, me parait digne d'etre signale. Envisageons I'equation oil a est une irrationnelle convenablement choisie, et f(x, y) une certaine fonction analytique de a; et «/ de periode 2 tt pour x et y. Pour I'equation de cette forme citee par M. Borel, il y a une seule solution periodique et cette solution n'est pas analytique. Soit a un nombre incommensurable Premiere Conference. 219 tel que — ^ etant I'une quelconque des reduites du developpement de a en fraction continue, on ait I Wj — M^a I < e-mi»-n« on forme ^ (x, y) = l. os^'J"' cos Qn^') cos (n^y) (a < 1, J < 1). C'est une fonction non analytique. Posons d'autre part la fonction i/r sera analytique. Done si on prend I'equation (1) a priori et qu'on cherclie une solution periodique, en x et y, il n'y en a qu'une ; c'est ^ qui n'est pas analytique. C'est encore, en se plagant a un autre point de vue, qu'il parait mauvais de reduire la theorie des fonctions a la theorie des fonctions analytiques. II y a de nombreuses questions, oii le fait pour les donnees d'etre analytiques ne donne aucune facilite pour la solution, et ou on risque, en portant trop son attention sur cette nature des donnees, de cherclier la solution dans des voies sans issues. Pour le probleme du refroidissement de la barre dont je parlais plus haut, qu'importe que les fonctions donnees A(x) et f(x) soient ou non analytiques ? Ce n'est pas tout ; il y a un dernier point sur lequel je tiens a insister. II pent arriver que la circonstance d'avoir a faire a des fonctions analytiques conduise a une solution, mais il se pent que celle-ci ne se presente pas sous la forme la plus favorable, forme a laqueUe on arrive au contraire en faisant ab- straction de la nature analytique des donnees. La theorie des equations differentielles fournirait des exemples a I'appui de cette assertion; bornons nous a citer le theoreme fondamental du Calcul Integral relatif a, I'ex- istence de I'integrale de I'equation differentielle -^=f(x,y'). Ce sont ax les demonstrations ne supposant pas que la fonction / soit analytique, qui donnent le plus grand intervalle comme region ou I'integrale est certainement determinee ; I'analyste, qui suppose analytique la fonction reelle f(x, «/) et veut n'envisager que des series entieres, est conduit par son mode de demonstration a un domaine plus restreint. J'ai simplement eu pour but dans ce qui precede de montrer qu'il ne faut pas restreindre systematiquement la notion de fonction. D'une maniere generale, admirons des systemes tres bien ordonnes, mais mefions nous un peu de leur apparence scolastique, qui risque d'etouffer I'esprit 220 Emile Picard: d'invention. II ne s'agit pas, bien entendu, de nier la grande importance actuelle de la theorie des fonctions analytiques, mais il ne faut pas oublier qu'elles ne ferment qu'une classe tres particuliere de fonctions, et on doit souhaiter qu'un jour vienne on les mathematiciens elaborent des theories de plus en plus comprehensives ; c'est ce qui arrivera peut-etre au siecle prochain, si I'idee de fonction, dont je vous ai bien incompletement esquisse I'liistoire, continue son evolution. Mais, pour le moment nous sommes encore au dix-neuvieme siecle ; j'aurai I'occasion demain et apres demain de faire amende honorable aux fonctions analytiques, qui depuis trente ans ont fait, comme vous savez, I'objet de travaux considerables. VI. Nous venons de voir les vastes perspectives qu'ouvre I'extension de plus en plus grande de la notion de fonction. II faudra certainement montrer dans cette voie beaucoup de prudence, et ne pas entreprendre avant I'heure des recherches qui resteraient steriles; mais il n'est pas douteux qu'un jour viendra ou I'analyste sentira le besoin d'etendre le domaine de ses recherches. L'extension de I'idee de fonction n'est pas la seule qu'aient poursuivie en ce siecle les mathematiciens qui s'interessent aux principes de la science ; la question des quantites complexes a vive- ment excite I'interet, d'autant plus qu'une certaine obscurite planait sur elle, qu'entrainait le mot un peu mysterieux de quantites imaginaires. Le sujet ne presente plus rien aujourd'hui de mysterieux. Dans un memoire publie en 1884 Weierstrass a developpe une theorie des nombres complexes. II suppose que Ton considere des nombres de la forme x^e-^ + x^e^-\ |-a;„e„, ou les X sont des nombres reels on imaginaires ordinaires. Les e sont de purs symboles. On fait I'hypothese que la somme, la difference, le pro- duit et le quotient de deux nombres de I'ensemble font eux-memes partie de eet ensemble. Les produits e^e^ (p, q= 1,2, •••, ri) sont done des expressions 1]^^^ lineaires et homogenes en ej, e^, •••, e„ qui jouent le role essentiel dans la theorie. Weierstrass suppose de plus que les theoremes dits commutatif et associatif subsistent tant pour I'addition que pour la multiplication. Pour I'addition, ils sont verifies d'eux-memes ; pour la multiplication, ils s'expriment par les egalites ah = ha, (ah') ■ c = a ■ (he), Premiere Conference. 221 a, 5, c etant trois nombres quelconques de I'ensemble. Ces conditions conduisent a certaines relations entre les coefficients des formes lineaires ^p_j. A tout systeme de formes E^^^ verifiant ces conditions corre- spondra un ensemble de nombres complexes. Les nombres complexes que nous venons de definir different seulement en un point des nombres complexes ordinaires. Quand n est superieur a deux, il pent exister des nombres differents de zero dont le produit par certains autres nombres est nul. Weierstrass appelle ces nombres des diviseurs de zero. M. Dedekind a montre qu'en general les calculs avec ces nombres complexes se ramenaient aux calculs de I'algebre ordinaire ; d'une maniere plus precise, si le carre d'un nombre ne pent etre nul sans que ce nombre soit nul, on pent aux n unites complexes primitives substituer n autres unites (le determinant de la substitution n'etant pas nul) de telle sorte que pour ces nouvelles unites e\, e'^, •••■, e'„, on ait d'ou Ton conclut que les calculs relatifs aux nombres complexes prece- dents se ramenent a des calculs relatifs aux nombres reels ou complexes ordinaires. Nous ayons admis que les lois commutative et associative subsis- taient dans I'algebre precedente. On s'est place a un point de vue plus general en supposant que, seule, la loi associative subsistait [c'est a dire (ah')c = a(Jc)]. On a alors une algebre beaucoup plus generale ; celle-ci est completement determinee par le systeme des expressions lineaires Ep^^. Un exemple celebre d'un systeme a quatre unites e^, e^, eg, e^ est fourni par les quaternions d'Hamilton ej = 1, ^2 = *' *3 = h ^4 = *' avec les relations i* = y^ _ p _ _ i ij = — ji = k jk ■^-kj = i ki = — ik = j. Une remarque tres interessante de M. Poincare ramene toute la theorie des quantites complexes a une question concernant la tbeorie des groupes. EUe consiste en ce qu'a chaque systeme d'unites complexes correspond un groupe continu (au sens de Lie) de substitutions lineaires 222 Emile Picard : a n variables, dont les coefficients sont des fonotions lineaires de n para- metres arbitraires, et inversement. Cette idee a ete approfondie par M. Scheffers qui a ete ainsi conduit a partager les nombres complexes en deux classes, suivant que le groupe qui leur correspond est integrable ou non integrable. A cette derniere classe appartient le groupe corres- pondant aux quaternions, et ceux-ci sont les representants les plus simples de cette categoric de nombres complexes. Le rapprocbement entre la tbeorie des groupes de Lie et les nombres complexes fait disparaitre le mystere qui semblait planer sur ceux-ci, et la veritable origine des symboles est ainsi bien mise en evidence. On pent se demander si ce symbolisme est susceptible d'accroitre la puissance de I'Analyse. En France, les geometres qui s'interessent a ces calculs sont tres peu nom- breux ; je sais qu'au contraire en Angleterre et, je crois aussi, dans ce pays les quaternions sont tres apprecies. Je ne les ai pas assez manies moi-meme, pour me rendre compte si leur emploi en mecanique ou en physique matbematique simplifie les calculs d'une maniere tres appre- ciable ; il y a probablement la surtout une affaire d'habitude. Le point vraiment interessant serait de savoir si ces quantites complexes presen- teront un jour quelque interet pour I'analyse generale, comme il arrive pour les imaginaires ordinaires. Les essais tentes jusqu'ici dans cette voie ne paraissent pas avoir ete heureux ; mais, maintenant que le lien avec la tbeorie des groupes est completement mis en evidence, il n'est pas impossible que de nouvelles tentatives n'aboutissent a quelque resultat interessant. Les idees de nombres reel ou complexe, la notion de fonction sont a la base meme de I'analyse ; il y a encore une autre notion que le travail matbematique de ce siecle a conduit a elargir considerablement. L'idee d'espace forme la matiere meme de la geometric ; elle aussi a ete sou- mise a une critique penetrante qui a renouvele les bases de la geometric. Je n'en referai pas I'histoire depuis Gauss, Bolyai et Lobatscbevski, his- toire tres souvent racontee, ni ne prendrai parti dans les querelles que se font encore a ce sujet les philosopbes. Je veux dire seulement un mot de I'interet qu'ont eu pour les mathematiques les speculations sur la nature de I'espace. Dans le memoire ceBbre de Riemann, apparaissent pour la premiere fois les notions relatives a la courbure de I'espace dans les differentes directions, c'est-a-dire les — ^= — ^ — - fonctions invariantes caracteristiques d'une multiplicite a n dimensions ; une vive impulsion Premiere Conference. 223 a ete ainsi donnee a la theorie des formes quadratiques de differentielles. Pour ne citer qu'un exemple, j'indiquerai seulement la forme qui doime le carre de I'element d'arc dans la geometrie de Lobatchevski ; at il est interessant de rappeler le role qu'elle a joue dans les recherches de M. Poincare sur la formation des groupes fuchsiens. Apres Rie- mann, Helmholtz posa la question sur un autre terrain: son idee fonda- mentale consiste a porter I'attention sur I'ensemble des mouvements possibles dans I'espace dont on fait I'etude. Le grand physicien traitait ainsi par avance de problemes se rattacbant a la theorie des groupes. Celle-ci n'etait pas encore creee a I'epoque ou Helmboltz ecrivait son memoire ; il a commis quelques erreurs apres tout secondaires, mais il n'en a pas moins la gloire d'avoir le premier regarde une geometrie comme I'etude d'un groupe. Les recherches d'Helmholtz furent reprises completement par Lie ; elles lui offraient une magnifique occasion d'ap- pliquer son admirable theorie des groupes de transformations. Dans ces etudes, I'espace est a priori regarde comme une multiplicite, et, en prenant le cas de trois dimensions, un point est defini par trois quantites (x, y, e) . Un mouvement dans I'espace n'est autre chose qu'une trans- formation a:' =/(a', y, s), y' = ^Q», y, s), s' = ^(x, y, z) valable pour une portion de I'espace. On suppose que tous les mouve- ments possibles forment un groupe a six parametres, qu'ils laissent invariable une fonction des eoordonnes de deux points quelconques, qu'enfin le mouvement libre soit possible, comme disait Helmholtz. Lie demontre alors que I'espace euclidien et les espaces non euclidiens sont les seuls qui satisfassent a ces conditions. Au point de vue ou s'est place Lie, I'etude des principes de la geometrie pent etre regardee comme epuisee, mais il se borne a considerer une petite portion de I'espace. Clifford et Klein out appele I'attention sur la question de la connexite de I'espace qui est extremement interessante ; nous ne savons rien sur la connexite de I'espace ou nous vivons. On peut aussi chercher a appro- fondir le postulat de I'espace regarde comme une multiplicite, et sub- ordonner la conception metrique de I'espace a la conception projective avec von Staudt, Cayley et Klein ; mais je dois me contenter de rappeler ces directions diverses. 224 EmiU Picard: J'ai seulement, messieurs, voulu montrer dans cette conference quelles perspectives ouvre aux chercheurs I'extension de nos idees sur les fonc- tions, sur le nombre et sur I'espace. Si I'elaboration mathematique est aussi feconde au siecle prochain qu'elle I'a ete en ce siecle, I'analyse differera beaucoup dans cent ans de ce qu'elle est aujourd'hui ; on maniera peut-etre couramment les fonctions les plus extraordinaires, et on verra tres clair dans des espaces ayant beaucoup de dimensions et des connexites elevees. Pour se representer I'etat de la mathematique en I'an 2000, il faudrait I'imagination de I'auteur de "Looking Backward"; il est malheureux que M. Bellamy dans son roman ne nous ait pas parle des mathematiques a cette epoque. Comme I'humanite, s'il faut Ten croire, aura alors beaucoup de loisirs, les mathematiques seront sans doute extremement florissantes et les problemes qui nous arretent aujour- d'hui ne seront plus que des jeux d'enfants pour nos successeurs. Sbcondb Conference. Quelques Vues Q-SnSrales sur la ThSorie des Equations jDiffSrentielles. Je voudrais aujourd'hui jeter un coup d'ceil sur la theorie des equa- tions differentielles, qui joue en analyse un role considerable et dont les progres importent vivement a ses applications; c'est un domaine tres vaste et j'eprouve quelque embarras a faire un choix entre les directions si diverses ou s'est developpee cette theorie. Les geometres du siecle dernier ne paraissent pas s'etre preoccupes d'etablir rigoureusement I'existence des integrales des equations differentielles; ils integraient, quand ils le pouvaient, les equations qui se presentaient dans leurs recherches, sans se soucier de ces theoremes d'existence, comme on dit aujourd'hui, auxquels nous attachons beaucoup d'importance. C'est a Cauchy que Ton doit les premieres recherches precises sur ces questions ; le champ en est tres vaste, et il ne I'a pas parcouru en entier, mais, au moins dans le cas ou les fonctions et les donnees sont analytiques, il a indique les principes qu'ont suivis tous ses continuateurs. Dans les theoremes relatifs a I'existence des integrales, on emploie des methodes differentes suivant que les equations et les donnees sont supposees on non analytiques. I. PlaQons nous d'abord dans le premier cas, de beaucoup le mieux elabore. L'idee essentielle de Cauchy consiste dans la consideration des Seconde Conference. 225 fonctions majorantes. On salt que les difficultes resident surtout dans la demonstration de la convergence de certaines series entieres que les equations differentielles permettent de former. Cauchy y parvient par des comparaisons avec d'autres equations facilement integrables. Pour les equations differentielles ordinaires, il n'y avait a faire apres Cauchy que des simplifications de forme, et, pour le cas d'une seule equation aux derivees partielles, quel que soit le nombre des variables, le grand geo- metre avait indique aussi les points essentiels de la demonstration, que Mme. Kovalevski, dans un memoire reste classique, a presentee sous une forme tres simple. Le tbeoreme fondamental est alors le suivant : Si on a une equation aux derivees partieUes d'ordre n relative a une fonction z de ^ + 1 variables independantes x, x^, •••, x^ et que I'equation con- tienne la derivee d'ordre n, — , une integrale sera en general determinee si on se donne pour a; = a les valeurs de z et de ses derivees par rapport a X jusqu'a I'ordre n — 1: ces donnees sont des fonctions holomorphes de x^, x^, •••, Xp dans le voisinage de a^, a^, •••, Up. On pent done dire, en s'appuyant sur cet enonce que I'integrale generale de I'equation consideree depend de n fonctions de p variables independantes. C'etait un point auquel on tenait beaucoup autrefois de savoir de combien de fonctions arbitraires dependait I'integrale generale d'une equation aux derivees partielles ; certains resultats paradoxaux avaient cependant deja appele I'attention comme les formes diverses de I'integrale generale de I'equation de la chaleur — - = — , qui se presentait tantot avec une, tantot avec dor oy deux fonctions arbitraires. De tels resultats ne nous etonnent plus aujourd'hui, quand il s'agit comme ici de fonctions analytiques. Nous n'avons qu'a nous rappeler qu'un nombre fini quelconque de fonctions a un nombre quelconque de variables independantes ne presente pas, au point de vue arithmetique, une plus grande generalite qu'une seule fonc- tion d'une seule variable, puisque dans I'un et I'autre cas I'ensemble des coefficients des developpements forme simplement une suite enumerable. Aussi s'explique-t-on que M. Borel ait pu etablir que toute integrale analytique d'une equation aux derivees partielles a coefficients analy- tiques peut etre exprimee a I'aide d'une formule ne renfermant qu'une seule fonction arbitraire d'une variable reelle. Nous venons de considerer une seule equation aux derivees partielles. L'etude des systemes d'equations differentielles presentait de plus grandes 226 Emile Picard: difficultes. Une premiere question est tout d'abord restee longtemps sans reponse ; il etait possible de se demander s'il pouvait exister des systemes qui comprennent un nombre illimite d'equations distinctes c'est a dire ne pouvant pas se deduire par differentiation d'un certain nombre d'entre elles. M. Tresse a etabli qu'un systeme d'equations aux derivees partielles etant defini d'une maniere quelconque, ce systeme est uecessaire- ment limite, c'est a dire qu'il existe un nombre fini s, tel que toutes les equations d'ordre superieur a s, que contient le systeme, se deduisent par de simples differentiations des equations d'ordre egal ou inferieur a 8. II importait ensuite de se rendre compte de la nature des elements arbitraires figurant dans I'integrale generale. Mme. Kovalevski n'avait examine que certains systemes composes d'equations en nombre egal a celui des fonctions inconnues et resolubles par rapport aux derivees d'ordre le plus elere de chacune des fonctions, ces derivees etant relatives a une meme variable x. M. Riquier d'abord, puis M. Delassus ont donne sous des formes differentes la solution du probleme dans le cas general ; M. Delassus arrive par des changements de variables a obtenir une forme canonique completement integrable, et montre que I'integration d'un tel systeme a m variables se ramene a I'integration successive de m systemes de Mme. Kovalevski contenant successivement 1, 2, ■■•, m variables; c'est en partant de cette propriete qu'on pent demontrer facUement I'existence des integrales analytiques, et determiner les fonctions et constantes initiales en nombre fini dont dependent ces integrales. II semble y avoir eu longtemps chez les mathematiciens quelques hesi- tations sur ce qu'on devait entendre par integrale generale d'une equation aux derivees partielles. Si I'on se borne aux cas ou il ne figure dans les equations que des elements analytiques, et si Ton n'envisage que les inte- grales analytiques, on considere aujourd'hui, conformement a I'opinion de M. Darboux, qu'une integrale est generale, si on peut disposer des arbitraires qui y figurent, fonctions et constantes, de maniere a retrouver les solutions dont les theoremes de Cauchy et de ses successeurs nous ont demontre I'existence. Anterieurement, Ampere s'etait place a un autre point de vue ; dans son grand memoire sur les equations aux differences partielles, il s'exprime ainsi : " Pour qu'une integrale soit generale, il faut qu'il n'en resulte entre les variables que Ton considere et leurs derivees a I'infini que les relations exprimees par I'equation donnee et par les equa- tions que Ton en deduit en la differentiant." II est bien clair qu'il s'agit de relations ne renfermant aucune des quantites arbitraires qui figurent Seconde ConfereTice. 227 dans I'integrale consideree. Les avis etaient partages entre les geometres, et on se demandait s'il y a identite entre la definition d' Ampere et celle de Cauchy. M. Goursat a montre bien nettement, sur differents exemples, qu'une integrals pent etre generale au sens d' Ampere sans etre generale au sens de Cauchy. II ne faudrait pas conclure des divers travaux qui precedent, que, tout en envisageant seulement des integrales et des equations analytiques, I'etude des conditions determinant les integrales d'un systems d' equations aux derivees partielles soit actuellement achevee. Les tlieoremes generaux indiques font connaitre certaines donnees qui determinent une integrals, mais celle-ci pent etre determines par uns infinits d'autres conditions. II n'est pas douteux que les types a trouver de ces theoremes d'existence sent en nombrs infini. Prsnons I'exsmple tres simpls ds I'equation B'^z , dz , , dz , n + a i- b ■— + cz = 0. dx dy dx Sy Une integrals est determinee par la condition de se reduire pour a; = a une f onction donnes ds y, et pour ^ = a une fonction donnee de x : voila un genre de determinations d'une integrale qui ne rentre pas dans les conditions du theorems gsneral ds Cauchy. Lss conditions tres varices, qui peuvent detsrminsr lss integrales des equations aux dif- ferences partielles appellsnt encore ds nombrsusss rschsrches. II. Nous venons de nous placer au point de vue de la theorie des fonctions analytiquss. Comme je le disais hier, il y a souvent grand interet, non seulement a un point de vue philosophique, mais mems en quslque sorte au point de vue pratique, a adopter dss hypothsses plus generales. C'est encore a Cauchy que Ton doit pour les equations dUBferentielles ordinaires la demonstration de I'existence des integrales sans supposer les equations analytiques. Sa methode, bien naturelle et bien simple, consiste a rsgarder les equations differentisUes comme limites d'equations aux differences. On pent fairs sur cstte methode de Cauchy une remarque tres interessante ; ells sst susceptible de fournir des developpements en series des integrales qui convergent taut que les intSgrales restent continues, et laissent continues les coefficients diffSrentiels. En ce sens, ells est 228 Emile Picard: superieure aux autres methodes qui ont ete proposees. Ainsi, pour prendre un exemple, soit le systeme d'equations -^ = Xi(xi, x^,—, xj (i = 1, 2, • • . m) ou les X sont des polynomes. On pent representer les integrales de ce systems prenant pour t = les valeurs x-^°, x^, •••, x„^ par des deve- loppements de la forme Pi(V, x^^, -, xj>, 0+ - + P„(V> a^a", -, xj>, 0+ - les P etant des polynomes en x-^,x^, •••i^n et t, et ces developpements sont convergents tant que les integrales restent des fonctions continues de t. D'autres methodes ont ete proposees pour demontrer I'existence des integrales, comme la methode des approximations successives qui donne pour les series une convergence tres rapide, mais ces series ne convergent pas necessairement dans tout le champ ou les integrales sont continues. Pour une equation differentielle ordinaire d'ordre n, on suppose generalement, quand on veut etablir I'existenee des integrales, qu'on se donne pour une valeur de x les valeurs de la fonction et de ses derivees jusqu'a I'ordre n— 1, mais on pourrait prendre beaucoup d'autres don- nees; et c'est ce qui arrive notamment dans les applications du calcul des variations. Ainsi pour une equation du second ordre, il arrive qu'une integrale soit determinee par les conditions de prendre pour x^^ la valeur y^ et pour x^ la valeur y^ On a peu travaiUe jusqu'ici dans cet ordre d'idees, et cependant maintes conditions initiales sont aussi interessantes que celles adoptees dans le theoreme general classique. Les recherches entreprises dans cette voie ont conduit a quelques resultats par I'emploi de methodes d'approximations successives, et on a pu ainsi reconnaitre des cas singuliers de divergence dans I'emploi de ces methodes d' approximation. Si nous passons maintenant aux equations aux differences partielles, les equations et les donnees n'etant pas necessairement analytiques, nous nous trouvons dans un domaine tres etendu ou on n'a fait que les pre- miers pas. II faut deja quelque soin pour etablir I'existence des inte- grales de I'equation lineaire Seconde Conference. 229 sans supposer que X(x, y) soit analytique. Pour les equations d'ordre superieur, il n'y a qu'un petit nombre de types pour lesquels on puisse definir avec precision ce que Ton entend par integrale generale. lis ont generalement pour origins des problemes de geometrie infinitesimale ou de physique mathematique ; les variables et les fonctions restent ici reelles. Prenons, comme exemple, I'equation -|-a7- + 5— + C2 = bx^y bx dy ou a, h, c sont des fonctions continues de x et y, sur laquelle Riemann a ecrit quelques pages extremement remarquables. Soit un arc de courbe MP tel que toute parallele a Oa; et a Oy le rencontre au plus en dz un point ; nous nous donnons les valeurs de z et -:;- sur cette courbe. ax II y aura une integrale et une seule, continue ainsi que ses derivees partielles du premier ordre, satisfaisant aux conditions donnees, et elle sera definie dans le rectangle de cotes paralleles aux axes et ayant M et P pour sommets opposes. On voit combien cet enonce est d'une nature plus precise que ceux qui ont ete donnes anterieurement en nous pla9ant au point de vue de la theorie des fonctions analytiques, ou pour une equation comme celle-ci on etablit seulement I'existence d'une solution dans le voisinage d'une •courbe, voisinage determine avec tres pen de precision. L'exemple si simple que nous avons choisi montre encore qu'il n'existe pas toujours d'integrale continue ainsi que ses derivees premieres satisfaisant aux conditions donnees sur un arc de courbe ; il en sera ainsi quand sur cet arc il y aura une tangente parallele a I'un des axes. Voici un second exemple dans le meme ordre d'idees ; on pent relativement a I'equation da? ^ by^ bz^ ~ se donner les valeurs de m et de ^ pour les points d'un cercle Q situe dans le plan s = ao ; I'integrale ainsi definie est determinee a I'interieur des deux cones de revolution passant par la eirconference Q et de gene- ratrices paralleles a celles du cone a^ + z/^ — z^ = 0. Les conditions determinant une integrale peuvent prendre des formes tres diverses. Ainsi des conditions de continuite sont susceptibles de remplacer certaines donnees : c'est un fait auquel nous sommes tres 230 Emile Picard: habitues, mais qui n'en est pas moins tres remarquable. L'equation du potentiel a provoque dans cette voie de nombreuses recberches, et le tbeoreme fondamental auquel Riemann a donne le nom de Diricblet, apres avoir ete approfondi par Schwarz et Neumann, a encore fait recem- ment I'objet des recberches de M. Poincare. Des problemes analogues ont ete poses et resolus pour un grand nombre d'equations, par exemple pour l'equation fla^ dy^ dx dy pour laquelle une integrale continue est determinee par ses valeurs sur un contour ferme dans toute region ou le coefficient c est negatif ; de telles questions ne sont d'ailleurs pas limitees aux equations lineaires. Ces divers examples caracterisent bien la nature des theoremes d'exis- tence des integrales, quand on ne se place pas au point de vue de la tbeorie des fonctions analytiques. II y a la un ordre immense de re- cberches egalement interessantes pour la tbeorie pure et pour les appli- cations de I'analyse. Sans meme aborder de questions entierement nouvelles, que de points seraient a reprendre dans les travaux celebres des pbysiciens geometres de la premiere moitie du siecle, de Fourier, de Poisson, de Cauchy meme, si on voulait y apporter la rigueur que Ton exige aujourd'bui en mathematiques. Je dois ajouter d'ailleurs, comme transition entre les deux directions relatives aux generalites sur les equations aux derivees partielles, qu'il existe des classes tres etendues d'equations dont totites les integrales sont analytiques. Citons les equations lineaires d' ordre n a deux variables independantes : dans une region du plan oil toutes les caracteristiques sont imaginaires, toute integrale bien determinee et continue ainsi que ses derivees partielles jusqu'a I'ordre n est necessairement analytique. II y a aussi de nombreuses equations non lineaires ayant toutes leurs integrales analytiques. Je viens de parler des caracteristiques d'une equation ; c'est la un sujet en connexion etroite avec les theoremes generaux d'existence qui viennent de nous occuper. Les caracteristiques sont certaines multipli- cites jouissant de proprietes particulieres relativement a une equation donnee, multiplicites singulieres en ce qu'elles ne definissent pas une integrale contrairement a ce qui arrive en general pour les multiplicites contenant les memes elements. Tandis que la notion de caracteristiques Seconde Conference. 231 est aujourd'hui tres nette pour les equations ou systemes d'equations a deux variables independantes, elle a encore besoin d'etre approfondie dans le cas de plus de deux variables. III. Si, quittant les generalites relatives a I'existence des integrales, nous voulons parler de la recherche effective des integrales et de I'etude d'equations particulieres, I'embarras est grand de tenter des classifica- tions dans un ensemble considerable de travaux, et nous sentons eombien nos classements sont toujours defectueux par quelque endroit. Peut-etre pourrait-on tout d'abord distinguer I'ancienne ecole mathematique, et le mot "ancienne" ne veut pas dire qu'elle ne continue pas a prosperer. C'est I'Ecole d'Euler, de Lagrange, de Monge dans son immortel ouvrage sur les applications de I'analyse a la geometrie, d' Ampere dans son celebre memoire de 1817 sur les equations aux differences partielles. En France, cette ecole des analystes geometres pour qui les problemes de geometrie infinitesimale sont I'occasion de belles recherches analytiques, a pour chef M. Darboux. Ses Legons sur la Th^orie des surfaces sont aujourd'hui un livre classique qui a rappele I'attention sur des questions quelque temps negligees. Relativement a I'integration effective des equations du second ordre, pendant de longues annees apres la publication du memoire d' Ampere, il n'avait ete rien ajoute d'essentiel a la theorie developpee par le grand geometre. En 1870, M. Darboux publia un memoire renfermant des vues profondes et originales qui est fondamental dans I'histoire de cette theorie. Depuis cette epoque, divers geometres ont developpe des methodes plus ou moins analogues. M. Goursat vient de rassembler dans un ouvrage considerable les methodes proposees, en y ajoutant ses decou- vertes personnelles sur ces questions difficiles. On peut caracteriser toutes ces recherches, en disant qu'on s'y propose de trouver explicite- ment des integrales avec le plus grand degre possible d'indetermination. Quelquefois, les methodes sont des indications de marche a suivre quand telle circonstance heureuse se presente, et on cherche des classes d'equa- tions pour lesqueUes il en soit ainsi ; dans d'autres cas, on renonce au moins temporairement a I'integration complete, et on recherche des solu- tions de plus en plus etendues au moyen de transformations convenables comme, par exemple, celles de M. Bianchi pour I'equation des surfaces a courbure constante. Les idees du grand geometre norvegien, Sophus Lie, dont la science 232 Emile Picard: deplore la perte recente, ont exerce aussi depuis vingt ans une grande influence dans I'etude des equations differentielles sous le point de tub qui nous occupe en ce moment. La theorie des groupes de transforma- tions, une des plus belles creations mathematiques de ce siecle, est venue apporter un element incomparable de classification ; elle a permis de faire une vaste synthese en donnant une origine commune a des notions eparses qui paraissaient sans liens. Je disais tout a I'lieure que nos classifications se plient difficilement a la complexite des choses. Certains problemes se trouvent a un confluent, ou se rencontrent I'ancienne Ecole de Monge et d' Ampere et I'Ecole plus recente qui se rattacbe a la theorie moderne des fonctions. Monge avait integre I'equation des surfaces minima, et c'est la un de ses titres de gloire. Ses formules ont ete transformees par Weierstrass, et alors a apparu le lien entre la theorie des fonctions d'une variable complexe et la theorie des surfaces minima. Un probleme appelle vivement I'attention dans cette theorie : c'est le probleme de Plateau relatif aux surfaces minima passant par un contour donne. II a ete resolu seulement dans des cas tres speciaux ; je crois qu'en exercant la sagacite des analystes il sera quelque jour 1' occasion de pr ogres importants dans I'analyse generale. IV. J'ai surtout parle jusqu'ici des equations aux derivees partielles. La theorie des equations differentielles ordinaires est plus speciale, d'autant que quelques uns ont une tendance a la regarder comme un chapitre de la theorie des fonctions analytiques. Apres les remarques que j'ai faites hier, je n'ai pas besoin d'ajouter que ce n'est pas la mon opinion ; je vous ai indique plusieurs problemes qui ne relevent en rien de la theorie des fonctions analytiques, et il me sufQra de citer encore 1' extension des idees de Galois aux equations differentielles. Ceci dit, il n'est pas douteux que les progres de la theorie des fonctions analytiques ont exerce la plus heureuse influence sur certains points de la theorie des equations diffe- rentielles ordinaires. Je ne ferai que rappeler le memoire celebre de Puiseux sur les fonctions algebriques, dans lequel etudiant a un point de nouveau les plus simples des equations differentielles a savoir les quadratures, il revele I'origine de la periodicite des integrales de differen- tielles algebriques. Les recherches de Briot et Bouquet ne sont pas moins classiques ; les auteurs y etudient les circonstances singulieres qui peuvent se presenter dans une equation du premier ordre quand le coefii- Seconde Conference. 233 cient differentiel devient infini ou indetermine. II faut se reporter a pres de cinquante ans en arriere pour bien juger ce memoire, ou pour la premiere fois est mis en evidence le role des points singuliers dans I'etude des fonctions ; ces notions nous sont bien familieres aujourd'bui, mais nous ne devons pas oublier que ce sont les memoires de Puiseux et de Briot et Bouquet qui en ont montre la haute importance. II semble que le memoire de Briot et Bouquet aurait du etre immediatement I'origine de travaux dans la meme voie, mais bien des annees se passerent avant qu'il ne fut repris et complete. C'est en AUemagne, sous I'influence de I'enseignement de Weierstrass que nous voyons d'abord reparaitre I'etude des singularites des equations differentielles, et cela pour les equations differentielles lineaires. II est vraiment curieux que Briot et Bouquet, apres avoir traite le cas plus difficile des singularites d'une equation non lineaire, fut-elle du premier ordre, n'aient pas songe a s'occuper des equa- tions lineaires, laissant a M. Fucbs I'bonneur de fonder une theorie, dont I'lllustre geometre allemand a fait lui-meme des applications du plus haut interet, et qui a provoque un nombre immense de recberches. On remplirait des bibliotheques avec les memoires composes depuis trente ans sur la theorie des equations lineaires. Je ne puis songer a vous parler des nombreuses classes d'equations dont I'etude a ete faite. En restant dans les generalites, je rappelle seulement que I'etude des points singuliers presente une grande difference suivant que ce point singulier est regulier, comme dit M. Puchs, ou presente les caracteres d'un point singulier essentiel. Ce dernier cas est de beaucoup plus difficile ; M. Thome a forme des series satisfaisant formellement a I'equation, mais qui en general ne sont pas convergentes. Remarquons.a ce propos que Briot et Bouquet ont les premiers montre qu'une equation differentielle pouvait conduire a une serie en general divergente ; leur exemple bien simple est I'equation a^-^ = ax + hy dx verifiee par une serie entiere dont le rayon de convergence est nul. Cette petite constatation a appele I'attention sur un fait d'une importance capitale, et qui ne se rencontre que trop frequemment dans les applica- tions; les developpements purement formels sont nombreux en meca- nique analytique et mecanique celeste, ou ils font le desespoir des geometres. Pour les equations lineaires, ces developpement ont un certain interet, comme I'a montre M. Poincare, au point de vue de la 234 Emile Picard. representation asymptotique des integrales. On pent d'ailleurs obtenir et de bien des manieres, une representation analytique des integrales autour du point singulier. Je dois enfin mentionner, relativement aux points singuliers irreguliers, les recberches de M. H. Ton Kocb qui a tire tres beureusement parti dans cette question des resultats obtenus sur les determinants d'ordre infini. Revenons aux equations du premier ordre. Briot et Bouquet ont surtout etudie les singularites en faisant les reductions au type ou / est bolomorpbe et s'annule pour a; = 0, y = 0, et leurs recherches ont ete depuis completees par la connaissance de la forme analytique des integrales au voisinage du point singulier. Le cas plus complique de r equation o^^ = fix,y-) (m>2) (1) n'avait fait jusqu'a ces derniers temps I'objet d'aucune recberche depuis les quelques lignes que lui avaient consaerees Briot et Bouquet. Cette etude vient d'etre reprise simultanement par M. Horn et par M. Bendix- son. Ces auteurs se servent d'une metbode convenable d'approximations successives dont j'indiquerai le principe. Nous supposons expressement que X reste reel et se rapprocbe de zero par Taleurs positives, et posons f(x, y-) = hy + F(x, y') F ne contenant pas de terme du premier degre en y independant de x. Si la partie reelle de b est positive, I'equation precedente a une infinite d'integrales tendant vers zero en meme temps que a;, et elle n'en a qu'une quand la partie reelle de h est negative. Les deux cas peuvent etre traites en faisant les approximation successives dx ^^ x-^^ = hy^ + F(x,y;) ^"'^=hn + F(x,y^.,^ Seconde Conference. 235 et on obtient ainsi une representation analytique des integrales (ou de I'integrale). II existe un developpement a^x + a^x^ H f- a„a;" + ••• satisfaisant formellement a 1' equation (1), mais dont le rayon de conver- gence est nul en general ; c'est la generalisation de la remarque de Briot et Bouquet, et on peut ajouter que la derivee d'ordre n de toutes les integrales considerees tend vers 1 • 2 ■■■ n • a„, quand x tend vers zero. De plus, quand il y a une infinite d'integrales tendant vers zero en meme temps, elles sont toutes representees asymptotiquement par le meme developpement, ce qui est evidemment defavorable pour I'interet que peut presenter une telle representation asymptotique. Les methodes preoedentes sont d'ailleurs susceptibles de s'etendre a un systeme d'equa- tions differentielles. Je ferai encore une remarque importante sur I'equation (1) ; le cas oii la partie reelle de b est nulle echappe complete- ment a la methode. L'equation a en general des integrales qui ne ten- dent vers aucune limite pour x = 0. On se trouve alors, sur un exemple tres simple, en presence des difQcultes considerables que Ton rencontre dans plusieurs questions de mecanique analytique ; c'est en vain que Ton a tente jusqu'ici de proceder par approximations successives con- vergentes et les developpements essayes sont en general divergents. Quoi qu'il en soit des difficultes restant encore a surmonter, des progres serieux ont ete realises ces dernieres annees dans I'etude des integrales des equations non lineaires au voisinage des points singuliers mis en evidence par la forme meme de l'equation differentielle. De tels points singuliers sont les seuls que puissent avoir les integrales quand il s'agit d'une equation lineaire, mais il en est autrement pour les equa- tions non lineaires. En dehors des points singuliers, qui sont apparents sur l'equation, il peut y en avoir d'autres variables d'une integrals a I'autre. Les equations du premier ordre ne presentaient pas a cet egard de bien grandes difficultes. En se bornant aux equations differentielles algebriques, tous les points singuliers qui ne sont pas apparents ne peuvent etre que des points critiques algebriques. Des exemples simples montraient que pour les equations d'ordre superieur au premier, il n'en etait plus de meme et qu'il pouvait y avoir des points essentiels mobiles; I'attention avait ete appelee sur ce point quand on avait voulu etendre aux equations du second ordre a points critiques fixes les methodes qui avaient reussi pour les equations du premier ordre possedant la meme 236 Emile Picard: propriete. La difficulte signalee restait entiere, quand M. Painleve est venu faire une importante distinction et signaler un fait inattendu. Les points singuliers mobiles peuvent se partager en deux classes, les points singuliers algebriques ou transcendants pour lesquels I'integrale et ses derivees acquierent une valeur determinee finie ou infinie, et les points singuliers essentiels. M. Painleve a etabli que, dans les equations diffe- rentielles algebriques, le cas ou les points singuliers essentiels sont mobiles est un cas exceptionnel. Ces equations se trouvent ainsi par- tagees en deux classes, une classe generale pour laquelle I'integrale generale n'a pas de singularites essentielles mobiles, et une classe singu- liere. L'interet de cette distinction est tres grand dans I'etude de quelques classes particulieres d'equations differentielles. Arretons nous specialement sur le cas ou la variable et les fonctions restent reelles; c'est le cas interessant pour les applications. Nous designerons par t la variable independante qui sera, si Ton veut, le temps. Pour etudier quantitativement les fonctions definies par les equations differentielles, c'est a dire pour pouvoir evaluer numerique- ment les valeurs de ces fonctions, on doit desirer d'avoir des represen- tations de celles-ci permettant de les calculer pour un intervalle de temps aussi grand que possible. II y a des classes assez etendues d'equations differentielles, d'apres la forme desquelles on est assure d'obtenir des developpements valables pour toute valeur de t. Un cas tres simple est celui des equations -^=fi(i^ Vv Vv •••' V'd a == 1, 2, -, Ji). On suppose que les fonctions / restent continues pour toutes les valeurs reelles et finies de t et des y, et que de plus les derivees -^ restent en valeurs absolues moindres qu'un nombre fixe. La methode de Cauchy ou la methode des approximations successives donne pour les y des developpements valables pour toute valeur du temps. En supposant que les fonctions / soient analytiques et regulieres pour toute valeur reelle finie ou infinie de t et des y, on peut proceder autrement dans la recherche d'un developpement valable pour toute valeur du temps. II suffit de faire, avec M. Poincare, une representa- tion conforme, sur un cercle situe dans le plan d'une variable z, d'une Seconde ConfSrence. 237 bande tres petite dans le plan de la variable t (supposee un instant complexe), bande parallels a I'axe reel, ce qui revient a poser s = - 6"* + ! On pent ici proceder encore d'une autre maniere en se rappelant que M. Painleve a etabli que toute fonction holomorphe d'une variable reelle dans un intervalle pent etre developpee en une serie de polynomes dont les coefficients dependent lineairement des valeurs de la fonction et de ses derivees pour une valeur particuliere t = t^. II y a des cas ou I'equation ne rentre pas dans les types precedents, et ou Ton sera cependant, au moins pour certaines integrales, assure de la possibilite d'un developpement toujours valable. Je citerai comme premier exemple les equations |=-a:.+/g,:.,y), ^^ = - hy + f(^^, x, y) ou a et J sont deux constantes positives ; / et Jf designe des series holo- morphes en -, x et y, et ne renfermant pas de termes constants et de termes du premier degre en x et y. II est aise d'etablir que, pour t=tf) suffisamment grand, les valeurs initiales etant suffisamment petites, les integrales correspondantes tendront vers zero pour t= oo. De tels exemples sont malbeureusement tres rares ; on pent encore citer les problemes de mecanique ou il y a une fonction des forces. Cbacun sait que I'equilibre est stable, dans le voisinage d'une position ou la fonction des forces est maxima, mais ce resultat classique provient de I'etude indirecte des equations differentielles ; le meme probleme nous montre vite combien une etude direote serait desirable, et combien de difficultes restent a vaincre. Ainsi, supposons qu'il n'y ait pas de fonction de forces et bornons nous a un point materiel. Ecrivons les equations g=a. + J,+ ... g=a'. + J'^+... (2) oii les seconds membres sont des developpements suivant les puissances de X et y, et convergents pour x Qt y assez petits. Le point a; = 0, y = correspond-il a une position d'equilibre stable? II est impossible ac- tuellement de repondre a cette question. II y a peut-etre quel'ques mecaniciens qui croient que la nature de I'equilibre depend seulement 238 Emile Picard: des termes du premier degre dans le second membre. Nous nous garde- rons bien de leur en vouloir, car c'etait au fond I'erreur de Lagrange, mais il est clair qu'en reduisant les equations a la partie lineaire, on pent avoir une solution stable qui cesse de I'etre quand on retablit les termes d'ordre superieur. Les equations (2) presentent une particularite curi- euse qui merite d'etre signalee. On peut se proposer de trouver une integrale premiere F etant en holomorphe en x, y, x', y\ et commengant par des termes du second degre. Or on trouve une telle fonction F au point de vue formal, mais la serie ainsi obtenue ne converge pas en general. J'ajoute que, si la force dependait non seulement de la position du point mais de la Vitesse, c'est-a-dire si dans (2) les seconds membres dependaient aussi de a;' et y\ la recherche de la fonction F ne pourrait plus generalement etre effectuee, mais il serait plus facile de repondre a la question relative a la stabilite. Quand on a aucune notion de la grandeur de I'intervalle pour lequel les fonctions definies par les equations differentielles sont continues, on peut cependant trouver des developpements valables pour tout le temps pendant lequel les fonctions resteront continues. J'ai dit tout a I'heure que Ton pouvait deduire de tels developpements de la methode classique de Cauchy ; c'est la un resultat interessant, mais malheureusement il n'a guere qu'un interSt theorique, car il semble bien difficile de deduire de ces developpements quelques renseignements sur le champ oii les integrales restent continues. II y aura cependant des cas ou certaines proprietes auxiliaires des equations permettent d'avoir des renseignements sur le champ oii les integrales restent continues. Que I'on prenne, par exemple, les six equations classiques en p, q, r, y, y', y" relatives au mouvement d'un solide pesant suspendu par un point ; I'integrale des forces vives et I'integrale y^, y'^, y"^ = const, permettent de reconnaitre que les six fonctions precedentes resteront finies pour toute valeur du temps, et nous sommes alors assure que pour ce probleme la methode de Cauchy donne des developpements valables pour toute valeur du temps. Seconde Conference. 239 VI. A I'ordre d'idees qui nous occupe, se rattachent les travaux de M. Poincare sur les solutions periodiques, et sur les solutions asymptotiques. L'etude des solutions periodiques d'une equation differentielle presente un interet particulier. Je connais peu d'exemples ou on puisse trouver directement une solution periodique. Dans ses travaux sur ce sujet, M. Poincare procede par voie indirecte ; il profite de la presence d'une con- stante tres petite dans les equations, et il raisonne par continuite en par- tant d'une solution periodique pour- la valeur zero de cette constante. II serait a desirer que Ton put penetrer par une autre voie dans l'etude des solutions periodiques. Quant aux solutions asymptotiques a une seule solution, leur etude resulte de developpements analytiques simples ; mais I'existence dans certains cas particuliers de solutions doublement asymp- totiques, c'est a dire de solutions asymptotiques pour ^ = — oo a une solution periodique et de nouveau asymptotiques pour i == + oo a cette meme solution etait extremement cachee, et leur decouverte a demande un effort considerable. L'etude des courbes definies par les equations differentielles est sur- tout une etude qualitative. Si Ton considere d'abord une equation du premier ordre et du premier degre. r^ = ^ (JT et T polynomes en x et y) (2) Tetude des points singuliers generaux se deduit des resultats de Briot et Bouquet. Ces points se partagent en trois types, que M. Poincare ap- pelle des cols, des nceuds et des foyers. Un point singulier d'une nature deja plus compliquee est fourni par ce que M. Poincare appelle un centre, qui en general presente de I'analogie avec les foyers mais autour duquel dans certains cas I'integrale constitue une courbe fermee. On a alors un exemple de solutions periodiques dont la periode depend des conditions initiales. Les travaux les plus recents sur les points singuliers de courbes integrales de I'equation (2) sont dus a M. Bendixson ; le savant geometre suedois a etabli en particulier que s'il existe pour I'equation (2) une courbe integrale allant a I'origine avec une tangente determinee, toutes les courbes integrales allant a I'origine y parviendront avec des tangentes determinees. L'etude des courbes integrales ne doit pas etre bornee au voisinage des points singuliers ; on doit chercber a se rendre compte de leur forme 240 Emile Picard: sur le plan tout entier ou sur la sphere en faisant une perspective. Si Ton chemine, pour I'equation (2), sur une courbe integrals, qu'arrivera- t-il? Cette courbe pent etre fermee de telle sorte qu'on reviendra au point de depart ; elle peut aussi avoir un des foyers comme point asymp- tote. Elle peut avoir encore pour courbe asymptote une courbe fermee satisfaisant d'ailleurs a I'equation differentielle. Ces courbes fermees, que M. Poincare appeUe cycles limites jouent un role capital, et c'est dans les cas ou il est possible de se rendre compte de leur position que la dis- cussion de I'equation peut etre faite d'une maniere complete. Pour les equations du premier ordre mais de degre superieur les dif- iicultes sont beaucoup plus grandes. L'etude des points singuliers ge- neraux a ete faite ; eUe trouve en particulier son application dans des problemes comme celui des lignes de courbure d'une surface passant par un ombilic. L'etude des courbes dans tout le plan est singulierement compliquee par un fait qui ne pouvait se rencontrer pour les equations du premier degre. II peut arriver qu'une courbe integrals couvre une aire, c'est a dire puisse se rapprocher autant qu'on voudra d'un point arbitraire dans une aire. D'apres les difficultes que presentent encore les equations du premier ordre, il est clair que pour les equations d'ordre superieur au premier l'etude qualitative des integrales soUicitera longtemps encore I'effort des chercheurs. Au point de vue analytique, une circonstance importante est a noter. Tandis que pour le premier ordre, on peut tirer parti dans quel- ques cas comme celui des centres de certains developpements en serie, il arrive au contraire ici dans les cas correspondants que les developpements analogues sont purement f ormels ; nous en avons vu un exemple en par- lant tout a I'beure de la stabilite de I'equilibre. Remarquons a ce propos que les questions d'instabilite sont beaucoup plus faciles a traiter que les questions de stabUite comme il resulte des interessantes recherches de M. Liapounoff. Quand il y a une fonction des forces I'equilibre est stable si, pour cette position, la fonction des forces est maxima. Quant aux positions d'equilibre pour lesquelles cette derniere condition n'est pas remplie, on les a toujours regardees comme instables, mais leur instabilite n'avait pas ete demontree. M. LiapounofE I'a etablie en particulier pour le cas que Ton peut appeler general ou la non existence du maximum de la fonction des forces se reconnait par les termes du second ordre. Je citerai seulement un exemple relatif aux courbes integrales d'une equation d'ordre superieur au premier. Dans un memoire recent, M. Troisieme Conference. 241 Hadamard vient d'etudier les lignes geodesiques des surfaces a courbures opposees et a connexion multiple ayant un nombre limite de nappes in- finies. II etablit que les tangentes aux lignes geodesiques passant par un point de la surface, et restant a distance finie, forment un ensemble par- fait non continu. Ce resultat est interessant au point de vue de la dispo- sition des lignes geodesiques de la surface ; il montre qu'il existe des lignes geodesiques se rapprochant d'une geodesique fermee determinee, puis abandonnant eelle-ci pour se rapprocher d'une autre, puis passant a une troisieme, et ainsi de suite indefiniment. II montre de plus que Failure des courbes integrales pent dependre dans certains cas, des pro- prietes discontinues je veux dire arithmStiques des constantes d'integra- tion. C'est sur cette idee que je veux m'arreter ; dans la theorie des equations differentielles comme en maintes parties des mathematiques, les recherches sent obligees de prendre un caractere arithmetique. C'est VarithmStisation des mathematiques dont parlait M. Klein dans un article recent. J'ai essaye, messieurs, en restant dans les generalites et sans prendre aucune classe particuliere d'equations, de faire une sorte de carte geogra- phique sommaire de la theorie des equations differentielles. Beaucoup de voies sont ouvertes et dans des directions tres variees ; sur plus d'un point, les questions sont seulement posees, mais elles paraissent bien posees ; et nous nous rendons compte, ce qui a son prix, de la nature des difficultes qu'il faudra vaincre. C'est une etroite alliance entre les dis- ciplines les plus diverses qui amenera maintenant de nouveaux progres. II n'est plus permis aujourd'hui au geometre inventeur d'etre I'homme d'un seul point de vue, et il faut nous resigner a de grandes complica- tions. C'est un privilege que les sciences mathematiques partageront probablement dans I'avenir avec d'autres sciences. Esperons seulement que des hommes de genie viendront, de loin en loin, donner au moins pour un temps I'illusion de la simplicite. Troisieme Contbrbnce. Sur la Thiorie des Fonctions Analitiques et sur quelques Fonctions SpSciales. La theorie des fonctions de variables complexes est devenue aujourd'hui une branche considerable de I'analyse mathematique. EUe doit son bril- lant essor a la decouverte de quelques propositions generales parmi les- quelles se trouvent au premier rang les theoremes de Cauchy sur les 242 Emile Picard: integrales prises le long d'un contour. Ces lois generales des fonctions analytiques appliquees a des fonctions speciales donnent souvent avec facilite leurs principales proprietes. L'application de ces lois constitue une methods synthetique, et des resultats auxquels avaient conduit une longue serie de transformations de calculs apparaissent quelquefois avec une evidence intuitive. La theorie des fonctions elliptiques en offre un memorable esemple, et n'y a-t-il pas quelque chose de merveilleux a integrer avec M. Hermite le long d'un parallelogramme de periodes et a obtenir ainsi d'un trait de plume les principales proprietes des fonctions doublement periodiques? La fagon dont Eiemann pose et resout dans sa dissertation inaugurale le problems des integrales abe- liennes n'est pas moins digne d'etre meditee comme exemple d'une methode synthetique dans la theorie des fonctions. II n'est plus douteux aujourd'hui que les principes essentiels qui sont a la base de la theorie n'aient ete connus de Gauss. On salt que celui-ci ne publia pas ses recherches sur ce sujet. On ne pent guere admettre qu'O. n'en ait pas saisi la haute importance ; fidele a sa devise " pauca sed matura " il attendait sans doute de s'etre livre a une plus longue elabora- tion, quand Cauchy fit connaitre ses decouvertes. On doit done regarder Cauchy comme le veritable fondateur de la theorie appelee a un si grand avenir; non pas certes qu'il I'ait presentee sous une forme didactique. Ouvrant des voies nouvelles, son esprit toujours en travail se souciait peu de donner a ses conceptions une forme parfaite. On suit le travail d'invention dans maintes publications de Cauchy, notamment quand on parcourt dans ses CEuvres Completes les notes innombrables extraites des Comptes-Rendus. Dans la theorie qui nous occupe, une place a part doit etre faite a I'idee fondamentale d'etendre la notion de I'integrale definie en faisant passer la variable par une succession de valeurs imaginaires ; cette conception a ete la source des plus belles decouvertes, et la represen- tation d'une fonction par une integrale le long d'un contour ferme gardera a jamais le nom d'integrale de Cauchy. Le point de depart de Riemann se rapproche beaucoup de celui de Cauchy ; il est tres philosophique de prendre comme base les deux equa- tions simultanees du_dv du _ dv dx Qy dy dx Troisieme Conference. 243 et de reduire ainsi la theorie des fonctions d'une variable complexe a I'etude de ces deux equations simultanees aux derivees partielles. En meme temps apparaissent les liens entre cette etude et plusieurs questions de physique mathematique comme le mouvement permanent des fluides sur un plan et celui de I'electricite sur une plaque conductrice ; et tous ces problemes sont susceptibles d'etre generalises si au plan simple dans lequel se meut la variable (ps, y) on substitue le plan multiple de Riemann. Les deux relations ecrites plus haut amenent a considerer I'equation Am= 0, equation qui contient toute la theorie des fonctions d'une variable com- plexe, et parmi les problemes qu'on peut se poser sur cette equation le plus celebre est celui de la determination d'une integrale par ses valeurs sur un contour ferme. Une application d'une autre nature concerne la geometric ; je veux parler du probleme des cartes geographiques qui amene a la question de la representation conforme d'une aire sur une autre. Weierstrass a edifie la theorie des fonctions de variables complexes sur une autre base que Cauchy et Riemann, en partant des developpements en series entieres ; en France, ces developpements avaient ete aussi envisages par M. Meray qui n'avait pas connaissance des legons de Weierstrass. Le memoire public en 1876 par I'illustre analyste de Berlin, qui a fait connaitre a un public plus etendu les resultats developpes depuis long- temps dans I'enseignement du maitre, a ete le point de depart d'un grand nombre de travaux sur la theorie des fonctions. Cauchy avait deja obtenu d'importants resultats sur le developpement en sommes ou en produits infinis de certaines categories de fonctions. II etait reserve a Weierstrass et a ses disciples de traiter ces questions dans toute leur generalite. La decomposition des fonctions entieres, c'est a dire des fonctions uniformes et continues dans tout le plan, en facteurs primaires est un des plus admirables theoremes de I'analyse moderne ; chacun de facteurs primaires est le produit d'un facteur lineaire par une exponentielle. Les developpe- ments des fonctions uniformes en sommes et en produits infinis out fait ensuite I'objet d'un grand nombre de travaux parmi les quels il faut citer tout particulierement le memoire de Mittag-Leffler qui a aborde ces prob- lemes avec la plus grande generalite possible. Je rappellerai aussi un memoire de M. Runge auquel des recherches toutes recentes viennent de redonner de I'actualite, ou se trouve en particulier etabli que toute fonction holomorphe dans un domaine connexe peut dans ce domaine etre developpee en une serie de polynomes. Cauchy et ses disciples frangais, en etudiant la theorie des fonctions 244 Emile Picard: uniformes, n'avaient pas penetre dans I'etude de ces points singuliers appeles aujourd'hui points singuliers essentiels, dont le point s = pour la fonction e' donne I'exemple le plus simple. La consideration des facteurs primaires permit a Weierstrass de montrer que dans le voisinage d'un point essentiel isole une fonction uniforme peut se mettre sous la forme d'un quotient de deux fonctions uniformes n'ayant pas de poles dans le voisinage de a ; Weierstrass montra aussi que dans le voisinage d'un tel point la fonction s'approche autant que Ton veut de toute valeur donnee. On a plus tard complete ce resultat, en etablissant que dans le voisinage d'un point singulier essentiel isole la fonction prend rigoureuse- ment une infinite de fois toute valeur donnee, une exception seulement etant possible pour deux valeurs particulieres au plus. La demonstra- tion de ce theoreme se deduit de la consideration d'une fonction pre- sentant precisement la propriete qu'on veut demontrer etre impossible ; cette fonction est la fonction modulaire de la theorie des fonctions elliptiques, mais ses points singuliers ne sont pas isoles. Un corollaire du theoreme indique conduit a la proposition suivante relative aux fonc- tions entieres : si, pour une fonction entiere 6r(s) il existe deux valeurs a et 6 telles que les deux equations G-^z) = a et G-{z) = b aient seulement un nombre limite de racines, la fonction Cr(z) est un polynome. , De nombreuses tentatives ont ete faites pour demontrer directement les theoremes precedents sans recourir a la tbeorie des fonctions ellip- tiques. Pour le theoreme sur les fonctions entieres, M. Hadamard avait 7n=ae reussi a I'etablir quand, la fonction entiere etant representee par ^ fflm^'™? on a (am^<-fz — -r, —, a etant positif. Plus recemment M. Borel est arrive a le demontrer pour toutes les fonctions entieres et meme a le generaliser considerablement. Les travaux de M, Hadamard et de M. Borel publics dans ces dernieres annees sont extremement remarquables. Dans ces recherches, une notion importante introduite par Laguerre, celle du genre d'une fonction entiere, joue un role capital ; ce qui fait I'interet de cette notion, c'est qu'elle est intimement liee a la distribution des racines de la fonction. M. Poincare avait fait le premier la remarque que le genre d'une fonction entiere est en relation etroite avec I'ordre de grandeur de la fonction pour les grandes valeurs de la variable. M. Hadamard a cherche une limite du genre a I'aide des coefficients du Troisieme Conference. 245 developpement, et il a 6tabli que si le coefficient de a;" est moindre que J-, la f onction est de genre E en designant par E +1 I'entier (1 • 2 - my immediatement superieur a \. II a reussi aussi a demontrer que, en designant par ^(m) une fonotion croissant indefiniment avec m, si le coefficient a^ decroit plus vite que la p*™* racine a un module superieur a (1 — e)<^(p) ou e est infiniment petit pour p = ^ le dSfaut de cette serie lineaire par rapport a la serie com- plete ; on a r = l la somme dans le second membre ne comprend qu'un nombre limite de termes, les a etant certainement nuls a partir d'une valeur assez grande de r. La formule precedente est fondamentale dans I'etude du genre numerique. Nous aTons parle plus haut des integrales doubles de premiere espece relatives a une surface. On pent aussi developper une theorie des inte- grales doubles de seconde espice dont la definition est la suivante: ce sent les integrales qui deviennent infinies comme Uet V etant des f onctions rationnelles de x, y et z [/(», y, s) = 0] . Le nombre des integrales distinctes de seconde espece, c'est a dire des integrales dont aucune combinaison lineaire n'est de la forme (a) est fini ; c'est un invariant de la surface. Mais il n'en est plus ici, comme dans le cas des courbes pour lesquelles le nombre des integrales abe- liennes distinctes de seconde espece etait egale a, 2p; le nouvel invariant //( 268 Emile Picard: d'une classe de surfaces algebriques n'est pas lie au genre, soit geome- trique soit numerique. La consideration des integrales doubles ne se presente pas seule. On peut aussi envisager des integrales de dififerentielles totales de la forme jP (x, y, z)dx+Q (x, y, z) dy ou P et Q sont rationnelles en x, y et s, et il y a encore lieu de parler des integrales de premiere et de seconde espece. Mais ici de telles integrales n'existent pas en general, c'est a dire pour une surface prise arbitraire- ment, et c'est une question assez delicate que de reconnaitre si une surface possede des integrales de seconde espece en dehors des fonctions ration- nelles. Les questions de connexite presentent aussi un grand interet dans la tbeorie des fonctions algebriques de deux yariables independantes, mais quelques precautions sont ici necessaires. Pour une surface determinee, et en procedant d'une maniere bien precisee, on peut obtenir deux nombres correspondant a la connexion lineaire et a la connexion a deux dimen- sions ; le premier p^ est veritablement un invariant pour toute transfor- mation birationnelle, tandis que le second p^ peut etre influence par la presence de points fondamentaux dans la correspondance birationnelle. C'est un resultat remarquable que le nombre ^i — 1 represente le nombre des integrales de differentielles totales distinctes de seconde espece rela- tives a la surface. Pour une surface arbitrairement choisie, il n'y a pas d'integrale de seconde espece et on &Pi= 1. On voit que les points de vue de la geometric analytique, de la tbeorie des fonctions et de la geometric de situation se retrouvent aussi dans I'etude des surfaces algebriques, mais il faut se mefier des analogies avec la theorie des courbes. Tout, dans ce nouveau domaine, se presente d'une maniere plus compliquee. Voici encore un exemple de cette complexite. Les courbes dont le genre est nul forment la classe tres restreinte des courbes unicursales. Au contraire les surfaces pour les quelles j»g = sont extremement varices, et on peut dans ce cas considerer un nouvel invariant que M. Enriques a decouvert et qu'il appelle le higenre. On peut le definir aisement dans le cas ou la surface / de degre m n'a qu'une ligne double. On envisagera a cet effet le systeme des surfaces d'ordre 2 m — 8 (ne se composant pas de / et d'une surface d'ordre w — 8) ayant comme ligne double la courbe Troisihme Conference. 259 double de /; le bigenre P est la dimension augmentee d'une unite de ce systeme. Cette notion a permis a M. Castelnuovo d'etablir un theoreme reellement merveilleux ; il s'agit des conditions necessaires et suffisantes pour qu'une surface soit unicursale. On pouvait penser que ces con- ditions seraient tres compliquees et non susceptibles d'une forme simple ; il n'en est rien, elles se reduisent a ^„ = 0, P = 0. Mais je dois m'arreter, me bornant a citer seulement le memoire si elegant de M. Humbert sur les surfaces byperelliptiques qui donnent un tres interessant exemple de surfaces irregulieres pour les quelles p„ = — 1, tandis que Pg='i- Nous avons, messieurs, jete un rapide coup d'ceil sur quelques unes des branches de la science mathematique. Vous avez pu vous apercevoir plus d'une fois de I'embarras dans lequel je me suis trouve, quand j'ai voulu, pour les necessites de mon exposition, faire une classification dans certaines theories. La penetration reciproque des diverses disciplines est aujourd'hui en effet un fait capital et sera de plus en plus la source d'im- portantes decouvertes. A cet egard, il y a une grande difference entre notre epoque et des temps un peu anterieurs. Nous avons peine aujour- d'hui a comprendre certaines histoires ou on voit des geom^tres mepriser des analystes et inversement ; nous sentons que I'ere des ecoles fermees et etroitement attachees a un seul point de vue est pour toujours terminee. II est bien vraisemblable que 1' erudition jouera a I'avenir un plus grand role qu'autrefois en mathematiques. Les mathematiciens perdront peut- etre ce privilege de la precocite qui etonne tant de personnes ; ils se rapprocheront des physiciens et des naturalistes qui doivent en general commencer plus tard leurs travaux personnels. En terminant, je me permettrai de donner un conseil aux etudiants mathematiciens qui m'ont fait I'honneur de m'ecouter ; je leur recommanderai de ne pas se can- tonner trop tot dans des recherches speciales. II leur faut acquerir d'abord des vues generales sur les diverses parties de notre science, sans lesqueUes leurs efforts risqueraient de rester steriles, et qui leur coute- raient plus tard iin bien plus grand effort. oi-'-'-t^-zX-c.^^-i,.^ o6>-i>-C^^^iL^,'»--»— -•>-»-»-*-«', tJBER DIE GRUNDPRINCIPIEN UND GRUND- GLEICHUNGEN DER MECHANIK. Von Professor Ludwig Boltzmann. Eestb Voklbsung. Die analytische Mechanik ist eine Wissenschaft, welche schon von ihrem Begriinder Newton mit solchem Scharfsinne und solclier VoUen- dung ausgearbeitet wurde wie es in dem gesammten Gebiete menschliclien Wissens fast ohne Beispiel dasteht. Die grossen Meister, welche auf Newton folgten, haben das von ihm errichtete Gebaude noch weiter gefestigt, und es hatte den Anschein, dass eine voUendetere und einheit- lichere Schopfung des Menschengeistes als die Grundlehren der Me- chanik, wie sie uns in den Werken von Lagrange, Laplace, Poisson, Hamilton etc. entgegentreten iiberhaupt nicht denkbar ware. Gerade die Begriindung der ersten Principien schien von diesen Forschern mit einem Scharfsinne und einer logischen Consequenz durchgefiihrt, die allezeit das Vorbild lieferten, welchem man die Begriindung der iibrigen Wissenszweige, wenn auch nicht immer mit dem gleichen Erfolge, nach- zubilden suchte. Es schien lange ganz unmoglich dieser Begriindung iiberhaupt noch etwas hinzu zu fiigen oder daran etwas zu andern. Um so auffallender und unerwarteter ist es, dass gegenwartig haupt- sachlich in Deutschland ziemlich lebhafte Controversen gerade iiber die Grundprincipien der analytischen Mechanik entstanden sind. Es ist dies gewiss nicht so zu verstehen, als ob die Ehrfurcht und Bewunde- rung, die wir dem Genius eines Newton, Lagrange oder Laplace zoUen, dadurch irgend wie geschmalert werden soUte. Diese haben aus den kleinen Anfangen, welche sie vorfanden, eine fiir alle Zeiten mustergiil- tige Herrin geschaffen. Sie hatten so viel des thatsachlich Neuen heraus zu arbeiten, dass sie sich nur aufgehalten und dem einheitlichen Ein- druck geschadet hatten, wenn sie bei gewissen Schwierigkeiten und Dunkelheiten zu lange verweilt hatten. Aber seitdem ist unsere Kennt- 261 262 iMdwig Boltzmann: nis von Thatsachen bedeutend gewachsen, unser Verstand ist geschult, so dass viele Vorstellungen, welche zu Zeiten Newtons noch den Gelehr- ten Schwierigkeiten machten, nun zum Gemeingut aller geworden sind. Dadurch erhielt man Musse die Construktion des Newton'schen Gebaudes gewissermassen mit der Lupe zu betrachten, und siehe es ergaben sich manche Schwierigkeiten, wie sie siqb ja dem Menschengeiste immer gerade da am meisten entgegen stellen, wo er die einfachsten Grund- lagen der Erkenntnis zu analysiren strebt. Diese Schwierigkeiten sind freilich mehr philosophischer oder wie man heutzutage sagt, erkenntnistheoretischer Natur. Wir Deutsche sind schon oft und viel verlacht worden wegen unserer Neigung zur philoso- phischen Speculation und in friiherer Zeit sicher oft mit Recht. Eine von den Thatsachen abgekebrte Philosophie hat nie etwas Brauchbares hervor- gebracht und kann es nicht hervorbringen. Von unmittelbar greifbarem Nutzen ist es vor allem, unsere Kenntnis der Thatsachen durch Experi- mente zu erweitern und auch unsere wissenschaftliche Naturkenntrds wird zunachst und am ausgiebigsten in dieser Weise gefordert. Aber trotz alledem scheint die Neigung die einfachsten Begriffe zu analysiren und sich iiber die Grundoperationen unseres Denkens Rechenschaft zu geben im Menschengeiste unbezwinglich. Viel hat sich auch die Methode dieser Analyse im Verlaufe der Zeit ver- vollkommnet, so dass dieselbe heutzutage wenn auch noch keineswegs sofort praktisch fruchtbringend, doch lange nicht mehr so wesenlos ist, wie die alte Philosophie. Im Verlaufe der Geschichte erf ahrt ja das ganze Gultur- bild der Menschheit stete und bedeutende Schwankungen. Die Deutschen sind nicht mehr die unpraktischen Traumer von ehemals. Sie haben es auf alien Gebieten der Experimentalwissenschaft, der Technik, Industrie, und Politik bewiesen. Die Bestrebungen der Amerikaner waren natur- gemass anfangs behufs Unterjochung des Grundes und Bodens der rein praktischen Thatigkeit der Industrie und Technik zugewandt. Aber sie sind es langst nicht mehr ausschliesslich und schon weist Amerika auf alien Gebieten der abstrakten "Wissenschaft Forscher auf, die den hervor- ragensten Europas voUkommen ebenbiirtig zur Seite stehen. Da sie daher, meine Herren, einen Deutschen zu Vortragen in ihrem Lande geladen haben, so will ich es wagen ein Gebiet der Erkenntnistheorie mit ihnen zu betreten. Ich will zunachst wieder zuriick kommen auf die Bedenken, welche gegen die Fundamente der Newton'schen Mechanik erhoben worden sind Erste Vorlesung. 263 oder (besser gesagt) zu den Stellen, wo diese noch einer naheren Beleucht- ung, einer Analyse der Schlussweise und Sichtung der Begriffe zu bediir- fen scheinen. Bei Aufstellung der Bewegungsgesetze betrachtet Newton die Bewegung der Korper als eine absolute im Raume. Der absolute Raum ist aber nirgends unserer Erfahrung zuganglich. Erfahrungsmas- sig gegeben sind immer nur die relativen Lagenanderungen der Korper. Es wird also da gleieh zu Anfang Yollstandig iiber die Erfahrung hin- ausgegangen, was gewiss bedenklicb ist in einer Wissenschaft, welche sich nur die Aufgabe stellt Erfabrangsthatsachen darzustellen. Diese Schwierigkeit ist natiirlich dem Genius Newtons keineswegs entgangen. AUein dieser glaubte ohne den Begriff eines absoluten Raumes zu keiner einfachen Formulirung des Tragheitsgesetzes gelangen zu konnen, um die es ihm an erster Stelle zu thun war und ich glaube, dass er Merin auch Recht behalten hat ; denn so viel diese Schwierigkeit auch beleuchtet oder durchdacht wurde, so ist doch kaum ein wesentlicher Fortschritt erzielt worden. Neumann fiihrt statt des Newton'schen absoluten Raumes einen rathselhaften idealen Bezugskorper ein, womit er offenbar ganz ebenso wie Newton iiber die Erfahrung hinausgeht. Streintz stellt sich die Aufgabe derartige Begriffe oder Korper zu vermeiden, indem er lehrt wie man mittelst der Bewegung eines Gyroskops, auf welches keine oder bekannte Krafte wirken relativ gegen ein gewahltes Coordinatensystem entscheiden kann, ob fur dieses Coordinatensystem die Newton'schen Be- wegungsgesetze gelten, ob es ein brauchbares Bezugssystem ist. AUein diese Streintz'schen Betrachtungen scheinen fiir die Fundamentirung der Mechanik wenig brauchbar, da sie ja bereits die Bewegungsgesetze ein- es rotirenden Kreisels und die Beurtheilung, ob auf denselben Krafte wirken oder nicht, voraussetzen, wozu schon die Kenntnis der Newton'- schen Bewegungsgesetze erforderlich ist. Lange versucht allerdings die Formulirung des Tragheitsgesetzes ohne irgend ein Bezugssystem bloss durch Betrachtung der relativen Bewegung. Sie gelingt ihm auch, f allt aber so complicirt und weitschweifig aus, dass man sich nur schwer entschliessen wird ein so wenig iibersichtliches Gesetz an Stelle der ein- fachen Newton'schen Formel zu setzen. Selbstverstandlich geht auch der Vorschlag Mach's Gerade, welche durch die Gesammtheit aller Mas- sen der Welt bestimmt sind oder der Vorschlag den Lichtather an Stelle des absoluten Raums zu setzen, beide freilich in ganz anderer Weise iiber die Erfahrung hinaus. Ersterer Vorschlag kniipft namlich wieder an rein ideale transcendente Begriffe an, wogegen letzterer eine Aussage 264 Ludwig Boltzmann: macht, welche zwar erfahrungsmassig moglicherweise bewiesen ■werden konnte, aber es gewiss noch nicht ist. Es miisste denn fiir den Ather eine ganz andere Mechanik gelten, dieser miisste etwa selbst die Ursache des Tragbeitsgesetzes nicbt aber demselben unterworfen sein. Eine gleicbe Scbwierigkeit begegnet man bei Einfiihrung des Begriffs der Zeit. Auch diese wird von Newton als eine absolute eingefiihrt, wabrend uns eine solcbe niemals gegeben ist, sondern immer bloss die Gleicbzei- tigkeit des Verlaufs mebrerer Vorgange. Jedocb ist bier die Abbilfe leicbter, indem man von einem Vorgange ausgeht, der sicb immer peri- odiseh unter ganz gleicben Umstanden wiederbolt. Freilieb ist es nicbt moglicb absolute Gleicbbeit der Umstande berzustellen, docb kann man im bocbsten Grade wabrscbeinlicb macben, dass aUe Umstande, die iiber- baupt -wesentlicben Einfluss baben, die gleicben sind. Man kann dies nocb dadurcb erbarten, dass man verscbiedenartige Vorgange von dieser Eigenscbaft (die Erddrehung, die Scbwingungen eines Pendels, einer Cbronometerfeder) untereinander vergleicbt. Die Ubereinstimmung aller dieser Vorgange in der Anzeige gleicber Zeiten scbliesst dann jeden Zweifel an der Braucbbarkeit der Methode aus. Eine dritte Scbwierigkeit betrifft die Begriffe der Masse und Kraft. Dass die Newton'scbe Definition der Masse als Quantitat der Materie eine nichts sagende ist, wurde langst erkannt. Aber aucb beziiglicb des Verhaltnisses der Kraft zur Masse ergeben sicb Zweifel. Ist die Masse das allein Existirende und die Kraft nur eine Eigenscbaft derselben oder ist umgekebrt die Kraft das wabrbaft Existirende oder ist ein Dualismus zweier getrennter Existenzen (Masse und Kraft) anzunebmen, so dass die Kraft eine von der Materie getrennt existirende Ursache der Bewegung der ersteren ist. Hinzu kam in neuerer Zeit nocb die Frage, ob aucb der Energie Existenz zuzuscbreiben ist oder ob gar letztere das allein Existirende ist. Es war vor alien Kirchboff, welcber in diesem Punkte schon der Art der Fragestellung entgegentrat. Oft ist ein Problem scbon balb gelost, wenn die ricbtige Metbode der Fragestellung gefunden ist. Kircbboff wies es nun zuriick, dass es Aufgabe der Naturwissenscbaft sei, das wabre Wesen der Erscbeinungen zu entrathseln und ibre ersten metapbysiscben Grundursacben anzugeben. Er reducirte die Aufgabe der Naturwissen- scbaft vielmebr darauf, die Erscbeinungen zu bescbreiben. Kircbboff nannte dies noch eine Bescbrankung der Aufgabe der Naturwissenscbaft. Wenn man aber so recht in die Art und Weise, icb mocbte sagen in den Erste Vorlesung. 265 Mechanismus unseres Denkens eindringt, so mochte man fast auch das leugnen. AUe unsere Vorstellungen und Begriffe sind ja nur innere Gedanken- bilder, wenn ausgesprochen Lautcombinationen. Die Aufgabe unseres Denkens ist es nun, dieselben so zu gebrauchen und zu verbinden, dass wir mit ihrer Hilfe allezeit mit grosster Leichtigkeit die richtigen Hand- lungen treffen und aucb andere zu richtigen Handlungen anleiten. Die Metaphysik hat sich da dem niichternsten praktischsten Standpunkte angeschlossen, die Extreme beriihren sich. Die begrifflichen Zeichen, welche wir bilden, haben also nur eine Existenz in uns, die aussern Erscheinungen konnen wir nicht mit dem Masse unserer Vorstellungen messen. Wir konnen also formell derartige Fragen aufwerfen, ob bloss die Materie existirt und die Kraft eine Eigenschaft derselben ist oder ob letztere von der Materie unabhangig existirt oder ob umgekehrt die Materie ein Erzeugnis der Kraft ist ; aber es haben alle diese Fragen gar keine Bedeutung, da alle diese Begriffe nur Gedankenbilder sind, welche den Zweck haben die Erscheinungen richtig darzustellen. Besonders klar hat dies Hertz in seinem beriihmten Buche iiber die Principien der Mechanik ausgesprochen, nur stellt Hertz daselbst als erste Forderung die auf, dass die Bilder, welche wir uns construiren, den Denkgesetzen entsprechen miissen. Gegen diese Forderung mochte ich gewisse Beden- ken erheben oder wenigstens sie etwas naher erlautern. Gewiss miissen wir einen reichen Schatz von Denkgesetzen mitbringen. Ohne sie ware die Erfahrung voUkommen nutzlos; wir konnten sie gar nicht durch innere Bilder fixiren. Diese Denkgesetze sind uns fast ausnahmslos ange- boren, aber sie erleiden doch durch Erziehung, Belehrung, und eigene Erfahrung Modifikationen. Sie sind nicht voUkommen gleich beim Kinde, beim einfachen ungebildeten Manne, oder beim Gelehrten. "Wir werden dies auch einsehen, wenn wir die Denkrichtung eines naiven Volkes wie der Griechen mit der der Scholastiker des Mittelalters, und diese wieder mit der heutigen vergleichen. Gewiss gibt es Denkgesetze, welche sich so ausnahmslos bewahrt haben, dass wir ihnen unbedingt vertrauen, sie fiir aprioristische unabanderliehe Denkprincipien halten. Aber ich glaube doch, dass sie sich erst langsam entwickelten. Ihre erste Quelle waren primitive Erfahrungen der Menschheit im Urzustand, allmalig erstarkten sie und verdeutlichten sich durch complicirtirte Erfahrungen bis sie endlich ihre jetzige scharf e Formulirung annahmen ; aber als unbe- dingt oberste Eichter mochte ich die Denkgesetze nicht anerkennen. 266 Ludwig Boltzmann: Wir konnen niclit wissen ob sie niclit doch nocli die eine oder andere Modification erfahren werden. Man erinnere sich doch mit welcher Sicherheit Kinder oder UngebUdete iiberzeugt sind, dass man durch das blosse Gefiilil die Richtung nacb oben von der nacb unten an alien Orten des Weltraums miisse unterscbeiden konnen und wie sie daraus die Unmoglicbkeit der Antipoden deduciren zu konnen glauben. Wiirden solcbe Leute Logik schreiben, so wiirden sie das sicber fiir ein a priori evidentes Denkgesetz halten. Ebenso wurden anfangs gegen die Coper- nicaniscbe Theorie vielfacb aprioristiscbe Bedenken erhoben und die Ge- schicbte der Wissenschaft weist zablreicbe Falle auf, wo man Satze bald begriindete, bald widerlegte mittels Beweisgriinden, die man damals fiir evidente Denkgesetze Melt, wabrend wir jetzt von ibrer Nicbtigkeit iiber- zeugt sind. Ich mocbte daber die Hertz'sche Forderung dabin modificiren, dass in so weit wir Denkgesetze besitzen, welcbe wir durcb state Bewahr- beitung in der Erfabrung als zweifellos ricbtig erkannt baben, wir die Ricbtigkeit unserer Bilder zunachst an diesen erproben konnen, dass aber die letzte und alleinige Entscbeidung iiber die Zweckmassigkeit der Bilder in dem Umstande liegt, dass sie die Erfabrung moglicbst einfacb und durcbaus treffend darstellen und dass gerade bierin wieder die Probe fiir die Ricbtigkeit der Denkgesetze liegt. Haben wir die Aufgabe des Denkens iiberbaupt und der Wissenschaft insbesondere in dieser Weise erfasst, so ergeben sich uns Consequenzen welcbe im ersten Augenblick etwas Frappirendes an sich baben. Eine Vorstellung von der Natur wer- den wir falscb nennen, wenn sie uns gewisse Thatsachen unrichtich dar- stellt oder wenn es offenbar einf achere gibt, welcbe die Thatsachen klarer darstellen, besonders wenn sie allgemein bewabrten Denkgesetzen wider- spricht, doch sind immerhin Theorien moglicb, welcbe eine grosse Zabl von Thatsachen ricbtig darstellen in andern Punkten aber unricbtig sind, denen also eine gewisse relative Wabrheit zukommt. Ja es ist sogar moglich, dass wir in verschiedener Weise ein System von BQdern der Erscbeinungen construiren konnen. Jedes dieser Systeme ist nicht gleich einfacb, stellt die Erscbeinungen nicht gleich gut dar. Aber es kann zweifelhaft, gewissermassen Geschmacksaobe sein, welches wir fiir das Einfachere halten, durch welcbe Darstellung der Erscbeinungen wir uns mebr befrie- digt fiiblen. Die Wissenschaft verliert hiedurch ihr einbeitliches Geprage. Man hielt doch ebedem daran fest, dass es nur Mne Wabrheit geben konne, dass die Irrthiimer mannigfaltig seien, die Wabrheit aber nur eine einzige ist. Dieser Ansicht muss von unserem jetzigen Standpunkte ent- Erste Vorlesung. 267 gegen getreten werden, freilich ist der Unterschied der neuen Ansicht gegeniiber der alten ein mehr formeller. Es war nie zweifelhaft, dass der Mensch niemals den voUen InbegrifE aller Wahrheit zu erkennen vermoge. Diese Erkenntniss ist nur ein Ideal. Ein ahnliches Ideal besitzen wir aber auch gemass unserer jetzigen Vorstellung. Es ist das voUkommenste Bild, das alle Erscheinimgen in der einfachsten nnd zweckmassigsten Weise darstellt. Wir wenden daher nach der einen Anschauungsweise den Blick mehr auf das unerreicbbare Ideal, welches nur ein einheitliches ist, nach der andern auf die Mannigfaltigkeit des Erreichbaren. Wenn wir nun die Uberzeugung haben, dass die Wissenschaft bloss ein inneres Bild, eine gedankliche Construction ist, welche sich mit der Mannigfaltigkeit der Erscheinungen niemals decken, sondern nur gewisse Theile derselben iibersichtlich darstellen kann, wie werden wir zu einem solchen Bilde gelangen? wie es moglichst systematisch und iibersichtlich darstellen konnen? Es war friiher eine Methode beliebt, welche der von Euclid in der Geometrie angewandten nachgebildet ist und daher die Euclidische heissen soil. Dieselbe geht von moglichst wenigen, moglichst evidenten Satzen aus. In den altesten Zeiten warden diese als a priori evident, als direkt dem Geiste gegeben betrachtet, wess- halb man sie als Axiome bezeichnet. Spater dagegen schrieb man ihnen lediglich den Charakter von hinlanglich verbiirgten Erfahrungssatzen zu. Aus diesen Axiomen wurden dann bloss mit Hilfe der Denkgesetze gewisse Bilder als nothwendig deducirt und man glaubte so einen Beweis gefunden zu haben, dass diese die einzig moglichen seien und nicht durch andere ersetzt werden konnten. Als Beispiel fiihre ich die Schliisse an, welche zur Ableitung des Krafteparallelogramms oder des Ampere'schen Gesetzes oder des Beweises dienten, dass die zwischen zwei materiellen Punkten wirkende Kraft in die Richtung ihrer Entfernung fallen und eine Function dieser Entfernung sein miisse. Aber die Beweiskraft dieser Sehlussweise geriet allmalig in Miscredit, der erste Schritt hiezu war der, dass man wie schon friiher geschildert von einer a priori evidenten Grundlage zu einer bloss erfahrungsmassig bewahrten iiberging. Man sah ferner ein, dass auch die Deduktionen aus jener Grundlage nicht ohne zahlreiche neue Hypothesen gemacht werden konnten, und so wies endlich Hertz darauf bin, dass namentlich im Gebiete der Physik unsere Uberzeugung von der Richtigkeit einer allgemeinen Theorie im Wesen noch nicht auf der Ableitung derselben nach der Euclidischen Methode, sondern vielmehr darauf beruhe, dass diese Theo- 268 Ludwig Boltzmann: rie in alien bisher bekannten Fallen uns zu richtigen Sdiliissen in Bezug auf die Erscheinungen leite. Er machte von dieser Ansicht zuerst in seiner Darstellung der Maxwell'schen Grundgleichungen der Lehre von der Elektricitat und dem Magnetismus Gebrauch, indem er vorschlug sich um deren Ableitung aus gewissen Grundprincipien gar nicht zu bekummern, sondern sie einfach an die Spitze zu stellen und die Rechtfertigung hie- von darin zu suchen, dass man nachweisen konne dass sie hinterher iiber- all mit der Erf ahrung iibereinstimme ; denn diese bleibt doch schliesslich die einzige Richterin liber die Brauchbarkeit einer Theorie, deren Urtheil inapellabel und unerschiitterlich ist. In der That wenn wir auf die Gegen- stande naher eingehen, welche mit dem Gegenstande am meisten zusam- menhangen, das Tragheitsgesetz, das Krafteparallelogramm und die iibri- gen Fundamentalsatze der Mechanik, so werden wir die verschiedenen Beweise, welche in alien Lehrbiichern der Mechanik fiir jeden einzelnen dieser Satze geliefert werden, bei weitem nicht so iiberzeugend finden, als die Thatsache, dass sich alle aus dem Inbegriffe aller dieser Satze gezo- genen Consequenzen so ausgezeichnet in der Erfahrung bestatigt haben. Die Wege, auf denen wir zu den Bildern gelangten, sind nicht selten die verschiedensten und von den mannigfaltigsten Zufallen abhangig. Manche Bilder wurden im Verlauf von Jahrhunderten durch das Zu- sammenwirken vieler Forscher erst allmalig construirt, wie die der mecha- nischen Warmetheorie. Manche wurden von einem einzigen, genialen For- scher, aber oft wieder auf sehr verschlungenen Umwegen, gefunden und erst dann von andern in die verschiedenartigste Beleuchtung geriickt, wie die besprochene Maxwell'sche Theorie der Elektricitat und des Magnetismus. Es wird nun eine Darstellungsweise geben, welche ganz besondere Vorziige aber auch wieder ihre Mangel besitzt. Diese Dar- stellungsweise besteht darin, dass wir eingedenk unserer Aufgabe, bloss innere Vorstellungsbilder zu construiren, anfangs lediglich mit gedank- lichen Abstractionen operiren. Hiebei nehmen wir noch gar keine Riicksicht auf etwaige Erfahrungsthatsachen. Wir bemiihen uns lediglich mit mog- lichster Klarheit unsere Gedankenbilder zu entwickeln, und aus denselben alle moglichen Consequenzen zu ziehen. Erst hinterher, nachdem die ganze Exposition des Bildes voUendet ist, priifen wir dessen tJbereinstim- mung mit den Erfahrungsthatsachen, motiviren also in dieser Weise erst hinterher, warum das Bild gerade so und nicht anders gewahlt werden musste, woriiber wir vorher nicht die leiseste Andeutung geben. Wir woUen dies als die deduktive Darstellung bezeichnen. Die Vorziige dieser Erste Vorlesung. 269 Darstellung liegen auf der Hand. Sie lasst zunachst gar keinen Zweifel dariiber aufkommen, dass sie nicht die Dinge an sich selbst bieten will, sondern bloss ein inneres geistiges Bild und dass ihr Bestreben bloss darin besteht dieses geistige Bild zu einer geschickten Bezeichnung der Erscheinungen zu formen. Da die deduktive Methode nicht fortwahr- end aussere uns aufgezwungene Erfahrungen mit inneren von uns will- kiirlich gewahlten Bildern vermengt, so ist es ihr weitaus am leichtesten diese letzteren klar und widerspruchsfrei zu entwickeln. Es ist namlich eines der wichtigsten Erfordernisse dieser Bilder, dass sie voUkommen klar sind, dass wir niemals in Verlegenheit sind, wie wir sie in jedem bestimmten Falle formen soUen und dass wir jedes Mai das Resultat ein- deutig und unzweifelhaft aus denselben ableiten konnen. Gerade diese Klarheit leidet durch zu fruhe Vermischung mit der Erfahrung und wird bei der deduktiven Darstellungsweise am sichersten gewahret. Dagegen tritt bei dieser Darstellungsweise besonders die Willkiirlichkeit der Bil- der scharf hervor, indem man mit ganz willkiirlichen Gedankenconstruc- tionen beginnt und deren Notwendigkeit nicht anfangs motivirt sondern erst hinterher rechtfertigt. Davon, dass nicht auch andere Bilder erdacht werden konnten, die ebenso mit der Erfahrung stimmen wiirden, wird kein Schatten eines Beweises geliefert. Es scheint dies ein Fehler zu sein, ist aber vielleicht gerade ein Vorzug, wenigstens fiir denjenigen, der die friiher auseinandergesetzte Ansicht von dem Wesen jeder Theo- rie hat. Ein wirklicher Fehler der deduktiven Methode besteht dagegen darin, dass der Weg nicht sichtbar wird, auf welchem man zur Auffindung des betreffenden Bildes gelangte. Aber es ist ja im Gebiete der Wissen- schaftslehre die Regel, dass der Zusammenhang der Schliisse dann am deutlichsten hervortritt, wenn man diese moglichst in ihrer natiir- lichen Reihenfolge und ohne Riicksicht auf den oft krummen Weg auseinandersetzt, auf welchem dieselben gefunden wurden. Hertz hat auch im Gebiete der Mechanik in seinem bereits citirten Buche ein Muster einer solchen rein deduktiven Darstellung gegeben. Ich glaube den Inhalt des Hertz'schen Buches hier als bekannt voraussetzen zu konnen und mich daher auf eine ganz kurze Charakteristik des- selben beschranken zu diirfen. Hertz geht von materiellen Punkten aus, welche er als reine Gedankenbilder betrachtet. Auch die Masse definirt er ganz unabhangig von aller Erfahrung durch eine Zahl, die wir uns jedem materiellen Punkte beigelegt denken miissen, namlich die Anzahl der einfachen Massenpunkte, welche er enthalt. Aus diesen 270 Ludwig Boltzmann: abstrakten Begriffen construirt er eine zunachst natiirlich bloss wie die Punkte selbst in Gedanken vorhandene Bewegung. Der Begriff der Kraft fehlt dabei vollstandig. An ihre Stelle treten gewisse Beding- ungen, welche sich in der Form von Gleichungen zwiscben den Differen- zialen der Coordinaten der materiellen Punkte schreiben. Diese letzteren sind nun mit gegebenen Anfangsgescbwindigkeiten ausgestattet und bewegen sich in jeder folgenden Zeit nacb einem sehr einfachen Gesetze, welches sobald die Bedingungsgleichungen gegeben sind, die Bewegung fiir alle Zeiten eindeiutig bestimmt. Hertz spricht es dahin aus, dass die Summe der mit den Massen multiplicirten Quadrate der Abweichungen der materiellen Punkte von der geradlinigen, gleichformigen Bewegung fiir jeden Zeitmoment ein Minimum sein muss oder nocb kiirzer, dass die Bewegung in den geradesten Bahnen geschieht. Es hat dieses Gesetz die grosste Ahnlichkeit mit dem Gauss'schen Principe des kleinsten Zwanges, ja es ist gewissermassen derjenige spezielle Fall, der eintritt, wenn man das Gauss'sche Princip auf ein System von Punkten anwen- det, welche zwar einem Zwange, aber keinerlei sonstigen aussern Kraften unterworfen sind. Ich habe in meinem Buche welches den Titel hat " Vorlesungen iiber die Principe der Mechanik" ebenfalls eine rein deduktive Darstellung der Grundprineipe derselben versucht, aber in ganz anderer Weise, weit mehr an die gewonliche Behandlung der Mechanik ankniipfend. Ich gehe wie Hertz von reinen Gedankendingen, exakten materiellen Punkten aus ; ich beziehe deren Lage auf ein ebenfalls gedachtes rechtwinkliges Coordina- tensystem und denke mir ein geistiges Bild von der Bewegung derselben zunachst in folgendex Weise construirt. Jedesmal, wenn sich zwei der- selben in irgend einer Entfemung t befinden, soil jeder derselben eine Beschleunigung in der Richtung von r erfahren, welehe eine Function /(r) dieser Entfernnng ist, iiber die spater nach Belieben verfiigt wer- den kann. Es sollen ferner die Beschleunigungen beider Punkte in einem zu alien Zeiten unveranderHcheii Zahlenverhaltnisse stehen, welches das Massenverhaltnis der beiden materiellen Punkte definirt. "Wie wir uns die Bewegung aller materiellen Punkte zu denken haben, das ist dann eindeutig durch die Angabe bestimmt, dass die wirkliohe Beschleunigung jedes Punktes die Vectorsumme aller fiir ihn nach der friiheren Regel gefundenen Beschleunigungen ist und sich zur schon vox- handenen Geschwindigkeit des Punktes ebenfalls so addirt wie Vector- grasaen addirt werden. Woher diese Beschleunigungen koaimen und Erste Vorlesung. 271 warum ich gerade die Vorsclirift gebe sich das Bild in dieser Weise za construiren wird nicht weiter discutirt. Es geniigt dass das Bild ein voU- kommen klares ist, welches in geniigend vielen Fallen durch Rechnungen im Detail ausgearbeitet werden kann. Dasselbe findet seine Rechtfertig- ung erst darin, dass sich die Function /(»•) in alien Fallen so bestimmen lasst, dass die gedachte Bewegung der eingebildeten materiellen Punkte in ein naturgetreues Abbild der wirklichen Erscheinungen iibergeht. Wir haben durch diese Behandlungsweise, welche wir die rein deduc- tive genannt haben, die Frage nach dem Wesen der Materie, der Masse, der Kraft, freilich nicht gelost, aber wir haben diese Fragen umgangen, indem wir ihre VoransteUung voUstandig iiberfliissig gemacht haben. In unserem Gedankenschema sind diese Begriffe ganz bestimmte Zahlen und Anweisungen zu geometrischen Constructionen, von denen wir wis- sen, wie wir sie denken und ausfuhren soUen, damit wir ein brauchbares Bild der Erseheinungswelt erhalten. Was die eigentliche Ursache sei, dass die Erseheinungswelt sich gerade so abspielt, was gewissermassen hinter der Erseheinungswelt verborgen ist und sie treibt, das zu erfor- schen, betrachten wir nicht als Aufgabe der Naturwissenschaft. Ob es Aufgabe einer andern Wissenschaft sei und sein konne, oder ob wir da nicht vielleicht bloss nach Analogie mit anderen vemiinftigen Wortzu- sammenstellungen hier Worte aneinandergefiigt haben, welche in diesen Verbindungen keinen klaren Gedanken ausdriicken, das kann hier voU- standig dahingestellt bleiben. Wir haben durch diese deductive Methode ebenso wenig die Frage nach dem absoluten Raume und der absoluten Bewegung gelost ; allein auch diese Frage hat keine padagogisehen Schwierigkeiten mehr ; wir brauchen sie nicht mehr beim Beginne der Entwickelung der mechanischen Gesetze vorzubringen, sondern konnen sie erst besprechen, wenn wir alle mechanischen Gesetze abgeleitet haben. Denn da wir ja anfangs ohnehin nur gedankliche Constructionen vor- fiihren, so nimmt sich ein gedachtes Coordinatensystem keineswegs fremd- artig unter denselben aus. Es ist eben eine der verschiedenen uns verstandlichen und gelaufigen Constructionsmittel aus denen wir unser Gedankenbild zusammensetzen, nicht mehr und nicht weniger abstract, als die materiellen Punkte, deren Bewegung relativ gegen das Coordina- tensystem wir uns vorstellen und fiir welche allein wir zunachst die Gesetze aussprechen und mathematisch formuliren. Beim Vergleiche mit der Erfahrung linden wir dann, dass ein unveranderlich mit dem Fixsternhimmel verbundenes Coordinatensystem praktisch vollkommen 272 L/vbdwig Boltzmann: ausreicht um die Ubereinstimmung mit der Erfahrung zu sichern. Was fiir ein Coordinatensystem wir einstens werden zu Grunde legen miissen, wenn wir einmal die Bewegung der Fixsterne durch mechanische For- meln ausdriicken konnten, diese Frage steht auf unserm Repertoire an allerletzter Stelle und wir konnen jetzt alle die Hypothesen von Streintz, Mach, Lange etc. welche eirigangs erwahnt wurden mit Leichtigkeit discutiren, da uns alle Gesetze der Mechanik bereits zur Verfiigung stehen. Wir kommen nicht in dieselbe Verlegenheit wie friiher, wo wir diese complicirten Betrachtungen der Entwickelung des Tragbeitsgesetzes batten voranstellen miissen. Freilicb baben wir dafiir bei der deduc- tiven Metbode wieder einen Beweis zu liefern, der bei den alten Methoden iiberflussig war. Da wir bei den letzteren direct von den Erscbeinungen ausgingen, so verstand es sicb von selbst, dass die Gesetze der Erscbein- ungen nicbt von der Wabl des lediglicb binzugedachten Coordinaten- systems abbangen konnen, und es musste eben frappiren, dass sicb diese Gesetze anders und viel complicirter ausnebmen, wenn wir ein sicb dreben- des Coordinatensystem einfiibren. Bei der deductiven Metbode aber baben wir von vorne herein dem Coordinatensystem im Bilde die gleicbe RoUe angewiesen wie den materiellen Punkten. Es ist ein integrirender Bestandtbeil des Bildes und es kann uns nicbt Wunder nebmen, dass dieses verscbieden ausfallt, wenn wir das Coordinatensystem anders wiihlen. Wir miissen bier im Gegentbeil aus dem Bilde selbst den Beweis liefern, dass dieses sicb nicbt andert, wenn wir beliebige andere Coordinatensysteme einfiibren, so lange sicb diese nicbt relativ gegen einander dreben oder nicbt mit Bescbleunigung relativ gegen einander bewegen. Wir woUen nun die zuletzt besprocbene Darstellungsweise meines Bucbes mit der Hertz'schen vergleicben. Herr Classen bat meine Dar- stellung als eine Polemik gegen Hertz aufgefasst und die Sacbe so darge- stellt, als ob icb mir einbildete etwas unbedingt Besseres als Hertz vorgebracbt zu baben. Nicbts weniger als dies. Icb erkenne die Vorziige des Hertz'schen Bildes unbedingt an, aber nacb dem Principe, dass es moglich und wiinscbenswert ist, fiir ein und dieselbe Erscbeinungs- gruppe mebrere Bilder aufzustellen, glaube icb, dass mein Bild neben dem Hertz'schen nocb seine Bedeutung hat, indem es gewisse Vorziige auf- weist, welche dem Hertz'schen fehlen. Die Principe der Mechanik, welche Hertz aufstellt, sind von aussererordentlicher Einfacbheit und Schonheit. Sie sind natiirlich nicbt voUstandig frei von Willkiirlich- Erste Vorlesung. 273 keit, aber ich mochte sagen die WillkurlicKkeit ist auf ein Minimum beschrankt. Das von Hertz unabhangig von der Erfahrung construirte Bild hat eine gewisse innere VoUendung und Evidenz. Es enthalt an sich nur wenig willkiirliche Elemente. Hingegen steht offenbar mein Bild weit zuriick. Letzteres enthalt wait mehr Ziige, welche den Stempel davon an sich tragen, dass sie nicht durch eine innere Notwendigkeit bestimmt sind, sondern bloss eingefiigt wurden, um hinterher dann eben die Ubereinstimmung mit den Erfahrung zu ermoglichen. Es enthalt auch eine ganz willkiirliche Function und von den vielen Bildern, welche entstehen, wenn dieser Function alle moglichen Formen er- theilt werden, entsprechen nur ganz wenige wirklichen Vorgangen, wahrend man beim Hertz'schen Bilde sofort sieht, dass wenn iiberhaupt einige, so doch jedenfalls nur wenige andere Bilder moglich sein konnen, welche sich einer gleichen Einfachheit und inneren VoUendung erfreuen, so weckt mein Bild sofort die Idee, dass es wohl noch so manche andere geben mag, welche die Erscheinungen mit gleicher Voll- kommenheit darsteUen. Trotzdem giebt es aber wieder Punkte, in denen mein Bild dem Hertz'schen iiberlegen ist. Hertz kann zwar einige Erscheinungen in director Weise, aus seinem Bilde erklaren, oder wie wir lieber sagen wollen, mittelst desselben darsteUen, so die Bewegung eines materiellen Punktes auf einer vorgeschriebenen Flache oder Kurve oder die Drehung eines starren Korpers um einen fixen Punkt, beides wolgemerkt, so lange keine fremdartigen aussern Krafte vorhanden sind. Man stosst aber sofort auf Schwierigkeiten, sobald man die gewohnlich- sten in der taglichen Erfahrung vorkommenden Vorgange darsteUen will, bei denen Krafte wirken. Betrachten wir zunachst eine der allgemeinsten und wichtigsten Naturkrafte, die Gravitation. Als Fernkraft diirfen wir dieselbe vom Hertz'schen Standpunkte natiirlich nicht auffassen. Es sind nun zwar zahlreiche Versuche gemacht worden, sie durch Wirkung eines Mediums mechanich zu erklaren. AUein es ist bekannt, dass keiner der- selben zu einem recht bestimmten, entscheidenden Resultate gefiihrt hat. Einer der bekanntesten ist die schon von Lesage aufgestellte, spater von Lord Kelvin, Isenkrahe und andern wieder aufgenommene Theorie der Molekularstosse. Dieselbe ist abgesehen davon, dass ihre exacte Durch- fiihrbarkeit, noch immer zweifelhaft, ist fiir die Hertz'sche Theorie unbrauchbar, well schon die Erklarung eines einzigen elastischen Stosses aus derselben Schwierigkeiten bereitet, wie wir sogleich sehen werden. Man miisste also erst eine ganz neue Theorie schaffen, die Gravitations- 274 Ludwig Boltzmann: wirkung etwa durch Wirbel, Pulsationen oder Ahnliches erklaren, wobei die Theilchen des betreffenden Mediums ebenfalls nicht durch Krafte im alten Sinne, sondern bloss durch Bedingungsgleichungen von der Form, wie sie Hertz aufstellt verkniipft sein diirften. Selbst, wenn dies gelingen soUte, so hiesse dies doch zu einem ganz willkiirlichen Bilde greifen, welches hochst wahrscheinlich im Verlaufe der Zeit durch ein ganz anderes ersetzt werden miisste. Der Vorwurf, welchen Hertz gegen die alte Mechanik erhebt, dass sie ein viel zu weites Bild gibt, indem von alien moglichen die Kraft darstellenden Functionen f{r) nur ganz wenige eine praktische Verwendung haben lasst sich in verstarktem Masse gegen sein eigenes Bild kehren, sobald man dasselbe auf bestimmte Falle anwen- den will. Schon bei der Anwendung auf die Gravitation muss man aus alien moglichen Medien, welche Fernwirkung vermitteln konnten irgend ein bestimmtes auswahlen, worin wohl noch mehr Unbestimmtheit und WiUkiirlichkeit liegt als in der Wahl gewisser Functionen /(»*). Die elektrischen und magnetischen Krafte hat bekanntlich Maxwell in seinen ersten Arbeiten mit Erfolg durch die Wirkung eines Mediums erklart. AUein abgesehen davon, dass dieses Medium einen hochst complicirten Ban hatte und von Eigenschaften strotzte, die den Stempel der WiUkiirlichkeit und eines rein provisorischen Charakters an sich trugen, so ware es fiir Hertz wieder nicht einmal brauchbar, indem seine Theile ebenfalls von Kraften im alten Sinne der Mechanik zusammen- gehalten werden. Ja auch die Eigenschaften der elastischen, tropf- barfliissigen und gasformigen Korper miissten durch neue Bilder ersetzt werden, da die bisherigen alle auf die Annahme von zwischen den TheU- chen wirkenden Kraften gegriindet sind. Man hat also nur folgende Wahl, entweder man lasst die Natur des Mechanismus, welcher die Gravitation, die elektrischen und magnetischen Erscheinungen erzeugen soil, unbestimmt und willkiirlich. Dadurch entsteht eine unertragliche Unanschaulichkeit, indem man genothigt ist immer mit Gleichungen zu operiren, von denen man nur einige ganz allgemeine Eigenschaften kennt, deren spezielle Form aber vollstandig unbekannt ist, oder man bemiiht sich einen bestimmten Mechanismus zu wahlen, wodurch man dann wieder in eben so viele Willkiirlichkeiten als Schwierigkeiten verwickelt wird. Doch ich will noch an einem viel einfacheren Beispiele die Schwierig- keiten zeigen, auf welche die Anwendung des Hertz'schen Fundamental- gesetzes schon in den trivialsten Fallen stosst. Es seien drei Massen m^, u und m^ mit der Bedingung gegeben, dass Erste Vorlesung. 275 sowohl die Entfernung m^ u als auch die u m^ stets gleich derselben Grosse a sein soil. Lassen wir dann die Masse u immer kleiner werden, so ephalten wir einen voUkommen dem Geiste der Hertz'schen Meclianik entsprechenden Fall, der uns ein getreues Bild des folgenden Natur- vorgangs gibt. In einer elastischen HoUkugel von der Masse m^ bewege sich eine kleine elastische VoUkugel ; die Differenz der Radien sei 2 a. Wir haben also hier ein Beispiel eines und desselben Naturvorganges, welcher auf zwei ganz verschiedenen Wegen erklart werden kann, eines- tbeils aus der Molekulartheorie, anderstheils nacb der von Hertz angegebenen Methode. Aber so verhalten sicli nicht alle Vorgange, Schon der ganz triviale Fall des Stosses zweier elastischen VoUkugeln ist aus dem Hertz'schen Schema nur durch zeimlich willkiirlich gewahlte Mechanismen oder complicirte Annahmen liber ein Zwischenmedium ableitbar, da ja die Hertz'sche Methode Ungleichungen ausschliesst. Es fiihrt also die Hertz'sche Methode schon in den einfachsten Fallen zu den grossten Complicationen. Ich betone hier nochmals, dass diese Ausfiihrungen keineswegs den Zweck haben soUen, den hohen Wert des Hertz'schen Bildes zu leugnen, welcher in der logischen Einfachheit seiner Grundprincipien besteht. Es ware ja moglich, dass man in ferner Zukunft einmal alle Wirkungen durch Medien erklaren kann, deren Eigenschaften nicht phantastisch gewahlt, sondern durch die Natur der Sache in nahe liegender und un- zweideutiger Weise geboten werden. Es ware moglich, dass die Theil- chen dieser Medien nicht Krafte im alten mechanischen Sinne aufeinander ausiiben, sondern dass man mit Bedingungsgleichungen im Hertz'schen Sinne zwischen den Coordinaten der Elementartheilchen ausreichen wiirde. Von diesem Augenblicke an hatte die Hertz'sche Mechanik in unzweifelhafter Weise den Sieg davongetragen und alle andern Dar- stellungen hatten nur mehr historisches Interesse. Ob man das einstige Eintreffen eines solchen Zeitmomentes fiir wahrscheinlich halt oder nicht ist natiirlich eine reine Geschmackssache. Bewiesen ist nicht einmal die Moglichkeit einer derartigen Entwicklung unserer Erkentnis. Wir wer- den daher auf unserem gegenwartigem Standpunkte zu jenem Ideale mit Bewunderung aufblicken, auch das Unserige zur Beforderung der An- naherung an dasselbe beitragen. Aber einstweilen werden wir solche einfache und unmittelbar brauchbare Bilder, welche sich jetzt schon ins Detail durchfuhren lassen neben den Hertz'schen nicht entbehren konnen. 276 Ludwig Boltzmann: ZWBITE VOELESUNG. Ich habe in der vorigen Vorlesung zwei Bilder der nieclianischen Er- scheinungen besprochen, welche beide rein deductiv sind, das Hertz'sche und das in meinem Buche iiber Mechanik dargestellte. Das letztere un- terscheidet sicb dem Wesen nach nicht von den alteren Theorien der Mechanik. Ich bemiibte mich nur diese durch eine moglichst conse- quents Darstellung gegen etwaige Einwiirfe besonders gegen die Be- denken zu sichern, welche Hertz in der Vorrede seines Buches gegen die altere Mechanik erhebt. Gerade zu diesem Zwecke schien sich die rein deductive Darstellung am besten zu eignen, weil sie das Bild ganz unabhangig von den Thatsachen in moglichster Klarheit zu entwickeln erlaubt. Man konnte jedoch das Bild auch nach der entgegengesetzten Methods entwickeln, indem man unmittelbar von den Thatsachen aus- ginge, wie sie sich der unbefangenen Beobachtung bieten, aus diesen That- sachen die Bilder erst allmalig entstehen liesse und jede Abstraction erst dann einfiihrte, wenn sie auf keine Weise mehr abgewiesen werden kann. Diese letztere Darstellung woUen wir die inductive nennen. Dieselbe hat der deductiven gegeniiber den Nachtheil, dass die Bilder von Anfang an nicht so rein hervortreten, daher ihre innere Consequenz nicht so klar zu libersehen ist. AUein sie hat auch wieder den Vortheil, dass" sie an Stelle der lange Zeit hindurch rein abstracten von der Wirklichkeit abgekehrten Darstellungsweise der deduktiven Methode rein an das unmittelbar Gegebene und Gelaufige ankniipfende setzt und moglichst klar erkennen lasst, wie die abstracten Bilder entstanden sind und warum wir gerade zu diesen Bildern unsere Zuflucht nehmen. Um die Vorziige und Nachtheile der deductiven Methode mit der inductiven zu vergleichen, ware es nicht ganz zweckmassig die im vorigen Vortrage geschilderte Methode mit den alteren in der Mechanik iiblichen Darstel- lungsweisen zu vergleichen, da die letzteren beide Methoden vermischen und dadurch wie mir scheint die Klarheit beeintrachtigen. So werden in der Regel sehr bald abstracte Begriffe, wie der des materiellen Punktes, der Masse etc., eingefiihrt, diese aber nicht, wie von uns in der vorigen Vor- lesung als rein gedankliche Werkzeuge aufgefasst. Es werden vielmehr davon mehr oder minder unbestimmte und nichts sagende Definitionen gegeben. So wird der materielle Punkt als ein Korper definirt, welcher so klein ist, dass seine Ausdehnung vernachlassigt werden kann. Man meint damit etwa, dass seine Tragheitsmomente beziiglich einer durch Zweite Vorlesung. 277 seinen Schwerpunkt gehenden Axe gegeniiber denen beziiglich einer andern Axe verschwinden, die sich davon in einer Entfernung befindet, die von der Grossenordnttng der Entfernungen ist, welche bei unsern Experimenten fiir gewohnlich vorkommen oder Ahnliches. Da aber der BegrifE des Tragheitsmomentes, Scbwerpunkts etc. noch niclit entwickelt worden ist, so wiisste ich nicbt was man sich unter einem Korper, an dem eine der wichtigsten Eigenschaften, namlich die Ausdebnung vernach- lassigt werden kann, denken soil. Die Masse wird oft definirt durch die Wirkung einer und derselben Kraft auf verscbiedene Korper, aber wie soil man constatiren, dass die Kraft dieselbe ist, wenn sie einmal auf diesen einmal auf jenen Korper wirkt? Es wird daher das Beste sein, wenn wir versuchen nocb eine neue rein inductive Darstellung der Grundprincipien der Mechanik wenigstens mit einigen Strichen zu ski- ziren. Wir bleiben dabei unserm Princip treu, dass wir vorlaufig keines- wegs eine einzige beste Darstellung der Wissenscbaft erstreben, sondern dass wir es fiir niitzlicb balten moglicbst viele verschiedene Darstel- lungen zu versuchen, von denen jede ihre besondern Vorziige, freilich auch wieder jede ihre Mangel bat. Das Hauptaugenmerk wird dabei wieder darauf zu richten sein alle Inconsequenzen und logiscben Fehler zu vermeiden, keinen Begriff oder keine Annahme stillschweigend einzu- schmuggeln, sondern uns aller gemacbten Hypothesen mit moglichster Klarheit bewusst zu werden. Es verstebt sich von selbst, dass ich bier bei der Kiirze der mir zur Verfiigung stehenden Zeit nicbt die ganze Mechanik erschopfend darstellen kann. Ich werde nur versuchen einige Andeutungen zu geben. Es ware wol auch kaum moglich eine so schwie- rige Aufgabe auf einmal ganz der Losung zuzufiibren. Viel wird an dem ersten Versuche nocb mangelhaft sein und erst allmalig werden sich die BegrifEe sichten und die Darstellungsweisen vervoUkommnen. Wir werden da gerade denjenigen Weg einschlagen miissen, der dem in der vorigen Vorlesung geschilderten und in meinem Buche iiber Mechanik verfolgten, direct entgegengesetzt ist. Die abstracten Begriffe des mate- riellen Punktes, der Masse, Kraft etc., von denen wir dort ausgingen, werden wir nun zwar auch nicbt ganz vermeiden konnen ; denn sie sind einmal die Grundpfeiler, auf welche die Mechanik aufgebaut ist. Aber wir werden sie jetzt so spat als moglich einfiihren und wahrend wir sie friiher postulirten, werden wir jetzt moglichst an die Erfahrung ankniip- fen und unsere Resultate daraus zu deduciren suchen. Daber sind jetzt auch diejenigen Gesetze, welche friiher die einfachsten schienen, nicht 278 Ludwig Boltzmann: voranzustellen, wie z. B. das Tragheitsgesetz. Dieses wird ge-wohnlich dahin ausgesproclien, dass ein materieller Punkt, weleher jedem ausseren Einflusse entzogen ist, sick geradlinig und gleichformig bewegt. Abge- sehen von der Schwierigkeit, die im Begriffe des materiellen Punktes liegt, konnen wir nun aber keinen Korper so weit von alien iibrigen entfernen, dass er jedem Einflusse entzogen ist und ware dies moglich, so konnten wir seine Bewegung nicht mehr beobachten, geseliweige denn deren Geradlinigkeit und Gleicbformigkeit constatiren. Wenn man aber das Tragheitsgesetz an Korpern verificiren will, an denen sich alle darauf wirkenden Krafte das Gleichgewicbt halten, so miisste man die gesammte Lehre vom Gleichgewicbte schon vorausscMcken. Man pflegt also in der gewohnlichen Darstellung Abstractionen und Thatsacben vielfach zu vermiscben, was zu vermeiden eben im folgenden unsere Hauptauf- gabe sein soil, da wir uns vornebmen streng von reinen Erfahrungsthat- sacben auszugeben. Die erste Unbequemliobkeit, die uns biebei entgegentritt ist folgende: Friiber batten wir es bei Auf stellung der ersten Grundprincipien mit rein Gedacbtem zu tbun, das wir in unserer Idee formen konnen, wie wir woUen, und wovon wir verlangen konnen, dass es immer exact unseren Anforderungen entspricbt, jetzt dagegen wollen wir von den direct beobacbteten Erscbeinungen ausgeben, welcbe immer sehr zusammenge- setzt und complicirt sind. Wollen wir daraus Grundgesetze gewinnen, so miissen wir die Erscbeinungen immer generalisiren und idealisiren, so dass wir scbon nicht mehr ganz exacte Thatsacben vor uns haben son- dern Vorgange, welcbe in der Natur immer nur mit grosserer oder gerin- gerer Annaherung realisirt sind. Wir konnen es daber aucb nicht ganz vermeiden Vorstellungen und Thatsacben zu vermengen aber wir sucben dies wenigstens auf das kleinste Mass zuriick zu fiibren und bestreben uns es nicht versteckt zu tbun, sondern wo wir dazu gezwungen sind uns dessen klar bewusst zu bleiben. Die Erscbeinungen, welcbe uns gegeben sind, haben eine ausserordent- licb verschiedene Natur. Die einfachsten besteben in Ortsveranderungen eines Korpers, welcber dabei weder seine Gestalt noch seine sonstigen Eigenschaften irgendwie zu verandern scheint. Scbon diese einfache Erscheinung ist in gewisser Beziehung eine idealisirte. In den wenigsten Fallen andert der Korper seine Gestalt absolut gar nicht ; ja alle, selbst die unveranderlicbsten Korper konnen durch sehr starke Krafte zer- brecben, durch Hitze, chemische Wirkungen, zu voUiger Yeranderung ihrer Zweite Vorlesung. 279 Eigenschaften veranlasst werden. Aber es gibt sehr viele Korper, die doch ihre Gestalt wahrend der mannigfaltigsten Bewegungen durch lange Zeit nicht bemerkbar andern. Wir nennen sie feste Korper und bilden uns das Ideal eines absolut unveranderlichen Korpers, welchen wir einen starren nennen. Andere Korper, die Fliissigkeiten andern wabrend ibrer Bewegung ibre Gestalt in der mannigfaltigsten Weise, entweder bei (natiirlicb wieder nur angenabert) gleicb bleibendem Volumen, (die tropf- baren Fliissigkeiten) oder unter steter sehr merkbarer Anderung des Vol- umens, (die Gase). Man kann die letzteren Erscbeinungen auf die erstern zuriickfiibren, indem man annimmt, dass die Fliissigkeiten aus sehr vielen sebr kleinen Tbeilchen besteben, deren Bewegung unabbangig von ein- ander, die Gestaltanderung bervorruft. Andert sicb dabei die durcb- schnittlicbe Entfernnng je zweier Nacbbartbeilcben, so ist dieselbe aucb mit Volumanderung verkniipft. Es ist nun die Frage, soil man sicb die Anzabl dieser Theilcben mathematiscb unendlicb oder bloss sebr gross aber endlicb denken. Viele Erfabrungstbatsachen deuten darauf bin, dass die letztere Annabme gemacbt werden muss, welcbe aucb pbiloso- pbiscb die befriedigendere ist. Aber da eine unzweifelbafte experi- mentelle Entscbeidung bisber nicbt erfolgt ist, so wollen wir getreu den Principien, nacb denen wir jetzt vorzugebn beabsicbtigen, diese Frage vollstandig in suspenso lassen. AUe Ortsveranderung beissen Bewegungen. Die Lebre von den Bewegungserscbeinungen ist die Mecbanik, welcbe sicb in die Geo-, Hydro- und Aero-mecbanik abtbeilt, je nacbdem man es mit der Bewegung fester, tropfbarer oder gasformiger Korper zu tbun iat. Die Mecbanik umfasst ibrer Definition gemass aucb die Bedingungen, unter denen sick ein Korper garnicbt bewegt. Es gibt noch vielerlei Erscbeinungen der Scball, die Warme, das Licbt, die elektriscben und magnetiscben Erscbeinungen, die ganzlicbe Anderung der Eigenschaften von Korpern bei chemiscben Prozesseu, die Geruchs-, Geschmackerscheinnngen etc. Letztere sind wabrscheinlich nur spezieUe Falle von Verdampfungs- oder chemiscben Erscbeinungen, und daber fiir die Pbysik von geringerer Wichtigkeit, welcbe ja die Action auf die Nerven und die Fortleitung durch dieselben bis zum Bewusstwerden der Physiologic und Psychologic iiberlasst. Aber sie miissen bier doch ebenfalls erwabnt werden. Es ist unzweifelhaft nacbgewiesen, dass den Scballerscheimingen Bewegungen der Korper zu Grunde liegen. Naturgemass suchte man 280 Ludwig Boltzmann: auch Licht, Elektricitat und Magnetismus, so wie die chemischen Erscheinungen durda Bewegungserscheinungen gewisser hypothetischer Medien oder hypothetischer kleinster Theile zu erklaren und bis vor Kurzem war wohl jeder Physiker iiberzeugt, dass hiemit dem Wesen nach die eigentliche Aufgabe der Physik ausgesprochen sei. Erst vor wenigen Decennien wurde unwiderleglich nachgewiesen, dass die besonders in Deutschland friiher allgemein verbreitete Theorie der elektrischen und magnetischen Fluide mit den Thatsachen nicht in Ubereinstimmung gebracht werden kann. Man wurde nun vorsichtiger, man suchte zwar die elektrischen und magnetischen Erscheinungen zunachst wieder durch mechanische Wirkung eines Mediums zu erklaren, allein da man hiebei nicht zu einem bestimmten eindeutigen Erfolge gelangte, so neigen in neuester Zeit manche Physiker zur Ansicht, dass es wol ein iibereilter Schluss sei, dass sich alle Erscheinungen durch Bewegungsphanomene miissten erklaren lassen oder in unsere Ausdrucksweise iibertragen, dass es vielleicht gar nicht moglich sei durch die Bilder von Ortsverander- ungen von Punkten und Korpertheilen allein sich ein ausreichendes Bild der Erscheinungen zu verschaffen ; dass man dazu noch qualitativ verschiedene Bilder wie dielektrische und magnetische Polarisationen, chemische Zustande oder anderes dazunehmen miisse. Es wiirde dadurch die Einheit der Naturwissenschaft ausserordentlich leiden, da man auf keinen Fall die alten einfachen Bilder vermeiden konnte und uns noch eine Menge fremdartiger dazu einfiihren miisste. Es wiirde dann auch die Bedeutung der Mechanik als Grundlage der gesammten Naturwissenschaft, auf welcher alle tibrigen Theorien derselben beruhen, in Frage gestellt. Aber immer hatte noch die Mechanik als die Lehre der einfachsten Erscheinungen, ohne die irgend welche andere nicht denkbar sind, alien andern physikalischen Theorien voranzugehn. Wenn man daher auch einerseits nicht leugnen kann, dass der Beweis der mechanischen Erklarbarkeit aller Naturerscheinungen noch nicht geliefert ist, so ist doch sicher ebenso wenig ein Beweis geliefert, dass gewisse Naturerscheinungen nicht durch mechanische Bilder erklarbar sein konnten, und man kann hochstens die Ansicht aussprechen, dass bei gewis- sen Naturerscheinungen der Versuch einer mechanischen Erklarung heute noch zu friih kommt. Die allgemeine Frage an sich kann erst nach Jahrhunderten entschieden oder wenigstens in ein wesentlich neues Licht geriickt und geklart werden. Wir woUen uns daher mit der Discussion des "Flir" oder "Wider" hier nicht aufhalten, sondern kehren zur Beweg- Zweite Vorlesung. 281 ung eines festen Korpers K zuriick, den wir sogleioh idealisiren, indem wir ihn als absolut starr denken. Wir fassen denselben nicht etwa als einen materiellen Punkt, sondern als einen erfahrungsmassig gegebenen, wenigstens dem Scheine nach continuirlicli ausgedehnten Korper auf. Wir miissen freilich wieder sogleioh mit einer Abstraotion einsetzen ; wir konnen die Bewegung des Korpers nicht auf einmal als Ganzes erfassen, da er ja (wenigstens fiir uns scheinbar) aus unendlich vielen Theilen besteht. Wir konnen bloss die Bewegung einzelner Punkte desselben klar mit dem Auge und Gedanken verfolgen. Wir wollen daher sehr kleine Stellen desselben A, B, O, . . . mit feinen selbstverstandlich ebenfalls starr mit dem Korper verbundenen Marken bezeichnen etwa mit feinen Farbepunkten, Mehlstaubchen oder durch die Kreuzung zweier feiner Linien etc. Wenn wir eine ausserordentlich enge Hohlung in den Korper bohren, so konnen wir auch Punkte im Innern desselben wirklich bezeichnen und wir konnen es auch ohne die Hohlung in Gedanken, wenn wir uns etwa einen geometrisch ahnlichen hohlen oder durchsichti- gen oder sonst an dieser Stelle zuganglichen Korper vorstellen. Es ist freilich schon wieder eine Idealisirung, wenn wir uns diese bezeichneten Stellen als mathematische Punkte denken ; allein wir bleiben doch dem thatsachlich Realen viel naher, wenn wir die Bewegung des ausgedehnten Korpers durch solche Punkte beschreiben und an erster Stelle einfache Gesetze fiir die Mechanik ausgedehnter Korper zu gewinnen suchen, als wenn wir direkt mit den Gesetzen fiir die Bewegung einzelner materieller Punkte beginnen. Wir konnen jetzt genauer beschreiben, was es heisst, wenn wir sagen die Gestalt eines Korpers andert sich wahrend seiner Bewegung nicht. Wir konnen durch Anlegen eines Massstabes oder zweier Zirkelspitzen, die wir dann auf einen Massstab iibertragen die Ent- fernung je zweier beliebiger Punkte des Korpers Kd. h. zweier beliebiger hervorgehobener Marken auf demselben messen. Wenn dieselbe fiir alle Punktepaare zu alien Zeiten unverandert bleibt, so sagen wir die Gestalt des Korpers ist unveranderlich. Fiir die Unveranderlichkeit des Mass- stabes oder Zirkels haben wir freilich keine objective Garantie, sondern nur die empirische, dass uns dieselben an alien Kprpern, welche schon dem Augenscheine nach ihre Gestalt nicht andern, die richtige Anzeige lief em. Wenn alle festen Korper in gleicher Weise ihre Dimensionen mit der Zeit andern wiirden, so konnten wir dies natiirlich nicht bemerken. Wir haben auch durchaus nicht die Absicht zu erklaren, wieso es feste Korper gibt, wieso wir die Entfernungen der damit fest verbundnen. 282 Ludwig Boltzmann: Marken messen konnen. Wir nehmen dies als Erfahrungsthatsachen hin, nur die Gesetze der Veranderung der Entfernungen der Marken ver- schiedener Korper oder auch desselben Korpers falls dieser nicht starr ist, woUen wir durch unsere Vorstellungsbilder darstellen. Vorbedingung jeder ■wissenschaftlichen Erkenntniss ist das Princip der eindeutigen Bestimmtlieit der Naturvorgange, auf die Mechanik ange- wandt der eindeutigen Bestimmtheit aller Bewegungen. Dasselbe sagt aus, dass die Bewegungen der Korper nicht rein zufallig bald so, bald anders vor sich gehn, sondern dass sie durch die Umstande, unter denen sicb der Korper befindet, eindeutig bestimmt sind. Wenn jeder Korper sich wie er woUte bewegte, wenn unter gleichen Umstanden bald diese, bald jene Bewegung je nach ZufaU erfolgte, so konnten wir dem Verlaufe der Erscheinungen nur neugierig zusehen nicht ihn erforschen. Auch hierin liegt wieder eine Unbestimmtheit, die Umstande, unter denen die Bewegung irgend eines Korpers Tor sich geht, umfassen streng genom- men das ganze Universum. Dasselbe ist nie zweimal im selben Zustande. Wir miissen also unsere Bedingungen dahin reduziren, dass immer die- selbe Bewegung erfolgt, wenn die unmittelbare Umgebung sich in dem- selben Zustande befindet. Wir sind hier bei der inductiven Methode wieder in einer weit ungiinstigeren Lage als bei der Deductiven. Denn da wir bei der letztern mit der Aufzahlung der Wirkungsgesetze ohne Riicksicht auf jede Erfahrung beginnen, so liegt es ganz in unserer Hand gleich anfangs willkiirlich festzustellen, von welchen Umstanden die Bewegung eines Korpers abhangt und welche darauf ohne Einfluss sind. Bei der inductiven Methode hingegen miissen wir den BegrifE der unmittelbaren Umgebung eines Korpers, deren Zustand auf seine Beweg- ung von Einfluss ist, nach der Erfahrung bestimmen. Nach der Nahe- wirkungstheorie sind es nur die unmittelbar anliegenden Volumelemente, welche die Bewegung irgend eines Volumelementes bestimmen. Nach dieser Theorie wirkt die Erde nicht direct anziehend auf den schweren Korper sondern sie wirkt nur auf die Volumelemente eines Mediums, durch welche sich die Wirkung bis zum schweren Korper fortpflanzt. Aber wenn wir den Principien unserer jetzigen Darstellungsweise treu bleiben woUen, so diirfen wir nicht die Nahewirkungstheorie zur Basis des gesammten Gebaudes der Mechanik machen, wir diirfen vielmehr hiezu nur Gesetze verwenden, welche nichts WiUkiirliches enthalten, sondern uns durch die Erfahrung eindeutig und notwendig aufgedrangt werden. Die Nahewirkungstheorie aber, so wahrscheinlich sie vielleicht manchem Zweite Vorlesung. 283 a priori erscheint, geht doch voUstandig iiber das rein Thatsachliche hinaus und kann heutzutage noch keineswegs ins Detail ausgearbeitet werden, Wir wiirden da in denselben Fabler verfallen, den wir der Hertz'schen Darstellungsweise vorgeworfen baben. Wir miissten entweder ganz will- kiirlicbe spezielle Hypotbesen fiir die Art und Weise der Nahe-^rkung erfinden oder uns mit allgemeinen unbestimmten Vorstellungen iiber die- selbe begniigen. Wir miissen daber die ganze Erde zur Umgebung des scbweren Kor- pers reebnen aber Mond und Sterne dabei ausser Acbt lassen, da letztere keinen bemerkbaren Einfluss ausiiben. Es ist also wieder eine reine Annabme, welcbe wir erst nacbtraglicb durcb die Erfabrung recbtf ertigen miissen, dass wir die unmittelbare Umgebung immer so abzugrenzen ver- mogen, dass wir alles Wesentlicbe einschliessen und dass wir so factiscb zu einer Aufstellung von Bewegungsgesetzen gelangen konnen. Wie werden wir uns nun bei unserer jetziger Darstellungsweise dem absoluten Raume und der absoluten Zeit gegeniiber verbalten? An einem Tbeile des absoluten Raumes konnen wir keine Zirkelspitze ein- setzen sondern nur an materiellen Korpern. Wir konnen daber nur die Bewegung von materiellen Korpern relativ gegen einander bestimmen. Wir diirfen jetzt nicbt wie bei der deductiven Metbode das Gedanken- bild eines fingirten Coordinatensystems unter die von uns gegenwartig allein betracbteten realen Korper mengen. Dem Geiste unserer Metbode entsprecbend miissen wir vielmehr unsere Betrachtungen moglicbst dem bistoriscben Entwickelungsgange der Mecbanik anscbliessen. Galilei bat die einfacben Bewegungsgesetze gefunden, indem er die Bewegung relativ gegen die Erde studirte. Seinem Beispiele folgend werden wir daber ausser dem Korper K, dessen Bewegung wir bescbreiben woUen, noch ein System von anderen Korpern in die Betracbtungen mit einbe- zieben, welcbe die Bedingung erfiillen, dass alle ihre Punkte ihre Ent- fernungen von einander nicbt andern, dass sie also alle relativ ruben. Dieses System nennen wir das Bezugssystem. Wenn wir daber die Bewegung eines festen Korpers gegen ein Bezugssystem studiren und wenn A, B, C . . . markirte Punkte des ersteren, E, F, Q- . . . solcbe des letztern sind, so andern sicb weder die Entfernungen AB, AQ . . . nocb EF, EG- . . . und unsere Aufgabe bestebt bloss darin, die Gesetze der Veranderungen, der Entfernungen AE, AF, BF . . . aufzustellen, Natiirlicb sind biebei aucb wieder vielerlei IdeaHsirungen notwendig. Wir werden kein System von Korpern als Bezugssystem auffinden 284 Ludwig Boltzmann: konnen, welche so beschaffen sind, dass sie zu alien Zeiten relativ gegen- einander ilire Lage absolut beibehalten. Es getiiigt, wenn diese Beding- ung angenahert durcb geniigend lange Zeit erfiillt ist. Ferner konnen wir nicht wissen, ob wir dieselben Gesetze erhalten, wenn wir das eine oder andere Bezugssystem wahlen. Wir werden daher jedenfalls ein solches Bezugssystem zu wahlen haben, dass wir ein- fache Gesetze fiir die Bewegung erhalten. Es zeigt sich in der That, dass die Gesetze, welche wir bei zu Grundelegung des Fixsternhimmels als Bezugssystem erhalten nicht ohne kleine Correctionen auf die Beweg- ung relativ gegen die Erde angewandt werden konnen und es muss als ein fiir die Entwickelung der Mechanik ausserordentlich giinstiger Zufall bezeichnet werden, dass der Einfluss der Erddrehung auf die verscliiedenen Bewegungen, welche wir auf ihrer Oberflache beobachten ein so ausser- ordentlich geringer ist. Sonst ware es weit schwieriger gewesen die Grundgesetze der Mechanik herzuleiten. Diesem Umstande ist es zu ver- danken, dass wir fiir die Bewegungen auf der Erde den Erdkorper als Bezugssystem wahlen konnen. Wir erhalten hiedurch einfache Gesetze, denen die wirklichen Bewegungen freilich nicht mit absoluter Genauig- keit folgen, aber die Abweichungen sind so gering, dass sie sich fast der Beobachtung entziehen. Dies konnten wir freilich nicht a priori wissen ; aber es ist kein logischer Fehler, wenn wir zunachst die Gesetze der Relativbewegung gegen die Erde studiren. Finden wir einfache Gesetze, so ist es wieder kein logischer Fehler, deren Anwendung auf die Beweg- ung der Planeten relativ gegen das Fixsternsystem zu versuchen. Bei dieser Erweiterung zeigt sich dann erst einestheils, dass sie auch fiir den ersten Fall angenahert richtig sein miissen, anderseits aber, dass derselbe doch kleiner Correctionen bedarf. Diese Correctionen sind so klein dass sie uns bei Auffindung der Gesetze aus den irdischen Bewegungen nicht storten, dass sie aber jetzt nachdem wir ihre Grossenordnung kennen gelernt haben dooh mit feinen Hilfsmitteln beobachtet werden konnen. Dass die wirklichen Bewegungen dann gerade die durch diese Correctionen bedingten Eigenthiimlichkeiten zeigen, rechtfertigt nachher in glanzender Weise unsere Methode. Hiemit ist wieder die padagogische Schwierig- keit beseitigt, welche durch die Relativitat aller Bewegungen bedingt wird. Die Frage, auf welches Bezugssystem wir die Fixsternbewegungen zu beziehen haben, ist hiemit freilich nicht gelost, aber es liegt in keiner Weise eine Notwendigkeit vor, diese Frage vor Aufstellung der sammt- lichen Gesetze der Mechanik zu behandeln. Zweite Vorlesung. 285 Wir haben bisher iiber die Gestalt und Anordnung der Korper des zu Grunde gelegten Bezugssystems keine besondere Annahme gemacht. Es hat nun keine Schwierigkeit mit denselben drei fixe auf einander rechtwinklige Gerade vorbunden zu denken, welche man als Coordinaten- axen wahlen kann. Die Lage jedes an dem betreffenden Korper mar- kirten Punktes ist dann zu jeder Zeit durcb dessen recbtwinklige Coordinaten beziiglich dieses Coordinatensystems bestimmt. Wenn sicb diese mit der Zeit nicht andern, so befindet sich der Korper in relativer Ruhe gegen das Bezugssystem. Wenn sie sich andern, so ist er in Bewegung Um den letztern Fall beschreiben zu konnen, ist noch die genaue Fixirung des Zeitmasses erforderlich. Gerade so wie wir schon mit Hilfe des Augenmasses oder des Tastgefiihles grossere raumliche Ausdehnungen von kleineren unterscheiden, einen genauen zahlenmassigen Ausdruck der Raumgrosse aber nur durch Ver- gleieh mit einem rationell construirten Massstabe gewinnen konnen, so konnen wir auch schon durch das Gefiihl (den Zeitsinn) langere Zeit- raume von kiirzern unterscheiden, miissen uns aber ein genaues quantita- tives Zeitmass durch die Hilfsmittel verschaffen, welche schon in der ersten Vorlesung angedeutet wiirden. Wir miissen uns da vor allem eine Reihe von Vorgangen verschaffen, bei denen wir vollkommen oder besser gesagt, thunlichste Garantie haben, dass sie sich in gleichen Zeiten abspielen. Wir konnen etwa ganz gleiche Korper unter ganz gleichen Umstanden fallen lassen oder ganz gleiche Pendel um gleiche Strecken aus der Ruhelage entfernen. Wenn das erste die Ruhelage erreicht, lassen wir das zweite seine Bewegung beginnen etc. Ob wir gegenseitige Storungen wirklich geniigend vermieden haben, kann natiirlich nur der Vergleich mit verschiedenen analogen Versuchen zeigen. Wir sehn natiirlich bald, dass auch ein Pendel die verschiedenen sich folgenden Schwingungen nahe unter den gleichen Umstanden voUzieht und konnen diese zur Zeitmessung benutzen. Freilich ist der absolute Isochronismus der Schwingungen wieder ein Ideal, Temperatur, Barometerstand, Sonne und Mond haben darauf Einfluss, aber wie alle diese storenden Umstande bei gut gearbeiteten Chronometern moglichst vermieden werden, wie durch eine treibende Kraft die Schwingungen sehr lange erhalten werden, dass man, wenn ein bestimmtes Chronometer endlich unbrauchbar wird, dafiir ein anderes moglichst gleichbeschaffenes substituiren kann, das alles ist nicht mehr Sache unserer gegenwartigen allgemeinen Betrach- tungen. 286 Ludwig BoUzmann: Wir wahlen einen bestimmten Zeitmoment z. B. den, der einem bestimmten willkiirlicb gewahlten Durchgang durch die Ruhelage ent- spricht, als Zeitmoment Null, den des nachsten Durchgangs durch die Ruhelage als Zeit 1, die welter folgenden als die Zeiten 2, 3 u.s.w. Die Unterabtheilungen konnen wir durch schneUer schwingende Stimmgabeln oder durch Bewegungen bestimmen, die sich fiir grossere Intervalle unter alien Umstanden als geniigend gleichf ormig erwiesen und Ton denen wir Ursache haben dies auch fiir kleinere Intervalle zu vermuten. So gewin- nen wir die Zeiten J, ^ u.s.w und es lasst sich keine Grenze der Unterabtheilung feststellen. Die negativen Zahlen bezeichnen die Schwingungen vor derjenigen der wir die Zeit Null zugeordnet haben. In dieser Weise konnen wir alle Zeiten durch positive, negative, ganze, gebrochene, irrationale Zahlen darstellen, wie wir die Langen durch die Zahl darstellen, welche angibt, wie oftmals sie die Langeneinheit enthal- ten. Die Differenz der Zahlen, welche zwei gegebene Zeiten darstellen heisst das dazwischen liegende Zeitintervall oder die Zeitdifferenz auch die inzwischen vorflossene Zeit. Unsere gewohnliche Zeiteinheit leiten wir von der Umdrehungszeit der Erde ab, deren Gleichformigkeit aber bei Ableitung der Principien der Mechanik wol besser durch einfachere Vorgange controlirt wird, da es ohne Kenntnis der mechanischen Gesetze nicht so ohne welters evident ist, dass die Umdrehungsgeschwindigkeit an alien Stellen der Erdbahn dieselbe bleibt. Wir kehren nun zuriick zu unserem Korper K, den wir auf ein mit dem gewahlten Bezugssysteme fest verbundenes Coordinatensysten Ox, Oy, Oz beziehen. Ein auf demselben hervorgehobener Punkt befinde sich zu einer bestimmten Zeit t'va. A und habe die rechtwinkeligen Coor- dinaten a;, y, z. Wir verbinden ihn durch die Gerade OA mit dem Coor- dinatenursprunge : Diese Gerade heisst der Lagenvector des Punktes A,, ihre Projectionen auf' die drei Coordinatenaxen sind die drei Coordinaten a;, y, z. Wenn nun der Korper eine gewisse gegebene Bewegung macht, so miissen wir zunachst jeden Zeitmoment der Bewegung etwa durch Vergleichung der gleichzeitigen Bewegung unseres Chronoskops durch eine Zahl darstellen. Es wird zu jeder Zeit eine bestimmte Lage des Korpers gehoren, daher auch des Punktes A desselben, daher auch be- stimmte Werte der Coordinaten y, a;, s, welche wir uns ebenfalls durch reine Zahlen (ganze oder gebrochene Vielfache der Langeneinheit) dar- gesteUt denken. Zu jedem Zahlenwerte der Zeit t gehort also ein ein- deutig bestimmter Zahlenwert der Coordinate a;, x ist eine eindeutige Zweite Vorlesung. 287 Funktion von t, ebenso y und 2. Wir schreiben dies so x = ^(i)? y = x(0, z = i/^CO und nennen < das Argument oder die independente Variabele, x, y, z aber die dependenten Variabeln. Wir konnen es zu- nachst als hinlanglich sicher gestellte Erfahrungstbatsache betrachten, dass ein Korper nie aus einer Lage plotzlich verschwindet und im nachsten Zeitmomente in einer andern um Endlicbes davon Ver- schiedenen wieder zum Vorschein kommt und dass dies aucb von jedem Theile eines Korpers gilt, dass also , %, i/r continuirliche Functionen der Zeit sind, d. h. ibre Zuwachse verschwinden um so mehr je kleiner der entsprecbende Zuwacbs der Zeit ist. Die von den verscbiedenen Lagen des Punktes A zu den verscbiedenen Zeiten gebildete Curve nen- nen, wir die Bahn dieses Punktes, denjenigen Tbeil derselben, welcber alien Lagen, die wabrend einer gegebenen Zeit durcblaufen werden ent- spricbt den wabrend dieser Zeit zuriick gelegten Weg. Nicbt ganz so sicber als die Continuitat der Functionen ^, j^, -^ ist es, ob sie aucb differenzirbar sind. Man driickte sicb in der alten Mecbanik folgendermassen aus. Es lege ein Punkt eines Korpers, wabr- end einer sebr kleinen Zeit ht einen sebr kleinen Weg Ss zuriick. Es sei nun a priori evident, dass sicb wabrend dieser kleinen Zeit, die Umstande, unter denen sicb der Korper befindet nur sebr wenig geandert baben kon- nen, dass es daber, wabrend der nacbst folgenden Zeit Bt wieder einen sebr nabe gleicben und gleicb gericbteten Weg Bs zuriicklegen muss, so dass also fiir kleine Zeiten sowobl der Weg als aucb die Coordinatenzu- wacbse der verstrichenen Zeit proportional sein miissen. Man glaubte damals iiberbaupt, dass jede iiberall endlicbe continuirlicbe Function einen Differenzialquotienten baben muss. Weierstrass bat bekanntlicb gezeigt, dass dies ein Irrtbum ist. Bezeicbnen wir z. B. mit y die Weierstrass- iscbe Reibe so nabert sicb der Zuwacbs des y, der irgend einem Zuwacbse des X entspricbt an alien Stellen immer mebr der NuUe, wenn sicb der betreffende Zuwacbs das x der Nulle nabert und trotzdem nabert sicb der Quotient beider Grossen niemals einer bestimmbaren Grenze. Bei der deductiven Darstellung ergibt sicb bieraus wieder nicbt die mindeste Scbwierigkeit. Wir konnen ja dann unser Bild formen, wie wir wollen und einfacb die Differenzirbarkeit von vornberein in dasselbe aufneb- men, es damit recbtfertigend, dass das Bild binterber mit der Erfabrung stimmt. Aber jetzt ist es unsere Absicbt von der Erfabrung auszugebn. Nun lehrt uns zwar diese, dass sebr baufig, wabrend kleiner nocb beob- acbtbarer Zeiten der Weg eines Punktes eines Korpers um so genauer 288 Ludwig Boltzmann: der verflossenen Zeit proportional ist, je kiirzer diese ist, woraus wir wolil auf die Differenzirbarkeit der Functionen 4>, %, i^ schliessen konnen. AUein wir kennen auch Beispiele sehr rascher Oscillationen und konnen nioht exact beweisen, ob nicht in gewissen Fallen Bewegungen vorhanden sind, wie z. B. die Warmebewegungen der Molekiile, welche durch eine der Weierstrass'schen Function ahnliche besser als durch eine Differen- zirbare dargestellt werden. Docli sind dies allerdings Dinge von gering- erer Wichtigkeit und wir woUen daher die Differenzirbarkeit der Coor- dinaten nach der Zeit unsern weitern Uberlegungen zu Grunde legen. Unter dieser Voraussetzung existiren die Ableitungen der Functionen <^, %, i/p nach der Zeit. Wir nennen sie die Componenten der Geschwin- digkeit des Punktes A des Korpers. Die Geschwindigkeit selbst konnen wir in folgender Weise construiren : Es befinde sich der markirte Punkt des Korpers zur Zeit tin A zur Zeit t + Wva. B, so dass also OA, und OB die dazu gehorigen Lagenvectoren sind. Die Gerade AB ist dann das, was man die Differenz der beiden Vectoren nennt. Wir construiren nun einen Vector, welcher die Richtung AB hat und dessen Lange der Quotient AB dividirt durch ht ist. Ferner suchen wir die Grenze, wel- cher sich dieser Vector in Grosse und Richtung nahei't, wenn ht immer mehr abnimmt. Die so bestimmte Lange ist die Geschwindigkeit, die Richtung aber, der sich der Vector nahert, die Geschwindigkeitsrichtung. Wir wollen hier noch eine Bemerkung anfiigen. Damit wir den Weg durch die verflossene Zeit dividiren konnen, miissen beide durch reine Zahlen ausgedriickt sein und wir haben gesehen wie dies geschieht. Wahlen wir die Langeneinheit a mal so gross, so wird die Zahl, welche nun eine gewisse Lange ausdriickt a mal kleiner. Es ist moglich, dass auch andere Grossen dieselbe Eigenschaft haben, dass sie durch a mal kleinere Zahlen ausgedriickt erscheinen, sobald wir die Langeneinheit a mal vergrossern. Von alien so beschaffenen Grossen sagen wir dann, dass sie die Dimension einer Lange haben. Jede Lange, (der Weg, die Coordinaten etc.) hat daher selbstverstandlich die Dimension einer Lange. Die Zahl, welche uns die Zeit t ausdriickt, ist natiirlich unabhangig von der gewahlten Langeneinheit, wird aber a mal kleiner, wenn wir die Zeiteinheit a mal grosser wahlen und wir sagen von jeder Grosse, welche durch eine Zahl von dieser Eigenschaft ausgedriickt wird, sie habe die Dimension einer Zeit. Die Geschwindigkeit wird durch den Quotienten zweier Zahlen gemessen, wovon der Zahler die Dimension einer Lange, der Nenner die einer Zeit hat. Sie ist also sowohl von der Wahl der Zweite Vorlesung. 289 Langen als auch von der Zeiteinheit abhangig, und wird a mal kleiner, weun die erstere a mal grosser, dagegen a mal grosser, wenn die letztere a mal grosser gewahlt wird. Wir sagen daher ihre Dimensionen sind : Lange dividirt durch Zeit, was aber hiemit jeder geheimnisvollen oder metaphysischen Bedeutung entkleidet ist. Man redet vielfach. statt von dem Quotienten der Zahl welche die Zeit ausdriickt in die, welche die Lange ausdriickt, einfacb von dem Quotienten einer Zeit, in eine Lange. Man hat da den Begriff der Division erweitert und muss den Quotienten einer Zeit in eine Lange ganzneu definiren, geradeso wie man den Begriff einer negativen oder gebrochenen Potenz neu definirt und darunter einen Bruch respektive eine Wurzel versteht. Der Vortheil dieser neuen Defi- nition besteht darin, dass man vielfach Rechnungsregeln, welche fiir die friihere Definition bewiesen wurden auf die neue Definition iibertragen kann. Man darf aber nicht a priori schliessen, dass dies von alien Rech- nungsregeln gilt ; es muss vielmehr die Ubertragbarkeit von jeder Rech- nungsregel besonders bewiesen werden. Ebenso ist es eine voUstandig neue Definition, wenn wir unter der zweiten oder dritten Potenz eines Cen- timeters die geometrische Figur eines Quadrats oder Wiirfels von 1 cm. Seitenlange verstehen und es muss gerechtfertigt werden, in wie weit diese neue Definition zweckmassig ist. Die Fixirung des Begriffs der Beschleunigung und ihrer Componenten nach den drei Coordinaten- richtungen hat nun nicht mehr die mindeste Schwierigkeit. Sei A C der Vector, welcher in Grosse und Richtung die Geschwindigkeit zur Zeit t, OD der, welcher sie zur Zeit t-\-ht darstellt. Wir ziehen die Gerade Ci), also die Differenz der beiden Vectoren. Dieselbe wird sehr klein sein, wenn ht sehr klein ist. Wir erhalten aber eine endlich bleibende Gerade, wenn wir sie im Verhaltnis der Zeiteinheit zur Zeit ht vergross- ern, wobei ihre Richtung unverandert bleiben soil. Die Grenze, welcher sich der so vergrosserte Vector QD mit abnehmendem ht nahert, heisst der Beschleunigungsvector, seine Lange stellt die Grosse, seine Richtung die Richtung der Beschleunigung dar. Seine Componenten in den drei Coordinatenrichtungen heissen die Componenten der Beschleunigung. Man iiberzeugt sich in bekannter Weise, dass es die zweiten Ableitungen der friiher mit ;^, <^, i/r bezeichneten Functionen sind. Wir miissen daher die Voraussetzung machen, dass diese Functionen auch zweite Ableitungen haben. Man Iiberzeugt sich auch leicht, dass die Zahl, welche die Grosse der Beschleunigung ausdriickt wieder sowohl von den gewahlten Langen als von der gewahlten Zeiteinheit abhangt und a mal 290 Ludwig Boltzmann: kleiner wird, wenn erstere a mal so gross, dagegen a? mal grosser, wenn die Zeiteinheit a mal so gross gewahlt wird. Wir werden daher sagen, die Beschleunigung hat die Dimensionen : Lange dividirt durcli das Quadrat der Zeit. Wir konnen wieder die Beschleunigung als solche definiren als den Quotienten einer Zeit in eine Geschwindigkeit oder des Quadrats einer Zeit in eine Lange ; diirfen aber die letzteren Defini- tionen nur mit einer gewissen Vorsicht anwenden, da sie Erweiterungen des Begriffs der allgebraischen Division darstellen, fiir welche die An- wendbarkeit der verschiedenen in der Algebra bewiesenen Rechnungs- regeln erst neu erprobt werden muss. Nachdem wir diese Begriffe moglichst an die Erfahrung ankniipfend entwickelt haben, miissen wir zur Aufstellung der Gesetze iibergehn, nach welchen die Bewegung der Korper geschieht. Wir werden da natiirlich wieder nicht mit Aufstellung der Gesetze fiir die Bewegung eines materiellen Punktes beginnen, da dieser eine reine Abstraction ist. Wir werden uns natiirlich auch nicht der Illusion hingeben, dass wir ohne alle Abstractionen auskommen. Wir konnen nach meiner Ansicht nicht einen einzigen Satz aussagen, welcher wirklich nur eine reine Erfahrungs- thatsache ware. Die einfachsten Worte wie gelb, siiss, sauer etc., welche blosse Empfindungen anzugeben scheinen, driicken schon Begriffe aus, die bereits aus vielen Erfahrungsthatsachen durch Abstraction gewonnen worden sind. Wenn Gothe sagt, die Erfahrung ist nur zur Halfte Erfahrung so will er mit diesem scheinbar paradoxen Satze sicher aus- driicken, das wir bei jeder begrifflichen Auffassung der Erfahrung oder Darstellung derselben durch Worte schon iiber die Erfahrung hinaus- gehen miissen. Die oft aufgestellte Forderung, dass die Naturwissen- schaft nie iiber die Erfahrung hinausgehen diirfe, soUte daher nach meiner Ansicht dahin ausgesprochen werden, dass man nie zu weit iiber die Erfahrung hinaus gehen diirfe und nur solche Abstractionen ein- fiihren soUe, die sich bald wieder an der Erfahrung priifen lassen. Wir werden auch nicht das Tragheitsgesetz an die Spitze stellen. Dieses mag theoretisch das einfachste Gesetz der Mechanik sein, physikalisch ist es keineswegs das einfachste, da es eine ganze Reihe von Abstractionen zur Voraussetzung hat, worauf ich schon friiher hingewiesen habe. Als die beiden physikalisch einfachsten Falle erscheinen uns vielmehr erstens der der relativen Ruhe zweitens, der freie Fall eines schweren Korpers. Wie wir sahen, konnen wir einen Korper niemals ganz den aussern Ein- fliissen entziehen. Wenn nun solche Einfliisse vorhanden sind, von denen Zweite Vorlesung. 291 jeder fiir sich allein eine Bewegung erzeugen wiirde, wenn aber unter dem vereinten Einflusse aller relative Ruhe gegen das Bezugssystem Platz greift, so sagen wir alle Ursachen der Relativbewegung compensiren sich. loll konnte mich auch des gebrauchlichsten Ausdruckes bedienen, die Krafte halten sich das Gleichgewicht, allein ich will absichtlich die gewohn- ten Ausdriicke vermeiden, well wir mit denselben unwillkiirlich eine Menge von Vorstellungen verbinden, die sich dann, ohne dass wir es woUen, unkontrolirt in unsere Schlussweise einschmuggeln und so den Schein erwecken, als batten wir etwas bewiesen, was wir nur gemass unserer alten Denkgewohnheit und Ideenassociation ohne Begriindung beigefiigt haben. Ich will ausserdem das Wort Kraft vermeiden, ehe ich gleieh- zeitig auch von der Masse sprechen kann. Endlich betrachten wir hier nur die relative Bewegung. Es kann aber ein Korper relativ gegen seine Umgebung ruhen, ohne dass sich die auf ihn wirkenden Krafte das Gleichgewicht zu halten brauchen wie ein Korper, der relativ gegen einen mit Beschleunigung sich bewegenden Lift ruht. Wir betrachten nun einen bestimmten Fall, wo die Ursachen der relativen Bewegung compensirt sind. Ein schwerer Korper sei an einen diinnen Faden aufgehangt. Wir konnten da meinen, dass gar keine Bewegungsursachen vorhanden sind. Doch finden wir, dass sofort Bewegung eintritt, wenn wir den Faden entfernen. Es miissen also mindestens zwei Bewegungsursachen vorhanden gewesen sein, welche sich gegenseitig compensirten. Wenn wir die nach Entfernung des Fadens eintretende Bewegung analysiren, so finden wir, dass sie, wenn gewisse allgemeine Bedingungen erfiillt sind, sehr angenahert immer in derselben Weise vor sich geht. Diese allgemeinen Bedingungen sind folgende. Die Oberflache des Korpers darf nicht zu gross gegen dessen Gewicht sein, es darf keine heftige Luftbewegung um den Korper herum stattfinden, der Faden muss ohne Erschiitterung durchgeschnitten oder ruhig durch Verbrennung oder sonst wie vernichtet worden sein. Dieselbe Bewegung tritt auch ein, wenn wir den Korper anfangs mit der Hand oder einer Zange oder einer sonstigen Vorrichtung halten und plotzlich ohne Erschiitterung sich selbst iiberlassen. Das Charakteristische aller dieser Anfangs- bedingungen besteht darin, dass sammtliche Punkte des Korpers in den ersten Momenten der Bewegung sehr kleine Geschwindigkeiten haben, Wir konnen daher annahernd voraussetzen, dass sammtliche Punkte des Korpers im ersten Momente der Bewegung keinerlei Anfangsgeschwindig- 292 Ludwig Boltzmann: keit batten. Wenn diese Bedingungen erfiillt sind, so lehrt die Erfahr- ung, dass der Korper stets fast genau nach denselben Gesetzen sich bewegt, wo immer er in der Nabe der Erdoberflacbe sicb selbst iiberlassen worden sei. Die Bewegung bestimmen wir dabei natiirlicb einstweilen relative gegen die Erde. Wenn wir uns nocb auf einen nicbt zu grossen Tbeil der Erdoberflacbe bescbranken, so ist aucb die Ricbtung der Bewegung iiberall dieselbe ; es ist die des Fadens, der friiber den Korper trug. Die Erfahrung lebrt nun fiir diese Bewegung die folgen- den Gesetze. Erstens der Korper bewegt sicb parallel zu sicb selbst, d. h. alle Punkte desselben legen in gleicben Zeiten, gleicbe und gleicbgericb- tete Wege zuriick. Da also die Babn fiir jeden Punkt dieselbe ist, so kann man sie als die Babn des ganzen Korpers bezeicbnen. Zweitens, alle diese Wege sind geradlinig. Drittens, die Gescbwindigkeit wacbst fort- wabrend, die Beschleunigung ist jedocb uberall, zu alien Zeiten und sogar fiir alle Korper dieselbe. Dass diese Gesetze in der Natur nur mit grosserer oder geringerer Annaberung realisirt sind, wurde bereits besprocben. Wir konnen nun dasselbe Experiment wiederholen, nur dass wir dem Korper im Momente, wo wir ibn sicb selbst iiberlassen einen Stoss geben, oder sonst wie bewirken, dass er schon anfangs eine Gescbwindigkeit bat. Da wir die Satze vom Scbwerpunkt und der Drebung der Korper nocb nicbt kennen gelernt baben, so miissen wir uns dabei auf die Falle bescbranken, wo sicb der Korper wieder parallel zu sicb selbst bewegt. Es wird dies zwar nicbt immer eintreten und wir konnen die Bedingungen dafiir, dass es eintritt nocb nicbt angeben, aber in vielen Fallen wird dies stattfinden und diese Falle wollen wir vorlaufig allein betracbten. In aUen diesen Fallen legen wieder alle Punkte des Korpers gleicbe Babnen zuriick, welche wir also als die Babn des Korpers bezeicbnen konnen. Die ganze Bewegung kann wieder dabin bescbrieben werden, dass die Bescbleunigung immer vertikal nacb abwarts gericbtet und iiberall zu alien Zeiten und fiir alle Korper dieselbe ist. Da wir nun geseben baben, dass die Bewegung, wenn wir sie an verschiedenen Stellen im Zimmer oder in dessen Umgebung beginnen lassen, immer in ganz gleicber Weise vor sicb gebt, so miissen wir scbliessen, dass die Beweg- ungsursacbe, welcbe wir Kraft nennen, daselbst iiberall unveranderlicb dieselbe ist. Anderseits ist aucb die Bescbleunigung unveranderlicb dieselbe, wir konnen daber scbliessen, dass wenigstens in diesem speziellen Falle die Bescbleunigung das fiir die Kraft Massgebende ist und well Dritte Vorlesung. 293 erstere iiberall vertikal nach abwarts gericlitet ist, so sagen wir auf den Korper wirkt eine constante vertikal nach abwarts gerichtete Kraft die Schwere. Deittb Vorlesung. Um tiefer in die Gesetze der Bewegungen einzudringen, mussten wir jetzt die nachst einfachsten Falle betrachten. Ein naives Gemiit konnte da wohl meinen, dass wir nun die Gesetze nach denen ein Grashalm wachst, untersuchen sollten. Leider aber wissen wir iiber diese noch heute fast gar nichts. Besser ware es schon die Gesetze der Wirkung gespannter Schniire, Federn etc. zu betrachten. AUein auch da treten die Beweg- ungsgesetze nicht in grosster Einfachheit hervor. Der historische Gang war vielmehr der folgende. Nachdem Galilei die Bewegungsgesetze soweit wir sie bisher betrachtet haben, gefunden hatte, suchte Newton sie vor allem auf die Bewegung der Gestirne anzuwenden und auch von ihm gilt, was Schiller von Wallenstein sagte: ^^Fiirwahr ihn hat kein Wahn betrogen als er auf warts zu den Sternen sah." Dem Laufe der Sterne hat er die Bewegungsgesetze abgelauscht, auf denen alle heute in der Technik und Machinenlehre benutzten Formeln ja iiberhaupt unsere ganze moderne Naturkenntnis basirt. Freilich bringt der Ubergang zur Sternenwelt manche Unbequemlichkeit mit sich. Erstens miissen wir um einfache Gesetze zu erhalten, unser altes Bewegungssystem, als welches der Erdkorper diente, verlassen und ein relativ gegen den Fixsternhimmel sich nicht drehendes Coordinatensystem wahlen. Zweitens ist auch die Bedingung, das die Planeten sich parallel zu sich selbst bewegen nicht erfiillt. An ihre Stelle tritt der Umstand, dass ihre Entfernungen vom Beobachter so gross sind, dass ihre einzelnen Theile iiberhaupt nur schwer unterschieden werden konnen, so dass wir also in der ersten Annaherung mit welcher wir uns wieder begniigen, iiberhaupt die Bahnen der ver- schiedenen Punkte eines und desselben Planeten gar nicht unterscheiden konnen. Wir konnen also wohl auch annehmen, dass die Gesetze dieselben waren, wenn die Himmelskorper sich parallel zu sich selbst bewegten. Wir kommen also hier einestheils dem Begriffe des materiellen Punktes sehr nahe, da die Ausdehnung der bewegten Korper so klein gegen die Lange ihrer Bahn ist, dass letztere fiir alle Punkte der Korpers merklich gleich wird. Anderseits aber sind wir von dieser Idee so weit entfernt als moglich, da wir es mit Korpern zu thun haben, die nichts weniger als materielle Punkte, vielmehr oft grosser als unser ganzer Erdkorper sind. 294 Ludwig Boltzmann : Die Beobachtung und Messung lehrt, dass sich im Weltraume haufig um einen Centralkorper ein System von Himmelskorpern bewegt, welche wir die Trabanten nennen. "Wir erhalten die einfachsten Gesetze, wenn wir die Bewegung der Trabanten auf ein Coordinatensystem beziehen, dessen Anfangspunkt im Mittelpunkte des betreffenden Centralkorpers liegt und dessen Axen dreien fest mit dem Fixsternhimmel verbundenen Geraden stets parallel bleiben. Fiir die Bewegung der Trabanten gelten erfahrungsgemass die drei Keppler'schen Gesetze. Da beim freien Falle die Bescbleunigung eine so wichtige RoUe spielte, so wollen wir auch in diesem Falle die Bescbleunigung berechnen, welcbe irgend ein Tra- bant in seiner Bewegung erfahrt. Diese Rechung ist sehr bekannt und ganz leicht. Es hat sie Kircbhoff in seinen Vorlesungen iiber Mechanik in sebr eleganter Form durcbgeftLhrt. Man findet aus dem ersten und zweiten Keppler'schen Gesetze, dass sie fiir jeden Trabanten zu jeder Zeit gegen den Centralkorper gerichtet und dem Quadrate des Abstandes r k von demselben verkehrt proportional, also in der Form — darstellbar ist. Aus dem dritten Keppler'schen Gesetze ergibt sich ausserdem, dass die Constante k von Centralkorper zu Centralkorper verschieden ist, aber fiir alle Trabanten eines und desselben Centralkorpers denselben Wert hat. Da wir schon bei der Schwere die Bescbleunigung als das mass- gebende fiir die Bewegungsursache oder Kraft erkannt haben, so wollen wir auch hier sagen, der Centralkorper iibt auf jeden Trabanten eine Kraft aus, welcbe die Richtung der vom Mittelpunkte des Trabanten gegen den des Centralkorpers gezogenen Geraden hat und der Lange dieser Geraden verkehrt proportional ist. Diese ist einstweilen sonst nichts als ein anderer Ausdruck fiir die Thatsache des Vorhandenseins dieser Bescbleunigung. Newton hat diesen Satz sofort enorm verallge- meinert indem er annahm, dass iiberhaupt jeder Himmelskorper auf jeden andern ja jedes materielle Theilchen auf jedes andere eine solche Kraft ausiibt. Wenn daher ein Himmelskorper mehreren andern so nahe ist, dass er von ihnen eine merkliche Einwirkung erfahrt, so haben wir den Fall, dass er gleichzeitig aus verschiedenen Ursachen verschiedene Be- schleunigungen nach verschiedenen Richtungen erfahrt. Da wir die Bescbleunigung durch einen Vector dargestellt haben, so ist es nicht die einzig notwendige, aber doch bei weitem die nahe liegendste, einfachste Annahme, dass sich diese BeschleunigUDgen wie Vectoren addiren. In der That zeigt sich, dass man unter dieser Annahme immer Ubereinstim- Dritte Vorlesung. 295 mung mit der Erfalirung erhalt. Es ergeben sich die Storungen der Plane- ten untereinander, der Monde durch die Sonne und durch die Planeten in genauer Ubereinstimmung mit der Erfahrung. Man kann jetzt auch den Horizont erweitern und alle Himmelskorper auf ein und dasselbe mit dem Fixsternhimmel fest verbundene Coordinatensystem beziehen und erhalt auch die Bewegung der Centralkorper gegen dieses Coordinaten- system in Ubereinstimmung mit der Erfahrung. Die Schwere erweist sich als identisch mit der Anziehung des Erdkorpers auf den schweren Korper. Schliesslich zeigen die Erscheinungen der Ebbe und Flut, die Versuche von Cavendish, Maskelyne, Airy etc. die Richtigkeit der Aus- dehnung des Newton'schen Gesetzes auf die irdischen Korper. Da die wirkliche Beschleunigung immer die Vectorsumme der verschiedenen von den wirkenden Korpem erzeugten Beschleunigung ist, so folgt jetzt als spezieller Fall des Newton'schen Gesetzes, dass ein Korper, welcher von alien iibrigen so weit entfernt ware, dass keiner derselben eine Wirk- ung auf ihn ausiiben wiirde, zu alien Zeiten die Beschleunigung Null erfiihre. Wir erhalten also erst jetzt das Tragheitsgesetz. Selbstver- standlich ist hiemit iiber die Ursache der Newton'schen Kraft, ob die- selbe eine direkte Fernwirkung ist oder durch ein Medium vermittelt wird, nicht das mindeste prajudicirt. Wir konnten auch jetzt schon den Begriff der Masse ableiten. Die Massen zweier Centralkorper wiirden sich ja wie die ihnen entsprechenden Werte der Constanten h des Gravi- tationsgesetzes verhalten und durch den Cavendish'schen Versuch konnte diese Definition auch auf irdische Korper ausgedehnt werden. AUein wir wiirden da die Proportionalitat der Constante k mit der als Tragheits- widerstand definirten Masse vorwegnehmen, was offenbar ein logischer Fehler ware. Wir mlissen daher zum Begriffe der Masse auf ganz an- derem Wege zu gelangen suchen. Wir haben bisher als das Massge- bende fiir die Kraft die Beschleunigung betrachtet. Es konnte nun als das einfachste erscheinen, die Grosse der Beschleunigung, welche ein Korper durch einen andern erfahrt, einfach als die Grosse der Kraft zu bezeichnen, welche der letztere auf den ersteren ausiibt. Es geschieht dies auch manches Mai und man bezeichnet die so definirte Kraft als die beschleunigende Kraft. AUein im AUgemeinen ist es besser einen andern Begriff einzufiihren. Wir denken namlich beim Worte Kraft in erster Linie an die Muskelanstrengungen, welche wir ausiiben konnen. Nun liegt freilich kein Grund vor, ja es ware ganz verkehrt anzunehmen, dass jedes Mai, wenn unbelebte Korper Krafte aufeinander ausiiben etwas 296 Ludwig Boltzmann: vorhanden sein miisse, was diesen Muskelanstrengungen irgendwie ent- spricht. Allein es wird sich doch empfehlen, wenn wir die Bezeich- nungen so wahlen, dass sie sich den durch diese Muskelanstrengungen erworbenen Begriffen moglichst gut anschliessen. Wir sahen, dass alls Korper durch die Schwere die gleiche Beschleunigung erfahren. Wiirden wir nun diese ohne weiteren Factor als Mass der Kraft wahlen, so ware die Kraft, welche die Schwere auf sie ausiibt, (das Gewicht) fiir alle Korper dasselbe. Nun lehrt aber die tagliche Erfahrung, dass die Mus- kelanstrengung welche wir brauchen, um den Fall aufzuheben, fiir ver- schiedene Korper sehr verschieden ist. Wollen wir daher mit unseren Vor- stellungen im Einklang bleiben, so iniissen wir sagen, dass auch die Schwere auf die verschiedenen Korper sehr verschiedene Krafte ausiibt, dass aber die Korper von grosserem Gewichte dieser beschleunigenden Wirkung der Schwere einen grosseren Widerstand, den Tragheitswiderstand, die Masse, entgegensetzen, so dass erst in folge beider Umstande zusammen alle Korper die gleiche Beschleunigung erfahren. Um die Masse in dieser Weise als Tragheitswiderstand zu definiren, miissen wir an verschiedene Korper die gleiche Kraft anbringen. Das Verhaltnis ihrer Massen kon- nen wir dann als das verkehrte Verhaltnis der Beschleunigungen defi- niren, die sie durch gleiche Krafte erhalten. Aber darin liegt eben die grosste Schwierigkeit wie man die Gleichheit der Krafte, wenn diese auf verschiedene Korper wirken, ohne logischen Fehler feststellen soil. Man konnte zwei Korper dem Zuge gleich beschaffener gleich gespannter Schniire oder elastischer Federn unterwerfen. Allein da miisste man erst durch complicirte der Erfahrung entnommene Argumente als wahr- scheinlich hinzustellen suchen, dass gleich beschaffene Schniire auf zwei ganz verschiedene Korper dieselben Krafte ausiiben, was gewiss nicht a priori evident ist. Wir konnten auch nach Mach einfach den Satz der Gleichheit der Wirkung und Gegenwirkung postuliren. Wenn dann bloss zwei Korper in Wechselwirkung begrifPen sind, so ware die Gleich- heit der Krafte, welche auf beide Korper wirken evident. Wenn sie sich zudem nur Parallelverschiebungen ertheilen, so ware das Verhaltnis ihrer Massen einfach zu deiiniren, als das verkehrte Verhaltnis der Be- schleunigungen, welche an ihnen zu beobachten sind. Allein bei der Wirkung dazwischen gebrachter Schniire, Faden etc. haben wir eigent- lich schon immer mehr als zwei in Wechselwirkung begriffene Korper und es wiirde auch die Deformation dieser Zwischenkorper in Betracht zu Ziehen sein. Der von Mach angenommene Fall konnte also in reiner Dritte Vorlesung. 297 Weise eigentlich nur bei directer Fernwirkung vorkommen und es ware selir misslich, wenii man vom rein empirischen Standpunkte aus die directe Fernwirkung a priori annehmen miisste. Streintz sucht eine einwurfsfreie Definition in folgender Weise zu gewinnen. Er denkt sich irgend ein System beliebiger Korper. In demselben kommen zwei Korper K^ und K^ vor. Diese ruhen im ersten Augenblicke und beginnen sich dann mit Beschleunigung aber jeder parallel zu sich selbst zu be- wegen. Es soil nun die Bewegung beider Korper dadurch aufgehoben werden konnen, dass man sie starr mit einander verbindet. Dies ver- wendet er als Kriterium, dass friiher auf jeden genau die gleiche Kraft wirkte, well sich beide Krafte durch blosse starre Verbindung jetzt auf- heben. Er nennt diese Begriffsbestimmung der Gleichheit der Kraft die statische. Sie hat das fiir sich, dass sie das Princip der Gleichheit der Wirkung und Gegenwirkung involvirt, wie man sofort sieht, wenn man den speziellen Fall betrachtet, dass das ganze System bloss aus den zwei auf einander wirkenden Korpern K^ und K^ besteht. Sie hat aber doch auch manches Willkiirliche. Dass durch die starre Verbindung die Wirk- ung der iibrigen Krafte nicht gestort wird, kann wieder hochstens erfahrungsmassig wahrscheinlich gemacht werden. Dass die Verbin- dungskrafte sich zu den iibrigen addiren, setzt schon gewisse Satze der Statik voraus. Noch grosser wiirden die Schwierigkeiten, wenn, die Korper K^ und K^ anfangs in Bewegung begriffen waren. WoUte man da nicht von vornherein annehmen, dass die Krafte bloss von der rela- tiven Lage abhangen, durch den aus der plotzlichen starren Verbindung resultirenden Stoss nicht gestort werden und Ahnliches, so miisste ihre Beschleunigung durch eine die Bewegung gestattende und auf beide Korper bloss beschleunigend wirkende plotzlich eingeschaltete Feder aufgehoben werden. Halt man einmal an der Streintz'schen Vorstellung fest, so hat die Definition der Massenverhaltnisses welter keine Schwierig- keit. Die Massen der beiden Korper K^ und K^ verhalten sich dann umgekehrt, wie die Beschleunigungen, die sie im ersten Falle, wo keine starre Verbindung vorhanden war, erhielten, da ja damals auf beide gleiche Krafte wirkten. Natiirlich ist sowohl bei der Mach'schen als bei der Streintz'schen Definition noch immer erforderlich, sich auf besondere Erfahrungssatze zu berufen, vermoge welcher das Massenverhaltnis zweier Korper immer gleich ausfallt, unter was immer fiir Umstanden man den hiezu dienenden Versuch angesteUt haben mag und vermoge welcher das Verhaltnis der Massen der Korper K^ and K^ stets gleich 298 Ludwig Boltzmann: dem Producte der beiden Massenverhaltnisse der Korper K^, K^ und K^ K^ ist. Zu bemerken ist nocb, dass wir nur das Verbaltnis zweier Massen bisher definirt haben. Um die Masse durcb eine Zahl auszudriicken, miissen wir irgend eine Masse willkiirlich als eine neue Einheit wahlen. Von alien Grossen, welclie daher durch Zablen ausgedriickt werden, deren Grosse von der Wahl der Masseneinheit abhangig ist, werden wir sagen dass sie gewisse Dimensionen beziiglich der Masse haben. Haben wir den BegrifE der Masse in der einen oder andern Weise festgestellt, so hat die Definition der Kraft im gewohnlichen Sinne oder wie man auch sagt, der bewegenden Kraft keine Schwierigkeit mehr. Dieselbe ist das Product der Masse in die Beschleunigungen und hat daher beziiglich der Masse die Dimension eins. Da sich die Beschleunigungen wie Vectoren addi- ren, so gilt dies auch von den Kraften, wenigstens insoweit wir diese bisher betrachtet haben. Dieser Satz vom Kraftenparallelogramm sowie die iibrigen bisher entwickelten Satze, konnen nun auch auf die Statik und Dynamik der durch gespannte Faden oder durch Federn erzeugten Druck und Zugkrafte iibertragen werden. Natiirlich zunachst bloss in dem idealen Falle, dass die Bewegung der einzelnen Theile der Faden und Federn nicht betrachtet wird und dass die bewegten Korper sich stets parallel zu sich selbst bewegen. Es konnte so z. B. die Mechanik der Atwood'schen Fallmaschine mit Hilfe des bisher Entwickelten ohne weiteres discutirt werden. Aus dem Umstande, dass sich das Newton'sche Gravitationsgesetz in symetrischer "Weise beziiglich beider wirkender Korper aussprechen muss und dass die Anziehungsconstante K fiir alle Trabanten desselben Cen- tralkorpers gleich ist, leitet man leicht ab, dass diese gleich dem Producte der Massen der beiden wirkenden Korper in eine fiir das ganze Universum constante Grosse sein muss, wahrend die Thatsache, dass alle Korper durch die Schwere die gleiche Beschleunigung erhalten, schon lehrt, dass das Gewicht der Masse proportional sein muss. Wir sind aber noch sehr weit davon entfernt aus den bisher entwickel- ten Grundlagen sammtliche Satze der Mechanik ableiten zu konnen. Wir haben ja bisher bloss die Bewegung eines festen Korpers parallel zu sich selbst betrachtet und haben den wichtigen Begriff des Angriffspunk- tes einer Kraft noch gar nicht gewonnen. Um diesen zu erhalten, um die Drehung der starren Korper, die Deformationen der elastischen und die Bewegungen der fliissigen behandeln zu konnen, miissen wir von neuen Dritte Vorlesung. 299 Thatsachen ausgehen. Wenn ein Faden an einem Korper befestigt ist oder eine Feder auf eine einzige Stelle desselbea driickend wirkt, so gibt es stets eine ganz kleine Partie des Korpers, welche znnachst von der Kraft afficirt wird. Losen wir diese los und stellen einen kleinen Zwischenraum zwischen ihr und den iibrigen Tbeilen des Korpers ber, so wird derselbe erst wieder afficirt, wenn dieser Zwiscbenraum durcb die Bewegung des kleinen abgetrennten Tbeiles sicb ausgefiillt bat. Wir nennen daber diesen Tbeil die Angriffstelle und konnen sie wieder zu einem Angriffspunkte idealisiren. Wir miissen nun nocb die bekann- ten Satze liber die Versetzbarkeit von Kraften an starren Korpern als idealisirte Erfabrungstbatsacben beifiigen. Mittelst derselben konnen wir dann in ebenfalls binlanglicb bekannter Weise die Satze iiber das Gleicbgewicbt von beliebigen Kraften, welcbe auf einen starren Korper wirken, die Satze von den statiscben Momenten ableiten. Wir scblagen bier insoferne einen analogen Weg ein, wie Streintz bei der Definition der Masse, als wir von der Statik ausgeben und erst von dieser zur Dynamik gelangen. Die Satze von den statiscben Momenten haben wir da freilicb zunacbst bloss fiir eine begrenzte Zabl von Kraften bewiesen, von denen jede nur auf einen einzelnen Punkt des Korpers wirkt. Wir miissen dazu nocb die Annabme binzufiigen, dass man im Falle, wo die Krafte den Korper oder einen ausgedebnten Tbeil desselben als Ganzes anfassen die Saebe immer so anseben kann, als ob sie auf sehr viele respective unendlicb viele Punkte seiner Oberflacbe oder seines Innern gerade so wirken wiirden, als ob an jedem dieser Punkte eine ein wenig gespannte Scbnur oder eine ein wenig driickende Feder befestigt ware. So muss mann z. B. von der Scbwere annebmen, das sie gleicbmassig auf alle Punkte des scbweren Korpers wirkt* Einen andere Weg, auf welcbem man den tjbe^^ng von der Bewegung parallel zu sicb selbst zur Drebbewegung veTsucben konnte, will icb bier nur ganz kurz andeuten. Wir konnen aus dem Principe der Erbaltung der lebendigen Kraft folgenden Satz ableiten. Wenn auf einen festen Korper eine Kraft wirkt, die ibn nur parallel zu sicb selbst zu bewegen sucbt, so muss immer eine ibrer Ricbtung parallele Gerade, welcbe wir die Angriffslinie nennen woUen, von solcber Bescbaffenbeit existiren, dass wenn man einen beliebigen Punkt des festen Korpers, welcber auf derselben liegt, festbalt, der Korper ins Gleicbgewicbt kommen muss. In gleicber Weise kann man beweisen, dass, wenn zwei feste Korper K^ und K^ so in Wechsel- wirkimg begriffen siad, dass jeder dem andern nur eine Bewegung parallel 300 Ludwig Boltzmann : zu sich selbst ertheilt, Wirkung und Gegenwirkung gleich sein muss und die AngrifEslinien zusammenfallen miissen. Denkt man sich dann einen Punkt A der gemeinsamen Angriffslinien festgehalten, so muss das ganze System ins Gleichgewicht kommen. Jeden solchen Punkt konnen wir als Angriffspunkt der Kraft betrachten. An diesen Begriff des Angriffs- punktes, konnen dann ebenfalls die Satze von den statischen Momenten gekniipft werden. Hat man einmal diese Satze so oder so gewonnen, so muss man zur Zerlegbarkeit der Korper in Volumelemente iibergehen. Man fiihrt wieder als Erfahrungssatz an, dass sehr viele Korper, wenigstens mit geniigender Annaherung in zwei Korper von je der halben Masse zerlegt werden, wenn man sie in zwei Theile von gleicbem Volumen zerschneidet. Analog, wenn man sie in drei gleiche Theile theilt u. s. f. Denkt man sich dies ins Unendliche fortgesetzt, so gelangt man zu einem Satze, den man dahin aussprechen kann dass diese Korper aus unendlich vielen Volumelementen dv bestehen und die in jedem Volumelemente enthaltene Masse dm — pdv ist. Bei andern inhomogenen Korpern gilt dies wenig- stens nahezu fiir jeden kleinen Volumtheil des Korpers, so dass wir die- selbe Formel anwenden konnen, wenn wir p als von Punkt zu Punkt veranderlich betrachten. Was nun die Krafte anbelangt, welche die Volumelemente fester Korper aufeinander ausiiben, so muss man annehmen, dass jedes Volum- element nur auf die unmittelbar benachbarten wirkt und dass es auf alle der Trennungsflache anliegenden Punkte Krafte ausiibt, welche gerade so wirken, als ob daran ziehende gespannte Faden oder driickende, auf- gestiitzte Stabe befestigt waren. Wenn die Trennungsflache eben und geniigend klein ist, so muss man zudem annehmen, dass diese Krafte gleichmassig auf alle der Trennungsflache anliegenden Punkte wirken. Diese Satze konnen wol kaum direct erfahrungsmassig bestatigt werden und finden ihre Rechtfertigung nur in der nachherigen Ubereinstimmung der aus ihnen entwickelten Satze mit der Erfahrung. Wendet man den Satz von den statischen Momenten auf ein Volumelement an, so findet man, dass im Falle des Gleichgewichtes die auf ein zur a;-axe senkrechtes Flaehenelement in der y-Richtung wirkende Kraft gleich sein muss der auf ein gleiches zur y-Richtung senkrechtes Flaehenelement in der a;-Richtung. wirkenden Kraft, was wir den Satz X nennen woUen. Zu den bisher aufgestellten Annahmen welche wir uns als durch die Erfahr- ung geniigend motivirt dachten, sind noch die folgenden hinzuzunehmen. Dritte Vorlesung. 301 Erstens, die elastische Kraft ist bloss von der augenblicklichen Gestaltver- anderung des betreffenden Korpers, nicht von den friiheren Zustanden desselben, noch auch von der Geschwindigkeit seiner Theilchen aibhangig. Zweitens, jedes Volumelement bewegt sich nach den Gesetzen, welche wir bisher bloss fiir die Bewegung parallel zu sicb selbst abgeleitet haben. Unter diesen Annahmen erhalt man dann sofort die Gleicbungen der gewobnlicben Elasticitatslehre. Dieselben gelten natiirlich wieder nur fiir einen idealen festen Korper, alle festen Korper zeigen innere Reibung und elastische Nacbwirkung, welche wir bisher ausgeschlossen haben. Auch der Satz, welchen wir den Satz X nannten, ist keineswegs a priori evident. Lord Kelvin hat sich einmal den Lichtather, sonst ganz mit den Eigenschaften begabt gedacht, welche wir an festen Korpern wahrnehmen, nur dass er die Richtigkeit dieses Satzes X fallen liess. Wir woUen uns hier nicht in eine Discussion einlassen ob durch die Annahme Lord Kelvins das Verhalten des Lichtathers erklart werden kann. Es geniigt uns, dass derselbe ohne alle inneren Widerspriiche Bewegungsgleichungen fiir die Volumelemente eines festen Korpers ausarbeiten konnte, fiir welchen der Satz X nicht gilt. Wir woUen jedoch vorlaufig bei Korpern stehen bleiben, welche den idealen Gleichungen der Elasticitatslehre geniigen. Wenn solche Korper so wenig deformirbar sind, dass man sie als Starr betrachten kann und wenn durch beliebige Systeme derselben beliebige Bedingungsgleichungen realisirt sind, so kann man jetzt leicht nachweisen, dass fiir dieselben das vereinigte Princip der virtuellen Geschwindigkeiten und d'Alembert's gelten muss. Denn wenn man alle Krafte auch die elastischen ins Auge fasst, so verschwindet jedenfalls die Summe da jedes Glied dieser Summe einzeln verschwindet. Da aber die Wirkung immer gleich der Gegenwirkung ist, so miissen die Glieder dieser Summe, welche sich auf die Wechselwirkung der Volumelemente beziehen separat verschwinden, wenn diese starren Korpern angehoren also keiner relativen Lagenanderung fahig sind, wahrend bei bloss einseitigen Verbindungen die bekannten Ungleichungen abgeleitet werden konnen. Dies kann auch auf Verbindungen iibertragen werden, die nur theilweise starr sind z. B. unausdehnsame Flachen, Faden etc. ; denn diese konnen immer als Grenzfall sehr diinner elastischer Korper betrachtet werden. Man erhalt 302 Ludwig Boltzmami : so das Tereinigte Princip der virtueUea Yerschiebungen uitd d'Alembert's; in der gewohnliclien Farm. Erst aua diesem Principe konnen wMr jefcat die Satze von der Bewegnng^ des Sdbwerpunkts, vom TragheitsnuoiiQente etc. ableiten. Diese Satze erscheinen daber in. unsereim Syateme, erst an dieser Stelle. Es kann dies nicht anders sein ; denn daria bestebt ja das Wesen der indactiven Metbode, dass wir nicbt den Begriff des. materiellen Pimktes als eines nnausgedebntem mit Masse begabten. Korpers posfeuliren, sondern die Scbliisse, welcbe man sonst mit Hilfe dieses Begriffes macbti erst ansfmbren^ wenn wir zur Vorstelliimg des Volumelementes gekommen. sind, welcbe wir eber der Erfabrung entnebmen. zu. konnen glauben, als die des materiellen Pnnktesi. Wir konnem dann diese Saitze erst erbalten, wenn wir die Wecbselwirkung der Volumelemente bebandelt baben. Wir mussten freilicb scbon friiber an zwei Stellea vom BegrifEe des matbematiscben Pnnktes Gebraueb macben, namlicb als wir die Beweg- ung eines einzigen bervorgebobenen Punktes eines Korpers betracbteten und als wir Krafte fingirten, welcbe an einem einzigen Punkte eines Korpers angreifen. Allein da war die Abstraction docb viel einfacber und klarer, als wenn wir das Ideal eines Timansgedebnten mit Masse begabten Korpers bilden und dessen Drebung einfacb vernaeblassigent obne dass wir die Gesetze der Drehung^ vorber kennen gelernt baben* Manche Satze konnten wir aHerdings auch auf einem andem als dem eingescblageuen Wege gewinnen. Ein Analogon des Scbwerpunktsatzes konnten wir z. B. ableiten, indem wir ein System von ausgedebnten Korpesm betraebten wiirdeB, zwiscben denem innere Krafte tbatig sin-d und auf welcbe auch. aussere Krafte wirken, welcbe ibnen aber alle nur Bewegungen parallel zu sicb selbst ertbeilen. Nimmt man dazu noeh die Annabme, dass fiir die innere Krafte Wirkung und Gegenwirkung immer gleich ist, so wiirde ein dem Scbweirpunktsatze abnlicher Satz fiir ein solcbes System in Wecbselwirkung begriffener ausgedebnter Korper folgan. Die Krafte, welcbe in Fliisaigkeiten wirkeai, konnen ala ein spezaeUear Fall, der in elastiscben Korpern wirkeaiden betrachtet wexden und sie konnen daber ebenfalls naeb der im bisberigen auseinandexgeaetzten Methode gewonnen werden.. Die Gestaltanderungen der FLiissigkeiten konnen dann dnrcb. die Bewegung der Volumtbeile derselben dargestellt werden,. welcbe die entwickelten Gesetze befolgt ; nur dass die Deforma- tion des Kckpers als Gauzes jetzt eine beliebig grosse sein kann. Wir baben biemit das Gebiet der eigentlichen mecbaniscben Erscbein- DriMe Vorlesung, 303 ungen erscMpft. Bei den dissipativen Erseibeiimiigieii (elasfcisehfi Naeh- wirk?img, S«ibFmig •etc.) spielt bereits die eafcwickellbe Warme eine Rolle. Wir konnen natiirlicli die Form der friiliern Gleichungen wahren, indem •WIT zu den bisher abgeleiteten Kraften nocb Glieder von solcher Be- schaffenheit hinzu addiren, dass deren Summe genau gleich dem Werte der mit der Masse multiplicirten Beschleunigung wird. Diese Zusatz- glieder konnen wir dann immer als Reibungskraft, Mittelswiderstands- kraft etc. bezeichjs'en, dooh hat diese DarstellTing einen rein formalen Wert, wenn die Zusatzglieder in ganz oomplicirter Weise von der Bewegungsgeschwindigkeitj den iruhera Zustanden etc. abhangen. Es bietet die Molekulartheorie da entscMedeii mebr Anschaulichkeit, da sie die Zusatzglieder doch durcih langsame Drehung der Molekiile in neue Rubelagen, Umsetzumg der sichtbaren Bewegung in Molekularbewegung etc. einigermassen versinnlichen kann. Das Princip der virtuellen Ver- schiebung bebalt dann natiirlich, so lange es auf das Gleicbgewicbt ruhender Korper angewendeit wird, seinen Sinn, da bei der Ruhe dissipa- tive Vorgange fehlen. Aber das d'Alembert'sohe Princip ist auch zu einer leeren Formel herabgesunken, so bald sich in den Ausdriicken fiir die Krafte Glieder finden, welche selbst -wieder von der Bewegung, von den vorhergegangienen Zustanden der Korper etc. abhangen. Uber die Darstellung der elektrischen und magnetischen Erscheimirigen will ich hier nur bemerken, dass dieselbe ebenfalls in die Form der mechanischen Gleichungen gebracht werden kann und muss, sobald diese Erscheinungen von Bewegungen ponderabler Korper begleitet sind. Des Naheren hier- auf einzugehn, ist jedoch nicht meine Absicht. Ich woUte in dem Bisherigen keineswegs eine consequente in sich abgeschlossene Darstellung der Mechanik vom inductiven Standpunkt geben. Ich wollte vielmehr bloss die Wege andeuten, auf denen eine solche vielleicht gewonnen werden komite und namentlich die Schwierig- keiten aufdecken, mit denen ihre Durchfiihrung verkniipft ist, wenn man sich bestrebt, das innere Bild ebenso klar hervortreten zu lassen und consequent durchzufiihreo, "wie dieses bei der deductiven Behandlung moglioh ist. Ich komme dah«r zu dem Resnltate, dass unter den bis- herigen Darstellungsversuchen der Mechanik die deductiven, wie die von Hertz und die von mir in meinem citirten Buche gemachte vorzuziehen seien. Da aber diese deductive Darstellung wie schon zu Anfang gezeigt wurde, den Mangel hat, dass sie so lange Zeit hindurch gar nicht an die Erfahrung aaknupfii und vielfach den Scheim des Willkiir- 304 Ludwig Boltzmann. lichen erweckt, so wiirde es mich sehr freuen, wenn es jemanden gelange, der deductiven Darstellung eine inductive an die Seite zu stellen, welche gleich einfach und naturgemass vorginge und doch das innere geistige Bild in gleicher Deutlichkeit und Consequenz hervortreten liesse. Es Vierte Vorlesung. 305 ware dies wohl in einer kurzen Abhandlung kaum moglich, sondern nur in einem grosseren Buche, wo man den Grundprincipien sogleich die An- wendung auf alle speziellen Falle folgen lassen konnte. Denn erst an der Moglichkeit der exacten Darstellung aller moglichen speziellen Falle erprobt sich die Klarheit und Consequenz der Bilder, wie sich das am besten an der Hertz'schen Darstellung zeigt, wo diese Anwendung auf spezielle Falle fehlt. SoUten sicb aber die Liicken, die sicb in meiner gegenwartigen Darstellung finden, nicht ausfiillen lassen, so wiirde mich auch dies freuen, denn es wiirde den definitiven Sieg der deductiven iiber die inductive Behandlungsweise bedeuten. Ich mochte gewissermassen die Vertreter der inductiven Richtung einladen, alle Fehler, die sicb in meiner gegenwartigen Darstellung finden aufzudecken, die Moglich- keit der genauen Durchfiihrung aller Schlussweisen, die ich hier nur kurz angedeutet habe, zu zeigen und ihre besten Krafte einzusetzen in dem Wettkampfe mit der deductiven Darstellung, damit beide mit ein- ander verglichen werden kounen und sich im Wettstreite stets ausbilden und vervoUkommnen^ Da der EnergiebegrifE nicht nur in der Mechanik, sondern in der ganzen Naturwissenschaft eine so wichtige RoUe spielt, so waren auch con- sequente Darstellungen der Grundprincipe der Mechanik vom Standpunkte der Energetik hochst erwiinscht, welche also nicht von den Begriffen der Beschleunigung und Kraft sondern von denen der lebendigen Kraft und des Potentiales auszugehen batten. Doch miissten die betreffenden Bilder auch nach der deductiven oder inductiven Methode durchaus klar consequent und einwurfsfrei entwickelt werden und es miissten vollkom- men pracise Regeln gegeben werden, wie dieselben eindeutig auf alle speziellen Falle anzuwenden sind, ohne dass die Kenntnis der alten Mechanik dabei vorausgesetzt wird. ViBBTB Vorlesung. Die vierte Vorlesung begann der Vortragende mit der Vorzeigung des Modells flir die Maxwell'sche Theorie der Elektricitat und des Magnetis- mus, welches in dessen Buch ^^Vorlesungen iiber Maxwells Theorie der Elektricitat und des Lichtes erster Theil " beschrieben ist. Es wurden alle dort erwahnten Experimente mit gutem Erfolge durchgefiihrt. Hierauf gab er noch folgende Ubersicht iiber die das Princip der kleins- ten Wirkung und das Hamilton'sche Princip umfassenden Gleichungen. 306 Ludwig Boltzmann: Wenn -wiv die Ealle einseitiger VerbindTiiigeii ausscHiessen, so 'wird das vereinigte Pxincip der virtuellen Versohiebungen mid d'Alembexts, wie wir sahen durch eine Gleichung ausgedriickt, welche wir erhalten, wenn wir den Ausdriiek auf Seite 36 gleich Null setzen. Piiiirt man darin generalisirte Coordinaten ein und setzt EinfacMieit halber vorans, dass eine Kraftfunction V besteht, welche aber die Zeit enthalten iann, so transformirt sich dieselbe in f olgende Gleichung dt dp Bjp wobei p irgend einev^eneralisirte Coordinate, q das dazu gehorige Mo- ment, T die gesammte kinetische Energie ist. Wenn jede beliebige Coordinate p zu jeder beliebigen Zeit t eine beliebige Variation Sp erf ahrt, so kann man die letzte Gleichung mit bp mniltipliciren und beziiglicli aller p summiren. Im speciellen Falle, dass alle hp integrable Functionen der Zeit sind, kann man nocli mit dt multipliciren und liber eine beliebige Zeit (von t^ bis f) integriren ; nacb partieller Integration der dq/dt ent- haltenden Glieder f olgt in dieser Weise : s fc^- r)dt = 2(3Sp - q,Sp,y (i) wobei sich rechts die erstern Grossen auf die obere die letztern auf die untere Integrationsgrenze beziehen. 1. HamiltonB Prinnp der stationaren Wirhunp. Aus der Pundamentalgleichung 1) f olgt das Princip der stationaren Wirkung, wenn man die Grenzen des Integrals und die Coordinaten- werte fur dieselben als unveranderlich voraus setzt. Dann ergibt sich, wenn man setzt A t-t. f olgende Gleichung : Sft=0 Oder S'F=0. «o O oder TThaben also fiir die Bewegung dieselbe Bedeutung, wie V ivx das Gleichgewicht in der Ruhe. Die Bedingungen, welche den Grenz- wert von €1 oder W unter den geschilderten Umstanden angeben, sind mit den Bewegungsgleichungen identisch, wesshalb Helmholtz diese Gros- Vierie Vorlesung. 307 sen als kinetisches Potential bezeichnet. Fiir das Gleichgewicht in der Ruhe, bestimmen diese Bedingungen einen Grenzwert von V, da dann T=0 umd V von der Zeit unabliangig ist. Der Satz, dass fiir das Gleich- gewicht, F'ein Grenzwert ist, ist also ein ganz specieller Fall des Satzes vom kinetische Potentiale oder des Hamilton'schen Princip der station- aren Wirkung, wie dieser auch genannt wird. 2. HamiltonB JPrincip der variireniesa, Wirkimg. Wir setzen in Gleichung 1) einmal nur die untere dann nur die olaere, dann nur den Wert einer Coordinate fiir die untere, endlich diesen Wert fiir die obere Grenze des Integrales als veranderlich voraus ; es folgen sofort die Hamilton'schen partiellen Differentialgleichungen : da an an an dtg ot opg dp Es soil nun F'die Zeit nioht enthalten, also die Energie T+ V sich mit der Zeitnicht andern. Wenn man dann in Gleichung 1) die Grenzen als variabel betrachtet, so transformirt man sie nach einigen Zwischen- rechnungen leicht in die folgende : 2S f'Tdt = rBCT+ V:)dt + 'L(gSp- joSpo) <2) •/to ^*J) wobei aber die 8p jetzt unter gleichzeitiger Variation der Grenzen fiir die Zeit und der Bewegung zu bilden sind. 3. Das alte Princip der kleinsten Wirhung. Setzt man in Gleichung 2) die Coordinatenvariationen fiir die Gren- zen von t gleich Null und nimmt ausserdem an, dass die Variation der Bewegung ohne Energiezufuhr geschieht also h(^T + F)= ist, so folgt also die alte Form des Princips der kleinsten Wirkung, welches in mancher Beziehung specieller, in so fern aber wieder allgemeiner ist, als das Princip der stationaren Wirkung, als es die Bewegungszeit als veranderlich betrachtet. 308 Ludwig Boltz'mann : 4. Analogien mit dem zweiten Hauptsatze. Wir woUen annehmen, dass das letzte Glied der Gleichung 2) verschwindet. Es gilt dies nicht bloss, wenn an den Grenzen fiir die Zeit hp = Spg = ist, sondern auch wenn die Bewegung periodisch ist und t — t^ die Dauer dieser Periode ist. Es gilt auch wenn die Verschiebungen sammtlicher materielleu Punkte des Systemes in folge der Variation der Bewegung senkrecht auf der augenblicklichen Geschwindigkeitsrichtung derselben steht. Bisher waren die Sp ganz willkiirlicKe Variationen. Wir woUen sie nun in folgender Weise erzeugt denken. 1. Mit dem Systeme, auf welches sich die Gleichung 2) bezieht, soil ein zweites Sys- tem verbunden sein, welches mit dem ersten in Wechselwirkung steht und letzteres soil eine unendlich kleine Bewegung machen. 2. Ausserdem soil dem ersten Systeme eine unendlich kleine lebendige Kraft S^zugefiihrt werden. Die in der Gleichung vorkommende Grosse S F"ist bloss die Veran- derung von F'in folge der Lagenanderung der Punkte des ersten Systems. Sei S'F'die in Folge der Lagenanderung des zweiten Systems, so ist i'V die Arbeit der vom ersten auf das zweite System wirkenden Krafte. Sie muss mit der zugefiihrten Energie hQ zusammen die gesammte Anderung hE der Energie des ersten Systems geben. Es ist also SJ?= &Q + h'V. Anderseits ist hE= BT+hV + h'V, da Sydie Anderung der kinetischen, SF+S'Fdie Gesammtanderung der potentiellen Energie ist. Aus bei- den Gleichungen folgt S^ = S(2'+F). Setzen wir C'BQdt _ f'Tdt g§=t% und T = ' so folgt aus Gleichung 2) unter den gemachten Annahmen sofort wo die Analogic mit dem zweiten Hauptsatze deutlich zu Tage tritt. Thermodynamisches Beispiel : Unter dem ersten Systeme verstehen wir die Molekiile eines Gases, unter dem zweiten einen das Gas begrenzenden beweglichen Stempel, BQ ist die dem Gase zugefiihrte Warme. Mechan- isches Beispiel : Das erste System ist ein mit einer punktformigen Masse verbundener Magnetpol der gezwungen ist, sich in einer Ebene zu bewe- gen, das zweite System ein kurzer Magnet, um welchen der Magnetpol Vierte Vorlesung. 309 eine Centralbewegung macht. Nun erfahrt der Magnet eine kleine Drehung wodurch sich das Wirkungsgesetz der Centralbewegung andert und ausserdem der Magnetpol einen kleinen Stoss. Das Gesagte soil gewissermassen ein Schema sein, in welchem die verschiedenen dem Principe der kleinsten Wirkung verwandten Principe zusammengestellt sind. Es zeigt sich, dass die Analogien mit dem zweiten Hauptsatze weder einfach mit dem Principe der kleinsten Wirkung, noch auch mit dem Hamilton' schen identisch sind, aber sowohl zum einen, wie auch zum andern in sehr naher Beziehung stehen. Ich habe zu Anfang betont, dass die Entwicklung der Wissenschaft nicht immer in stetiger Verfolgung der alten Wege vor sich geht, son- dern sehr haufig durch plotzliche Einfiihrung ganz neuer Methoden und Ideen gefordert wird. Wo konnte fiir letztere Art der Entwicklung ein fruchtbarer Boden sein als in Amerika, wo alles neu ist, wo die Geschick- lichkeit des Geistes, Ungewohnliches zu unternehmen, die grossten unvor- hergesehenen Schwierigkeiten zu besiegen stete Ubung findet, wahrend wir in Europa wolgedrQlt in den Bahnen der alten wissenschaftliohen Me- thode uns zwar mit grosserer Leichtigkeit und Sicherheit bewegen, als die Bewohner der neuen Welt, aber dem Ungewohnten und Neuen gegen- iiber verbliifift und unbehiilflich sind. Sicher werden daher nicht bloss die Amerikaner aus ihren rastlosen Bestrebungen die Pflege der reinen Wissenschaft zu fordern den grossten Nutzen. ziehen, sondern auch die Wissenschaft wird durch die Mitwirkung der Amerikaner stets mehr und grossartiger gefordert werden. Auch ich fiihle den hohen bildenden Wert, den es fiir mich hatte meinen engbegrenzten heimatlichen Hori- zont durch die Bekanntschaft mit der grossartigen Natur und Cultur Amerikas zu erweitern, wol das fruchtbringendste Experiment, das ich je angestellt habe. Ich sage Ihnen daher meinen besten Dank fiir die hohe Ehre, welche Sie mir durch die Berufung zu diesen Vortragen erwiesen, und wiinsche nur, dass das von mir gebotene nicht ganz hinter der Grosse dieser Auszeichnung zuriiekstehen moge. €^c CC-it^C, giant pyramid of 7th layer ; c, 6, axons of smaU pyramids of 6th layer. a. good part of the 7th layer. In the brain at birth their terminals present no special peculiarities ; but in one twenty days old I have found that a number of these arborizations surround the giant pyramids, form- ing terminal nests. Only their arrangement is not so definite here as in the motor region, where we find it wonderfully developed. (Compare with description below.) Visual Cortex. 355 Eighth Latbk. Examined in Nissl preparations this layer presents a mass of medium- sized pyramids and a remarkably dense formation of granules. This is the reason Meynert and other writers have called this the layer of deep granules or inferior granular layer. Golgi's method reveals in this formation elongated cells of pyramidal form. They have the radial trunk continued, up to the plexiform layer and also descending basilar dendrites which become subdivided and end within the 8th layer. Among these there is no lack of fusiform or tri- angular cells, but they always present the long radial trunk which we find over the whole cortex (Fig. 22, C). In general form, it will be observed that these cells resemble true pyramids. However, the peculiar behavior of their axons establishes a very clear distinction between them. As may be seen in the figure (22, i), this axon at first descends, then describes an arc, ascends into the 7th, 6th, and 5th layers, and finally ends in a horizontal arborization chiefly distributed to the layer of stellate cells, but a few of its branches go to the 5th layer. From the loop of the axon, and in the course of its ascent, spring several collaterals, which ramify in different planes of the 8th layer. In a few of these cells we may observe that, at the bend of the axon, a slender branch, similar to a collateral, is given off, which crosses the 8th and 9th layers and enters the white matter as a medullated fibre (Fig. 22, g). The great majority of these collaterals, however, terminate com- pletely within the 8th and 9th layers. At any rate, we must distinguish, considering the morphology of their axons, two kinds of cells : (a) cells with arched axon none of whose collaterals extend to the white matter ; (J) cells whose neurite divides, at the arch, into a fine descending branch, which becomes a medullated fibre of the white matter, and into a larger ascending branch with its terminal arborization in the 4th or 5th layers. This arched arrangement of the axon in cells of the 8th layer appears very strange. It occurs not only in the infant brain, but in the visual cor- tex of the adult as well. It seems, at first sight, to violate all laws that govern the length and direction of the axons in other sections of the nervous system. And, what seems still more remarkable, all these whim- sical windings seem to subserve solely the purpose of shortening the stretch between the cell body and the first collaterals given off by the arch. This same phenomenon occurs in many other nerve cells. ' Were Fia. 22. — Seventh and 8th layers, Tisual coitez of cat, aged 20 days. A, deeper portion of layer of stellate cells ; B, layer of giant pyramids ; C, layer of medium-sized pyramids with arched axon; a, b, pyramids; c, d, small pyramids with axons distributed to 7th layer; g, tri- angular cell, whose axon gives rise to a large ascending collateral ; i, another whose axon forms an arch and ascends ; 1, pyramid with axon descending to white matter ; j, element from the deep- est levels of the layer of medium-sized pyramids (corresponding to layer of fusiform cells in man) which gives origin to a large axon that ascends possibly to the 1st layer. Visual Cortex. 357 it not for a deviation from our present theme, I might adduce very con- vincing instances of this tendency of the axon to take the direction most favorable for the nerve impulses which arise in the cell to very quickly reach the elements connected with their initial collaterals. Permit me also to add that the 8th layer contains giant stellate cells with ascending axon (Martinotti's cells), which runs to the plexi- form layer (Fig. 22, j), and also a similar but smaller cell, whose axon gives rise to an arborization between the neighboring cells. Ninth Layer. Coinciding closely with the so-called polymorphic layer of other authors, this layer contains elongated elements, fusiform, triangular, or ovoid, possessing a radial dendrite, extending up to the plexiform layer, and also one or several basal dendrites, which take a descending or oblique direction. Finally, these cells have an axon which descends in a straight line to the white matter; where, after giving off several col- laterals, it continues as a meduUated fibre. There are also in the 9th layer a few fusiform cells with short radial dendrites and ascending axon and a number of stellate cells with short axon of the so-called Golgi type. In addition, the arrangement of the cells of the 9th layer varies greatly in different parts of a convolution. In the convex portion they are very numerous, fusiform, and slender, elongated and perfectly radial ; while opposite the sulcus they have a quite different form, are stouter, more variable, and frequently lie with long axis parallel to the white matter, i.e. perpendicular to their ordinary direction. Their peripheral processes perform the most whimsical contortions in order to become radial and reach the plexiform layer. Their axon appears frequently horizontal, describing a very open curve on its way to the white matter. All these forms and many others represent adaptations of the cells to the foldings of the cortex and to its varying thickness in different parts of a convolution. I will not impose further upon your indulgent attention with these tiresome enumerations of layers and forms of cells, in the mazes of which nature herself seems to have intended to lose the investigator and put his patience to the test. And I wiU close this tedious lecture 'with a 358 Santiago Ramon y Cajal: succinct exposition of the anatomico-physiological inductions that seem to follow from my observations on the minute structure of the visual cortex of man and the mammalia. 1. The visual cortex of man and gyrencephalous mammals possesses a special structure very different from that of any other cortical area. 2. The visual region is characterized, above all, by fewness of giant pyramids and by presenting, at the level of the granular layer of other cortical areas, three distinct layers of cells of special form, to wit : the layer of large stellate cells, the layer of small stellate cells, and the layer of pyramids with arched ascending axon. 3. Grennari's or Vicq d'Azyr's stripe contains principally terminal arborizations of certain very large fibres, originating probably in the primary optic centres (external geniculate body, pulvinar, anterior cor- pora quadrigemina). 4. Since these optic fibres are distributed chiefly to the stellate cells of the 4th and 5th layers, it seems natural to consider these elements the substratum of visual sensation. 5. The innumerable cells with short axons in the 4th and 5th layers represent, probably, the intermediate links between the optic fibres on the one side and the stellate cells of the 4th and 5th layers and the pyram- idal cells on the other. 6. As these intermediate cells are often very small and have short axons, it may be that, besides their function of diffusing the incoming impulses through the cortex, they play also the special role of augment- ing the visual impulses by fresh discharges of nerve force, in order that they may reach, in sufficient strength, the cortical regions in which the function of commemorative recording of optical images occurs. The pathways for conveyance of visual residues from the median occipital region to the association centres in the parietal cortex are possibly repre- sented by axons of the stellate cells of the 4th and 5th layers. 7. Grr anting that the giant pyramids of other cortical regions give rise to motor fibres, it would follow that in the 7th layer they possess the same function. These cells, whose dendritic trunks come into con- tact with the optical plexus, 4th and 5th layers, serve probably to mediate the reflexes of the eyeball and head (conjugate movements of the eyes) occasioned by elective stimulation of the visual cortex, a theory which would seem to be supported by the physiological experiments of Schafer, Danillo, Munk, and others. Visual Cortex. 359 8. Granting that each giant pyramid comes into contact in the 4th and 5th layers, as well as in the first layer, with fibres that are proba- bly associative, we may suppose that motor discharges of these cells can be effected by two kinds of impulses : by ordinary optical stimulation and by stimuli of a volitional order, possibly coming from the association centres and reaching, finally, the plexiform layer. My own researches do not furnish grounds for further conclusions. Many points still remain to be cleared up ; but their complete eluci- dation will be the fruit of researches more detailed and exact than those I have been able to undertake. LECTURE III. The Sbnsoki-Motok Coetbx. After the study that we have just made of the -visual cortex, we can be more concise in our examination of the motor area. In all cortical regions we notice general structural characters and special features which constitute the physiognomy proper of each cerebral area. Naturally, the latter will be of more interest to us, and they wiU form the subject of the present lecture. I shall not stop here to give any history of researches undertaken upon the minute anatomy of the psycho-motor areas. A bibliography of the subject would be very long, tedious, and altogether superfluous, since it has already been provided in the recent studies of Retzius, Hammar- berg, and Kolliker. It will suffice to name, among those to whom we are most indebted for a knowledge of the structure of the motor cortex, Mey- nert, Baillarger, Kolliker, Krause, Betz, Lewis, Golgi, Martinotti, Retzius, Flechsig, Kaes, Hammarberg, Nissl, etc. All these writers have selected the psycho-motor cortex for special study ; and it is safe to assert that all our knowledge of the minute structure of the entire cortex has taken its character from this region, which some writers have denominated " typical." They have done this because it was thought at the time when the fundamental works of Meynert and Golgi appeared that in histologi- cal structure the whole cortex corresponded to a uniform design, present- ing only unimportant variations in different regions. Neither have I time to enumerate the layers which have been described for this cerebral region. Their number has varied under the pen of each writer with the animal and the method he has happened to employ. Thus Meynert, who made his observations on man, distinguished five layers ; Stieda, Henle, Boll, and Schwalbe limited their number to four ; while writers like Krause admitted as many as seven. I myself, at the time of my investigations upon the small mammals, recognized four, naming them : (1) molecular layer ; (2) layer of small and medium-sized pyramids ; 360 SensorirMoior Cortex. 361 (3) layer of large pyramids ; (4) layer of polymorphic cells. This number, derived particularly from study of the small mam- mals, is not valid in the more complicated human cortex. To the four classical layers of smooth-brained mammals we must add one at least, the so-called granular layer of Meynert and other writers. This layer, situated in its very midst, divides the layer of giant pyramids into two, which we may call respectively the external, or superficial, and the internal, or deep, layers of giant pyramids. To sum up, the following are the layers which it is possible to recognize by Nissl's method in the human motor cortex (ascend- ing frontal and ascending parietal convolu- tions). To conform to our scheme in the visual cortex, we have altered the terminol- ogy for this region also. 1. Plexiform layer (layer poor in cells of Meynert, molecular layer of some writers). 2. Layer of small and medium-sized pyramids. 3. External layer of giant pyramids. 4. Layer of small stellate cells (gran- ular layer of the authors). 5. Internal, or deep, layer of giant pyramids. 6. Layer of polymorphic cells (fusiform and medium-sized pyramids of certain writers). Fig. 23. — Section of adult human motor cortex, stained by Nissl's method (semischematic) . 1, pleziform layer ; 2, layer of small pyramids ; 3, layer of medium- sized pyramids ; 4, external layer of giant pyramids ; 5, layer of small stellate cells ; 6, internal layer of giant pyramids ; 7, layer of polymorphic cells or deep pyramidal layer of medium-sized cells ; 8, layer of fusiform cells. 5:{ -mm^im /'M^.i^■*i)^•*4.■i'..lw•.iill.l9i.•,1 8 'I o 5 362 Santiago Ramon y Cajal: These layers correspond particularly to the concave portions of the motor convolutions. Over the convexities the gray matter is thickened especially at the level of the polymorphic layer, which here appears divided into two sub-layers : an external, very rich in pyramidal and triangular cells (Fig. 23, 7) ; the other, internal, presenting, besides the heavy bundles of white fibres, fusiform cells disposed in parallel series (Fig. 23, 8). 1. Plexiform Layer. — This is similar in structure in the motor and visual areas. It contains, therefore : (1) dendritic arborizations of the pyramidal and polymorphic cells, that is to say, of all the ceUs of deeper layers (2, 3, 4, 5, 6) except stellate cells of the 4th layer and the cells with short axons scattered through the entire cortex ; (2) terminal arbori- zations of the ascending axons of Martinotti; (3) the ramifications of the recurrent collaterals which come up from the axons of certain small and medium-sized pyramids ; (4) the fibres, terminal and collateral, which arise from the white matter; (6) stellate cells of variable size with short axon which ramifies within the 1st layer ; (6) the special, or hori- zontal, cells with long tangential dendrites ; (7) finally, neuroglia cells of the two well-known types, with long radiating processes close underneath the pia (Martinotti, Retzius, Andriesen, Bevan Lewis, et al.^, and type with short processes, located at all levels of the plexiform layer (Golgi, Cajal, Retzius, Martinotti). We shall not enter upon their descriptive details, since all the struc- tures present the same characters here as in the visual cortex. We shall merely add that in the motor cortex the plexiform layer is notably thick. It also contains a greater number of horizontal cells and terminations of the trunks of pyramidal cells (Fig. 25, A, B, (7). Its greater thickness arises probably, as Lewis remarks, from the extraordinary number of pyramidal cells in the underlying layers. 2. Layer of Small and Medium-sized Pjrramids (Fig. 24, 2 and 3). — We shall not stop upon these, because they are so well known. Permit me merely to call to mind the fact that their radial trunk, often forked near its origin, makes its arborization in the plexiform layer ; while from the base springs a fine neurite which, in case of the small mammals, we can trace into the white matter. In the child's cortex this is made diffi- cult by the distance, but I have been fortunate on two occasions in fol- lowing this axon into the medullary substance, where it was continued as a meduUated fibre. The neuritic collaterals are also very numerous SensorirMotor Cortex. 363 and a number of them may be seen to recur and make their arbo- rizations in the superficial lamina of the plexiform layer. Cells with Short Axons. — These are numerous, although it does not seem to me that they are so extremely abundant as in the visual region. In Fig. 25 I have reproduced some of these ele- ments which habitually occur in my preparations. We remark especially: a, a large stellate type, whose ascending axon subdivides into horizontal or oblique branches covering a great extent of the layer of small and medivmi-sized pyramids (Fig. 25, K^; b, a second type of similar form but whose axon forms its terminal arboriza- tion very close to the cell (Fig. 25, j^) ; e, still another form with horizontal axon the superficial branches of which penetrate into the plexiform layer (Fig. 25, i)) ; d, arachniform cells with axons subdivided into dense plexuses (Fig. 25, F, a^; e, fusiform, bi- panicled cells, which have been sufficiently described. Fio. 24. — Ensemble of layers of motor cortex of infant aged one and a half months ; Golgi's method (semlschematlc) . Layers are numbered as follows: 1, plexiform; 2 and 3, small and medium-sized pyramids; 4, super- ficial giant pyramids ; 5, granular or small stellate cells ; 6, deep giant pyramids ; 7, poly- morphic cells, or deep medium-sized pyramids. (In this figure I have not represented the deepest portion of the 7th layer.) 364 Santiago Ramon y Cajal. Having studied all these types and many others in the visual cortex, it is unnecessary here to enter upon a more detailed description. One Fig. 25. — Cells with short axons of the plezifoTm and small and medium-sized pyramidal cell layers from motor cortex of infant aged one month and a few days. A, B, C, horizontal cells of the plexiform layer ; D, cell with horizontal axon ; M, large cell with very short diffusely subdivided axon; F, G, spider-shaped cells whose delicate axons form a dense plexus (&) up to the plexiform layer ; S, J, hipanicled cells. thing concerning the bipanicled cells I may add, viz., that in the motor cortex there appear to be two kinds : one, small cells provided with slender axon disposed in very delicate vertical pencils (Fig. 25, .ff) ; the SensorirMotor Cortex. 365 other consisting of relatively large cells having very long and thick den- drites and with an ascending or descending axon giving rise to terminal arborizations of extreme complexity, producing nests or terminal bas- kets about the bodies of the small and medium-sized pyramidal cells (Fig. 25, tT"). Possibly this type, which I take to be a variety of the common bipanicled cell, is present over the whole cortex ; but as yet I have succeeded in finding it only in the motor convolutions of the infant at over one month of age. 3. Superficial Layer of Giant Pyramids. — Being a continuation by imperceptible gradations of the above, this layer contains the well-known large pyramids of the writers. In addition to the observations of Betz, Lewis, Golgi, and myself, however, I must add a single detail to their classical description. The radial process varies greatly as to the extent of surface it covers in the plexiform layer. When its dendrites must cover a large surface, the trunk forks near the cell, and the two trunks, deviating at an acute angle, ascend to give rise to two or more terminal sprays, in some cases at considerable distances apart. This amounts to saying that certain medium-sized and large pyramids stand related to a large number of nerve fibres in the 1st layer, while other cells of the same size have more limited connections (Fig. 24). In gyrencephalous mammals, dog and cat, the superficial large pyra- mids are smaller than in the infant. They might be considered as a sub- ordinate element in the layer of medium-sized pyramids. Most frequently the only giant pyramids in the cat occur below the granular layer, — a layer which, I. may add, is very slightly developed in this animal, being often blended with the layer of medium-sized pyramids. The number of superficial, medium-sized, and giant pyramids is very large in the motor area both in animals and man ; and this is one of its characteristic features. However, the regions designated by Fleehsig as association centres possess also a notable number of large pyramids. From this feature alone it would be quite difficult to distinguish the frontal and parietal from the motor convolutions. The axon of the large and medium-sized pyramids descends, as is well known, to the white matter and is continued as one or two nerve fibres. I must call special attention to the fact that, as shown by my own researches, this fibre may fork usually into a fine branch which goes, probably, to the corpus callosum and a larger branch to the corpus stria- tum. This may be easily observed in the brain of a newborn mouse or 366 Santiago Ramon y Gajal: in one a few days old. It may also be seen that tlie fibre entering the corona radiata passes beyond the corpus striatum, giving off to it a few collaterals. It is thus well established that the axon of the large pyra- mids is true projection fibre which takes part in forming the pyramidal tract. But we must be on our guard about accepting the view of certain writers, — v. Monakow, for example, — who ascribe this role, participa- tion in the motor tract, exclusively to the giant pyramids, because I have demonstrated beyond all doubt, in the motor region of the mouse and rabbit, that a number of the axons of medium-sized pyramids and many from polymorphic cells also penetrate the corpus striatum. I therefore consider as wholly arbitrary all the opinions which tend to attribute an exclusive function to elements in each distinct cortical layer. In the cor- tical layers, as well as in the ventral horn of the spinal cord, there occur together elements with axons of very diverse character and connections. The motor cell takes its place beside the associational cell along with the element whose axon or collateral goes to the corpus callosum. There are, accordingly, in the cortex no " sensory layers " nor " motor layers " ; because, as we shall see in a moment, the great majority of the cells are related, either by their cell bodies or by their radial trunks, to the plexus of sensory fibres. We find thus reproduced the arrangement of the spinal cord, where all the cells, or almost all, come into contact with sensory fibres of the first or second order, and all represent links in the chain of reflex connections. 4. Layer of Small Stellate Cells (^Q-ranular Layer of the Authors). — Stained by Nissl's method the layer of small stellate cells appears as a great number of nuclei surrounded with little protoplasm which contains a few fine granules of chromatin (Figs. 23, 5, and 24, 5). Most of these elements, the granules proper, are very small and globular or stellate in form. Others, I have observed, are comparable to small pyramids, being of triangular form and having a fine radial trunk. Nor is there any lack of stellate or fusiform cells of considerable size, which call to mind those of the visual cortex. All these elements appear to be mingled. However, in certain places I thought I could discover that the small globular cells are situated chiefly in the external plane of the layer, while the minute pyramids were more numerous in the deeper levels, but there are exceptions to this. But Nissl's method does not enable us to study the fine processes of these elements. To this end we must have recourse to the chromate Sensori-Motor Cortex. 367 of silver method, and by its application — especially in case of an infant fifteen to thirty days old, a time at which the reaction is easily obtained — I have been able to demonstrate the extreme complexity of the granular layer. Good preparations show that it consists of elements with very diverse characters, which in spite of their minor differences may be classed into two groups : (1) cells with long axons which extend down to the white matter ; (2) cells with short axons which end within the granular layer or in layers above it. OelU with Long Axons. — These may be classed into two varieties, small pyramidal cells and medium-sized stellate cells. (a) The small pyramid is specially numerous in the deep level of the 4th layer (Fig. 26, A, JB'). It has been figured by various writers, notably by KoUiker, although even he does not give us any information on the character of its axon. The cells are ovoid-pyramidal in form. They possess a radial trunk which extends up to the plexiform layer, where it ends in a few very slender varicose twigs without contact granules. It also has a few tiny descending or oblique dendrites which divide repeatedly. Finally, I have very often traced its axon to the white matter, in which it is continued as a slender medullated fibre. From its initial portion arise two, three, or four collaterals, some of which curve upward to distribute themselves through the 4th layer. In some cases the diameter of these collaterals is so large, compared with that of the axon, that they might be considered the real axons. (5) Stellate Cells. Very hard to stain, and possibly quite scarce. Their dendrites arise from the angles of the cell body and run in all directions, but are distributed exclusively to the 4th layer (Fig. 26, D). Their axons spring from the inferior surface, descend almost in a straight line, and, after giving off a few large collaterals, very frequently arched and re- current, are lost in the white matter. These interesting cells, exactly similar to the stellate cells of the visual cortex, are also found in the motor cortex of gyrencephalous mammals, although, to judge from my own preparations, only in small numbers. Their presence would seem to indicate distinctively sensory regions of the brain. Elements with Short Axons. — These are also very numerous in the infant brain, representing, perhaps, the chief morphological factor of the 4th layer. Several varieties have been distinguished, of which the most common are the following : — (a) Stellate or IJ'usiform Cells of Medium Size. Their dendrites 368 Santiago Ramm y Cajal. diverge in all directions, but chiefly above and below, and end in the midst of the 4th layer. Their axon springs from the superior surface, ascends for a variable distance, and at varying levels of the layer of stel- Fra. 26. — Cells with long axons from 4th layer of motoi eoitez of infant aged one month. A, B, C, small pyramidal cells; D, laige stellate cell; E, mediuiu-sized pyramid; a, axon; b, c, large descending collaterals. late cells forms an arborization of horizontal or oblique branches of con- siderable length and distributed exclusively to the 4th layer. Very often the axon branches in the form of a T before proceeding to its ter- minal arborization, and from its initial part arise collaterals whose course Sensori-Motor Cortex. 369 and terminations resemble those of the terminal branches. These cells, we may add, correspond in all points to the cells with ascending axons described for the 4th and 5th layers of the visual cortex (Fig. 27, A, C, D). (6) Fusiform, Triangular, or Stellate Cells. These are somewhat Fig. 27. — Cells with short axons from 4th layer of motor cortex of infant. A,B,C, cells, stel- late or fusiform, with ascending axon divided into long horizontal branches ; E, arachniform cell ; F, cell with axon distributed to layer of medium-sized pyramids. larger than the preceding. Their axon ascends to the plexiform layer, in which it subdivides and terminates. In its ascent it supplies a few collaterals to the 4th and 3d layers. These elements, as we see, corre- spond to the so-called cells of Martinotti. In a few cells of this class the axon possibly does not reach the first layer, becoming lost in the layers below (Fig. 27, A). 2b 370 Santiago Ramon y Cajal: (e) Small Stellate or Spider-shaped Cells. These possess fine and richly subdivided dendrites and also a neurite, which forms a very rich arborization close to the cell (Fig. 27, E'). (d) Bipanicled Cells. These have the characteristics already de- scribed in our study of the visual cortex. (e) Finally, in the cat and dog I have found a few stellate cells with very numerous dendrites, whose descending neurite forms a very dense and complicated arborization, for the most part in the 4th layer, but in some cases extending down to the deep layer of giant pyramids. Possibly these cells are homologous to the spider-shaped cells in man, which they resemble in the extraordinary richness of the plexus formed by the axon. It would then be necessary to suppose, however, that in the cat and dog these cells are much larger than in man. In order to complete my description, permit me to add that there is no lack of ordinary pyramidal cells, in some cases large, scattered irregu- larly in the 4th layer (Fig. 26, E^. In mammals like the cat and dog, and to a much greater degree in the rabbit, the profusion of pyramidal cells obscures our picture of the granular layer. Sensory Nerve Plexus of the 4th Layer. — One of the most significant facts which I have discovered' in the motor cortex is a plexus of very large fibres whose numerous subdivisions occupy the 4th layer and extend even into the 2d and 3d. They probably enter the cortex from the corona radiata. As early as in my first work I called attention to these fibres as being different in diameter, direction, and origin from axons of pyramidal cells, but at that time I had not succeeded in deter- mining the region to which they are peculiar or the precise place of their termination in the cortex. My recent researches upon the brain of man and also small mammals enable me to add a few details to my description of some years ago (Fig. 28). First of all, I have been able to determine exactly their origin and position in the brain. These are both easy to observe in the brain of a rabbit at birth and still better in that of a mouse a few days old. In the mouse it may be seen especially well that certain large fibres (called by KoUiker, who has confirmed their existence, fibres of Cajal) proceed from the corpus striatum, enter the white matter, and often extend horizon- tally in it for great distances. In their course they throw off long col- laterals, which penetrate into the overlying gray matter. All these collaterals, as well as finally the original axon itself, ascend through the Fig. 28. — Plexus of heavy sensory fibres from motor cortex of cat 25 days old. A, plexiform layer ; B, layer of small and medium-sized pyramids ; C and D, layers of granules and superficial layer of giant pyramids ; E, deep layer of giant pyramids ; F, layer of polymorphic cells ; a, fibre from white matter ; 6, ascending collateral ; c, varicose terminal arborization ; d, fibre directed to the plexiform layer, which appears to be distinct from the large fibres. 372 Santiago Ramon y Gajal: polymorphic layer, dividing once or twice, then, passing obliquely through intervening layers, form an arborization of heavy fibres within the layers of small, medium-sized, and large pyramidal cells. However, in the rat and rabbit these branches are most numerous in a relatively superficial plane, which corresponds probably with the granular layer of the human brain, — a layer that is not differentiated in the small mammals. We also find a relatively small number of branches that ascend to the plexiform layer. As to the cortical distribution of this plexus, we may also place on record a fact of interest. It never covers the whole cortex. It begins to appear some distance from the median fissure and disappears below long before reaching the olfactory area or limbic lobe. I have never observed it in the cortex of this sulcus, nor in the anterior portion of the frontal lobe, nor even in the region of the auditory or visual centres. I shall return to this matter in a future investigation, for I think it merits most thorough study ; because, if it can be confirmed in a positive manner and by other methods, we shall possess a criterion by which to distinguish between areas of association and projection in the cortex. The projection areas will probably be found to be not, as Flechsig thinks, those possessing fibres that go to the corpus striatum (since Dejerine and others have discovered these fibres in the so-called association centres) but those receiving sensory fibres. At the same time, the association centres will be characterized by the absence of these direct sensory connections. At any rate, I believe that even in the brain of the smallest mammal there are areas, of small extent it may be, specialized to store up the images or residues of the sensory projection centres. It would be most astounding if the brains of the smafl. mammals possessed a different architecture from that of man, taking into consideration the fact that all the senses have the same essential structure in all mammals and that memory — visual, tactile, muscular, etc. — is just as necessary to their lives as to our own. The sensory plexus is highly developed in gyrencephalous mammals and in man. I have found it well impregnated in the brains of infants at birth and a few days old. Here it appears made up of large fibres having an oblique direction and a flexuous or even staircased course. After dividing several times in the 6th and 5th layers they give rise to a singularly extended arborization of horizontal fibres distributed chiefly to the layer of granules or small stellate cells. We thus see in the motor SensorirMotor Cortex. 373 cortex, as was the case in the visual, that the layer of granules is the principal focus of sensory impressions. From this terminus they are propagated by the numberless cells with short ascending axons to the layers above and especially to the medium-sized and giant pyramids. However, it must be acknowledged that the sensory plexus is not so narrow and well defined as the optic. For, although its greatest density occurs in the 4th layer, its terminal branches divide in their ascent to the superficial layer of medium-sized and giant pyramids. The fibres which extend up to the small pyramids in man are not numerous. It is for this reason that I cannot agree with Bevan Lewis in ascribing to them sensory functions. I do nbt wish to be understood to deny the sensory function of the small and medium-sized pryamids. According to my view, all the cells of the motor cortex are sensory because they all, possibly, come into contact either directly (cells of the 3d, 4th, and 5th layers) or indirectly, through the intervention of cells with short axons, with sensory terminal arborizations. But, since some cells send their axons to the pyramidal tracts, we are able to distinguish them as sensori-motor cells of the first order. The others, which send their neurites to other motor areas of the brain, possibly effect contact with sensori-motor cells of the first order located elsewhere. These cells of indirect sensori-motor communication we may be warranted in calling sensori-motor cells of the second order. It goes without saying that this distinction is purely hypothetical ; for no method enables us to determine the precise point within the brain where the axons of the pyramidal tracts of the corpus callosum or of bands of association fibres form their terminal arborizations. 5. Layer of the Giant and Medium-sized Pyramids. — In the adult human brain stained by Nissl's method, a section of the motor cortex reveals, below the granular layer, a layer of plexif orm or granular aspect filled very thickly, but in no particular order, with a few giant and a great number of medium-sized pyramids (Fig. 29). Usually the giant pyramids are located near the 4th layer, forming there a few irregular ranks. Impregnated by Golgi's method, they appear similar to the same cells in other regions of the cortex, but differ in a few particulars. The body is generally conical, very much elon- gated, giving rise at the apex to a large trunk, often dividing near the cell, which terminates in the 1st layer in the usual manner. A group of long complicated dendrites diverges from its base, and from the sides 374 Santiago Ramon y Cajal . spring several very long horizontal processes whioli subdivide into ter- minal brushes, and these, intertwining with similar structures from neighboring cells of the same level, form a dense and very characteristic 1- £ b FiQ. 29. — Deep layer of giant pyramidal cells from motor cortex of Infant aged 20 days. A, B, pyramidal cells ; D, C, elements with short axons. protoplasmic plexus. It is the same arrangement we already know so well in the visual cortex, except that, instead of one plexus, there are many. The axon is large and, after giving off very long collaterals to the 5th and 6th layers, it passes on to become a medullated fibre of the white matter. The medium-sized pyramids are very numerous, much scattered, and SensorirMotor Cortex. 375 occur in greatest profusion in the lower levels of the layer. They do not differ in character from the giant pyramids, except as to the lateral somatic dendrites, which are few and not characteristic. Besides the pyramidal cells the 5th layer contains a few other kinds of elements. From the point of view of their morphology the following are the more striking types. (a) Cells which form Terminal Nests. — These cells, very similar to those which give rise to the basket fibres of the cerebellum, are most numerous in the 5th layer between or below the giant pyramids. I have found them also in the layer of granules or small stellate cells. Their volume is small, similar to that of a small pyramid, and in form they appear stellate or triangular with very long and much-branched varicose dendrites. The neurite, however, presents the most distinctive feature. It ascends, forking close to its origin, and breaks up into a ramification of very many branches, ascending, oblique, or horizontal. After a few subdivisions, all these branches make their way to the giant and medium-sized pyramids to form very complicated varicose arboriza- tions close around their cell bodies and principal processes, after the manner of the terminal baskets of the cerebellum or the nests found in Deiter's nucleus. Each nest contains arborizations from several cells, and each basket cell helps to form a large number of nests (Fig. 30, c?). (J) Cells with a Diffusely Branched Ascending Axon. — This is a fusiform or stellate cell located at different levels of the 5th layer, to which it sends its dendrites. The axon ascends to the superior limits of the layer where it forks, and its terminal branches form a loose horizon- tal arborization of an enormous extent and connected probably with the deep giant pyramids (Fig. 29, C, D). (c) Small Pyramids with Arched Axons. — This cell, which I have studied particularly in the motor cortex of the cat, is entirely similar to the element which we found in the 6th and 7th layers of the visual cortex. The cells possess a fine dendrite which ascends to the first layer, where it ends in a very modest and delicate arborization. Their axon descends and, after giving off a few relatively long recurrent collaterals, appears to fork and end in the midst of the 5th layer. The branches which spring from the bend of the arch descend in some cases, but I have not been able to trace them down to the white matter. (c?) Cells with Long Ascending Axon. — These are fusiform or tri- angular cells with long polar dendrites which never reach the first layer. 376 Santiago Ramon y Cajal: Their axon arises from the superior surface of the cell, and, after giving off a few branches to the 5th and 4th layers, it continues its ascent to the plexiform layer and there makes its terminal arborization. 6. Layer of Polymorphic Cells. — This layer contains the same elements as the layer of the same name (9th) in the visual cortex (Fig. 31), that Fig. 30.— Pericellular terminal arborizations from the deep layer of giant pyramids, motor cortex (ascending frontal convolution) of infant aged 25 days, o, axons giving rise to oblique and horizontal branches ; h, c, d, terminal nests. is to say, fusiform cells with two long polar dendrites, triangular cells, and true pyramids. Their axons all go to the white matter. Their ascend- ing trunks, which are never lacking, become very attenuated on account of the branches given off while passing through the 4th layer and reach the 1st layer as an exceedingly delicate fibril, which ends in a fine, slightly extended, notably varicose dendritic spray. In Fig. 31, I have reproduced the principal types of cells found in the polymorphic layer. Besides the medium-sized pyramidal and triangular types having long descending axons (Fig. 31, A, E), there occur other SensorirMotor Cortex. 377 forms in great numbers. These are fusiform or triangular cells whose axons penetrate into the superposed layers, furnishing to them a great FiQ. 31. — Principal types oi polymorphic cells f lom motor cortex of infant aged 20 days. A, B, cells with long axons extending to white matter ; C, D, E, fusiform cells with ascending axon ; H, giant stellate cell. number of branches. Some of these axons seem to end in the deep layer of giant pyramids, but others appear to pass beyond this. Finally, there 378 Santiago Ramon y Cajal: is no lack of arachniform cells (Fig. 31, J), cells with short axon of the sensory type of Golgi, whose axons form terminal arborizations in the layer under consideration. I may add that I have found in two cases giant stellate cells with heavy horizontal axon which gives off collaterals (Fig. 31, -H"). I do not know the ultimate fate of this process and am unable to say whether these scattering cells form a constant feature of the motor cortex. Cortex of Acottstio, Olfactory, and Associational Areas. Unfortunately, my own researches are not as yet in a very advanced state in regard to these important cortical centres. So that any in- formation that I can give must necessarily be fragmentary and of little value. The acoustic resembles exactly the motor cortex as to general arrangement of cells and layers, but differs from it in a few pecu- liarities : (1) by the fineness of the fibres forming the plexus at the level of the layer of granules or small stellate cells ; (2) in the profusion of bipanicled cells with their very delicate and complicated neuritic brushes ; (3) above all, by the presence of certain special cells scattered irregularly through the entire thickness of the cortex. The very large axon of these special cells extends in a horizontal or oblique direction, but I have not yet been able to determine exactly its manner of termination. These large cells are fusiform and lie horizontally. From their polar dendrites spring a number of fine ascending branches, which subdivide repeatedly but do not extend up as far as the plexiform layer. The olfactory cortex, that of the limbic lobe, is characterized by the following peculiarities : (1) the enormous development of the plexiform layer and the presence in it, in addition to its usual structures, of the antero-posterior fibres that come from the external root of the olfactory tract ; (2) the absence of the layers of small pyramids and granules ; (3) the presence of certain large horizontal cells below the plexiform layer ; (4) the peculiar form of the medium- and large-sized pyramids which emit from the deep end of the cell body a brush consisting of numerous much subdivided dendrites; (5) above all, the fact that the sensory plexus, i.e. the fibres which come from the olfactory bulb, makes its terminal arborization exclusively in the plexiform layer and in the most superficial portion of that layer, corresponding to that of the small SensorirMotor Cortex. 379 pyramids. TMs significant fact, brought to light by the studies of Calleja, shows us that the sensory fibres do not end in the same level of the cortex in all regions. Hence, the layer specialized to serve as substratum for the phenomena of sensation may change its position in different sensory areas. Our task is now drawing to its close. My work upon the topo- graphical structure of the cortex has been fragmentary and leaves much to be desired. Many things, in fact, are still undiscovered. But, despite the very incomplete state of my researches and the narrow limits of the field they cover, I may draw a few anatomico-physiological conclusions, of which the chief are the following : — And first, as to the hierarchy of centres in the cortex of the human brain, comparing it with the mammalian brain, we may call to mind that, while it does not contain wholly new elements, it presents very distinc- tive characteristics, to wit : — 1. The enormous development of the horizontal cells of the plexi- form layer and the considerable length of their so-called tangential fibres. 2. The great abundance of cells with short axons scattered through- out the whole cortex, cells which form special varieties by reason of differences in their forms and the directions of their axons. 3. The presence of cells with short axons, very slender (bipanicled spider cells), with terminal arborizations whose delicacy is not approached by anything found in any animal. 4. The considerable development of basilar dendrites of the pyram- idal cells. 5. The presence among the mid-layers of the cortex of a formation of so-called granular cells, a kind of focus occupied by enormous num- bers of pyramids with short axons descending, arched, and ascending. This granular formation is present in gyrencephalous mammals, but in them it is very poor in cells with short axons and in small pyramids. In the smooth-brained animals it is almost wholly lacking. The human cortex has evolved, accordingly, along three different lines: by multiplying cells with long axons and, above all, those with short axons ; by decreasing the volume of cells and the diameter of cer- tain fibres in order to make possible within the limits of space a deli- cate and greatly improved organization ; finally, by varying and infinitely 380 Santiago Ramon y Cajal: complicating the external morphology of the nerve elements, undoubt- edly with the purpose of multiplying, in correspondence with their complexity, functional associations of all kinds. As to differences and analogies in regional structure, the following propositions may be regarded as established : — 1. The sensory as well as the so-called associational areas are made up by a combination of two orders of structural factors. The first order consists of common factors, which show very little modification. They are represented by the plexiform layers and the layers of pyram- idal and polymorphic cells. The second order comprises special fac- tors, structures peculiar to each cortical area. Their chief anatomical feature resides especially in the ' granular layer and is related mainly to the presence of particular centripetal fibres and of special types of cells with long axons (stellate cells of different kinds). 2. It seems probable that the common factors perform functions of a general order concerned, possibly, with ideas of representations of all kinds of movements related to the special sensations of which the cortical region is the seat. It seems also probable that the special anatomical factors of the sensory areas perform the function of elab- orating specific sensations (sensation of seeing, hearing, etc.) and also of conveying sensory residues to the so-called association centres, where they may be transformed into latent images. 3. Each sensory cortical centre receives a special category of nerve fibres (fibres of central sensory tracts). Their cells of origin, as has been shown by the researches of v. Monakow, Flechsig, v. Bechterew, and many others, reside in the particular nuclei of the medulla, corpora quad- rigemina, and optic thalami. It is precisely the presence of these sen- sory fibres of the second order that constitutes the prime anatomical characteristic of the centres of sensation or projection. 4. The absence of these sensory fibres, which come from the corona radiata, may be used in all mammals to distinguish the so-called associ- , ation centres. These centres, which exist even in the mouse, also have a nerve fibre plexus distributed among their median layers (layer of gran- ules in the association areas in man). The fibres, however, which consti- tute them are very fine and appear to come from sensory centres of the brain. Possibly the cells about which these sensorio-ideational fibres terminate represent the substratum or, at any rate, the first link in the chain of nerve elements whose function is the representation of ideas. SensorirMotor Cortex. 381 5. Since we have seen that each afferent fibre in the sensory cortex comes into contact with an extraordinary number of nerve cells appar- ently scattered without any order, we must suspect that these relations conform to the preconceived design of a well-determined and constant organization. As, at present, it seems to be impossible to discover these relations, we may surmise that each sensory fibre comes into contact, directly or through other cells, solely with those pyramids whose stimulation is nec- essary in order to effect, after the manner of the reflex arc, movements coordinated and intentional. We may also surmise (supposing that the stellate cells of the tactile and visual cortex form the link between the sensory and ideational centres) that each sensory afferent fibre, bringing a unit of sensation (the impression received by a cone of the retina or by the terminal arborization of any peripheral nerve fibre), enters into rela- tion exclusively with the group of nerve cells entrusted with the func- tion of conveying this impression to a particular point in the associational cortex. Many other hypotheses are possible, but I must conclude for fear of tiring your kind and sympathetic attention and exhausting your patience. I fear that I have already made too free use of hypotheses and have pre- tended to fill the gaps of possible observations with arbitrary supposi- tions. It is a rule of wisdom, and of nice scientific prudence as well, not to theorize before completing the observation of facts. But who is so master of himself as to be able to wait calmly in the midst of darkness until the break of dawn ? Who can tarry prudently until the epoch of the perfection of truth (unhappily as yet very far off) shall come ? Such impatience may find its justification in the shortness of human life and also in the supreme necessity of dominating, as soon as possible, the phe- nomena of the external and internal worlds. But reality is infinite and our intelligence finite. Nature and especially the phenomena of life show us everywhere complications, which we pretend to remove by the false mirage of our simple formulae, heedless of the fact that the simplicity is not in nature but in ourselves. It is this limitation of our faculties that impels us continually to forge simple hypotheses made to fit, by mutilating it, the infinite uni- verse into the narrow mould of the human skull, — and this, despite the warnings of experience, which daily calls to our minds the weakness, the 382 Santiago Ramon y Cajal: Sensori-Motor Cortex. childislmess, and the extreme mutability of our theories. But this is a matter of fate, unavoidable because the brain is only a savings-bank machine for picking and choosing among external realities. It cannot preserve impressions of the external world except by continually simpli- fying them, by interrupting their serial and continuous flow, and by ignoring all those whose intensities are too great or too small. I cannot conclude this, my third and last lecture, without a word of tribute to this great people of North America, — the home of freedom and tolerance, — this daring race whose positive and practical intelligence, entirely freed from the heavy burdens of tradition and the prejudices of the schools, which weigh still so heavily on the minds of Europe, seems to be wonderfully endowed to triumph in the arena of scientific research, as it has many times triumphed in the great struggles of industrial and commercial competition. "tx'-V-.^i ) o'^y, V PSYCHIC PROCESSES AND MUSCULAR EXERCISE. Bt Professor Anoelo Mobso. First, let me give expression to my gratitude to Clark University, whose invitation made it possible for me to take part in this celebration. To the American schools of psychology, a subject which in Europe forms so characteristic a branch of the development of science, we are aU deeply indebted. Psychology is a fertile field, where philosophers and scientists can unite for common labor, a field, indeed, where they cannot be separated from each other, for here the idealists and the empiricists are held together by a common bond, laboring, as they all are, at the solution of the greatest and the most difficult of all problems — the inves- tigation of the human mind. Clark University, moreover, can boast of having given to pedagogy also a new impulse. Many excellent teachers come hither to perfect themselves for their profession. I may be permitted, therefore, to make both fields, psychology and pedagogy, the subject of my lectures, which will treat of the relations existing between the psychic processes and muscular exercise. I. It had long been known that our brain has at birth a grayer hue, and only later takes on a whitish color. This whitish color originates from the fact that the cerebral nerve fibres, after their complete development, are surrounded by a sheath which has this color. To Paul Flechsig ^ is due the great credit of having shown that our cerebral nerve fibres are not complete at birth, and that the white nerve- paths come from the medulla, extending from the periphery toward the centre. In man, the brain develops later than in all the other animals, because his muscles also develop later. The striped muscles are more incomplete at birth in man than in any other animal. For this fact, that the human brain develops so slowly, I am able to discover no other reason than 383 384 Angeh Mosso : this, that at birth the organs which effect movement, over which the brain later exercises its authority, are not yet complete. The muscles of the adult human being are thirty-seven times as heavy as those of the newborn child, while the brain of the former is only 3.76 times as heavy as that of the latter. It had been long known also that the brain of man slowly increases in weight up to the fortieth year. Recently Kaes ^ has shown that, up to the fortieth year, there are formed in the cerebral convolutions new plex- uses of nerve fibres, which are lacking in younger brains. Excitation of the senses and impulses to movement hasten the devel- opment of the nerves in question. The experiments of Ambronn and Held' have shown that, if one eye of a newborn kitten is opened to the light, the other remaining closed, the optical fibres of the eye which is stimulated by the light are more quickly surrounded with myelin than those of the other. Another important fact is that the motor nerve fibres are complete earlier than the sensory. These facts we must apply to pedagogy. Only that science can show how injurious is precocious instruction for the development of the child. If we wish to hasten the maturity of the brain, we must decide whether the formation of the myelin can better be hastened by stimulations of the senses and intellectual work, or better by muscular exercises. The latter way seems to me the more natural. We must, therefore, to begin with, consolidate the motor nerve paths which develop first, and after that seek to develop the portion of the brain concerned with intellectual work. Modern views show a tendency to confirm what the great philosophers of Greece already recognized, viz., that children ought to begin to read and write only with the tenth year. The conviction is again slowly maturing that our children begin to learn too early, that it is injurious for the development of the brain to be fettered to the school-desk when only five or six years old. The conviction is slowly making its way that no more time should be devoted to intellectual work than to muscular exercise. The modern education of youth, however, resembles more an artificial hothouse culture than a natural training of the human plant. II. The fact observed by me that in man the phenomena of intellectual fatigue are identical with those of muscular fatigue, caused me to inquire whether or not the conscious processes and those of movement are identi- Psychic Processes. 385 cal processes, which take place in like cells, or, perhaps, alternately in one and the same cell. The new phrenology exhibits a tendency to localize the mental func- tions, but the old idea, which distributed the nervous functions over the whole cerebral cortex, does not yet acknowledge its defeat, and what I have to say to-day will show that there exists an intimate connection between the conscious processes and muscular exercise. Doubtless, there are regions known in the brain which are traversed by the will impulse which sets certain muscle groups in motion, but they are the junctions of roads, they are the tracks upon which the trains run, not the stations where the trains are formed, and where they receive the will impulse. In fact, in cases where it was possible to stimulate electri- cally the motor region of the human cerebral cortex, the subject declared that he felt, in that part of the body in which the current caused a mus- cular contraction, sensations which resembled the creeping or running of ants. If the so-called motor region of the brain is destroyed, it is found that a change of sensibility also takes place. These facts suiifice to show that, up to the present, no absolute local separation of movement and sensibil- ity is demonstrable. Moreover, all agree that every will impulse is joined to the idea of the movement to be executed. If, in a monkey, the roots of the sensory nerves which go to the arm are severed, the animal no longer moves the hand spontaneously, although the voluntary nerve paths are uninjured, because the uhi consistam of sensibility is lacking. Our mechanisms are so complete that the move- ment-command is never given by the cells without a clear idea of the place where it is to be carried out. In every voluntary movement there exists between the periphery and the centre such an intimate connection that patients who have lost the muscle sense can contract the muscles of the hand around an object and keep them contracted, as long as they look at the object. So soon, how- ever, as they turn their eyes away, the muscles instantaneously relax. For a movement impulse to express itself, it must be controlled by the sensory nerves ; for the will and the sensibility are functions inseparably con- nected with each other. ni. Attention, which has been called an internal sense, shows really in the best way how isolation from the influence of the external world is possi- 2 c 386 Angela Mosso : ble in the study of psychic phenomena. Attention is the most intense activity of the mind, and yet we all know that we are not capable of absolutely controlling it. The more or less favorable disposition for intellectual work, which we perceive on certain days and at certain hours, awakes the suspicion that attention itself is, to a great extent, conditioned by internal reflex phenomena. I have already shown in my writings * that, in a state of attention, the respiration becomes slower and deeper, the blood-vessels in the forearm and in the foot contract, the blood flows more abundantly to the centre, the form of the brain and arm pulse changes, and the activity of the heart is increased. In the state of attention, moreover, there exist an increased secretion of sweat, a greater consumption of the organism — the blood is poisoned by the products of intellectual fatigue.^ Attention produces not only the same chemical effects and the same fatigue as muscular exertion does, but we feel also, when we are attentive to anything, the characteristic muscular strain on the occiput, the fore- head, and other parts of the body. One of the characteristic phenomena of attention is its periods, which have been so well studied by Wundt and his pupils, — periods which exhibit a great resemblance to those observed by Dr. W. P. Lombard® in the case of continued muscular contraction. Under the direction of Dr. G. Stanley Hall, Lindley^ has investigated the involuntary move- ments which we make when we think of anything, muscular contractions of the face, hands, and feet. These movements are like those which we make during muscular exertion. We cannot force the attention to fix itself upon one object contin- ually, because it quickly becomes exhausted, and renews itself only when a new object is offered it, when new paths for its activity are opened. It is not we who direct the attention. We can only indicate to it the direction which it is to take according to our wishes. After that it is free and does what it pleases ; it flits about Uke a butterfly on the path which we have pointed out for it. The excitability of artists, the peculiarity of their character, show that in them the involuntary movements are more easily executed, and that intelligence and mobility increase together. But the fact that artists see objects in a particular way, and that the thing seen by artists, like that seen by litterateurs, is retained by the memory in very characteristic fash- Psychic Processes. 387 ion, proves that attention works in a different way with them. The plastic talent of southern peoples, the ease of their movements, their more lively gestures, the more intense expression of their emotions, disclose to us the nature of the artists' genius. I believe, however, that there is also contained in attention an emotional factor. rv. Great impressionability and the capacity to fix the attention for a longer time are, doubtless, two of the chief conditions for artistic genius. But I believe also that the exercise of the hands exerts an influence upon the development of the mind. During the first epoch of the Renaissance, the greatest artists of Florence were all apprentices in the workshops of the goldsmiths. Luca della Robbia, Lorenzo Ghiberti, Filippo Brunelleschi, Francia, Domenico Ghirlandajo, Sandro Botticelli, Andrea del.Sarto, — to mention only a few examples, — performed, during their apprenticeship, the simplest labors in the workshop of a goldsmith. But the exercise with which they gained their manual dexterity surely influenced also the development of their genius. In the beginning of the sixteenth century this school ended, but from the pedagogical standpoint it is still worth studying. If I may be per- mitted to express an opinion, I would say that the manual dexterity favored by this labor contributed much to the development of the great masters of genius. A fact which cannot be doubted is the manysidedness of genius which some Italians of the Renaissance possessed, and which has never again appeared with like copiousness. Giotto was painter, sculptor, and architect. Leonardo da Vinci was a celebrated musician, a great painter, an engineer, an architect, a man of letters and of science. Andrea del Verrocchio was goldsmith, sculptor, engraver, architect, painter, and musician. These facts are to be read in many histories of art. An incomparable example, however, is Michel- angelo. For twelve years he studied anatomy on the cadaver, and after- wards painted the Sixtine Chapel and executed the tombs of the Medici and the dome of St. Peter's. In the artist, better than in other human beings, is seen the inti- mate connection between the psychic processes and muscular exercise. Power of resistance against fatiguing labors, dexterity, and capacity 388 Angela Mosso : for concentration, are the secret of their marvellous life. I am con- vinced that muscular movements have formed the omnipotence of genius, just as, vice versd, intellectual exercises effect advantageously the develop- ment of the muscles. Michelangelo ground his colors himself. Raphael, while as an engineer in Rome he carried on excavations and painted the rooms of the Vatican, wrote a treatise on how the smoking of the chimney in the kitchen of a prince might be prevented. As Vasari relates, Perino del Vaga made every mechanical object; he fabricated often trumpeters' pennons, portieres, drapery, flags, embroidery, and carv- ing, and painted sarcophagi. He was a great painter, and his stucco works belong to the most valuable of the Renaissance period. Even if the genius of these mighty men will remain a secret for all time, yet we can say this much, that their hand was just as dexterous as their mind was lofty. These men, who are the greatest representatives of our race, have carried the dexterity of their hands to the highest degree of perfection. They were simple workers, who, laboring untiringly with their hands, lifted the human mind to the highest ideals of beauty. If the Greeks excelled all other peoples in genius, it was because they paid more attention than did the others to bodily exercise ; they brought gymnastics, the study of bodily positions and bodily exercise, to a height which has never been reached by other peoples since their day. V. Our brain possesses probably more substance than we generally use, so that a not inconsiderable part of it may be looked upon as an organ of luxury. The fact observed by me, that we breathe in more air than is necessary, together with the fact observed much earlier, that we eat much more than we need, allows us to designate as luxury all that is not abso- lutely necessary. Our brain has on the average about a milliard of nerve cells. Many men have more, and others less brain substance, without it being possible to detect a difference in the intensity of their psychic processes. Large and heavy brains are often found in men who do not make full use of them. Such a brain was that of Rustan, which Rudolphi has described. It weighed 2222 gr., while that of Helmholtz^ weighed only 1420 gr. The brain of the unknown, commonplace individual, Rustan, was therefore 802 gr. heavier than that of Helmholtz. The Psychic Processes. 389 great facility with whicli, in the case of partial destruction of the brain, the individual parts can substitute one another has been demonstrated by Flourens and Goltz. Not all the brain cells work simultaneously, but they relieve one another probably with such punctuality that only under certain conditions do we notice that some groups are fatigued. That this relief process exists can be argued from the fact that the nerve cells offer only a very small resistance to fatigue. The attention itself works in periods of activity and rest. These periods have been observed in the case of the sense of sight, as well as in the senses of hearing, taste, and touch. Since, as Bowditoh has shown, the nerves, as such, do not become fatigued, we must ascribe such fluctua- tions to the centre. If we close one eye, and with the other look at an equally illuminated wall or the sky, we notice that the visual field now darkens, now lights up again.* The dark color becomes green, yellowish, or blue, and appears in regular intervals, 5-12 times a minute. These periods vanish as soon as the eye in attention is directed towards a certain object. I do not believe that this phenomenon arises from the movement of the blood-vessels, for it appears only when we look with one eye. I am of the opinion that it points to a relief-process in cerebral activity, and to a period during which a slight fatigue of the brain cells takes place, if the latter are not incited by the attention to more intense labor. Our atten- tion turns automatically now to one, now to the other eye.^" There exists a remarkable agreement between the periods of activity and rest of the brain cells and of the sympathetic system. If we investi- gate the movements of the blood-vessels with the plethysmograph,ii and also the movements of the bladder,^ we notice great undulations, coincid- ing with some respiratory movements. In the curves also, observed in man and animals when the blood pressure is investigated, these fluctua- tions, which were first described by Traube, are seen. I myself have shown that the respiratory curve exhibits periods of greater and less activity. These fluctuations are particularly characteristic in mountain sickness. With each period of rest the excitability of the nervous centres is decreased. From all these phenomena it seems to follow that the nerve cells have only a small power of resistance, and that they show on the average every ten seconds a tendency to rest. S90 Angeh Mosso: I have further been able to show, by means of the ergograph, that to strongly contract the hand suffices to induce in the brain the first symp- toms of fatigue, and that a few seconds of rest are enough to make the nerve ceUs capable of functioning again. The very short duration of the capacity to resist in the nerve cells makes it plain that the brain must necessarily possess a great number of cells. It is the task of pedagogy to show how the brain cells can most fitly be employed for the welfare of the individual and of society. It is already well known that the barbarians were able to learn foreign languages with greater facility than the Greeks and Romans.^^ When we say of young peoples that they will some day excel us in literature, as in art and in science, we, unconsciously perhaps, intimate thereby that their brain still possesses tracts of virgin soil, which, with later cultivation, will become fertile. VI. The more mobile the extremities of an animal are, the more in- telligent it is. Among aU birds the parrot is the most intelligent, because it makes more use than do other birds of its legs, beak, and tongue. The elephant is more intelligent than all other wild animals, because he makes use not only of his legs, but also of his snout, as organs of movement. Another consideration : The most mobile parts of the body are at the same time the most sensitive, e.g. the tongue, the hand, the snout. This increased sensitiveness depends neither on a more numerous ramification of nerves, nor on the more complicated character of the end organs, but arises from the fact that the brain itself is more irritable, as shown by the passions of animals, which are more violent the more mobile the creature is. Romanes ^ has already said that the higher intelligence of monkeys and the highest intelligence of man are related to a more perfect instrument of motion, viz. the hand, in which the ideal of perfection seems to have been reached. The cephalopods, which have eight arms, formed of muscle-substance and provided with suckers, stand, among the molluscs, nearest to the vertebrates on account of their strength and power of movement. It was movement, probably, that developed their brain-ganglia, for these are larger in the cephalopods than in the other molluscs. As they possess a good memory and a high intelligence, so they also exhibit more intense Psychic Processes. 391 emotions, as may be seen from the great facility with which the color of their skin changes. The mutual relation of intelligence and movement is one of the most constant factors in nature. The movements always change when the intelligence changes. We need only consider the gait of the Indians in order to convince ourselves of the truth of my assertion. Their walk is characteristic, being heavier and slower than ours. Microcephalic indi- viduals have an awkward gait, and an inconsiderable dexterity in the movement of the hands. This change in movement is still more striking in the case of idiots. In some parts of Italy and of Switzerland there are many cretins. On my frequent Alpine excursions, I was often able to recognize by their gait the degree of intelligence of persons who were near me. I have con- vinced myself of the fact that the first signs of cretinism can be detected in the heavy gait, the arched vertebral column, and the manner of moving the arms in walking. vn. Neither anatomy nor physiology has hitherto been able to decide whether like brain cells have different functions, or whether all cells perform the same service. Since neither chemically nor by the use of the strongest microscopes can we demonstrate differences in the nerve cells of the cerebral cortex, it is therefore probable that none such exist. Hence, I believe that the psychic functions cannot be separated from the motor, that rather the psychic phenomenon and that which imparts the movement impulse both have their seat in the same cell. How closely connected thought and movement, consciousness and muscular activity, are, is best seen in the phenomena of sleep. If, shortly before going to sleep, we hold a book or some other object in the hand, we notice that the object falls, the muscles relaxing, the moment consciousness ceases. The significance of the fact emphasized here is not decreased by the phenomena of movement observed in somnambulists and individuals who have been hypnotized. It is well known that one can ride and walk when asleep. By practice one can learn to play the pianoforte without distinguishing the individual finger- movements. Some can play an instrument when asleep. But these are not voluntary, but instinctive and reflex movements. In a diseased arm, in which the muscles have been atrophied, the sensitiveness of the fingers is simultaneously improved if one seeks to 392 Angela Mosso : remove the atrophied condition of the muscles by exercises in contrac- tion. When the brain has been fatigued by exclusively intellectual activity, the sensitiveness of the hand and direct irritability of the muscles are also decreased. These observations force us to the assumption that the intelligence, the sensitiveness, and the movement are phenomena which cannot be separated from each other, that their fusion and their con- nection belong to the conditions which permit us to comprehend the nature of the mind. Imbecile signifies weak in body, but particularly weak in mind. In Latin, however, in hacillum means "leaning on a staff." The ancients have thus understood the relations in question better than I am able to express them in words. vm. It is well known that an injury on a certain spot in the left temporal lobe of the brain carries with it the loss of speech. Forty years ago Broca first described a case of this kind. At the autopsy of a man who had lost his speech, whose right arm and leg were paralyzed, and who, besides, exhibited disturbances of intelligence, there was found a broad and deep depression of the brain substance, extending from the Sylvian fissure to that of Rolando. Afterward appeared the celebrated treatises of Broca, which form an imperishable monument in the history of cerebral localization. It is the merit of James to have shown that the motor impulse develops itself before the appearance of language in the convolu- tions of the left cerebral hemisphere. In our development gestures and other movements appear first ; then, later, the sounds of language. It is not the process of consciousness which makes our hands dex- terous, but perhaps the movements of the right extremities, which effect the higher psychic development of the left cerebral hemisphere. The influence of the hand upon the development of language is evi- dent from the fact that an aphasic patient is made to write in order that he may gradually regain the power of speech. The relation between muscular movements and conscious processes is so intimate that when the arms and hands of a hypnotized person are brought into certain positions and certain muscles by external contact made to contract, certain emotions are induced corresponding to those muscular contractions. Here, then, intellectual processes are certainly effected by external muscular activity. Psychic Processes. 393 There is no doubt that the first human beings were dumb, and that men for a long time made use of gesture-language for purposes of mutual understanding before they discovered sound-language. The child, too, before it is able to speak, expresses itself by gestures. It observes the looks of its parents and of the persons who speak to it, in order to com- prehend the meaning of the words heard. Pantomime is the heightened expression of the involuntary movements which accompany the individual phases of mental activity. In the hieroglyphs of the Egyptians and in the representations on Greek vases we recognize the gestures and the involuntary movements which men made more than three thousand years ago. IX. Leonardo da Vinci, in his treatise on painting, had already attempted to describe the passions by detailing how to represent a man in a state of rage and despair. The first men who were able to make themselves intelligible to each other must also have been the most excitable, and in them the motor ideas must have been very active. The word and the language of a people, superhuman gifts, according to the ancients, are produced by reflex movements, gestures, and interjections. Even now artists still feel more keenly than others the intimate relation between muscular movements and psychic functions ; they have the gift of repre- senting the effects of the emotions upon bodily posture and of idealizing them. The great, picturesque mode of representation of the human body, which was the glory of the Renaissance, had its basis in this physiological law. A pleiad of the greatest artists, who perceived the internal power of the emotions, popularized the study of bodily postures by representing in sacred and profane creations the feelings that thriUed the soul. They glorified the naked body, busying themselves with showing through the study of bodily forms and their movements the perfection and the phi- losophy of art. We need here neither to think of the heroic figures of Michelangelo and their powerful musculature, nor of the pleasing, feeling, and directly perceived figures of Botticelli, nor yet of the sublimely sensual, passion- stirred figures of the Venetian school, in order to comprehend how in works of art the mind is revealed in muscular contractions. It suffices to recall the sublime figures of Perugino, the teacher of Raphael, which 394 Angela Mosso : compel us to admiration with their expression of the devotion, the enthu- siasm, and the ardor of faith. Everything here is kept calm ; in these figures we find nothing exciting, the expression of the face alone mirror- ing the mood which the artist himself felt during the production. In my next lecture I will speak further of the basic conditions of the emotions. Here, however, I will close. The nervous system, as you know, consists of an intimate union between sense-surface and muscles. Golgi and Cajal, the greatest dis- coverers in the structure of the nervous system, tell us now that there is no difference to be found in the cells of the central organs, that there is no evidence of a morphological distinction between motor and sensory cells in the brain. The structure of the nervous cells is the same ; the relations alone are different. Probably there is but one nervous substance, which is active for all functions. The immense number of the brain cells is easily explained, since the cells can relieve one another and the nervous activity go on uninterruptedly from one series of cells to another. The greatest complication lies in the life of a single brain cell. In this lecture I have sought to show how intimately related are mental processes and movements. If we desired to make a pedagogical application, we might say that physical education and gymnastics serve not only for the development of the muscles, but for that of the brain as well. 1. P. Flechsig. Die Leitungsbahnen im Gehim und Ruckenmark des Mensohen. Leip- zig, 1896. 2. Th. Kaes. Ueber die marklialtigen Nervenfasem in der GeMrnrinde des Mensohen. Neiirologisches Centralblatt, 1894, p. 410. 3. H. Ambronn und Held. Ueber experimentelle Beifung des Nervenmarks. Arch. f. Anat. u. Entwicklungsges. Leipzig, 1896, p. 227. 4. A. Mosso. Periodische Athmung und Luxusathmung. Archiv f. Anat. u. Physiol. 1886. Die Diagnostik des Pulses. Leipzig, 1879. Ueber den Kreislauf des Blutes im menschlichen Gehim. Leipzig, 1881. 5. Die Ermiidung. Leipzig, 1892. 6. W. P. Lombard. Alterations in the Strength which occur during Fatiguing Voluntary Muscular Work. Journal of Physiology, Vol. XIV., 1893, pp. 97-124. 7. Lindley, E. H. A Preliminary Study of Some of the Motor Phenomena of Mental Effort. Amer. Joum. Psychol., Vol. VII., pp. 491-517. 8. D. Hansemann. Ueber das Gehim von H. v. Hehnholtz. Ztschr. f. Psychol, u. Physiol, d. Sinnesorgane, 1899, p. 922. Psychic Processes. 395 9. H. V. Helmholtz. Physiologlsclie Optik., p. 922. 10. Sohon und Mosso. Eine BeobachlDung betreffend den "Wettstieit der Sehf elder. Arch, f. Ophth. , Berlin, 1874, pp. 269-277. 11. A. Mosso. Ueber den Krelslaui des Blutes im mensohllohen Gehim. Leipzig, 1881, p. 101. 12. A. Mosso et Fellacani. Sur les fonctlons de la vessie. Arch. ital. de Biol., Tome I., p. 97. 13. Max Mijller. "Vorlesungen iiber die Wissensohaft der Spraohe. Leipzig, 1866, p. 79. 14. G. J. Romanes. L'^volutlon mentale chez les animaux. Paris, 1884, p. 4. THE MECHANISM OF THE EMOTIONS. Bt Professor Angelo Mosso. I. To-DAT I may be permitted to express my own ideas about the mech- anism of the emotions. We are sometimes surprised by a sad or a joyful piece of news. We all know what happens in a state of fear and distress. Physiological phe- nomena occur that cannot be described. But when we learn suddenly that the news which has troubled us is false, that our fear and distress had no foundation, the internal disturbance does not cease, the physio- logical phenomena continue in the organism in spite of all efforts of the will to suppress them. The investigation of these processes has shown that the seat of the emotions lies in the sympathetic nervous system. Before we were born, and for a long time after birth, our life was entrusted to the activity of the sympathetic system and the reflex move- ments derived from the spinal cord. We need not be surprised at this, . when we reflect how great an importance nature has attributed to the vegetative and generative life processes in the formation of the organism. In decisive moments of life, when the emotions are most violent, it is just the sympathetic nervous system that comes into action. The intes- tines and the smooth muscular fibres contract in order to raise the press- ure of the blood, and to utilize the blood better for the brain and the muscles. The first observations concerning this subject were made by me more than twenty years ago. I was able to see that in sleep a contraction of the blood-vessels always takes place as soon as the sense organs and the skin are stimulated, even when the stimulation is so weak that the subject does not wake up.^ These changes, which result without our knowledge, form one of the most remarkable arrangements which we can observe 396 Emotions. 397 among the perfections of our organization. During the interruption of consciousness our body does not remain helplessly exposed to the influ- ences of the external world, or in danger of becoming the prey of its ene- mies. Even in sleep a portion of the nerve centres watches over the operations of the external world, and prepares in good time the material conditions for the awaking of consciousness. If we glance back at the unconscious processes which we saw take place in sleep under external influences, we shall see that they are all coordinated in correspondence with a final object ; they all coincide in favoring the circulation of the blood in the brain, and thereby making it possible that, in case of danger, the organ may awake to full activity. I do not believe myself far from the truth in maintaining that the totality of the reflex movements to be observed during sleep forms a real defensive apparatus for the organism. Other investigators have since demonstrated the same thing. Two years later, in 1881, Dr. Pellacani and I found that even very weak sensa- tions caused a contraction of the bladder.^ These facts had, in general, been already known, for these contractions have become proverbial in connection with fear and other emotional conditions ; but no one had previously observed that this organ reacts with such facility to all sense impressions that its tonicity changes in consequence of attention and incon- siderable psychic processes. II. The organs of the abdomen and the pelvic cavity are just as sensitive to the emotions as the heart. I have studied the movements of the abdominal organs, the stomach, and the rectum. In the smallest emotions movements of the intestines and stomach always occur. In the movements of the bladder, we must distinguish between active and passive, i.e. between such as are peculiar to the bladder itself, and such as are transferred to it from the diaphragm and from the walls of the abdomen. In order to investigate with exactness these movements of the bladder itself, I have carried on experiments both on the dog and on woman. I shall first explain the construction of the apparatus employed, and then give an account of the experiments performed. The instrument made use of was my plethysmograph, which has the advantage of maintaining the pressure constant and of registering the slightest movements of contraction and relaxation of the bladder. 398 Angela Mosso : A catheter for female use (Fig. V) A is in communication with a glass tube BQ -which, with a rectangular curve, sinks to the depth of 1 or 2 cm. below the level aJ of the liquid contained in the large receptacle, P. This descending tube must be put into a perfectly vertical position before FiQ. 1. — Axrangement of the pletbysmograph for tracing the movements of the bladder. every experiment, and fixed firmly in that position by the iron support BE. The pressure-screws at the foot of the support facilitate this nec- essary arrangement. A test-tube F, like those used for chemical reactions, with very thin walls, and suspended by two silk threads from a pulley Q, is held in equilibrium by means of a piece of lead S, which has the same weight as the cylinder F. To this counterpoise is fixed a pen for Emotions. 399 tracing on a smoked cylinder, or on the continuous roll of a Ludwig kymograpli. The cylinder F is suspended in such a manner that it has the vertical glass tube O in perfect correspondence to its axis and so that it can move up and down without touching it. In order to avoid the attraction of the cylinder by adhesion to the tube running down its axis, and the consequent development of resistance, it is advisable to furnish the lower end of the tube with a little ring of sealing-wax, or of india-rubber, cut from a tube of corresponding diameter. The cylinder F is drawn up until its bottom touches the lower end of the vertical tube ; the jar P, for the time being, we suppose to be full of water. The catheter A and the bladder of the animal or human being into which it is introduced must be on the same level ah as the liquid in the large vessel. The true level is easily found by placing the plethys- mograph and the cylinder on which the tracing is done on a strong iron table, which may be raised or lowered by means of a screw ; a photog- rapher's table serves the same purpose. The tube AIBQ and part of the cylinder J' being filled with water, the catheter is introduced into the bladder, and the clip I opened. If a contraction of the bladder takes place, a quantity of water correspond- ing to the diminution of the capacity of the bladder will flow into the cylinder F. The cylinder F, becoming heavier through this afflux of water, is bound to sink into the liquid of the jar below until it has dis- placed a volume of liquid corresponding to the increase of water received. If a dilatation of^ the bladder takes place, a certain volume of water will flow into it, and the cylinder becoming lighter will rise to a corresponding height above its original level. Had the walls of the cylinder neither volume nor weight, and were the jar full of water P so wide that the immersion of the cylinder would not sensibly alter the level of the water contained, it is clear that the cylinder might rise or sink without any change taking place in the level of the water, either in the cylinder or in the jar P. But since the walls of a glass ' cylinder, however thin they may be, have nevertheless a certain weight and volume, the immersion of the cylinder in water will cause a loss of so much of its weight as would correspond to the weight of a cylinder precisely similar with walls of water. This diminution of weight 400 Angeh Mosso : at the side J' of a system FH, which is held in equilibrium by means of the pulley Cr, must produce a displacement. The counterpoise H, which has remained constant, will repair the loss in weight of the cylinder F in raising above the level ah a weight of water in the cylinder which will equal the loss in weight of the cylinder in its immersion. A column of water being raised in this manner above the level ah, there is of necessity an augmentation of pressure within the bladder cor- responding to the height of the column. In order to remedy this defect, which as a rule is not more than a column of 2 cm. of water, we fill the jar P with a liquid which is less dense than water, that is, with alcohol and water. At every contraction of the bladder a corresponding quan- tity of water will pass into the cylinder, and the latter will sink into the diluted alcohol in the jar P. As, however, the density of this liquid is less than that of water, the cylinder F will not only, in its descent, dis- place a volume of alcohol equal to that of the water which it contains, but will tend to sink lower, thus carrying the level of the water it contains below the level ah of the surrounding alcohol. Then, again, we have already noticed that the cylinder in plunging into the liquid loses gradually in weight, in accordance with the well- known principle of Archimedes, and that the counterpoise, which remains constant, seeks to repair this loss by raising the inner level of the water ah above the level of the surrounding alcohol, until the equilibrium is reestablished. We have, therefore, in this case two forces acting in opposition : that is, gravity, which tends to bring the water level below the alcohol level ah, and the loss in weight undergone by the cylinder F during immersion, which gives it an upward impetus. If these two forces are equal they will cancel each other and the cylinder F will be able to rise and fall to the extent of its entire length, the level ah of the water contained in it remaining meanwhile unaltered. In order to obtain the exact degree of density necessary to this end we make use of an empirical method ; that is, we prepare a mixture of water and absolute alcohol if the cylinder has thickish walls. The liquid will have the required degree of density when the cylinder is filled to the top with water or empty ; in other words, when the cylinder is immersed up to its neck in the liquid or has its base merely touched by it, the level ah of the water contained in it remains constant on the plane db of the surrounding liquid. Emotions. 401 For all these necessary operations of filling, emptying the cylinder, adding or taking away water from the bladder, a glass tube L graduated in cubic centimetres is made use of. This tube communicates by means of another of india-rubber closed by a clip K and of a T-tube with the horizontal tube BQ. In order to empty the cylinder F or take water from the bladder, an inward breath is drawn at the mouth of the tube N, the tube L meanwhile being closed with the stopper M, which has a glass tube running through it ; in order to add water, one need only open the nipper K. For the experiments explained in the sequel a graduated and calibrated cylinder which contained 30 cc. to 18 cm. length was made use of, therefore every centimetre measured on the ordinates of our tracings corresponds to a little less than 2 cc. Care must be taken that the pulley Q- be sensitive enough and so well balanced that it remains in equilibrium in every position. A description of the apparatus that puts the cylinder S in movement, its velocity being constant or variable as required, is here unnecessary, as it is a piece of clockwork with a Foucault regulator which is to be found in all labora- tories. When a certain pressure was to be exercised on the bladder in order to dilate it, it sufiiced to raise the table on which the plethysmograph stood, so that the level db was above the plane of the bladder, and to add water with the tube L or to lower the animal or human being. In order to measure exactly the pressure exercised on the bladder during our experiments, we made use of a water level consisting of a simple india-rubber tube with an inner diameter of 5 mm., 1 m. in length, which had at its end two pointed glass tubes about 20 cm. in length. One of these tubes being placed near the symphysis pubis, the other was put against the jar P, and the difference of level between the bladder and the plane db was read on a double decimetre measure. This height is the pressure exercised on the bladder. Six days after a fistula had been applied to a male dog the bladder was connected through it with my plethysmograph, and the curve thus obtained recorded on a rotating cylinder. Simultaneously I had the tho- racic and the abdominal respiration registered. The movements of the bladder and of the abdomen are by this means directly fixed upon the cylinder, while the thoracic respiration is represented reversed upon it, i.e. a sinking of the curve corresponds in the latter case to expiration, a 2d 402 Angela Mosso : rise to inspiration. Since the three curves were recorded exactly over each other, the movements could be studied independently and com- pared (Fig. 2). The curve for the bladder showed, as was to be expected, also the respiratory movements. In this curve we see that the bladder begins to contract before the abdomen rises. This comes from the fact that the sinking of the diaphragm depresses the intestines, and, with them, also the bladder. The effect must first appear in the very place where the resistance is least, i.e. in the open bladder ; then the abdominal walls Fig. 2.— Relation l)etween the respiratory moyement of the thorax (line T) and of the abdomen (line A) with the passive movements of the bladder (line B). are forced forward. Some time after the contraction of the diaphragm the expansion of the chest begins. But, besides these respiratory movements, there can be perceived in the bladder curve a slight sinking, and, after it, again a rising of the whole curve. These are active movements proper to the bladder itself. They are easily distinguished from the passive movements, since they occur less quickly. Another day whUe we were recording the movements of the bladder, a servant, to whom the dog was much attached, entered the laboratory. Immediately the curve showed an active contraction of the bladder, as may be seen in Pig. 3 at Cf-. In abc we see passive movements of the Emotions. 403 bladder, which have become weaker because the respiration is more superficial. When, shortly before, another person, whom the dog did not know so well, had entered the room, we had also noticed another, but stronger, contraction of the bladder. In order to keep the dog quiet, one of us laid his hand on his head. (See P in the curve of Fig. 3.) When the hand was taken away, and the servant laid his upon the dog, there occurred again an active, but less marked, contraction of the bladder. As soon as the respiration became more superficial, the passive movements of the bladder became also less distinct. After these observations, the dog lay with eyes half-closed, as if he was about to go to sleep. His tail was touched, and immediately afterward the curve showed an active contrac- tion of the bladder, while — what is noteworthy — the rhythm and depth of the respiratory movements did not change. After the bladder had again assumed its full volume, and whUe the dog was perfectly quiet, his skin was touched, and the curve recoi'd showed at once a stronger, active contraction of the bladder. In like manner, sensations of pain, which we produced by pulling the dog's ears, caused strong, active con- tractions of the bladder. Such experiments were many times repeated. They were also carried on with bitches, the bladder being directly con- nected with the plethysmograph by the introduction of a cathe- ter, without previous establishment of a fistula. The results which we obtained were always the same. It was sufficient to speak kindly to the animals, or to caress them, to make the curve express the psychic influence upon their active move- ments. But I could not rest content with these results obtained from animals. I needed to corroborate them by experiments on human beings. Naturally this can be done better with woman, since with her the bladder can be easily brought into connection with the plethysmograph by the introduction of a catheter. My clinical colleagues were kind enough to place at my disposal some girls from the hospitals, who readily offered themselves for the purposes of these experiments. 404 Angela Mosso : I may be permitted to give an account of these experiments also. These experiments were carried on, otherwise, as the first. Again I had the thoracic and abdominal respiration and the move- ments of the bladder independently recorded. The subject lay comfortably on a bed. Here, in a state of complete r^st, the whole curve of the bladder was, at times, horizon- tal, showing, at others, slight active undulations. To touch the hand of the subject lightly sufficed, however, to produce at once an active contraction of the bladder. (See Tin the curve of Fig. 4.) While the subject was lying quietly on the bed, the clockwork of the kymograph was wound up (see (T). The noise resulting was entirely unknown to the subject, but the impression sufficed to cause itself to be reflected in the bladder, and to induce a contraction, visible in the curve. When the subject was addressed (see P), it could be seen that the bladder contracted immediately, while, if she herself spoke (see K), a series of such contractions took place. All these contractions are movements proper to the bladder. As was shown by other experiments as well, they were not transferred to the bladder from the abdominal walls or from the diaphragm, and were not, therefore, passive movements F. The lower line T marks the seconds. I was particularly interested in the movements pro- duced in the bladder by purely psychic influences. These are shown, e.g., by the following experiment. While the girl lay quietly on the bed, and respiration was quiet and normal, — this is always shown by the curves, — some one said to her, " Now I'm going to pinch you," but without doing so. Immediately the bladder contracted, without the slightest change being noticed in the thoracic and abdominal respiration. After rest had been again restored, a jest was spoken to the girl, and again we perceived a contraction of the bladder on the curve, without seeing any modification whatever of the two respiratory curves. Beyond all doubt, then, the contractions of the bladder which we observed were movements proper to that organ itself. Emotions. 405 All these phenomena may be considered the most delicate reflex move- ments which occur in the organism. I was particularly interested to know what influence a direct activity of the brain would exercise upon the movements of the bladder, and I carried on experi- ments to that end. The subject had only a slight education; she was especially a bad mental arithmetician, very easy problems in arithmetic causing her difficulties. She needed, therefore, in such work to exert her brain very much. While she lay quietly on the bed and her respiration was quite normal, she was given the following example in arith- metic : "How many eggs are seven dozen?" Immediately the bladder was seen to contract (Fig. 5). After this prob- lem was solved (see TT), we had her multiply in her head thirteen by twelve, and then a relaxation of the bladder was to be seen. I noticed, also, that merely speaking to the girl, without her answering, was sufficient to produce a contraction of the bladder. rn. The preponderating activity of the sympathetic system in the emotions is so great that the brain effort is not able to suppress it. Many men feel a contraction in the abdomen when they look down from a tower or other high place. These troublesome sensations, which are connected with the idea of a possible fall, are simply caused by the contraction of the bladder and the intestines. When we investigate, by means of the plethysmograph, the movements of the intestines during emotional states, we obtain the same curves as we receive from the movements of the blood-vessels of the extremities or of the brain, or from the movements of the bladder. All these facts ena- ble us to understand the mechanism of the emotions better. Mmotio signifies movement. We understand now that the constant and fundamental movements taking place in emo- tions are the movements of the internal organs of vegetative life. The investigations carried on in my laboratory by Dr. Kiesow have convinced me that in certain emotions the blood pressure increases, and 406 Angela Mosso : the blood-vessels and smooth muscular fibres contract in order to prevent the blood from being dammed up in the abdominal cavity. In order to increase the circulation of the blood in the brain and muscles our bodily machine has to work under a higher blood pressure. This end could be attained only through the sympathetic system, which sends its fibres every where to the smooth musculature. During blushing a paling of the skin can be noticed before the blood-vessels expand, and the blush proper takes place. In the study of the emotions the reflex movements of the striped mus- culature of the face, the extremities, and the trunk are of secondary signifi- cance to the physiologist. They are simply accompanying phenomena and, just because they are more complicated, less fundamental. However useful the first reactions of the nervous system are, yet we all know that they do not suffice for the defence of the organism in strong emotions. The nerve substance is so irritable that a small shock is enough to disturb the equilibrium. I wiU not enter into detail here, since I have already shown in my book on " Fear," how unstable is the equilibrium of the nervous system, and how easily the brain and the sympathetic system go beyond the proper measure in their activity when danger threatens, and existence is at stake. Even a practiced observer is often unable to decide from the gestures and facial expression of an individual whether he is enraged or in a state of the greatest joy. To recall the expressions of two so opposite emotional conditions suffices to convince us that the reflex phenomena accompanying them are not only useless, but even injurious. Indeed, in great pain and great pleasure we have the same phenomena : trembling of the muscles, secre- tion of tears, expansion of the pupils, decrease of visual acuity, buzzing in the ears, oppression of the breathing, palpitation of the heart, inability to speak, exclamations, convulsive movements of the diaphragm, etc. All these phenomena are injurious. After the emotion is over we feel nervous fatigue, have headache, and suffer from insomnia. I am sorry to find my- self in this matter in disagreement with Darwin, but I cannot concede that the unconscious processes occurring during the emotions (at least the best known and most characteristic) have always a physiological purpose. If we compare the expressions of pleasure and satisfaction in their high- est degrees with those of pain, it will be seen that there is one and the same mechanism for both. In my book on " Fear " I have shown that it is the Emotions. 407 quantity and not the quality of tlie excitation which disturbs the equilibrium of our organism. Only the processes which take place in the system of the great sympathetic are purposive and advantageous for the preservation of life. And it cannot be otherwise. The animals, whose involuntary move- ments preserved them from destruction in danger, won in the struggle for existence over others who possessed in less marked degree this capacity. Whatever the emotions may be, we always see that in these states the blood pressure increases, the heart beats become stronger, and the respira- tion deeper. These advantageous effects are the same in man as in ani- mals, when they fix the attention, are passionately excited, curious or jealous, or when they run at play or in pursuit of prey. But as soon as the emotion becomes more intense, the equilibrium of the organs ceases. The condition of excitability is increased and becomes more complicated, contractions of the muscles and changes in the sense organs take place, from which it results that the capacity for resistance of the organism is lowered. In strong emotions, as in rage and anger, we are overpowered by unconscious and discoordinated movements, and a penetrative and irresistible transformation occurs in us, as if the influ- ence of education had been extinguished, as if our reason had suffered an eclipse. We are no longer able to suppress the internal excitement, the voice refuses its office, and we utter a wild cry. Many persons in such states gnash their teeth like wild beasts, others act foolishly, like children. These disturbances occur not only in the reflex movements, but also in the conscious processes, and more even in the latter than in the former. Education has taught us that we must seek to master and to calm our- selves during this internal excitement, for in these states we lack mental clearness and power of judgment, and consciousness cannot again regain control until these discoordinated reflex movements have ceased. Even the ancients knew that strong emotions resembled a suddenly occurring sick- ness. The legend of ancient Rome idealized a king in order to represent war. They gave him the name Hostilius, which is derived from hostis. Tradition further informs us that this king erected a temple to "Pallor and Fear," for pallor and fear were looked upon as malevolent, destructive deities who must be appeased in order that the soldiers might be victorious in battle.^ 1. A. Mosso. TJeber den Kreislauf des Blutes im menschliohen GeMrne. Leipzig, 1881. 2. A. Mosso e Pellacanl. SuUe funzioni della vesoia. Mem. d. E. Accad. dei Liacei, 1881. 3. E. Pais. Storia di Roma. Torino, 1898. Vol. I., Parte I., p. 305. HYPNOTISM AND CEEEBEAL ACTIVITY. By Pkofessor August Forel. Gentlemen : — I beg to present to you as few hypotheses as possible, and to put together as far as feasible merely the facts which must form the foundation of the present state of the doctrine of hypnotism. We cannot, of course, get along with no explanatory theory at all. Before all, we must maintain that everything that is known can be traced alto- gether to phenomena of brain activity. Everything that one has tried (and still tries) to bring over from the field of mysticism, or so-called occultism, has, as far as it could be controlled, turned out to be mistaken phenomena of brain activity. We may calmly leave the rest to metaphysi- cal speculators and to the famous breadth of the imaginary knowledge of the ignorant. Should there be anything in telepathy, for instance, it would not belong here ; certainly its representatives would have to furnish better evidence than so far exists. That much is yet unexplained is perfectly evident — as obvious as in any other domain of human knowledge. It does not follow, how- ever, that facts should be ignored, even if their connections present many obscurities ; nor can we respect here the famous dogmatic line of division between psychology and cerebral physiology with the traditional awe, and for this I beg to excuse myself at the outset. Anatomical Foundation. However difficult it may be to this day to grasp even the rudiments of the relation of the brain as an organ to the physiological and psycho- logical aspect of its function, we should not cease one moment to work on this problem. Nearer and nearer we must get to it, and, truly, what has already been reached stands inspection well and need not cause us, in the least, to despair. We know to-day that there is only one kind of nervous elements, 409 410 August For el: that is, the neurone, the cell with its fibre and branched processes. When, in 1886-87, about the same time as His, I first put forth this view as a probable hypothesis on the ground of numerous facts, I had no idea that three years later my illustrious colleague, S. Ramon y Cajal, would establish the matter histologically in such a beautiful and conclusive manner. The nerve elements do not anastomose, as was formerly be- lieved, but touch one another by ramifying branches, end-baskets, arbor- izations, etc. Every nerve fibre (axone), together with its ramifications, is merely a part of the protoplasm of a certain cell. Further, Schiller showed in my laboratory that the number of nerve elements in the new- born (oculomotor nerve of the cat) was approximately as large as in the adult, and that only the caliber of the medullary fibres differed enormously. Since it appears certain that, in a lifetime, destroyed ele- ments of the central nervous system are never replaced by newly formed ones, we may draw the conclusion that the nerve elements of an old person are the same as those of his childhood, a point very important for the theory of memory. A matter of further importance is the relation of chromatic reaction of the nerve cell, established by Nissl, to the details of its finer structure. The fibrils, already recognized by v. Kupffer, Schultze, Leydig, and others, and the chromatic bodies present, as it were, ele- ments of a second order, which increase considerably the complication of nerve structure and open new perspectives. The same holds for the change of cell structure after exhausting activity, demonstrated first by Dr. Hodge of this University, and for the grave changes due to the use of alcoholic beverages established by many investigators — an addi- tional reason why we should banish those abominable social and indi- vidual nerve poisons from human diet. Hand in hand with the progress mentioned, we notice the advances in the recognition of local structural conditions in. the brain of man and animals, of systems of neurones, etc., especially through v. Gud- den's method of experimental atrophy; but also by direct anatomical study. The works of Dejerine and Mme. Dejerine-Klumpke, and of KoUiker, are encyclopsedic monuments of those researches. I mention further the doctrine of localization built up by Broca, Hitzig, Ferrier, Munk, etc., which can only lead slowly to a clear and objective under- standing of the whole in connection with an accurate knowledge of anat- omy, of pathology, and of the experimental method of v. Gudden. At Hypnotism. 411 the same time, we must always guard ourselves against speculations built on ' insufficient and unsafe ground, such as the recent doctrines of Flechsig. While it is possible to establish, to a great extent, the func- tion of the peripheral nerves and their nuclei of origin by direct observation and experiment, and while we have also a certain direct access to the study of the spinal cord, we recognize the function of the cerebral cortex in two ways : (a) by physiological experiments and investigations; (6) by so-called introspective or psychological observa- tion and experiments. But the mutual relations of sensory stimulation and muscular action to the hemispheres must also be observed both psychologically and physiologically. If I prick some one, the subse- quent reflex contraction is observed by me physiologically; whereas the character and intensity of the pain which the person claims to feel can only be measured by him on the psychological side. I see and hear his answers physiologically only, but make out their sense psycho- logically only, etc. If we consider more accurately this continual interaction between psychological and physiological phenomena in the light of our knowl- edge of the brain, we are bound to become sure of one thing, viz. that there is a dark field between the subjectively accessible, psycho- logical, sentient, and perceptive parts of the hemisphere cortex, and those representing the physiologically accessible, sensory receiving sta- tions and the motor, or efferent, mechanisms of motion. In this dark, intermediate field, powerful accumulations of stimuli of an unconscious nature must go on, and obscure, instinctive automatic mechanisms, inherited from our animal ancestors, must work and influence us un- consciously to a great extent in the shape of impulses and feelings. We are driven to assume that the great ganglionic nerve centres of the base of the brain, corpora striata, thalami, pons, tegmentum, cere- bellum, must play a part utterly obscure, which perhaps might clear up many points, if we could penetrate more deeply. Unfortunately this point is still far from accessible, since the fragments furnished by physiology are hardly fit to be digested. We should not forget in this whole question what recent investiga- tions have demonstrated, viz. that the field of expansion of a single nerve element, a neurone, may be very large. Just think of a Betz- cell of the central convolutions, the nerve process of which reaches through the corona radiata, the crus, pons, and pyramid, as far as the 412 August Forel: spinal cord, or of a cell of the anterior horn of the lumbar cord, whose process reaches muscles of the foot. Thus, neurones of varied significance and destination cross and interweave in a thousand ways in the central and in the peripheral nervous systems, in order to form the wonderful machinery. One sees, from this alone, how brutal and defective the physiological experiments in the brain must be, and how indefinite the physiological concept of a "centre" is. Physiological Remarks. There is but little in the old nerve physiology that can be used to-day, because it rested, to a great extent, on erroneous histological concepts. "We must accept the well-known fundamental facts concern- ing stimulation, inhibition, reflexes, etc., and also the results of the pioneers of brain physiology, Flourens, Magendie, Vulpian, Duchenne, etc. We may conceive that the brain is a powerful accumulator, a kind of very highly complicated dynamo, in which a still enigmatical physico- chemical wave-like power prevails, for which I have used the expression "neurokyme," (the "force neurique" of the French). This force does not cause any motion of the masses, and consequently belongs to the type of molecular motion, or vibration, as is shown by its great velocity of conduction. Its action leaves in the cell visual changes in the form of material signs of exhaustion. It may be accumulated as energy by so-called mechanisms of inhibition, and again be discha,rged in definite channels by what Exner calls "Bahnung." In this connection, O. Vogt has justly insisted on the important fact that in excessive stimulation the effect is often suddenly stopped because a radiation of neighboring centres of neurones takes place, which is apt to lead away the entire neurokyme, if those centres are more easily excitable. In this way it is in a manner possible to understand associative activity. To enter upon detail would lead too far ; but I beg to say, in a general way, that it is well known that certain functions become much easier and stronger after a while through practice ; whereas, in an obscure but very frequent manner, on the other hand, certain single impulses may leave behind lasting inhibitions, or stimuli, and perhaps disorders of function which may take a pathological character, and seriously tantalize the victim. Such points were used, a few years ago, by Breuer and Freud in Vienna, for the foundation of their doctrine of arrested emotions, which, Hypnotism. 413 unfortunately, was developed into a one-sided system, although it started from correct facts. Thus especially violent affects are apt to leave be- hind all sorts of nervous disorders (convulsions, paralysis, pains, dyspep- sia, menstrual disorders). Breuer and Freud tried to lead the patients in a hypnotic condition to the causative, frequently forgotten, and fre- quently sexual moment of the trouble, to make them dream over that moment and to give, once and forever, a counter suggestion, curing the disorder. In many cases this works ; but by no means always. Before all, we must acknowledge with Isidore Steiner that the greatest nerve centre has the dominant position in this interaction of the neurokymes, owing to its greater mass. It becomes the guide and director of the whole, and the activity of the other centres is brought into subjection. Steiner proved this by a clever experiment on a fish, and showed that in those animals the mid-brain, and not the fore-brain, is the director and the soul of the animal ; consequently it is not the morphological homology which decides the absolute anatomical size or physiological strength, and hence the eminently important fact that the relative size of the individual part of the central nervous system is of great -importance for the relative independence or dependence. We see the proof for this fact in the comparative physiology of the animal series. The spinal cord and ganglia are far more independent in the lizard than in the rabbit ; much more independent in the latter than in the dog ; and in the dog, much more independent than in man. In man these organs have become the subordinated servants of the hemispheres and totally dependent, although their structure is much more complicated than in the lizard. We need not wonder, therefore, if the function of these lower centres is governed and influenced most powerfully by the dynamics of the fore- brain just named, even when, as in the sympathetic, only loose connection exists, such as would suggest, ordinarily, a greater independence. How is a neurokyme, which spreads over an axone, transferred from one neurone to the others by the contact of dendritic ramifications? Duval thinks, by an amoeboid motion of the dendrites, and we read that lately such motions have been directly observed in transparent animals. This hypothesis seems, however, quite immature as yet. It does not explain the extreme rapidity of the conduction of the neurokyme. The functional play of the neurones is better explained by pure molecular motion, as, for instance, in electricity. It would seem that these hypoth- v 414 August Forel: eses are quite premature, and we must wait for actual progress in observations. Finally, we must maintain the fundamental fact of memory, conscious or unconscious, viz. the residual of a dynamic trace of every nerve activ- ity. Such a trace always facilitates the repetition of a corresponding activity, even if it should be forgotten subsequently, and the entire activity may be called forth again by the effect of the stimulus merely associated with the first one ; for instance, ordinary remembrance. Or- ganic memory is independent of consciousness and is the same for motor as for sensory and central activities, and even for reflexes and functions of the sympathetic. Sleep and Waking State — Consciottsness. Man is normally limited to two states of his brain life : sleep and waking condition. Physiologically considered sleep means a relative rest from cerebral activity with recuperation of the exhausted neurones by chemical synthesis, whereas in the waking state processes of oxidation predominate. This is certain beyond doubt, but to draw the conclusion that sleep is called forth by the formation of fatigue products, such as lactic acid, or that sleeplessness could be cured by swallowing lactic acid, as Preyer did, is to become a victim of fallacies. It does not take much acuteness of observation to see that there is a form of sleep which is not rest, and that the brain can rest fairly well even in the waking state. Further, one may sleep much and excessively though not exhausted, and again may keep awake in a state of cerebral exhaustion. Again, every unprejudiced observer must be struck with the usually rather sudden qualitative change in the attitude of a wak- ing and of a sleeping person. That sleep is readily called forth by certain associations, regular hours, etc., is also obvious. Finally, dreams give us a chance to look into the life of sleep from the psychological side. All these factors tend to present sleep as a state of qualitatively modi- fied cerebral activity. This is, however, only intelligible in connection with the concept of consciousness. It was a fundamental mistake of practically all physicians and most psychologists, to think of consciousness as a something, as a form of cere- bral activity, i.e. to confuse the plastic concentrative activity of our Hypnotism. 415 attention witli the purified phenomenon of guljectiveness. We will not quarrel over words. I, for one, am satisfied to be able to rest my view on such a psychologist as Spencer. If any one cares to use the word " consciousness " in any other sense, he may do so as long as he gives us another word for that which I understand to be consciousness, viz. the phenomenon of the inner reflection of the ego, the subjective side of the phenomena. Slight activities of the brain, as well as violent ones, are reflected by it and become "" conscious " ; but equally violent activities seem not to become conscious; they remain "unconscious." Conse- quently we are forced to distinguish between a conscious and an uncon- scious life of the brain. The entire discord of the phenomena rests on the peculiar facts : (1) that the activity of the brain does not take place in one single conti- nuity and connection, that, for instance, two subjective reflexes may occur simultaneously without being connected or " associated," so that the one does not know of the other and one is unconscious in reference to just that other reflex ; (2) that everything which is subjectively " forgotten " drops out of the connection of consciousness so that amnesia and uncon- sciousness are continually confused. The resulting fallacies are evident ; we always call unconscious such actions or states of the brain as were conscious and appear to us to be forgotten, or which were illuminated by a consciousness other than our ordinary remembered consciousness. In order to be concise, I venture to offer a hypothesis which agrees very well with all the facts : Every nerve activity is conscious, i.e. possesses internal reflection ; but these reflections are by no means aU capable of remaining in a synthetical connection with one another. For this we need a more intense associated activity, especially where the connection is to be fixed by memory. Everything which appears no longer, or not at all, in this connection, loses the subjective connection with our memory ego, and we erroneously deem it unconscious, whether it be a past or actual activity of the hemisphere, or only one of the sym- pathetic or of the spinal cord. In order to express such a view consist- ently we must : — a. Eliminate the word " unconsraous," and replace it by "subconscious" or "otherwise conscious." h. Accept a multiplicity of fields of consciousness, or consciousnesses, the contents, i.e. the illuminated cerebral activities, of which are physio- 416 August Forel: logically connected and influence one another subjectively, according to the kinds of activities underlying them ; they are only rarely, or partially, or never connected (associated). That subjective associations require higher intensity and more synthesis than the objective (physio- logical) ones has been shown by psychology (Hoffding). c. Consider all brain activity as completely independent of the accom- panying (subjective) illuminations by consciousness, whether it appears to us psychological or physiological. This is theoretically possible, at least for psychological phenomena. d. Consider the word " consciousness " as the expression of an inner aspect of life, not as the name for any special thing, an activity, a peculiarity. We use the words " energy " and " matter" in a similar way ; there is no energy without matter, as little as matter without energy. In the same way consciousness in our sense is nothing in itself, but merely the subjective aspect of brain life, an aspect probably common to all life. If we adhere to what is said, we find sleep intelligible. We observe the following in the condition of sleep : — 1. The cerebral activity is highly dissociated. The ideas follow one another in a chaos which does not correspond any longer to the connec- tion of things in the actual world. Things which exclude one another in reality appear identical, and the reverse. My friend may be at once a dog, water, or a piece of wood. I may be simultaneously dead and mar- ried, or simultaneously in Europe and America, or see my head before me at a distance of twenty yards. If you study this dissociation more closely, you readily see that it affects not only the logical sequence of higher con- cepts, but the very make-up, even the constituents, of perceptions. The notion of time and place, the single (usually subconscious) sensations con- stituting a perception, are frequently disjointed, and dance together a veritable Walpurgis dance. Again, there prevail powerful inhibitions which prevent all orderly association and keep us in an oppressive despair and impotence. The same chaos prevails in the field of emotions and of volitions, but here the inhibition, or, in the emotions, powerful ebullitions predominate. 2. The conceptions of dream life are hallucinations. When asleep we no longer distinguish between perception and spontaneous conception. The sensory stimuli either do not become conscious at all or they are alle- gorized; on the other hand, all perceptions appear as actual happenings. Moreover, the concept of a motion is usually not capable of eliciting the Hypnotism. 417 corresponding actual muscular contraction. It is merely represented by a motor hallucination. 3. Since there are no corrective concepts, some emotions and ideas may, in this condition, obtain an enormous power, overcome obstacles unsurmountable in the waking condition, and hence produce especially intense consequences. Just think of the evil after-effects of dreams, of nocturnal pollutions, etc. Duval has lately ventured to make a new hypothesis of sleep. He believes that all the terminations of the neurones are in active contact during the waking state by some kind of amceboid activity. During sleep he thinks they simply withdraw, so that the contact ceases. "What a beautiful and simple explanation for all the dissociations and elimina- tions of all the senses! For the time being this view is a mere hypothesis. Nothing demonstrates so thoroughly the deficiencies of Weber's and Fechner's psycho-physical law as sleep. There are too many intermediate forces between the " subject " and the measurable external stimuli. Heer- wagen, for instance, tried to measure the intensity of sleep by the inten- sity of a noise necessary to wake the sleeping person I These two quan- tities are practically without any connection. Everything depends on the kind of association. The same sleeping person can be aroused by a very slight unusual sound, while the greatest noise need not disturb the sleep. Heerwagen further tried to make statistics on dreams by asking people for them ; but he forgot that most dreams are forgotten, and that the forgetting of dreams and the " not dreaming " are two utterly differ- ent things. I am convinced that everybody dreams all the night through. I, myself, if I observe myself at all, cannot be aroused at any time of the night without just having dreamed. Finally, there are all degrees of sleep, from the lightest, best asso- ciated, to the deepest. The former shows all transitions to the waking state. The difference in the cerebral activity during the sleeping and the waking condition implies a corresponding difference of the contents of consciousness. We consequently have two alternating conscious states every day and every night, and our ego is quite characteristic in each. A good trustworthy man may become a thief, a murderer, and a licentious person, a courageous man may be cowardly during sleep, etc. We usually forget our dreams owing to the dissociation, so that our two states of consciousness in sleeping and waking condition show only a slight and fragmentary connection. Not infrequently we find somnambulists who act 2e 418 August For el: in a coordinate manner during sleep. One who did all sorts of house- work in her sleep was very tired after it, but did not remember anything. This is also the rule in the very frequent somnambulism of children. Out of such an orderly activity of a sleeping brain, i.e. out of the spon- taneous somnambulism, originates an extraordinary and especially instruc- tive form of double consciousness, such as has been described by McNish, Azam, Dessoir, and myself. In my case (see Zeitsehrift fiir Sypnotismus, 1898), a German made an eight months' journey to Australia and back without in the least remembering it. The amnesia of retrograde and antegrade character came on after dengue fever. Later I was able to revive the memory by suggestions. It was, however, impossible to establish a connected associ- ation between the two visits to Melbourne on his journey out and back. Those two Melbournes remained for him two entirely different cities. The Data of Hypnotism. At all times in the history of mankind, hypnotism has played a great r81e. Magicians, miracles, miraculous cures, sorcerers, the fakirs of India, are so many proofs of this. The principal fact was always the apparent and subsequently also actual power of certain persons over others, the ecstatic catalepsy or sleep produced by them, the asserted prophecies of the hypnotized, the cure of diseases, the miracles, etc. A magnificent instance of hypnotic influence may be found in the history of King Zoroaster (cf. Stoll's book on this topic). In the beginning of this century Mesmer thought to have discovered a new natural law in those phenomena, a new " fluid," which he assumed to be magnetism. Espe- cially in living beings he called it animal magnetism. He produced hys- terical convulsions usually by contact of men, finally " magnetized " trees and did other absurd things; but also cured a number of patients. Con- demned by the French Academy as an obvious fraud, he came to a sad end. But he retained adherents. One of them, Puysegur, discovered the quiet hypnotic sleep. They all adhered to the belief in a mysterious magnetic fluid. Braid, an English physician, was the first to take a great step toward a scientific elucidation of the question. He found that the whole series of phenomena depended not on a fluidum coming from the outside, but on the brain and nervous system of the person influenced. The very title of his book, " Neurohypnology," shows this. He found that Hypnotism. 419 certain stimuli and also certain ideas could produce this changed cerebral state, hypnotism. By this he had established the principal fact, but he made a mistake in the method by ascribing a capital role to the periph- eral stimuli, just as Charcot did later on. He hypnotized with brill- iant objects, and, therefore, did not obtain thoroughgoing results. These we owe to Liebault, at Nancy, and to his medically and philosoph- ically highly educated friend. Professor Bernheim. The doctrine of Liebault and Bernheim has placed hypnotism among the fields for scien- tific research, from which it will not disappear again. This doctrine reduces hypnotism to the concept of suggestion. In this light we shall mention briefly the principal manifestations. The fact that in falling asleep or awaking the entire mode of brain . activity is suddenly altered, gives us, I believe, the key to an under- standing of hypnotism. Conceive some means by which we are able to produce those two kinds of activity according to our needs, and, more- over, to localize, — to limit them to certain fields, — and you see before you almost the entire series of hypnotic phenomena. For this purpose you should merely be able to direct the cerebral activity of your neighbor, inhibit and facilitate, associate and dissociate. This actually happens by means of evoking certain concepts, which are known to lead most easily to dissociation. A priori, this may appear peculiar and improbable. As a matter of fact, it is exceedingly simple and common. AU human beings are naturally more or less suggestible and, therefore, hypnotizable, although not all are equally influenced by others. Everything that pro- duces the concept of sleep, everything that makes man passive, or throws him into ecstasy, admiration, or confidence, may be used by the rapid and concentrated action of the hypnotizer to dissociate, inhibit, or stimulate, any activity of his subject, — it may produce the desired and foretold effect, the mechanism of which remains subconscious in the person influ- enced. It is especially advantageous to begin with such effects as are readily obtained. This is the principle of Liebault's method. For instance, I yawn; it becomes "infectious." Another yawns; with him it has the effect of a suggestive influence. He yawns because I yawned ; however, he remains subconscious of the mechanism which pro- duces the yawning. Now, I use the beginning dissociation, and tell him rapidly and with assurance : "You are quite sleepy, you cannot keep your eyes open, you cannot open them, you have a warm feeling in your feet ; look at me ; you are already asleep, your arms are heavy," etc. Quite fre- 420 August Forel: quently the subject will feel and even show the one or the other of these phenomena. If he is very suggestible, he will, perhaps, be asleep in a few seconds, to the surprise of those around. This sleep is, however, dis- tinguished from ordinary sleep by remaining under my direction, i.e. by my remaining in connection with the sleeper through his hearing. As soon as I have reached this point a further mastership over his cerebra- tion is an easy matter. I take his arm, lift it, and declare that he cannot lower it ; and he cannot with all his efforts. I put both hands into a rotating motion, and he cannot stop without my permission. I declare that his hand, which I touch, is not sensitive, and no prick of a needle is felt any longer. I give him water to drink, declaring that it is chocolate ; he tastes the chocolate. I tell him to open his eyes, make the dead appear before him, make him hear music which does not exist, assure him that he is a piece of wood, another person ; in short, any fantastic non- sense ; he feels it, believes it, lives through it. I awake him when I want to, put him asleep by another word in a quarter of a second, and allow him to either remember or forget everything that has been said or done to him. In short, I make his cerebration play as in a dream, but fol- lowing my orders, surprise himself and all the spectators, and gain with the public the name of an accomplished magician. The whole trick con- sists in getting, to start with, an easily suggestible person, readily passing into somnambulism. If one is shown to be hypnotized, the others follow like the sheep of Panurge. The case described was that of a person easily put into artificial somnambulism. He need not be a spon- taneous somnambulist for this purpose. The latter are rather rare, whereas fully twenty-five per cent of mankind can be thrown into arti- ficial somnambulism. The spontaneous somnambulism, however, usually represents the autohypnosis of a hysterical person. With others the matter is slower and more difficult, although it is facilitated by example (imitation). Many suggestions may at first be without effect ; but with patience and practice one obtains at least a par- tial influence in ninety-six per cent of men. The person to be hypno- tized must be neither insane nor in a state of emotion, of excitement, or fear. He must before all be treated in a friendly and quieting manner. Flies are caught with honey. First you must gain his confidence. Put him into a comfortable easy-chair, the head resting ; put the right hand on the forehead, tell him to look into your eye, and explain to him that you are going to let him fall asleep, or, at least, to influence him. According Hypnotism. 421 to Bernheim, you have him look at two fingers of the left hand, after a few seconds lower them slowly in order to make the eyelids sink and, if the eyes do not close by themselves, you order them to be shut. Then you begin with easy suggestions, and pass to more difficult ones as soon as the others succeed. By no means all suggestions succeed with all people. According to the success of the more important categories, one may distinguish tliree or four degrees of hjrpnotism, of course with numerous transitions: — 1. Somnambulism, in which practically everything succeeds. 2. Deep sleep, in which at least amnesia for the time of the hypnosis is obtained. 3. Hypotaxia, in which the hypnotized yield to most suggestions, but have the subjective feeling of being awake and remember everything afterward. 4. Somnolence, in which only few suggestions succeed, and in which the hypnotized can resist with some effort. There are, however, cases of deep sleep with little suggestibility and, again, others of simple hypotaxia with very great suggestibility, but with- out amnesia. Moreover, the hypnotizer can at any time transfer a somnambulist into one of the other degrees, according to suggestion. The following are a few especially interesting phenomena which suc- ceed chiefly in somnambulists : — Posthypnotic Suggestions. You declare that a certain phenomenon will take place after awaking, during the waking condition ; for instance, he will feel, do, see, or think some particular thing. This actually occurs as foretold in the suggestion. Suggestion d SehSance (to take effect at a definite time). You suggest the same thing for a later time ; for instance, the next day or a week afterward, or even later. This, too, usually succeeds in somnambulists with a little patience and practice. Suggestion in the Waking Condition. After a little practice of the subject almost every suggestion succeeds nearly as well in the waking condition as during sleep or a somnolent state. 422 August Forel: Not only laymen, but also many physicians, have imagined that hypnosis and wake-suggestion are totally diffei-ent things. Nobody can show his ignorance of this question more thoroughly than by such a state- ment. Sleep, i.e. the subjective sensation of sleep of the person hypno- tized, is merely a generalization of the suggested dissociation in the sense of ordinary sleep. When this generalization becomes too broad and the hypnotizer leaves the subject, he may at times lose the " rapport " with the subject, and when he tries to give further suggestions he may fail to succeed or he awakes the subject, just as out of ordinary sleep. It requires some precaution to reestablish the connection or " rapport " with- out putting an end to the sleep. On the other hand, in a circumscribed suggestion, in a completely waking state, it is easiest to show the symp- tom of localized dissociation. As soon, however, as you increase the number of suggestions, i.e. of dissociations, in a perfectly waking condi- tion, you see how the looks of the hypnotized change, become more dreamy ; in other words, how the dissociations become more generalized and produce a state resembling general sleep. Beaunis and others tried to make out that this condition in complicated wake-suggestions and that of execution of post-hypnotic suggestions — practically the same thing — is something peculiar, a "veiUe somnambulique." This is quite unnec- essary. We are dealing merely with a more or less localized or general- ized condition of dissociations or sleep. It is true it differs from ordinary hjrpnosis, because in the latter a great part of brain-activity is not influ- enced by the hypnotizer, viz. the spontaneous impulses of the hypnotized ; whereas in the intentional wake-suggestions everything is governed by the hypnotizer. Spontaneous is, of course, not to be taken in the sense of undetermined free will, which does not exist. What we understand by " spontaneous " is merely the resultant of all actual and past plastic and automatic braia activities as they are inherited and developed under the external influences during life. Suggested Falsificatioks op Memory. This is one of the most surprising illusions produced by suggestion, described in a masterly manner by Bernheim. You suggest to some one that he remembers accurately to have done, experienced, seen, or heard something, while there is absolutely no truth in it. This succeeds remarkably well. If external conditions make it possible very dan- Hypnotism. 423 gerous false witnesses might "be produced in this way. Children espe- cially are surprisingly disposed to such suggestions; also hysterical women, and even normal persons. For this it does not take a professional hypnotizer. Ordinary attorneys, and also physicians, obtain sometimes unknowingly such suggested confessions or symptoms. Curiously enough it is sufficient to suggest the chief points of the situation, and to leave the rest to the imagination of the subject. He completes himself every- thing that was missing in the suggestion given, and furnishes a mass of precise details, which he makes up, and believes in, and by which the deception is increased. Conscientious judges will, of course, find that the statement does not agree with the facts ; but unfortunately sufficient pains are not always taken. We cannot say that the witness lies; he speaks with the greatest conviction, and makes a deep impression on the audience, especially on the jury. Thus we see a series of phenomena, the beginning of which is insig- nificant, and which all occur, more or less, in normal sleep and in certain people, which, however, when called forth rapidly and in a condensed form, makes a very baffling, confusing, and almost miraculous impression. Especially confusing are the mass-suggestions, which take hold of a great number of enthusiastic believers, produce hallucinations of all senses, even of the tactile sense, and thus create convincing witnesses for appari- tions, even for "materialized" spirits. Such is indeed the great tendency of our brain toward illusions. Only the more thorough psychologists are less surprised by these phenomena, because normal psychology has led them already to similar concepts. The essential feature of suggestion is evidently the production of a sleeplike dissociation of brain activity by the means of ideas. Dissocia- tion is used to call forth inhibition, facilitations, hallucinations, reenforce- ment of stimuli, decisions, impulses, affects, etc. A further characteristic feature is that the person influenced is never really conscious of the mechanism of the actual realization of a suggestion. In a general way suggestion makes it possible to eliminate consciousness, i.e. conscious memory, from any phenomenon whatever, and to bring it into the circuit again. You may make the "skin" (or rather the parts of the brain connected with it) totally insensitive to pricks, and yet later make con- scious the sensation which was not actually present at the moment of the prick. Or you may produce the sensation of a prick and later make the subject amnesic for the pain felt, so that he will emphatically assure you 424 August Forel: that he did not feel anything, although this is not true. Again, you may suggest the pain of a prick which never occurred. In short, a weird play is possible with memory, consciousness, motion, and sensation in som- nambulists. The effect of facilitating or inhibiting suggestions goes even further. It may involve the sympathetic, and call for, or arrest, menstrual hemor- rhages, and influence blushing, bleeding from the nose, peristalsis, etc. Constipation, as well as menorrhagia, can be cured as if by miracle ; per- spiration and even the pains of labor can be influenced. Surgical anses- thesia is quite often easily obtained. Even blistering of the skin has been produced by Wetterstrand beyond doubt. All these things are continually doubted, especially by our esteemed colleagues, the physicians, and the bona fides of the hypnotized is continu- ally denied. They cry: Mystification! Illusion! I hardly care to men- tion as a proof that I had several women controlled to whom I suggested menstruation to take place on a definite day of each month, exactly at 7 A.M., to last three days exactly, not merely once, but after the sugges- tion had had its regular effect for months. After all, theoretical criti- cisms can always be made against all such controls. If, however, I submit to your consideration the fact that the many thousands who were hypno- tized by Liebault, Bernheim, Wetterstrand, van Renterghem, Vogt, and myself, almost all came in order to be cured of some disorder, and certainly not in order to deceive me, the objection that it might be hum- bug falls naturally, especially if you consider the regularity of the phenomena. It would be inconceivable that thousands of independent people, who come to a physician in order to be cured, should agree on the same story to deceive the physician in the same manner, and to simulate both hypnosis and cure. These considerations alone demonstrate the absurdity of the objection. Yet if I mention cases of perfectly honorable and loyal men and friends whom I have cured of constipation and similar things, if I mention a professor of surgery whom I made anaesthetic and again sensitive in a quarter of a second, not only in hypnosis but also in the waking state, such a hackneyed objection might finally be dropped. It is chiefly traceable to a fundamental ignorance of psychology and of the life of the brain on the part of the majority of physicians. Universities ought to put an end to this. It is, after all, by no means astonishing that a dynamo weighing three pounds, as the brain does, should be able to produce strong effects on the circulation, peristalsis, etc., by means of Hypnotism. 425 the neurokyme current through the peripheral nerves and ganglia. And if we are obliged to admit that an affect or a dream may have grave and lasting psychological consequences, such as paralysis, convulsions, pains, etc., why should not a suggestion be able to undo such consequences ? We cannot help admitting that, so far, we have greatly underrated the dynamic effects of the neurokyme in the brain, both on its evil and on its good side. We must go farther and declare that many diseases which internal medicine, gynecology, etc., have been in the habit of treating from a local point of view are nothing but affections of the brain which ought to be treated by suggestion alone. I merely speak of habitual constipa- tion, of sleeplessness, of chlorosis, of most dyspepsias, and of most men- strual disorders. And further, we must claim that a larger number of our so-called remedies, such as electro-therapeutics, balneotherapy, many prescriptions, etc., cure merely by suggestion, and by.no means through some imaginary specific action. The irregularity of their results, indica- tions, and application prove this sufficiently. It must be admitted that such a remedy gives, in many cases, a stronger suggestion than mere verbal suggestion. In America, we ought not to forget the famous Keeley Gold Cure for inebriates, as a beautiful instance. Since Keeley suggested total abstinence, he was bound to have lasting results. Let us not forget that therapeutic results of suggestion are nothing but lasting post-hypnotic effects, which, however, like everything normal, have a tendency to become lasting. We do not put anything new into the body ; we merely lead the nerve paths back to the normal dynamic course. It is rarely possible to hypnotize a pei-son against his will, because confidence is the first condition of success. As soon as the hypnotized loses confidence in the hypnotizer, the infiuence of the latter is usually over. The brain does not submit any longer to voluntary dissociation, but it associates and concentrates all its energy against the lightly built dynamic structure. There remain a few special points : — Autosuggestion. — By this we mean suggestions which arise spontane- ously, or at least without intention. Hypnosis and Hysteria. — It was a serious blunder of Charcot, and especially of his pupils, to mistake hypnotism for hysteria, i.e. a normal fundamental quality of the human brain for a pathological condition. It was, therefore, inevitable that the Paris school of hypnotism had to yield 426 August For el: to that of Nancy. Bernheim showed quite correctly that the so-called great hypnosis of Charcot, with its supposed three phases appearing on definite stimuli, was nothing but an artefact by suggestion in pathological hysterical subjects. Nevertheless, hysteria deserves special mention here, hecause itsfwnda- mental symptom consists precisely in a pathological exaggeration and degenera- tion of dissociability or auto suggestibility. The hysterical, men and women, are, moreover, known to be much predisposed to convulsions, so that the hysterical react peculiarly to hypnosis. They are, as a rule, very sensitive to all hypnotic procedures, but exceedingly difficult to direct. They add to every suggestion a mass of autosuggestions, begin to get convulsions or headaches, or all sorts of other disorders which their brain adds on account of its oversensitiveness and excessive dissociability. So it easily happens that for one pathological symptom removed by suggestion, auto- suggestion favors one with three new ones. Hence, hypnosis is an excellent, though double-edged, reagent for testing a hysterical subject. As a rule, however, it will be possible to see after one attempt how an un- obtrusive and well-calculated suggestion may suffice in a conversation with- out the title " hypnosis," and in a perfect waking state. An awkward hypnotizer, or one ignorant of hysteria, will usually do harm to the hysterical, produce hysterical attacks, etc. The hysterical are apt to pass into deep cataleptic, and even lethargic, conditions from which they are difficult to rouse. In short, to play on them with hypnotism is play- ing with fire. All the unintentional damage which is attributed to hypnotism concerns hysterical subjects. I therefore tell every physician who wants to hypnotize : " Beware especially of the hysterical, and do not run any risk before you sit well in the saddle." Suggestion can do much good in the hysterical, but the physician must proceed exceedingly cautiously, individualizing, without even mentioning the word hypnotism. Crime and Hypnosis. This chapter was exaggerated to the extreme by Li^geois, and dealt with too lightly by Delbceuf. That misuse, especially sexual misuse, of hypnotized persons, may occur once in a while, is certain and possible, especially in deep hypnosis, in hysterical lethargy, etc. Even more dangerous is, however, the blackmailing by hysterical impostors. Hence the rule : Never hypnotize a woman alone, without a witness. That the Hypnotism. 427 hypnotized might be used for crime is theoretically possible and experi- mentally proved. But no such case has really occurred yet. False testi- mony through suggested falsifications of memory is about the most serious possibility. Abnormal love-affairs of pathological persons, especially of the. hysterical or of pathological impostors, in which hypnotism plays a r81e (case of Czinsky, etc.) rather belong to psychiatry. Of late those suffering from paranoia and other forms of insanity show a predilection for the delusion that they are secretly hypnotized. Crimes through hypnosis are probably so rare because, as is said above, confidence is the first condition of hypnosis. The insane can usually not be hypnotized, because the instrumental dynamo, the brain, fails to work properly, attention is defective, etc. One can hypnotize only in one's mother tongue, or in another lan- guage which one knows very well, for it takes, before all, great certainty and rapidity, and a blunder in a foreign language which makes it difficult to understand, disturbs the " rapport " considerably. For the purpose of watching patients dangerous to themselves, I have hypnotized the watching nurses with great success, and in this way pro- duced a " sleeping night watch," who watches much better than a waking person, and does not become exhausted or overtired. I hear that my successor at Zurich, Professor Bleuler, continues the matter with equally good success. I give the nurse the suggestion to sleep quite well, but to notice during his sleep every unusual action of the patient, so that he awakes at once when the patient makes an attempt at suicide, and at once falls asleep again when the danger is averted. In artificial somnambulism this succeeds remarkably well. Therapy of Neevous Diseases by Woek. G-eneral Psychotherapy. Starting from the experience that agricultural occupation is the best for the insane, and that the natural man does not work as one-sidedly as the " civilized," but always has, as the condition of getting along, depended on a combination of mental occupation with muscular activity, I have tried for a number of years to treat severe cases of so-called nervous diseases (neurasthenia, etc.), i.e. psychopathias, with such occupations. A severe case which I thus cured by agricultural work encouraged me. Mr. Grohmann, a civil engineer, himself a patient, had recovered his health by 428 August Forel: gardening, and was much interested in the matter. I encouraged him in his attempt to occupy nervous patients in his gardens. This was the beginning of his institution for the occupation of nervous cases, which increased from year to year. Carpentry was added among other occupa- tions, and very good results were obtained in severe cases. P. J. Moebius later gave the method much support, and the data were published in the dissertation of Menier (Zurich), and later more fully by Grohmann him- self. Grohmann emphasizes the observation that a combination of his treat- ment with suggestions by Dr. Ringier in Ziirich led very frequently to good results. My principal idea in the matter was that not the muscular labor as such, but especially the centrifugal concentration of attention on deter- mined muscular innervation for an occupation, mentally satisfying and with a purpose, diverts the brain from pathological activities, and acts as a cure. Stupid muscular labor, as gymnastics, dumb-bells, and turning of the ergostat, does not give any satisfaction, and, above all, does not keep the mind or attention from going astray. Moreover, such useless activi- ties cannot be pursued for any length of time as a real pursuit. Now I should like to go a step farther to-day, and to sketch with a few cases a partially new chapter of psychotherapy, not touched upon by me so far. Not all neuropaths are fit patients for horticultural, agricultural, or other work, nor is the pathology of brain life done justice to merely by the ordinary suggestions of sound sleep, appetite, and like functions. You further know that genius and insanity are somewhat related. Whereas, however, it is well known that many a genius perished with insanity, it is perhaps less clear to many physicians that under the picture of hysteria or other psychopathias, many a genius, or at least many a talent, may slumber and fret like a bird in a cage, and also that the thera- peutic cant of neurologists paralyzes the wings of the bird instead of liberating them. Here, if anywhere, a correct diagnosis and individualiz- ing treatment is necessary. To be sure, not everybody who feels himself to be a genius is a genius. The experience of the alienist must find out of the hundreds of defective brains suffering from exaltation and mental weakness, the few which are not really defective, but contain a wealth of high talent, the development of which is inhibited or paralyzed by certain disorders. If, however, you have discovered such a hidden, tied- Hypnotism. 429 down treasure among the numerous nervous patients (brain-patients or encephalopaths), it is your grand duty to leave the path of cant, and to restore the wings to the eagle. Hypnosis and occupation with manual labor may be a very helpful accessory remedy ; but they are not the chief thing. It is necessary to gain the full confidence of the patient by affection and by penetrating into all the sides of his mental life, to make every fibre of his emotional life vibrate. Let the patient tell you the story of his entire life, live it over again with him, and allow yourself to be thoroughly penetrated by his feelings. In this you should, of course, never forget the sexual feeling which varies so strongly from one case to another. But it should not be examined after the ordinary medi- cal routine, which usually considers only the seminal emissions and the coitus ; but with full consideration of all the loftier vibrations connected with the sexual life. This being done, you search for the real definitive aim in the life of the patient, and lead him with determination and con- fidence. It is a cause of much surprise to see all the psychopathologi- cal disorders disappear as if by witchcraft, and to watch how the unhappy, incapable, nervous wreck becomes an energetic, efficient person, who may amaze others by his working capacity, and remains a warm friend to the physician who understood him. A miserable person becomes happy; a "failure," a "talent" or even a "genius"; a patient, a healthy being. Allow me to give briefly a few instances. My friends may recog- nize themselves, but will pardon this publication in the interest of mankind. 1. A highly educated young lady, the daughter of a talented father and a very nervous mother, had the reputation of being less endowed than her sisters, was nervous, and became more and more hysterical. She finally developed very marked paralysis, and was brought to the hospital for the insane. At first she was almost completely cured by ordinary hypnosis ; but after a number of months she had a relapse, with almost total inability to walk. She was again cured by continual agricultural work with farmers. But she felt unhappy over not having an aim in life. Not without hesitation I allowed her to yield to her anxious desire to become a nurse ; her parents were much afraid of the night service. But the latter was endured without trouble with the help of a few sugges- tions regarding it. She took up her work enthusiastically, carried it out with all its trials and fatigues, and became more and more active in every 430 August For el: direction, and to-day she is one of the most active members of a com- mittee of philanthropic ladies, doing remarkable work. 2. A physician suffered for some time with "severe neurasthenic disorders," and tried in vain to cure himself with all sorts of remedies. He came to me with his complaints. I encouraged him, advised him not to consider all those disorders, and insisted on the higher ideals of his life. We agreed on a definite plan and he left. Later he wrote me that by that one conversation he had been cured. 3. A young man with some hereditary taint, from a very religious family, very talented, became " neurasthenic " and nearly insane. He attempted suicide, and was taken to various sanitariums with complete interruption of his studies and very gloomy prognosis. He was abso- lutely unable to work any longer, suffered from headache, sleeplessness, and inability to keep his attention on any mental activity. Gloomy and in despair, he did not show any symptoms of melancholy inhibition, etc. He was quite clear concerning his " psychopathia " and " absolute failure in life." He also had suffered from various imperative ideas and actions which had played him many a trick. Sexually he was perfectly calm. He was brought to me as a case given up. Before long the talent of the young man struck me. More intimate relations showed him to be in a totally dissatisfied state of mind. Brought up in strict orthodoxy, he never could believe in those religious dogmata, and therefore thought himself to be an outcast and lost. The forced formal training, too, with which he was brought up was a source of disgust to him. Life seemed aimless to him. First I calmed him concerning his religion, and showed him that one can be a happy and valuable man without any positive belief. Further, I showed him that learning by heart is the " mind of the mindless," and that a mere understanding with interest stands much higher. I told him not to try to learn anything further, but to merely read with interest what interested him, and not to care whether he kept it or not. In this way I revived some confidence and some pleasure in life. He began to read his books with interest and pleasure, instead of learning them with disgust. As a philosopher and freethinker he returned to life, became an enthusiastic abstainer and a member of the Independent Order of Good Templars. He helped me found new lodges. My patient, who at first required watching for fear of suicide, soon became my friend and associate in the work. The nervous symp- toms disappeared, one after another. Finally he made a rather long Hypnotism. 431 journey alone in a tropical country, returning completely cured and with perfect self-confidence. He resumed his studies, passed his final exami- nation summa cum laude a few years later, was admired by all his col- leagues for his enormous working capacity, and gives every promise of a splendid career. 4. An hysterical lady consulted me — highly talented, but psycho- pathic from childhood, with attacks of "grande hysteric," and greatly excited by her living together with her mother. Notwithstanding numerous opportunities, she did not want to get married for a number of intellectual reasons. I tried hypnosis. Deep hysterical sleep came on and convulsions began to show. I waked her up with much trouble, told her boldly the result was deep beyond expectation, that she would be cured in a short time, and that she had been only too deeply influ- enced. From that time I gave her merely wake-suggestions. In a few days almost all the disorders had gone, also the constipation, and especially the convulsions Qsapienti sat!^. I explained to her that she was most in need of work and of a definite aim in life. She did not care to found a family, with some justification, but was interested in depraved youth. Now she started out. Instead of cures in water- ing places, electricity, and massage, I gave her a number of books on criminal anthropology and introductions to the directors of prisons, of asylums, of the reformatories for children, etc. She took up the work with enthusiasm, joined the prohibition movement and the Inde- pendent Order of Good Templars, visited prisoners, the insane, destitute children, showed great interest in everything, an equally good judgment, and an astonishing working capacity. She improved every day, and left in a few weeks for a larger city, where she wishes to continue her studies. In such cases, I should formerly have prescribed mental rest, inac- tivity, manual labor, or what not. My patients did not improve. In such cases the brain is not exhausted, as one might suppose at first sight. It is merely misled, and works in abnormal paths ; its natural talents starve, are inhibited, and the activity offered it does not agree with it, or certain scruples of a religious or sentimental kind paralyze its activities, and paths for pathological brain activity are created. This we must recognize and change by a bold diversion. But beware of believing every psychopath who poses as a mistaken genius and wants to study higher philosophy. There are fifty cases of 432 August Forel: Hypnotism. these to one of those described above. For these, agriculture is as good as for imbeciles and the insane. True inhibited greatness is not wont to brag or to think too highly of itself. We must look after it, must seek it and find it. Then we can go to the root of the matter and not remain content with mere trivial suggestions about gardening or carpentry. A SKETCH OF THE BIOLOGY OP ANTS. By Professor August Forel. ToGETHBE with the bees and the wasps, the real ants belong to the insect family of hymenoptera, whereas the termites, or white ants, belong, like the dragon-flies, to the neuroptera. All these insects live in social organizations. More than all the rest, the ants have developed social life most highly and variedly. This is why they deserve our special interest. They not only present an innumerable array of individuals, but also a magnificent variety of forms. Nearly 3000 species, divided into 154 genera, are already described from the five continents, and this number continues growing every year. The social state of ants has brought about a peculiar phenomenon called polymorphism of the species. Just as the difference of sex in man and animals is generally marked by so-called correlative differences of organization (as, for instance, the beard in man), so we find in certain animals that these differences become especially pronounced (compare, for instance, the cock and the hen). In the ants, the difference of the sexes becomes so excessive that the females and the males look like dif- ferent animals. But that is not all. An additional differentiation takes place in the species, in the female germs ; a certain number develop into a second category of females with totally different shape of the body, much diminished ovaries, without wings, but with a more highly devel- oped brain. This specialized category of females is called the " working ant." In many species, even a third specialization of the female sex has formed, with powerful head and strong jaws, called "soldiers." The females and the males are usually winged, the workers and the soldiers always without wings. Consequently, a family or a state of ants of any kind consists of three or four different forms of adult individuals. In rare instances, additional forms exist. Moreover, there are many species in which an incomplete division of the workers into two categories with transition forms occurs (large, me,dium, and small workers). To these 2 F 433 434 August Forel: we must add the young brood, which consists of eggs, the footless and eyeless, white and tender larvae or maggots of all sizes, according to age and sex; and, finally, the antlike nymphs or chrysalides. In many species, the larva spins a fine silk cocoon, which is erroneously called the egg. The real ant eggs are extremely small, and look almost like a white powder. The architecture of the ant body shows several important social peculiarities. The real brain, independent of the sense organs, is rela- tively very large in the worker and the soldier, smaller in the female, and almost rudimentary in the male, in accordance with the fact that the male ant plays a pitiably transient and good-for-nothing role, notwithstanding its powerful eyes and strong wings. Its immense imbecility and help- lessness, in contrast with the well-developed senses, are a clear expression of its lack of brain. The real brain, Dujardin's pediculated body, possesses a highly developed, small-celled cerebral cortex, especially in the worker. The ants possess a social stomach or crop. It is situated at the entrance to the abdomen, is very elastic (when it is overfed, the cubic contents of the abdomen may be ten times enlarged), and does not digest, since it has no glands. Its undigested contents can be vomited forth at any time by the ant and distributed to its fellows, or to the larvae by feeding from mouth to mouth. The mutual feeding is one of the vital conditions of the state of ants. Behind the crop lies the chewing, or pumping, stomach. It has four hard valves, which usually close hermetic- ally the digestive tract of the ant. When the ant wants to eat, it opens the valves and pumps some of the contents of the crop into its peculiar, individual stomach, which is lined with digestive glands and where diges- tion begins. I have demonstrated these conditions by an experiment. I gave some honey stained with Berlin blue to a hungry ant. After it had eaten very eagerly, I put it with a few equally hungry companions, who at once surrounded it, begging. They all were filled with blue droplets before long. I then dissected one after another and found that the first stomach, filled with the blue mass, had not at first allowed a trace of the blue fluid to pass into the chewing stomach and into the digestive stomach. Only, during the following days, the digestive stomach slowly became stained more and more blue. On the fore legs the ants have a fine, spurlike comb which they use to clean the rest of the body. This is very necessary in the busy workers. Biology of Ants. 435 In the mouth, too, they have a comb with which they clean the combs of the legs, the larvae, and their companions. Of great importance are further the mandibula, or upper jaws, which are usually dentated and serve as grasping tongue, biting weapon, mortar spoon, carrying instrument, scissors, etc. They replace our hands, our weapons, our scissors and knives. In the mouth they have, further, a tongue for licking, with fine organs of taste. The most important social organs of the ant are, however, the anten- nae, or feelers. They contain exceedingly delicate and numerous sense- organs for the tactile sense and odor, terminating in hairlike structures. The function of these sense-organs is experimentally established. It is especially remarkable that this protruding and mobile olfactory organ not only gives the ant information on the chemical constitution of bodies, through contact (I called this contact-odor of the insects), but also makes possible an appreciation of space by olfaction, owing to position and motility, an ability which we, with our invaginated, rudimentary olfactory organs, can form no conception of. This appreciation of space is possible, since the different nerve endings may convey to the brain simultaneously, or in successive moments, the impression of the various chemical proper- ties (odors) of various objects or parts of objects, lying side by side. Numerous relations of space are perceived for this reason, and especially, owing to the high mobility of the feelers, not merely by contact but already at a certain distance, at which the differences of behind and before, of right and left, can readily be furnished by smell. This ability must produce a knowledge of space which lies between that of our tactile sense and that of the senses of hearing and seeing. When lately Bethe imagined he had discovered a " polarization " of the olfactory traces of the ants, he mistook and overlooked these conditions completely. More- over, the ants perceive odor from a distance with their antennse. It is experimentally established that ants recognize one another as friends or foes merely by the means of the feelers, as Huber supposed as early as 1810; and that, in their migration, they are largely oriented, or guided, by the feelers, although the eyes, too, help considerably in the orientation out- side of the nest. An ant without feelers is lost, and at once excluded from the social life; whereas without eyes it may go, on working, recognizing its companions from its enemies, and find its way, although with more difficulty, at least in the nest and in its near neighborhood. Lubbock has proved that ants feel the ultra violet rays of the solar 436 August For el: spectrum which we do not see. With the help of complicated experi- ments (by varnishing the eyes, or by the application of aesculin which absorbs the ultra violet rays) on the known instincts of ants, I have dem- onstrated that they see the ultra violet rays with the eyes, not photo- dermatically, i.e. with the skin, as many lower animals do. The flying females, and especially the males, have good eyes, with very distinct vision ; the workers, however, see usually but poorly. The workers form the most important social elements of the ant com- munity, whereas the soldiers serve for certain special functions, and the females and males solely for the propagation of the species. The socialism of the ants is limited to the solitary state of the ant colony. All the individuals of one colony live up to complete solidarity, whereas the rest of the world — with but few exceptions — and especially all the other states of ants, even of the same species, are rather consist- ently treated as enemies. Each state builds one or more nests. In these the immense wealth of instinct in ants shows itself. Almost every single species has some peculiarity in its architecture; yea, the same species knows how to adapt itself to the varying conditions, and to build accord- ingly. Our most common European ant, occurring also in North America, the small dark brown Laaius niger Linne, builds in the meadows large, regular labyrinth-like hills of earth. In stony ground it makes its nests under stones ; in the woods, in rotten stumps ; in houses, in rotten frames. Most European and North American species mine in the earth labyrinth- like complexes of galleries and rooms, where they nurse their brood. Many build a dome of earth on it, serving, like flat stones, to take up the radiating heat of the sun. When the sun shines in cool weather, the ants carry their whole brood under the cupola or under the stone. Dur- ing the night, or in rain or in hot weather, everything is carried into the depth. The ants build with their jaws and forelegs, working up moist earth into little lumps, during or after a rain, and making walls with them. They are splendid masons and know how to use a blade of grass as timber or a leaf for a roof. Occasionally a little stalk is sawed with the teeth of the upper jaw wholly or partly bent, pulled sideways, etc. I recommend every friend of nature to watch this activity after a warm rain in a meadow. Other ants with strong, hard jaws mine their nest in hard wood. In a species living in trunks of trees (^Oamponotus s. Colobopsis truncatus) a very narrow hole leads out. It is constantly watched by a peculiarly Biology of Ants. 437 transformed soldier; — its big head just fills the hole and is trimmed flat anteriorly, so that it closes the hole flush, like a cork. Even a trained eye has difficulty to find the hole stuffed in this manner. A closely related species lives in North America. Yet other species nest under the bark of trees, under stones, in rocks or cracks of walls, even in walls of our houses. In tropical America I found a great number of the species in hollow, dry sticks of the brush, also in the thorns of acacia and in hollow trees. The ant of our woods, Formica rufa, and its next Euro- pean and North American cousins cover a dome of fir needles, small fragments of wood, etc., which keep warm the nest, built as a hollow labyrinth. The gates are opened by the ants in the morning and closed in the evening, in excessive heat frequently the reverse. Other ants evidently use a resin-like secretion of the maxillary gland, and cement with it meal of wood, earth, plant-fibres, and similar material to form a sort of cardboard or pulp out of which they make wonderful nests, either in hollow trees, as our European Lasius fuliginosus and Liometopum microcephalum (and the North American Liometopum apiculatum'), or out- side on branches of trees or on trunks, as we have found it in many Central American species of Azteca and Cremastogaster. Finally there are ants which build nests spun between the leaves of the trees out of a fine, silk-like texture, as the species Polyrhachis and Oeco- phylla, and in Costa Rica the Componotus senex s. textor. According to the most recent observations they are said to use their larvse, which fur- nish the thread, and which they use with the jaws as a spinning instrument. Certain species (Formica exsecta in Europe and exsectoides in the AUe- ghanies) form powerful states or colonies, which, according to McCook, may consist in the AUeghanies of up to 1600 nests, which are all in friendly relations with one another and are able to govern a whole forest. How does a colony form ? Huber, McCook, Blochmann, and Lubbock have established the following facts : At a certain season, the mature young brood, the winged females and males, fly out from all the nests of the same species. In the air, on trees, or on the tops of hills, a wild mass-wedding takes place in which I was able to establish mutual, but especially female, polygamy. Shortly afterward the stupid males perish on account of inability to feed themselves. The females remove with their own legs the loosely attached wings and creep into the earth or into wood, singly or several together. They build a little room, lay a few eggs, and sparingly nurse the larvse, or maggots, out of their own body 438 August Forel: juice (they are very stout and fat) until three or four very small workers have grown up. These begin to work at once and to feed and care for their mother or mothers, which have nothing to do after this. The wonderful feature is that the mother or the mothers keep so many sper- matozoa in their seminal pocket from the one multiple copulation or wedding, that they remain fertile for many years and are able to lay mill- ions of eggs. They evidently remain as a rule the mothers of the entire colony as long as it exists. At least Lubbock kept alive fertilized females in artificial nests for eight and even eleven years, and the existence of most colonies of ants probably does not last much longer. It is, however, not impossible that once in a while, later on, a female brought home by the workers, or a female of their own progeny fertilized already within the nest, may be added to their number. Except ia parasitic species, strange females are always killed by the workers of a colony. The mothers or queens are well cared for and fed by the workers. Their sole work con- sists in laying eggs. A court of workers constantly surrounds the fertil- ized female, takes charge of the eggs, etc. The interior life of an ant colony represents the purest anarchistic socialism. Each individual works for the community. Some build the nest; others clean every corner of it; yet others nurse the brood, feed it, clean it, and carry it, according to the temperature, into various parts of the dwelling. Others, again, leave the nest and see to the food supply of the community by filling first their social crop, or first stomach. The workers serve one another attentively, feed, clean, and carry one another, and have a mutual understanding by means of the feelers and certain butts. The understanding, as well as the motor impulse, of that language of signs, evidently depends on inherited instincts, and is decidedly quite limited, but must be sufficient for the social require- ments. The males, and usually also the females, are inactive, and are, the former wholly, the latter largely, fed and cared for by the workers. Toward the outside world the whole number is usually hostile to every- thing living, which leads to offensive and defensive wars and expeditions, the study of which is uncommonly interesting for the comparative psychologist. As I said before, the workers find their way outside with the help of their sense of smell and of touch, and partly, also, with their eyes. But this is frequently very difficult for them, and they help one another in two ways. Individuals with especially good sense of smell (with stronger Biology of Ants. 439 olfactory bulbs of the antennae) which have found something useful or dangerous, come home, butt impetuously against many companions, turn round, and are accompanied by a number of workers to the place of the finding or of the danger, guided by means of their sense of smell. On the way they often turn round to find out whether they are followed. Ants with relatively poorer sense of smell return home after having found something; take hold of a companion with the upper jaws, and induce him to have himself carried to the new place, motionless and partly rolled up. The carried, apparently motionless, ant sees and smells the way all the same, even if it amounts to thirty or forty yards. She returns to the nest herself and again brings new companions to the place of emigration. In this way, ants which have lost their way have themselves carried home when they meet a companion. If for any reason a colony of ants becomes tired of its old nest, the same course is chosen. The most enterprising workers search for new places, and the most fortunate and active ones among them finally bring the entire colony, with its brood, to the new site selected by them. These migrations are exceedingly instructive, since there are competitions between two or three new sites until one is victorious, because the ants come back from the others and reemigrate. Every working ant is capable of doing all the labors mentioned in turn, although many individuals, especially always the partially dimor- phous forms of workers, usually have their preference for the one or the other. Huber has shown, and I have found it corroborated several times, that ants completely separated recognized one another after weeks and months, and saluted one another as friends, merely by the help of the peculiar olfactory organs of the antennae. This kind of memory varies according to the species. There are immense variations in the mode of nutrition of the ants, and this is one of the most important causes of variety of the habits, as a few instances will show. The plant-lice are well known. On most of our plants we find these tiny, succulent parasites, imbibing with their trunks the juice of the plants, but digesting their rich and ever-present meals quite insufficiently, so that their excrements are a clear fluid containing sugar. It is anatomi- cally demonstrable that these clear droplets are not secretions of special glands, but really the excrements of the lice. Most ants of our regions are in the habit of considering the plant-lice as a kind of cattle, to look for them everywhere, to tickle them with their feelers until the louse passes 440 August For el: the clear drop, which is at once eagerly sipped by the ant. When no ants are present, the louse waits longer, and finally kicks like a horse, at the same time spurting forth the drop. By this the leaves get a brilliant coating of sugar, the so-called honey dew. In the manner described the ants fill their social stomach for the community. Certain species build a dainty mason-work of stables for the lice on the roots of the plants in their underground dwellings, and even take care of the eggs of the root- lice. Other species build stables above ground with moist earth, and galleries around the stalks of plants which bear leaf-lice, in order to pro- tect their wealth in cattle against attacks by strangers. In other regions, especially in the tropical countries, little larvse of cicadas and caterpillars of butterflies are used in a similar way as cattle for ants. The ants always know enough to unite their efforts, in order to lug home both pieces of prey and larger pieces for the construction of the nest. In America, Africa, and India there are ants (Dorylides) whose enormous colonies live as nomads above or beneath the surface. They usually nest for a while in the ground or in a hollow tree, whence they make enormous expeditions for prey, in which they attack, kill, cut to pieces, and carry home everything alive : cockroaches, rats, mice, spiders, etc. When they attack a human habitation, all the inhabitants are forced to leave at once ; and they are glad to do so, because within a few hours all the vermin, big and small, are chopped up and carried away. Small children in the cradle must be protected against the intruders and taken away. But in return the house is free of vermin, and very soon all the ants, together with their prey, have disappeared. In the Dorylides the huge females are always devoid of wings and eyes; the males, also very large, are winged, however, and in possession of powerful eyes. In a short excur- sion through Colombia, I could watch the expeditions of the Dorylides species, in part at least. Far more remarkable even is the mode of life of the ants which raise fungi. They belong to the South American tribe of the AUini. In their frequently very large nests these animals form caves which reach the size of a fist. The workers climb the trees in long pro- cessions, every worker cuts out a spherical piece of a green leaf with its strong jaws, and thousands of them return laden with such leaves. They have three sizes of wgrkers : big-headed giants, minute dwarfs, and between them a scale of medium-sized individuals. The latter are the leaf-cutters, whereas the giants are at the same time defenders of Biology of Ants. 441 the nests and crushers of the leaves. The harvest of leaves is prepared into a kind of a leashed pulp, which is built up in the form of a laby- rinth, or rather sponge. This pulp of leaves serves as culture medium for the spores of the fungus (^Rhozites gongylophora Moller), which are present in the nest in large quantities. The leaf-pulp rapidly becomes covered with a white film. The army of working dwarfs watch that the fungus does not fill the nest and stifle its inhabitants. Every growing twig or thread is at once cut off by these pigmies, hardly two millimetres long, until the fungus gets ready to produce its second form, which Moller has called ant-kohlrabi, because they are little nodes resembling miniature kohlrabi. The fungus produces immense quantities of these kohlrabi, and the whole ant-colony lives on them. But the nutritive power of the pulp for the fungi is not infinite. As soon as a part of a sponge-like fungus garden is exhausted and becomes brownish, it is torn down by the ants and thrown in small brown grains, out of the nest, around which they form wall-like hills. In return, these parts are continually replaced by the fresh supplies of leaves. Thus they work continually, day and night, throughout the year, the leaf-cutters, the leaf-crushers, and the weeders of the fungus garden, in busy harmony, for this magnificent culture of fungi destroy- ing the forest. They are so numerous that they give the life of the virgin forests of South America a peculiar stamp. At every step you come across processions of leaf-carrying ants and their nests. I my- self was able in a short trip through Colombia to corroborate a great part of the beautiful and careful scientific discoveries of Professor Moller, and to discover the as yet unknown gardens of fungi of several species and genera. Certain Attini have a rudimentary instinct of horti- culture, and merely use the excrements of caterpillars, wood pulp, etc. They raise another fungus. The final form of fungus of Rhozites is a large, beautiful agaric, which grows on the nests of the ants. My attack with spades on a nest of Atta sexdens L., one metre high and six metres in diameter, turned into a real battle. The Indian who helped me took to his heels. In a few seconds my hands bled all over from the sharp bites of the large warriors. But I succeeded in un- covering about twenty gardens in a corner of the nest. Almost every bite of a warrior bleeds. The natives use these animals for suturing wounds ; they have the ant bite together the two wound margins, and then they sever the body from the head. The head remains fastened with 442 August Forel: the jaws, and closes the wound like a small forceps, v. Jhering has shown that the fertilized females of Attini carry in the mouth a piece of the fungus taken from the nest. In this manner they have the germs from which their brood raises a new garden. North America has a small horticultural ant, Atta (Trachymyrmex) Tardigrada Buckley, var. septentriondlis McCook. The habits of other species of ants were well known to, and inter- preted by, King Solomon. I speak of the subgenus Messor, which lives in masses around the Mediterranean Sea. These animals also make large caves in the ground. They collect the seeds from all kinds of plants, and accumulate their subterraneous granaries. There they know how to prevent the sprouting until it is convenient for them. Then, in the moment of beginning germination, when the starch changes into dias- tase and sugar, they eat the grains, both in summer and in winter. There are no real winter provisions, as Solomon thought. In Texas there is an ant (^Pogonomyrmex molefaciens) which allows just one kind of grass, Aristida oligantha, to grow around its nest, while all the other plants are weeded out. It feeds on tke seeds, and is the famous agricultural ant of Lincecum. A closely related form (P. harbatus) makes peculiar pavements on the surface of its nest with little stones. Other ants QMyrmecocystus melliger and Mexicanus) use part of their workers as provision-pots. These ants are so overfed by the other workers that their first stomach or crop reaches the size of a wine-grape, and correspondingly distends the abdomen. These so-called "nurses" cannot walk any longer, and hang in the subterraneous spaces as pro- vision-pots for the community. Types of this kind live in Mexico, Colorado, and Texas, and are dug out and eaten by children. McCook has studied their habits. A topic worthy of admiration is the so-called symbiosis of a South American ant, Azteca MiXlleri, with the Cecropia tree Imbanba (^Cecropia peltata). The tree is hollow inside. On peculiar cushions of the shoulders of its leaves it produces granules rich in albuminous substance and not present in other Cecropias (Miiller's granules). The ant lives in the hollow space of the Cecropia, where the mother of the colony digs into an apparently specially adapted, thinner portion. In this tree the Azteca finds a home and its food in the granules of Miiller. But it is very bellicose. As soon as the leaf-cutting ants, just mentioned, attack the Cecropia, the furious Aztecas defend the tree and throw them back. Biology of Ants. 443 With what fury the Azteca species defend their trees with the help of a very odorous, resinous substance secreted by the anal glands, I have been able to see repeatedly in Colombia, where some live in self-made pulp- nests, hanging on the branches of trees, others in the Cecropias and other hollow trees, and one even under the flat leaves of a kind of ivy. The symbiosis of Azteca Mulleri with the Cecropia peltata is, however, incom- plete, inasmuch as a complete mutual dependence of the two organisms does not exist ; the Cecropia, at least, can live without the ants, at least in its first years. But the symbiosis of the fungus Mhozites gongylophora with the Atta species is complete. Neither fungus nor ant can live by itself ; each is absolutely dependent on the other. The ant nests have their parasites and domestic animals like the dwell- ings of man. Certain lice and worms trouble the ants, and lay their eggs into their brood. There also exist very wonderful relations between certain beetles, lepismas, centipedes, etc., and the colonies of ants. They are called guests, although as a rule they are rather harmful lodgers for the ants. They are tolerated or even loved by the ants on account of a certain odor or pleasant secretion of their hairs, which the ant licks passionately. They live as members of the colony in the ant nest, and, as Wasmann has so well described and Janet corroborated, take the habits of ants. They are fed by the ants from mouth to mouth, and even feed each other. They communicate by means of their feelers with the ants, and with one another. Even their brood is usually fed and raised mostly by the ants as if they were their own. Long ago I observed the feeding, transportation, and nursing of the larvae of Atemeles (a beetle living with the ants), and wondered why the ants cared for these strangers just as for their own brood, without, however, knowing then that these larvse belonged to the same beetle which is a guest of the ants as an adult. Wasmann has proved this ; he also has demonstrated the harmful influence of these guests on the ant colony which begins to produce pathological malformations between the worker and female, described by me formerly without a knowledge of the cause. Other guests are rather mischievous thieves, which creep into the nests and eat the ants or their brood (JMyrmedonia), or merely in order to eat the excrements of ants (^Dinarda). The excellent biologist, Was- mann, knew that in migrations of a colony of ants to a new nest the whole gang of little guests (beetles, centipedes, epismas) know how to follow the ants into the nest, following the trace by their sense of smeU. 444 August Forel: I myself have corroborated this observation. This is, however, not the case with the small, round Thorictus Foreli living in the nests of the large and long-legged Myrmecocystus megalocola in Algeria. It is too small and too slow to be able to follow the swift ant. Consequently this beetle (discovered by me in Algeria, and called after me by Wasmann) always clings to the shaft of the feeler of the ant, and is carried in this way. A peculiar notch in the head-shield allows it to wholly embrace with its jaws the feeler of the ant without hurting it. Lately Wasmann believed that he found that the beetle bores a hole into the shaft of the feeler of the ant with its lower jaws and suck its blood. But Escherich denies this, and the matter is not settled. Even more remarkable than the relations of these guests are the slaves and the friendly relations of some species of ants to one another. Many years ago I accidentally discovered that some of our ants (for instance, Formica rufa, the common ant of our forests), which usually live by themselves and work hard, in very exceptional cases, probably after a war in which they were victorious, let the chrysalides of other weaker species (Formica fusca') hatch, rear them, and consider them as members of their community. This is the origin of the rare mixed colonies which give the explanatory history of evolution in the animal series for the following long-known fact. Charles Darwin had theo- retically surmised that mode of origin of the instinct of slavery in ants. The Formica sanguinea, as Huber first discovered, is almost always in the habit of making irregular raids in June, July, and August, in which they surround the nests of Formica fusca, attack this weaker species, and chase away after a violent struggle the inhabitants of the nest, whose brood they seize and carry home. The larvae and chrysalides, kidnapped in this manner, hatch in the nests of the sanguinea, where they feel at home very much as kidnapped infants. There they render the greatest service as workers to the robbers, so that the latter, although also rela- tively active, lead an easier and more insolent life of prey than their nearest relations. This gives the Formica sanguinea a very peculiar, enterprising, and intelligent biological stamp. It is taken up by the daily labor much less than other species. The so-called slaves, or better, helpers, feel themselves so well at home that they do not recognize their real brothers and sisters from the robbed nest, and treat them as enemies. It is established that the ability of ants to recognize begins only a few days after the hatching of the chrysalis, when the soft chitine is getting Biology of Ants. 445 harder. In order to show this, I have put together larvae and new-born ants of various species and genera, and raised a mixed but peaceable colony. In North America there are families of Formica sanguinea (ruhicunda Emery, etc.) which have similar habits. The Amazon ant of Huber (JPolyergus rufescens') has developed fur- ther the system of slaves. Their dagger-shaped, bent jaws are already unfit for work. Like a Macedonian phalanx, its rust-colored army, con- sisting of usually from 300 to 1200 ants, rushes from its nest on summer afternoons. In a close array and forced march it follows the path pre- viously reconnoitred by a few robbers, and in one half to one hour it covers distances of from fifty to one hundred metres. It is true the army often loses its way or stops until a few ants have found it again, rapidly butt with their heads against the others, and give them the sign to follow. If not, the swarm returns unsuccessfully. As a rule, however, they reach a nest of Formica fusca or rufiharhus, rush with an incredible haste into the entrances of the nest, and sack in a few minutes the entire brood of the unfortunate, overpowered ants in order to run home, and to throw the prey simply to their helpers. The observation of such an expedition is probably the most interesting zoological spectacle I ever have witnessed. I have observed them very often in the canton of Vaud, and kept statis- tics on the number of expeditions, of the soldiers, of the robbed nests, and the rapidity of the march. The Amazon ant completely depends on its helpers. Their entire brood is fed and cared for by them. Yea, the robber cannot even eat without help, and starves, as Huber and I have shown, in presence of the richest food, if it is not poured into its mouth by the helpers. It is able to swallow if its mouth happens to get into honey ; but the instinct to eat has been lost. The North American Polyergus luoidus (which robs Formica pallida falva') and brevioeps have the same habits. The little genus Strongylognathus shows how the instinct of robbing slaves can slowly develop into parasitism. In 1871, I discovered a new species in Wallis, Strongylognathus Suheri, and I was able to show on the spot by an experiment that it can rob like Polyergus. The more frequent and smaller Strongylognathus testaceus, however, cannot do this any longer. This small and weak animal, in which the workers are dying out, according to my observations, still shows ridiculous remnants of the fighting tactics of its relatives. Wasmann has proved that the fertilized female of this ant sneaks into the nests of another kind. 446 August Forel: Tetramorium ccBspitum, is received by the workers beside the Tetramorium mother, and lives beside her. For some cause the Tetramoriums raise from that time on the workers of their own species only ; whereas they allow the larvae of the males and females of their own species to perish ; instead of this they raise the whole brood of the Strongylognathus mother, perhaps merely since it causes less trouble and work. At last the parasitism of the Anergates atratulus goes even further, they having become totally devoid of workers. Here the fertilized female of Tetramorium ccBspitum is received ; whereas the own mother of the colony of this species disappears in a manner not yet explained. As long as the existing workers live, they nurse the entire brood of the Anergates female, consisting merely of winged females and wingless males. The Tetramorium workers from that time merely work for the parasites. The females of Anergates are fertilized in the nest by their own brothers ; not till then do they fly out to found new nests. In this manner the species is subject to continued inbreeding, since there is always only one mother in a nest ; but it does not seem to suffer from it. In North America, Epoeous Pergandei lives as a parasite with Monomorium minutum. But nothing definite is known of its biology as yet. Another ant, Formieoxenus nitidulus Nyl., lives as a small but active tolerated guest with its entire brood in the partitions of the nests of the common wood ant. It also lives in the Rocky Mountains. The northern Tom^gnathus sublcevis, however, according to Adlerz, penetrates as a brutal, uncalled-for guest into the nest of a weaker ant (Leptothorax aeervorum), and forces its brood on these animals, more- over allowing itself to be lazy and comfortable and fed by the host. The wingless worker of Tomognathus is at the same time female; the male is winged. Tomognathus Amerioanus from Washington probably lives in a similar manner. The tiny but warlike Solenopsis fugax lives in very small rooms and channels, which it burrows into the partitions of the nests of larger ants ; but it lives there as an enemy, robber, and thief, sneaking among the brood of the larger kind and eating it up. Since my first publication of this point in 1869, it has become known that this manner of living occurs in a large group of the Solenopsis species and related genera, such as .Mromyrma, certain Monomorium species, etc., which all represent, in this manner, small robbers hidden in the walls of the nests of larger species. Biology of Ants. 447 It seems that in North America Solenoptia modera, pollux, and molesta live in a similar manner. In Africa and India the Carebara species lire in the same way in the nest of Termites, also .Mromyrma in Madagascar. In the Colombian virgin forests, I discovered in 1896 a new, previ- ously unknown relation of two ant-colonies, which I called parahiosis. A small Doliohoderus and a still smaller Oremastogaster, both of a deep black and glossy, live usually, though not always, together in the follow- ing manner: They inhabit the same nest, probably robbed from a species of Termites. The cavities and galleries are all in open connection, and are inhabited by the two species in a mix-up, almost inextricable to the human eye. This much is certain, that the two species do not mix. Each occupies definite rooms and galleries, and cares for its own brood only, notjvithstanding the open communication. But there is peace, never war ; in common expeditions, the two species leave the nest in order to find food on plants and trees, but only to the point where the final aims divide ; there they separate, and each species goes on to its special aim (the plant-lice or flowers). Thus we have a peaceable symbiosis without mixing and without any intimate relations. The relation of guests might well be called "Xenobiosis," the helpers' relation "boethobiosis." These expressions would be preferable not only among ants, but also for analo- gous relations of other animals. Wasmann's expressions (" Symphilie," etc.) are, however, preferable. Apart from the raids and the other con- ditions described, the ant colonies, even those of the same species, have warfare usually about the source of nutrition. We men believe our- selves the sovereigns of the earth. Obviously, the ants do the same in their little world, since the larger colony considers a certain district around its nest as its property. This district comprehends trees, plants, and the soil ; whoever enters it is attacked, and, if possible, slain. Hence the wars between neighboring colonies, wars which are often carried to the annihilation of the weaker part. A victory is accounted for by the number and courage of the warriors, and also by certain weapons, as stings, poison-sacks, hardness of body, swiftness, resinous secretions of the anal glands which are spurted out, certain tricks, as for instance in Polyergus the piercing of the brain of the enemy, in Formica exsecta the sawing off of the neck, or the like. The smaller kinds usually take hold of the legs of the larger ones, seize them this way, and finally kUl them by the number of their pricks or bites ; whereas the big ones cut or crush the small with their jaws. Whole chains of combatants are formed, of which 448 August Forel: few may survive the battle. Slowly the victor gains ground, until the enemy either faces about or finally is surrounded in its own nest, chased away, or killed with its entire brood. Besides such larger wars, which may last days or weeks, there are innumerable skirmishes along the fron- tiers, especially about the possession of plant-lice. Yet ants do not merely murder and carry on warfare ; they also can make peace. This does not only happen because two exhausted colonies often give up fighting and avoid a certain strip of contested land, but also, in rare cases, by coalition and complete union. I have produced this experimentally by mixing rather large parts of nests of various colonies of Formica fu»ca with their inhabitants, or at least putting them close together in a strange place, where they were forced to build a new nest. Necessity and circumstances, the mutual need for food and habitation, reduced the warlike impulses. After usually insignificant threats, taunts, and weak attempts at fighting, the ants began to work together, and in the course of one or two days formed one harmonious colony. If, how- ever, you bring part of a colony near the nest of another one, it is driven away and often annihilated. Once (1871) I poured the inhabitants of two colonies of very hostile different kinds (Formica sanguinea and pratensis') into one bag and allowed them to struggle one hour, in order to put them into connection with an artificial glass-nest. Fighting, with the greatest excitement and total confusion, the ants reached the glass-nest where they carried their larvae. Necessity gradually reduced the fever of the battle. The next day several hundred had killed one another ; the survivors began to work together, though defiant and threatening. A few kept up the fighting spirit. After five days the union was perfect. Ten days later I allowed them to get out on the meadow, where they built a common nest and after that lived in undisturbed friendship. When, however, I put a few ants from the original nest of the pratensis with the new allies, the new arrivals were kindly received by their former sisters, but fiercely attacked and partly killed by the sanguinea. This case is very instructive, and shows that the sanguinea had closed friendship with only the definite set of pratensis, and were quite well able to distinguish them from the, as yet, unknown sisters. The instinctive feeling of duty of the workers has been illustrated by me in the following manner : One meter from a nest of Formica pra- tensis, I placed a strong portion of a strange colony of the same kind. Biology of Ants. 449 They soon began the attack, and a great battle began, lasting several hours and costing nearly a thousand lives on the two sides. While the inhabitants of the nest rushed out to the defence of their home, I poured honey quite close to the soldiers running into the battle. Under ordi- nary circumstances the honey would have become black with ants in a short time. But the workers passing by sipped for only one or two seconds, could not be tempted any longer, and rushed into the combat — as a rule into death — although the ants have neither criminal law nor court-martial. Whoever wants to be a coward or egoist may do so with- out any interference. But the ant cannot act or will antisocially, and this is the secret of their socialism. In the struggle between the individ- ual instincts and impulses against social ones the latter usually have the upper hand. There are, of course, short hesitations which are very in- structive to observe. As has been said already, the community of ants realizes the purest ideals of our modern anarchists. No government, no king, no laws, no bureaucracy, no officials. Nobody commands, nobody obeys. Even the so-called slaves are perfectly free and work voluntarily, from mere in- stinct. Hence, absolute freedom with absolute solidarity. When a worker wants to be lazy, he is cared for none the less (this is seen in the Amazon ant, which is totally dependent on its "slaves"). But this laziness does not occur at all, except with the slave-makers and the parasitic species. Consequently there are no 'cracies, no parties, no rebellions, no crimes; at least almost none (and we must remember no alcoholism either) ; at the most only occasional individual differences which, however, are almost always quite short and insignificant.^ And yet, there is the most perfect order, indeed, a wonderful skill to create order by harmonious, energetic work in a short time, in the most difficult and confused situations possible. If, for instance, you demolish brutally a nest of ants, take all the inhabi- tants into a bag, and throw them in a completely unknown region amidst 1 1 have described one exception in my "Fourmis de la Suisse" ; a mixed colony of Amazon ants suffered for lack of food, owing to prolonged drought. Then I saw how a few helpers (slaves), importuned for food by the Amazons, would bite their "masters," and finally carry them as far as possible to throw them away. The hard Amazons took it good- naturedly, but always returned home at once. Tired of such a Sisyphus labor, one of the helpers began to bite, so that an Amazon lost patience, pierced the brain of the rebellious slave, and thereby killed it promptly. This fact is quoted by the famous criminal anthropolo- gist, C. Lombroso, and has been interpreted as a case of crime among ants. This interpreta- tion stands discussion, and the case is certainly instructive. 2g 450 August Forel: enemies, they reconnoitre rapidly, gather the brood, find a place for a nest, hide the brood provisionally under leaves or in the hole of a cricket ; the enemies are kept away, the nest buUt, food, especially plant-lice, is sought for and found, etc. The wonderful and manifold social instincts of ants have called forth many erroneous views, and produced a sort of anthropomorphism of the ant's mind. There are, indeed, enough analogies and points of contact be- tween the society of man and of ants, — slavery, raising of cattle, horticulture, war, treaties, etc. These are phenomena of convergence, the complicated connection of which in both ant and man is brought about by the fact of social community of living brains. The chief difference lies in the inherited automatism of instinct in the ant, and the immensely individual plasticity of the human brain. You may ask how it is that the brain of an ant, only the size of a pin-head (Charles Darwin calls it the most won- derful atom of substance of the world), can do as complicated things as the human brain, which weighs two and one-half to three and one-quarter pounds ; but you must consider the other side of the matter, namely, the immense limitation of an ant as soon as it ought to do something that does not lie in its inherited instinct. We see the Amazon ant, which has such complicated ways of plundering, perish beside ample food although it can lick and swallow, because it has lost the instinct to eat. Every species has its special tricks, but only those, and it never devises anything else. It is true, that ants adapt themselves to new conditions to some extent, and better than other insects, because their brain is relatively a little larger ; but this is the case only in a very limited manner. In its whole life, an ant learns almost nothing apart from a certain knowledge of places, and the ability to distinguish other ants ; shortly after it comes forth from its chrysalis it knows almost all it will ever know, innate and inherited ; whereas the mammals, and even the birds, learn very much during their lives, have far more memories, and combine and use them. Hence, it follows that mental or cerebral activities which are one-sidedly complicated, fixed in the brain and inherited, necessitate far fewer brain elements than the ability to learn individually to combine, to adapt itself, to practise new activities, and to make them become secondarily automatic by practice. This ability, which may be called plastic in comparison with the automatism of instinct, especially distinguishes the human brain, although even we think and feel and act far more from inheritance than we believe. Still there is no actual contrast between instinct and the Biology of Ants, 451 plasticity of reason. There rather are thousands of transitions, especially the so-called hereditary dispositions, which are, so to speak, rudimentary, not completely developed instincts, and which, for instance, distinguish a Mozart or a Koszalzki, who were able to become virtuosi and composers as children, from unmusical persons over whom all the teachers labor for years in vain. The animals with complicated high instincts are, therefore, by no means more stupid than those which have only slight instincts. All depend on two different modalities of brain activity which may go, side by side, to a varying height, without excluding one another mutually. As I wrote over twenty-five years ago, the community of ants teaches us further that the social state of man cannot be arranged after the pat- tern of the ants. Man has too much and too little for this. He lacks the sexless workers, the social first stomach, and, above all, the high social instinct which, without any legal compulsion, works much rather for the community than for itself. In return, he can receive, digest, and combine in his powerful brain a world of plastic concepts, which the little ant, with her automatic, one-sided, though extremely well-built and remarka- bly well-used, brain is unable to do. The highly developed human brain contains an unlimited number of plastic powers, capable of development, connected with overpoweringly strong inherited egoistic instincts and pas- sions of animals of prey, but capable of being influenced in manifold manners by selections and by individual adaptations. Man and his brain cannot be forced into one single collective or anarchistic dogma, because overwhelming impulses lead him forcibly toward a higher evolution, which cannot be defined beforehand. We are, of course, in a position to recognize, to some extent, the laws of this psychical evolution, especially by the help of history, of ethnology, of psychology, connected with anatomy and physiology of the brain, and to remove, in a negative man- ner at least, that which deranges and inhibits it, as the use of alcohol, of opium, the cult of the golden calf and of illusory gods, and other causes of degeneration, and to try positively to increase the number of the fittest germs at the expense of the unfit. But, unfortunately, the higher insight of man has to meet continually the obstinate narrowness of prejudice, so that the victory of truth is not easy. Notwithstanding the difference of their physical organizations and size from ours, with all their relatively low rank in the animal series, the ants, with their social biology and psychology, are an extremely valuable 452 August Forel: Biology of Ants. and interesting object of comparison, both of living nature and of the social relations of man, and for human psychology generally. They prove how the eternal, divine powers of nature produce equal or similar phenomena in completely different ways, whether they be those of living beings in their various combinations, or those which are called the physico- chemical powers of inorganic and organic nature. Have not slavery, the raising of cattle, and horticulture been practised by ants long before there were any men on earth ? These ants very probably have acquired these arts in the way of natural selection, automatically, in the course of innu- merable generations, with the helps of inherited combinations, without there ever having existed an ant which could have got a perspective of the adequacy of the process, individually. Man, however, invents indi- vidually, with the help of innumerable combinations of plastic impulses, and he often devises, individually, things which long before had been pro- duced by natural powers, or living beings before him. Let me mention the sail long used by the nautilus, electricity, etc. In Proverbs vi. 6-8, we read : " Go to the ant, thou sluggard ; con- sider her ways, and be wise ; which having no guide, overseer, or ruler, proyideth her meat in the summer and gathereth her food in the harvest." To this sentence, which is scientifically true, word for word, I add the following : She gives man the social doctrines of work, of harmony, of coxirage, of sacrifice, and of a spirit of solidarity. DEGREES CONFERRED. Following are the degrees conferred by the University during its first decade. In case of the degree of Doctor of Philosophy, the subject of the dissertation and the date of the examination are given. DOCTORS OF PHILOSOPHY. MATHEMATICS. J. W. A. Young, Sept. 16, 1892. On the Determiaation of Groups whose Order is a Power of a Prime. American Journal of Mathematics^ Apxil, 1893, Vol. 15, pp. 124-178. William H. Metzleb, Jan. 4, 1893. On the Roots of Matrices. American Journal of Mathematics, Oct., 1892, Vol. 14, pp. 326-377. Thomas F. Holgate, May 9, 1893. On Certain Euled Surfaces of the Fourth Order. American Journal of Mathematics, Oct., 1893, Vol. 15, pp. 344-386. John E. Hill, June 17, 1895. On Quintic Surfaces. Mathemaiical Jtevievo, July, 1896, Vol. 1, pp. 1-59. L. Watland Dowling, June 19, 1895. On the Forms of Plane Quintic Curves. Mathematical Beview, April, 1897, Vol. 1, pp. 97-119. Thomas F. Nichols, June 20, 1895. On Some Special Jacobians. Mathematical Beview, July, 1896, Vol. 1, pp. 60-80. Waeeen G. Bullaed, June 17, 1896. On the General Classification of Plane Quartic Curves. Mathematical Beview, Vol. 1, pp. 193-208, 3 plates. Feedeeick C. Feret, June 15, 1898. Geometry of the Cubic Scroll of the First Kind. Archiv for Mathemaitilc og Naturvidenskab, B. 21, Nr. 3. 453 454 Degrees Conferred. Ebnbst W. Eettgeb, June 16, 1898. On Lie's Theory of Continuous Groups. American Journal of Mathematics. (In press.) John S. Fkbnch, March 28, 1899. On the Theory of the Pertingents to a Plane Curve. (In press.) PHYSICS. T. Peoctor Hall, June 19, 1893. New Methods of Measuring the Surface-Tension of Liquids. Philosophical Magazine, Not., 1893, Vol. 36, pp. 385-413. Clakence a. Saundeks,^ July 6, 1895. The Velocity of Electric Waves. Physical Beview, Sept.-Oct., 1896, Vol. 4, pp. 81-105. Thomas W. Edmondson, July 11, 1896. On the Disruptive Discharge in Air and Liquid Dielectrics. Physical Beview, Feb., 1898, Vol. 6, pp. 65-97. Samxiel N. Tatlob, July 31, 1896. A Comparison of the Electromotive Force of the Clark and Cadmium CeUs. Physical Beview, Sept.-Oct., 1898, Vol. 7, pp. 149-170. Albebt p. "Wills, June 21, 1897. On the Susceptibility of Diamagnetic and weakly Magnetic Substances. Physical Beview, April, 1898, Vol. 6, pp. 223-238. William P. Botnton, June 23, 1897. A Quantitative Study of the High-Frequency Induction Coil. Physical Beview, July, 1898, Vol. 7, pp. 35r-63. CHEMISTKY. Thomas H. Clabk, June 13, 1892. The Addition-Products of Benzo- and of Toluquinone. American Chemical Journal, Dec, 1892, Vol. 14, pp. 553-576. John L. Beidge, Jan. 8, 1894. Ueber die Aether des Chinonoxims. (p-Mtrosophenols.) Liehig's Annalen, Sept., 1893, Vol. 277, pp. 79-104. Julius B. Weems, June 20, 1894. On Electrosyntheses by the Direct Union of Anions of Weak Organic Acids. American Chemical Journal, Dec, 1894, Vol. 16, pp. 669-588. 1 Died Dec. 19, 1898. Degrees Conferred. 455 BIOLOGY. Heemon C. Bumptis, Sept. 29, 1891. The Embryology of the American Lobster. Journal of Morphology, Sept., 1891, Vol. 6, pp. 215-262, 6 plates. William M. Wheeuek, May 10, 1892. A Contribution to Insect Embryology. Journal of Morphology, April, 1893, Vol. 8, pp. 1-160, 6 plates. EDWi2sr 0. Jordan, May 11, 1892. The Habits and Development of the Newt. Journal of Morphology, May, 1893, Vol. 8, pp. 269-366, 5 plates. James R. Slonakee, June 20, 1896. A Comparative Study of the Area of Acute Vision in Vertebrates. Journal of Morphology, May, 1897, Vol. 13, pp. 446-502, 5 plates. Colin C. Stewaet, June 19, 1897. Variations in Daily Activity Produced by Alcohol and by Changes in Barometric Pressure and Diet, with a Description of Recording Methods. Journal of Physiology, January, 1898, Vol. 1, pp. 40-56. PSYCHOLOGY. Heebeet Nichols, Sept. 29, 1891. The Psychology of Time, Historically and Philosophically Considered with Extended Experiments. American Journal of Psychology, Eeb., 1891, Vol. 3, pp. 453-529 ; April, 1891, Vol. 4, pp. 60-112. Alexandee E. Chambeelain, March 9, 1892. The Language of the Mississaga Indians of Skflgog. A Contribution to the Linguistics of the Algonkian Tribes of Canada. MacCalla & Co., Philadelphia, 1892. 84 pp. William L. Betan, Dec. 13, 1892. On the Development of Voluntary Motor Ability — with a Preface on the Requirements of Work in Experimental Psychology. American Journal of Psychology, Nov., 1892, Vol 5, pp. 125-204, 3 charts. Feedeeick Teact, May 29, 1893. The Psychology of Childhood. D. C. Heath & Co., Boston, 1893. 94 pp. Aethue H. Daniels, June 21, 1893. The New Life : A Study of Regeneration. American Journal of Psychology, Oct., 1893, Vol. 6, pp. 61-106. 456 Degrees Conferred. John A. Bebgsteom, May 14, 1894. An Experimental Study of Some of the Conditions of Mental Activity. American Journal of Psychology, Jan., 1894, Vol. 6, pp. 247-274. Fletcher B. Dbbsslae, June 14, 1894. Studies in the Psychology of Touch. ATtierican Journal of Psychology, June, 1894, Vol. 6, pp. 313-368. Thaddbus L. Bolton, April 30, 1895. Ehythm. American Journal of Psychology, Jan., 1894, Vol. 6, pp. 145-238. Fbank Dkew, Jiily 29, 1895. Attention : Experimental and Critical. American Journal of Psychology, July, 1896, Vol. 7. pp. 533-573. James H. Leuba, July 29, 1895. A Study in the Psychology of Keligious Phenomena. American Journal of Psychology, April, 1896, Vol. 7, pp. 309-385. Colin A. Scott, June 30, 1896. Old Age and Death. American JoumM of Psychology, Oct., 1896, Vol. 8, pp. 67-122. Ellsworth G. Lancaster, June 11, 1897. The Psychology and Pedagogy of Adolescence. Pedagogical Seminary, July, 1897, Vol. 5, pp. 61-128. Ernest H. Lindley, June 12, 1897. A Study of Puzzles with Special Eeference to the Psychology of Mental Adaptation. American Journal of Psychology, July, 1897, Vol. 8, pp. 431—493. A. Caswell Ellis, June 18, 1897. The History of the Philosophy of Education. (In press.) George E. Dawson, August 2, 1897. Psychic Rudiments and Morality. American Journal of Psychology. (In press.) Edwin D. Staebuck, August 3, 1897. Some Aspects of Religious Growth. American Journal of Psychology, Oct., 1897, Vol. 9, pp. 70-124. Feedeeic Buek, June 8, 1898. From Fundamental to Accessory in the Development of the Nervous Sys- tem and of Movements. Pedagogical Seminary, Oct., 1898, Vol. 6, pp. 5-64. Linus W. Kline, June 10, 1898. The Migratory Impulse vs. Love of Home. American Journal of Psychology, Oct., 1898, Vol. 10, pp. 1-81. Degrees Conferred. 457 J. RiCHAKD Street, June 11, 1898. A Genetic Study of Immortality. Pedagogical Seminary, Sept., 1899, Vol. 6, pp. 267-313. Daniel E. Phillips, June 13, 1898. The Teaching Instinct. Pedagogical Seminary, March, 1899, Vol. 6, pp. 188-245. Feedebick "W. Colegeovb, June 13, 1898. Individual Memories. American Journal of Psychology, Jan., 1899, Vol. 10, pp. 228-255. Henet S. Cuetis, June 16, 1898. Inhibition. Pedagogical Seminary, Oct., 1898, Vol. 6, pp. 65-113. Feedeeick E. Bolton, Aug. 15, 1898. Hydro-Psychoses. American Journal of Psychology, Jan., 1899, Vol. 10, pp. 171-227. Henry H. Goddard, June 12, 1899. The Effects of Mind on Body as evidenced by Faith Cures. American Journal of Psychology, April, 1899, Vol. 10, pp. 431-602. The following gentlemen have taken the examination for the doctor's degree, but have not yet completed all the formal requirements. Eugene W. Bohannon, I Cephas Gxiillet, Edmund B. Hubt, | George E. Paeteidge, Charles H. Walkee. DOCTORS OF LAWS. HONORIS CAUSA. LuDwiG Boltzmann, July 10, 1899. Professor of Theoretical Physics, University of Vienna. Santiago Eamon t Cajal, July 10, 1899. Professor of Histology, and Eector of the University of Madrid. August Foeel, July 10, 1899. Late Director of the Burgholzli Asylum, Switzerland. Angelo Mosso, July 10, 1899. Professor of Physiology, and Rector of the University of Turin. i^MiLE PicARD, July 10, 1899. Professor of Mathematics, University of Paris. TITLES OF PAPEES Published bt Past and Present Members of the Staef, Fellows, and Scholars. H. AUSTIN AIKINS: — B.A., University of Toronto, 1887; In- structor, University of Southern Cali- fornia, 1888 ; Graduate Student, Yale University, 1888-91 ; Lecturer on History of Philosophy, iUa., 1890-91 ; Ph.D., Yale University, 1891 ; Professor of Logic and Philosophy, Trinity College, North Carolina, 1891-92 ; Fellow in Psychol- ogy, Clark University, Oct., 1892- Jan., 1894 ; Professor of Philosophy, College for Women, Western Reserve University, Cleveland, O., Jan., 1894-. Author of : — The Philosophy of Hume, in extracts, with Introduction. (Sneath's Series of Mod- ern Philosophers.') Henry Holt & Co., N. Y., 1893. 176 pp. I^om the Reports of the Plato Club. At- lantic Monthly, Sept. and Oct., 1894, Vol. 74, pp. 359-368 ; 470-480. The Daily Life of a Protozoan (with C. P. Hodge). Am. Jour, of Psy., Jan., 1895, Vol. 6, pp. 524-533. Education of the Deaf and Dumb. Edvr- cational Beview, Oot.j 1896, Vol. 12, pp. 236-251- The Field of Pedagogy. Western Reserve University Bulletin, April, 1897, Vol. 3, pp. 15-21. H. AKIYAMA: — School of Science, Totio, Japan, 1888- 90 ; College of Pharmacy, San Pran- cisGo, Cal., 1890-91 ; Student In Chem- istry, University of California, 1891-93 ; Scholar in Chemistry, Clark Univer- sity, 1893-94. ERNEST AIiBEE: — A.B., University of Vermont, 1887 ; Scholar in Philosophy, Clark Univer- sity, 1889-90 ; Fellow in Philosophy, 1890-91 ; Fellow Sage School of Phi- losophy, Cornell University, 1891-92 ; Instructor in Philosophy, ibid., 1892- ; Ph.D., Cornell University, 1894 ; Mem- ber of the Am. Psy. Ass'n. Author of : — The Ethical System of Richard Cumber- land. Philosophical Beview, May and July, 1895, Vol. 4, pp. 264-290 ; 371- 393. The Relation of Shaftesbury and Hutche- son to Utilitarianism. Ibid., Jan., 1896, Vol. 5, pp. 24-35. Guy's Ethical System. Ibid., March, 1897, Vol. 6, pp. 132-145. Hume's Ethical System. Ibid., July, 1897, Vol. 6, pp. 337-355. ARTHUR ALLIN: — A.B., Victoria University, Toronto, 1892 (Double Gold Medalist in Classics and Philosophy) ; University of Heidelberg, 1892 ; University of Breslau, 1892-93 ; Ph.D., Berlin University, 1895; Hono- rary Fellow in Philosophy, Clark University, 1895-96 ; Professor of Psy- chology and Education, Ohio University, 1896-97 ; Professor of Psychology and Education, University of Colorado, 1897- ; 459 460 Titles of Consulting Psychologist, State Industrial School of Colorado. Author of : — TJeber das Grundprincip der Association, Berlin, 1895. The Kecognition-Theory of Perception. Am. Jour, of Psy., Jan., 1896, Vol. 7, pp. 237-248. Recognition. Ibid., Jan., 1896, Vol. 7, pp. 249-273. The Psychology of Tickling, Laughing, and the Comic (with G. S. Hall). Ibid., Oct., 1897, Vol. 9, pp. 1-41. Pedagogy in Ohio. Trans. Ohio College Ass'n, 1897. Extra-Organic Evolution. Science, Feb. 25, 1898, N. S., Vol. 7, pp. 267-269. Extra-Organic Evolution and Education. Northwestern Monthly, May and June, 1899, Vol. 9, pp.400-408; 436-439. LOUIS W. AUSTIN: — A.B., Middlebury College, 1889; Stu- dent, University of Strassburg, 1889-90 and 1891-93 ; Fellow in Physics, Clark University, 1890-91; Ph.D., University of Strassburg, 1893 ; Instructor in Physics, University of Wisconsin, 1893-96 ; Assist- ant Professor, ibid., 1896- ; Member of the Wisconsin Academy of Sciences. Author of : — Experimentaluntersuohungen liber die elastische Langs- und Torsionsnach- wirkung in Metallen. Annalen der Fhysik und Chemie, 1893, N. P., Bd. 50, pp. 659-677. The Efiect of Extreme Cold on Magnet- ism. Physical Peview, March-April, 1894, Vol. 1., pp. 381-382. An Experimental Research on the Lon- gitudinal and Torsional Elastic Fa- tigue. Ibid., May-June, 1894, pp. 401-425. On Gravitational Permeability. (With Charles B. Thvying. ) Ibid. , Nov.-Dec, 1897, Vol. 5., pp. 294-300. Exercises in Physical Measurement. (With Charles B. Thwing.) Allyn and Bacon, Boston, 1896. 208 pp. N. P. AVERT: — A.B., Amherst College, 1891 ; Principal, Yates Academy, Chittenango, N. Y., 1891- 96 ; Scholar in Psychology, Clark Uni- versity, Oct., 1895-Jan., 1896; ad- mitted to the Massachusetts bar, June, 1896. FRANK K. BAILEY : — S. B., Colorado College, 1898 ; Scholar in FbysiCB, Clark University, 1898-99. THOMAS P. BAILE7, JR.: — A.B., South Carolma College, 1887; Principal Winyah School, Georgetown, S. C, 1887-88; Tutor in English and History, University of South Carolina, 1888-89 ; A.M., University of South Carolina, 1889 ; Secretary, ibid., 1889-91 ; Ph.D., University of South Carolina, 1891 ; Adjunct Professor of Biology, South Carolina College, 1891-92 ; Fellow in Psychology, Clark University, 1892-93 ; Lecturer, South Carolina Col- lege for Women, 1893-94 ; Superinten- dent of Schools, Marion, S. C, 1894-95; Assistant Professor of Science and Art of Teaching, University of California, 1894- 98 ; Associate Professor of Education as related to Character, ibid., 1898-. Author of : — The Development of Character (Doctor's Thesis), 1891. Humanity of the Spiritual Life. Christian Thought, Oct., 1892. Ejective Philosophy. Am. Jour, of Psy., July, 1893, Vol. 5, pp. 465-471. Herbart and Character Culture. So. Ed. Jour. Dec. 1893-Jan. 1894. Psychology for Teachers. Proc. 8. C. Teachers^ Ass'n, 1893. The Practice of Medicine and the Practice of Teaching. Ibid., 1894. Comparative Child-study Observations. Handbook Ml. Soc. for Child-study, 1895. The Teaching Force — its General Culture. Proc. Gal. Teachers' Ass'n, 1894. Child-study for "Naturalists." Pacific Ed. Jour., April-May, 1895. Published Papers. 461 The Education of the Human Animal. Froc. Gal. Teachers'' Ass'n., 1896. Adolescence. Ibid. , 1896. Child-study Notes. Overland Monthly (School Edition), 1896-97. "Work and Play. Froe. Col. Teachers' Ass'n, 1896. Ethological Outlines. Oakland School Re- port, 1896-97. Ethology and Child-study. Northwestern Monthly, Nov., 1897, Jan., 1898. Ethology and Child-study. Froc. S. Gal. Teachers' Ass'n, 1898. Reformers in Ethology. Bui. jffb. 13, Library Univ. of Gal., 1899. Ethology : Standpoint, Method, Tentative Results. University Ghronicle (Uni- versity of California), Dec, 1898, Eeb., 1899. HENRT ROIiFB BAKER: — A.B., Iowa College, 1882; A.M., 1885; B.D., Yale University, 1886; Congrega- tional Ministry, 1887 ; Graduate Student, Andover Theological Seminary, 1889-90 ; Hopkins Graduate Student in Philosophy and Comparative Religion, Harvard Di- vinity School, 1890-91; Student In Psychology, Clark University, 1894- 95 ; Fellow, 1895-97 ; Honorary FeUow, 1898-99. Author of : — The Position of Myth, Science, and Na- ture Study in the Philosophy of Edu- cation. FRANKLIN "W. BARROWS: A.B., Amherst College, 1885; Instructor in Sciences, Worcester Academy, 1885-88 ; A.M., Amherst College, 1888 ; Instructor in Natural Sciences, Central High School, Buffalo, N. Y., 1888-J'an. 1894; M.D., University of Buffalo, 1893 ; Fellow in Physiology, Clark University, Jan.- June, 1894 ; Instructor in Zoblogy and Physiology, Central High School, Buf- falo, N. Y., 1894 ; Instructor in Histology and Biology, Medical Department of Uni- versity of Buffalo, 1894-97 ; Professor, ibid., 1897-. GEORGE H. C. L. BAUR: — Academy of Hohenheim, 1878-79 ; Uni- versity of Munich, 1879-81 ; University of Leipzig, 1881-82; Ph.D., University of Munich, 1882 ; Assistant to Professor C. Kupffer, Munich, 1882-84; Assistant to Professor O. C. Marsh, Yale Univer- sity, 1884-90; Docent in Osteology and Paleontology, Clark University, 1890-92 ; In charge of the Salisbury Ex- pedition to the Galapagos Islands, May- Oct, 1891 ; Assistant Professor, Osteology and Paleontology, University of Chicago, 1892-95 ; Associate Professor, ibid., 1895- 97. Died June 25, 1898. Author of : — Der Tarsus der Vogel und Dinosaurier, Eine Morphologische Studie. Inau gural-dissertation. Univers. Miinohen Leipzig, 1882, Wilh. Engelmann, pp 1-44, 2 taf. Same in Morph. Jahrb. 1883, Bd. 8, pp. 417-456, Taf. XIX and XX. Der Carpus der Paarhufer. Eine Mor- phogenetische Studie. (Vorl. Mittheil.) Morph. Jahrb., 1884, Bd. 9, pp. 597- 603. Dinosaurier und Vogel. Eine Erwieder- ung an Herrn. Prof. W. Dames in Berlin. Ibid., 1885, Bd. 10, pp. 446- 454. Note on the Pelvis in Birds and Dinosaurs. American Naturalist, Dec, 1884, Vol. 18, pp. 1273-1275. Bemerkungen tiber das Becken der VSgel und Dinosaurier. Morph. Jahrb., 1885, Bd. 10, pp. 613-616. Zur Morphologic des Tarsus der Sauge- thiere. Ibid., 1885, Bd. 10, pp. 458- 461. On the Morphology of the Tarsus in the Mammals. American Naturalist, Jan., 1885, Vol. 19, pp. 86-88. Ueber das Centrale Carpi der Saugethiere. Morph. Jahrb., 1885, Bd. 10, pp. 455- 457. On the Centrale Carpi of the Mammals. American Naturalist, Feb., 1885, Vol. 19, pp. 195-196. 462 Titles of Das Trapezitun der Cameliden. Morph. Jahrb., 1885, Bd. 10, pp. 117-118. The Trapezium of the Camelidse. Ameri- can Naturalist, i'eb., 1895, VoL 19, pp. 196-197. A Second Phalanx in the Third Digit of a Carinate-Bird's Wing. Science, May 1, 1885, Vol. 5, p. 355. A Complete Pibula in an Adult Lining Carinate-Bird. Ibid., May 8, 1885, Vol. 5, p. 375. On the Morphology of the Carpus and Tarsus of Vertebrates. American Naturalist, July, 1885, Vol. 19, pp. 718-720. Zur Morphologie des Carpus und Tarsus der Wirbelthiere. Zool. Anz., 1885, No. 196, pp. 326-329. ZurVogel-Dinosaurier-Frage. Ibid., 1885, No. 200, pp. 441-443. Ifachtragliche Bemerkungen zu : Zur Mor- phologie des Carpus und Tarsus der Wirbelthiere (Zool. Anz., 1885, No. 196). Ibid., 1885, No. 202, pp. 486- 488. Zum Tarsus der Vogel. Ibid., 1885, No. 202, p. 488. 3!Tote on the Sternal Apparatus in Iguano- don. Ibid. , 1885, No. 205, pp. 561-562. Einige Bemerkungen liber die Ossification der "langen" Knochen. Ibid., 1885, No. 206, pp. 580-581. Bemerkungen Tiber den " Astralagns " und das "Intermedium tarsi" der Sauge- thiere. Morph. Jahrb., 1886, Bd. 11, pp. 468^83, Tat XXVIL Zxa Morphologie des Carpus und Tarsus der Eeptilien. 0. 221, pp. 245-252. Ueber das Quadratum der Saugethiere. Sitzungsber. Q-esell. Morph. u. Phys- iol., Munchen, 1886, pp. 45-57. On the Quadrate in the Mammalia. Quart. Jour. Micr. Sci., 1886, Vol. 28, new ser., pp. 169-180. •Ceber die Morphogenie der Wirbelsaule der Amnioten. Biol. Centralbl., 1886, Bd. 6, Nos. 11, 12, pp. 332-342, 353-363. The Intercentrum in Sphenodon ^Hat- teria), American Naturalist, May, 1886, Vol. 20, pp. 465-466. Beriiohtigung. Zool. Anz., 1886, No. 228, p. 323. The Ribs of Sphenodon (Hatteria). American Naturalist, Nov., 1886, Vol. 20, pp. 979-981. Ueber die Homologien einiger Schadel- knochen der Stegooephalen und Rep-, tiUen. Anat. Anz., 1886, Jakrg. 1, pp. 348-350. Osteologlsche Notizen iiber Reptilien. Zool. Anz., 1886, No. 238, pp. 686-690. Published Papers. 463 Osteologisohe Notizen titer Eeptilien. Eortsetzung I. IbU., 1886, No. 240, pp. 733-743. On tke Morphogeny of the Carapace of the Testudlnata. American Natural- ist, Jan., 1887, Vol. 21, p. 89. Osteologisohe Notizen uher Eeptilien. Forsetzung II. Zool. Anz., 1887, No. 244, pp. 96-102. Erwiederung an Herm Dr. A. Giinther. Ibid., 1887, No. 245, pp. 120-121. Ueber Lepidosiren paradoxa Fitzinger. Zool. Jahrb., 1887, Bd. 2, pp. 575-583. Nachtragliohe Notiz zu meinen Bemer- kungen: "Ueber die Homologien einiger Sohadeltnochen der Stegoceph- alen und Eeptilien" in No. 13 des ersten Jahrgangs dieaer Zeitschrift. Anat. Anz., 1887, Jahrg. i. No. 21, pp. 657-658. On the Phylogenetic Arrangement of the Sauropsida. Jour, of Morph.y Sept., 1887, Vol. 1, pp. 93-104. Ueber die Abstammnng der Amnioten Wirbelthiere. Biol. Oentralhl.,. 1887, Bd. 7, No. 16, pp. 481-493. On the Morphology and Origin of the lohthyopterygia. American Natural- ist, Sept., 1887, Vol. 21, pp. 837-840. On the Morphology of Bibs. Ibid., Oct., 1887, Vol. 21, pp. 942-945. Beitrage zur Morphogenie des Carpus und Tarsus der Vetebraten. 1 Theil. Batraohia. Jena, -GrustaT Fischer, 1888, pp. 1-86, Taf . I.-UI. Ueber den Ursprung der Extremitaten der lohthyopterygia. Bericht. uber die SO. Versam. d. Oberrhein. Cfeolog. Vereins, Jan. 16, 1888, 4 pp., 1 taf. Dermochelys, Dermatochelys oder Sphar- gis. Zool. Am., 1888, No. 270, pp. 44-45. Unusual Dermal Ossifications. Science, March 23, 1888, Vol. 11, p. 144. Notes on the American Trionychidse. American Naturalist, Dec, 1888, Vol. 22, pp. 1121-1122. The Theory of the Origin of Species by Natural Selection. Ibid., Dec, 1888, Vol. 22, p. 1144. Osteologische Notizen tiber Eeptilien. Fortsetzung III. Zool. Ane,, 1888, No. 285, pp. 417-424. Osteologische Notizen ilber Eeptilien. Fortsetzung IV. Ibid., 1888, No. 291, pp. 592-597. Osteologische Notizen tiber Eeptilien. Fortsetzung V. Ibid., 1888, No. 296, pp. 736-740. Osteologische Notizen tiber Eeptilien. Fortsetzung VI. Ibid., 1889,. No. 298, pp. 40-47. Eevision meiner Mittheilungen im zool- ogischen Anzieger, mit Nachtragen. Ibid., 1889, No. 306, pp. 238-243. Neue Beitrage zur Morphologie des Carpus der Saugethiere. Anat. Anz., 1889, Jahrg. 4, No. 2, pp. 49-51, 4 figs. The Systematic Position of Meiolania, Owen. Ann. Mag. Nat. Hist., (6) Jan., 1889, Vol. 3, pp. 54-62. On " Aulaoochelys," Lydekker, and the Systematic Position of Anosteira, and Pseudotrionyx, Dollo. Ibid.^ 1889, (6) Vol. 3, pp. 273-276. On Meiolania and Some Points in the Osteology of the Testudinata.: a Eeply to Mr. G. A. Boulenger.. Ibid., 1889, (6) Vol. 4, pp. 37-45, PL vi. Mr. E. T. Newton on Pterosauria.. Ibid., 1889, pp. 171-174. Die systematische Stellung von Dermo- chelys Blainv. Biol. Gentralbl., 1889, Bd. 9, Noa. 6 und 6, pp. 149-153, 180- 191. NachtragUche Bemerkungen tiber die sys- tematische Stellung Ton Dermochelys Blainv. Ibid. , 1889, Bd. 9, Nos. 20 und 21, pp. 618-619. Palseohatteria Credner and the Progano- sauria. Am. Jour, of Sci., April, 1889, Vol. 37, pp. 310-313. Kadaliosaurus priscus Credner, a new Eeptile from the Lower Permian of Saxony. Ibid., Feb., 1890, pp. 156- 158. Bemerkungen tiber den Carpus der Pro- boscidier und der Ungulaten im Alge- meinen. Morph. Jahrb., 1889, Bd. 15, Heft 3, pp. 478^82, 1 fig. On the Morphology of Eibs and the Fate of the Aotinosts of the. Median Fins in 464 Titles of Fishes. Jour, of Morph., Dec, 1889, Vol. 3, pp. 463-166, 7 figs. On the Morphology of the Vertebrate- Skull. Ibid., 1889, Vol. 3, No. 3, pp. 467-474. A Review of the Charges against the Paleontological Department of the U. S. Gteologioal Survey, and of the Defence made by Prof. O. C. Marsh. American Naturalist, March 26, 1890, Vol. 24, pp. 298-304. Note on Carettochelys, Eamsay. Ibid., Nov., 1889, Vol. 23, p. 1017. The Gigantic Land Tortoises of the Gala- pagos Islands. Ibid., Dec, 1889, Vol. 23, pp. 1039-1057. The Relationship of the Genus Dirochelys. Ibid., Dec, 1889, Vol. 23, pp. 1099- 1100. The Genera of the Podocnemididse. Ibid., May, 1890, Vol. 24, pp. 482-484. Note on the Genera Hydraspis and Bhine- mys. Ibid., May, 1890, Vol. 24, pp. 484-486. The Genera of the Cheloniidse. Ibid., May, 1890, Vol. 24, pp. 486-487. On the Classification of the Testudinata. Ibid., June, 1890, Vol. 24, pp. 530- 536. Professor Marsh on Hallopus and Other Dinosaurs. Ibid., June, 1890, Vol. 24, pp. 569-571. An Apparently New Species of Chelys. Ibid., Oct. 1890, Vol. 24, pp. 967-968. On the Characters and Systematic Posi- tion of the Large Sea Lizards, Mosa- sauridse. Science, Nov. 7, 1890, Vol. 16, No. 405, p. 262. Two New Species of Tortoises from the South. Ibid., Nov. 7, 1890, Vol. 16, No. 405, pp. 262-268. The Problems of Comparative Osteology. Ibid., 1890, Vol. 16, No. 407, pp. 281- 282. Das Variieren der Eideohsen-Gattung Tropidurus auf den Galapagos Inseln und Bemerkungen uber den Ursprung der Inselgruppe. Biol. Centralbl., 1890, Bd. 10, Nos. 15 und 16, pp. 475- 483. The Very Peculiar Tortoise, Carettochelys Bamsay, from New Guinea. Science, Apr. 3, 1891, Vol. 17, No. 426, p. 190. American Box Tortoises. Ibid., Apr. 3, 1891, Vol. 17, No. 426, pp. 190-191. The Horned Saurians of the Laramie Formation. Ibid., Apr. 17, 1891, Vol. 17, No. 428, pp. 216-217. The Lower Jaw of Sphenodon. American Naturalist, May, 1891, Vol. 25, pp. 489-490. Notes on the Trionychian Genus Peloohe- lys. Ann. Mag. Nat. Mist. , May, 1891 , (6) Vol. 7, pp. 445-446. Eemarks on the Reptiles generally called Dinosauria. American Naturalist, May, 1891, Vol. 25, pp. 434-454. On the Origin of the Galapagos Islands. Ibid., March and April, 1891, Vol. 25, pp. 217-229, 307-326. On the Relations of Carettochelys, Bam- say. Ibid., July, 1891, Vol. 25, pp. 631-639, Pis. x.-xvi. On Intercalation of Vertebrse. Jour, of Morph., Jan., 1891, Vol. 4, pp. 331-336. The Pelvis of the Testudinata, with Notes on the Evolution of the Pelvis in General. Ibid. , 1891, Vol. 4, No. 3, pp. 345-359, 13 figs. Notes on Some Little-known American Fossil Tortoises. Froc. Acad. Nat. Sci. Phil., 1891, pp. 411^30. [Dr. Baur's Trip to the Galapagos Islands.] American Naturalist, Oct., 1891, Vol. 25, pp. 902-907. The Galapagos Islands. Froc. Am. Ant. Soc, Oct. 21, 1891, pp. 3-8. Das Variieren der Eidechsen-Gattung Tropidurus auf den Galapagos-Inseln. Festschr. z. 70. Cfeburtstage B. Leuck- arts. Leipzig, 1892, Wilhelm Engel- mann, pp. 259-277. Professor Alexander Agassiz on the Origin of the Fauna and Flora of the Gala- pagos Islands. Science, March 25, 1892, Vol. 19, No. 477, p. 176. Der Carpus der Schildkroten. Anat. Anz., 1892, Jahrg. 7, Nos. 7 und 8, pp. 206-211, 4 figs. On the Taxonomy of the Genus Emys, C. Dum^ril. Froc. Am. Fhil. Soc^ 1892, Vol. 30, pp. 40-44. Published Papers. 465 Addition to the Note on the Taxonomy of the Genus Emys, C. Dum6ril. Ibid., 1892, Vol. 30, p. 245. On Some Peculiarities in the Structure of the Cervical Vertehrae in the Existing Monotremata. American Naturalist, Jan., 1892, Vol. 26, p. 72. [Visit to the Galapagos Islands.] Proc. Bost. Soc. Nat. Mist., March, 1892, Vol. 25, p. 317. The Cervical Vertebrae of the Monotre- mata. AmeHcan Naturalist, May, 1892, Vol. 26, p. 435. Bemerkungen tiber verschiedene Arten von Sehildkreten. Zool. Am., 1892, No. 389, pp. 155-159. Ein Besuch der Galapagos-Inseln. Biol. Centralbl., 1892, Bd. 12, pp. 221-250. On the Morphology of the Skull in the Mosasauridse. Jour, of Morph., Oct., 1892, Vol. 7, pp. 1-22, Pis. i. and ii. Notes on the Classification and Taxonomy of the Testudinata. Proe. Am. Phil. Soc, May 5, 1893, Vol. 31, pp. 210-225. Notes on the Classification of the Crypto- dira. American Naturalist, July, 1893, Vol. 27, pp. 672-675. Two Nev7 Species of North American Tes- tudinata. Ibid., July, 1893, Vol. 27, pp. 675-677. Further Notes on American Box-Tortoises. Ibid., July, 1893, Vol. 27, pp. 677-678. G. Jager und die Theorie von der Conti- nuitat des Keimprotoplasmas. Zool. Am., 1893, No. 425, p. 300. Ueber Bippen und ahnliche Gebilde und deren Nomenclatur. Anat. Am., 1893, Jahrg. 9, No. 4, pp. 116-120. The Discovery of Miocene Amphisbsenians. American Naturalist, Nov., 1893, Vol. 27, pp. 998-999. The Relationship of the Lacertilian Genus Anniella Gray. Proc. U. S. Nat. Mus., Vol. 17, No. 1005, pp. 845-351. Bemerkungen ilber die Osteologie der Schlafengegend der hoheren Wirbel- thiere. Anat. Am., Dec, 1894, Bd. 10, No. 10, pp. 315-330. Ueber den Proatlas einer Schildkrote (Pla- typeltis spinifer Les.). Ibid., Jan., 1895, Bd. 10, No. 11, pp. 349-354, 6 figs. 2h Die Palatingeg'end der Ichthyosauria. Ibid., 1895, Bd. 10, No. 14, pp. 456- 469, 1 fig. The Differentiation of Species on the Galapagos Islands and the Origin of the Group. Biol. Lect. M. B. L. Woods Soil, 1895, pp. 67-78. Pithecanthropus erectus. Jour. Geol., Feb. and March, 1895, Vol. 3, No. 2, pp. 237-238. The Fins of Ichthyosaurus. Ibid., Feb. and March, 1895, Vol. 3, No. 2, pp. 238-240. The Experimental Investigation of Evolu- tion. The Dial, May 1, 1893, p. 278. Cope on the Temporal Part of the Skull, and on the Systematic Position of the Mosasauridse. A Reply. American Naturalist, Nov., 1895, Vol. 29, pp. 998-1002. Ueber die Morphologic des Unterkiefers der Reptilien. Anat. Am., 1896, Bd. 11, No. 13, pp. 410-415, 4 figs. Das Gebiss von Sphenodon (Hatteria) und einige Bemerkungen tiber Prof. Eud. Burckhardt's Arbeit iiber das Gebiss der Sauropsiden. Anat. Am., 1895, Bd. 11, No. 14, pp. 436^39. The Paroccipital of the Squamata and the Affinities of the Mosasauridse Once More. A Rejoinder to Prof. E. D. Cope. American Naturalist, Feb., 1896, Vol. 30, pp. 143-147, PI. iv. Nachtrag zu meiner Mittheilung fiber die Morphologie des Unterkiefers der Rep- tilien. Anat. Am., 1896, Bd. 11, Nos. 18 und 19, p. 569. RevievT of Dr. A. E. Ortmann's " Grund- ziige der marinen Thiergeographie." Science, March 6, 1896, Vol. 3, No. 62, pp. 359-367. The Stegocephali. A Phylogenetio Study. Anat. Am., 1896, Bd. 11, No. 22, pp. 657-673, 8 flgs. Mr. Walter E. CoUinge's "Remarks on the Preopercular Zone and Sensory Canal of Polypterus." Ibid., 1896, Bd. 11, Nos. 9 und 10, pp. 247-248. Professor Cope's Criticisms of my Draw- ings of the Squamosal Region of Cono- lophus subcristatus Gray (^American 466 Titles of Naturalist, Teb., 1896, pp. 148-149), and a Pew Eemarks ^bout his Draw- ings of the Same Object from Stein- dachner. Ibid., A^ni, 1896, Vol. 30, pp. 327-329. Bemerkungen zu Prof. Dr. O. BSttger's Keferat uber : Seeley, H. G. on Theoo- dontosaurus and Palseosaurus. Zool. Centralbl., Jahrg. 3, No. 11, 1896, p. 896. Der Schadel einer neuen, grossen Schild- krbte (Adelochelys) aus dem zoologis- chen Museum in Mlinohen. Anat. Am., 1896, Bd. 12, Nos. 12 und 13, pp. 314^319, 4 figs. Bemerkungen iiber die Phylogenie der Sohildkroten. Ibid., 1896, Bd. 12, Nos. 24 und 25, pp. 561-570. On the Morphology of the Skull of the Pelycosauria and the Origin of Mam- mals. (With E.G. Case.) ijid, 1897, Bd. 13, Nos. 4 und 5, pp. 109-120, 3 figs. Remarks on the Question of Intercalation of Vertebra. Zoological Bulletin, Aug., 1897, Vol. 1, No. 1, pp. 41- 55. Birds of the Galapagos Archipelago : A Criticism of Mr. Robert Ridgway's Paper. American Naturalist, Sept., 1897, Vol. 31, pp. 777-784. Archegosaurus [Review of 0. Jackels's "Die Organisation von Archegosau- rus"]. Ibid., Nov., 1897, Vol. 31, pp. 975-980. New Observations on the Origin of the Galapagos Islands, with Remarlts on the Geological Age of the Pacific Ocean. Ibid., Aug., 1897, Vol. 31, pp. 661-680, and Oct., 1897, pp. 864-896 (incomplete). HENR7 BBNNBR: — B.S., State Normal School, West Chester, Pa., 1885; M.S., ibid, 1887, and Uni- versity of Michigan, 1889 ; Pellow in Mathematics, Clark University, 1889- 90 ; Instructor in Mathematics, Prepara- tory School, Northwestern University, 1890-92 ; Instructor in Mathematics, Chicago Manual Tralaing School, 1892-. JOHN A. BERGSTROM: — A.B., Wesleyan University, Middletown, Conn., 1890 ; Fellow in Psychology, Clark University, 1891-94; Ph.D., Clark University, 1894 : Assistant Pro- fessor of Psychology and Pedagogy, Indiana University, 1894-96 ; Associate Professor of Psychology and Pedagogy, ibid, 1896-. Author of : — Experiments upon Physiological Memory by Means of the Interference of Asso- ciations. Am. Jour, of Psy., April, 1893, Vol. 5, pp. 356-369. An Experimental Study of Some of the Conditions of Mental Activity. Ibid., Jan., 1894, Vol. 6, pp. 247-274. The Relation of the Interference to the Practice Effect of an Association. Ibid., June, 1894, Vol. 6, pp. 433-442. School Hygiene. (Translation of Dr. Ludwig Kotelmann's Ueber Schul- gesundheitspflege. With Edward Con- radi.) Bardeen, Syracuse, N.T., 1899, 391 pp. ADOLF BERNHARD: — A.B., Johns Hopkins University, 1889 ; Teacher of Mathematics and Science, National German-American Teachers' Seminary, Milwaukee, Wis., 1889-91 ; Fellow in Chemistry, Clark Univer- sity, 1891-92 ; Fellow in Chemistry, University of Chicago, 1892-94; Ph.D., University of Chicago, 1894 ; Laboratory Assistant in Chemistry, ibid., 1894-95. Author of : — Ueber die Einf iihrung von Acylen in den Benzoylessigather (Thesis). Chicago, 1894, pp. 43. FRANZ BOAS:— Ph.D., Kiel, 1881 ; Expedition to Baffin Land, 1883-84 ; Privatdocent, University of Berlin, Assistant Royal Ethnographi- cal Museum of Berlin, 1884-86 ; Expedi- tion to British Columbia, 1886-87 ; As- sistant editor of Science, 1887-89; Do- cent in Anthropology, Clark Univer- sity, 1889-92 ; Chief Assistant, Depart- Published Papers. 467 ment of Anthiopology, World's Colum- bian Exposition, Chicago, 1892-94 ; Ex- pedition to Alaska, Britisli Columbia, and California, 1895 ; Assistant Curator, Department of Anthropology, American Museum of Natural History, New York, 1896- ; Lecturer on Anthropology, Colum- bia University, 1896-99 ; Professor of An- thropology, ibid., 1899- ; Member of : the- New York Academy of Sciences, the American Statistical Association, the American Psychological Association, the American Folk-Lore Society, the Berlin Anthropological Society, the Berlin Geo- graphical Society ; Corresponding mem- ber of the Anthropological Society of Vienna, the Imperial Society of Friends of Natural Sciences, Anthropology, and Ethnology at Moscow, the Roman An- thropological Society, the Anthropological Society of Paris, the Anthropological Society at Washington, the American Antiquarian and Numismatic Society of Philadelphia ; Past Vice-President of the Anthropological Section of the American Association for the Advancement of Science ; Associate Editor of the Inter- nationales ArcMv fur Ethnographie, and of the American Anthropologist, N. S. Author of : — Beitrage zur Erkenntniss der Farbe des Wassers. Inaugural Dissertation. Kiel, 1881. Ein Beweis des Talbotschen Satzes. An- nalen der Physik und Ohemie, 1882, pp. 359-362. TJeber eine neue Form des Gesetzes der Unterschiedsschwelle. P/Jiijrer's Ar- chiv, 1881, pp. 493-500. Ueber die verschiedenen Formen des Unterschiedssohwellenwerthes. Ibid., 1882, pp. 214-222. TTeber die Berechnung der Unterschieds- schwelle naoh der Methode der richti- gen und falschen Falle. Ibid., 1882, pp. 84-94. Die Bestimmung der Unterschiedsemp- findlichkeit nach der Methode der iibermerkliohen Unterschiede. Ibid., 1882, pp. 562-566. Ueber die Grundaufgabe der Psycho- physik. Ibid., 1882, pp. 566-576. Ueber den Unterschiedsschwellenwerth als das Mass der Intensitat psychisoher Vorgange. Philosophische Monats- hefte, 1882, pp. 367-375. Ueber die ehemalige Verbreitung der Eskimos im arktisch-amerikanischen Archipel. Zeitschrift der &esellschaft fur JErkunde, 1883, pp. 118-186. Die Wohnsitze der NeitchiUik Eskimos. Ibid., 1883, pp. 161-172. Arctic Exploration and its Object. Pop. Sci. Man., May, 1885, Vol. 27, pp. 78-81. Bemerkungen zur Topographic der Hud- son Bay. Petermann's Mittheilungen, 1885, pp. 424r-426. Baffin Land. Geographische Ergebnisse einer in den Jahren 1883 und 1884 un- ternommenen Forschungsreise. Gotha, 1885, 104 pp., 2 maps. Die Sprache der Bella Coola Indianer. Verh. Anthrop. Ges., Berlin, 1886, pp. 202-206. Zur Ethnologie von Britisch Columbien. Petermann^s Mittheilungen, 1887. Mittheilungen iiber die Bilqula Indianer. Originalmittheilungen aus dem K. Museum fur Volkerkunde, Berlin, 1885, pp. 177-182. On certain songs and dances of the Kwa- kiutl Indians. Jour. Am. Folk-Lore, April-June, 1888, Vol. 1, pp. 49-64. Meteorologische Beobachtungen im Cum- berland Sunde. Annalen der Hydro- graphie, 1888, pp. 241-262. The Game of Cat's Cradle. Internatio- nales Archivfur Ethnographie, 1888. Chinook Songs. Jour. Amer. Folk-Lore, 1888, pp. 220-226. Das Fadenspiel. Mittheilungen der An- thropologischen Gesellschaft, Vienna, 1888, p. 85. Sagen der Eskimos von Baffin Land. Verh. der Berliner Anthropologischen Gesellschaft, 1888, pp. 398-405. The Study of Greography. Science, 1887, Vol. 9, p. 157. Arrangement of Ethnological Collections. Ibid., 1887, Vol. 9, pp. 485, 587, 614. 468 Titles of Ice and Icebergs. Ibid., 1887, Vol. 9, p. 324. Formation and Dissipation of Seawater Ice. Ibid., Vol. 10, p. 118. The Eskimo Tribes. Review of Rink's Eskimo Tribes. Ibid., Vol. 10, p. 271. Eskimo and Indian. Ibid., Vol. 10, p. 273. The Central Eskimo. Sixth An. Bep. Bur. Ethn., Washington, 1888, pp. 399-669. Die Eisverhaltnisse des sudostlichen Theiles von Baffin-Land. Peter- manri's Mittheilungen, 1888, pp. 296- 298, 18 plates. Eskimo Tales and Songs (Texts). H. Rink and F. Boas. Jour. Am. Folk- Lore, Vol. 2, pp. 123-131. Notes on the Snanaimuq. American Anthropologist, 1889, pp. 321-328. Die Ziele der Ethnologic. New York, 1889, 30 pp. Fourth Report of the Committee on the Northwestern Tribes of Canada. British Ass'n Adv. Science, 1888, pp. 1-10. Fifth Report of the Committee, 1889, pp. 1-96. Sixth Report, 1890, pp. 1-163. Seventh Report, 1891, pp. 1-40, 4 tables. Ninth Report, 1894, pp. 1-16. Tenth Report, 1895, pp. 1-74, 11 tables. Eleventh Report, 1896, pp. 1-28. A Critique of Psycho-Physio Methods. Science, Vol. 11, p. 119. The Indians of British Columbia. Pop. Set Mon., March, 1888, Vol. 32, pp. 628-636. Is Stanley Dead ? Nor. Am. Bev., 1888. On Alternating Sounds. American An- thropologist, 1889, pp. 47-53. On the Census Maps of the United States. Science, Vol. 12. Cranium from Yucatan. Am. Antiq. Sac, 1890, pp. 350-357. The Use of Masks and Head Ornaments in British Columbia. InternH Arch. Eth., 1890. Mixed Races. Science, 1891, Vol. 17, p. 179. Dissemination of Tales in America. Jour. Am. Folk-Lore, 1891, pp. 18-30. Petroglyph in Vancouver Island. Verh. der. Berliner Ges.fur Anth., 1891, pp. 158-159. Sagen der Kootenay. Ibid., pp. 159- 172. Notes on the Chemakum Language. Amer- ican Anthropologist, 1892, pp. 37-44. Vocabularies from the North Pacific Coast. Trans. Am. Phil. Soc, 1891, pp. 30. Chinook Jargon. Science, Vol. 19, p. 474. The Growth of Children. Ibid., Vol. 19, pp. 256-258, 281-283. Anthropologic in Amerika. Oorrespon- denzblatt deutsch. Anth. Qesellschaft, 1892, pp. 114-116. Notes on the Chinook Language. Ameri- can Anthropologist, 1888, pp. 55-63. The Growth of Children. Science, 1892, Vol. 26, p. 351. Vocabulary of the Kwakiutl Language. Am. Phil. Soc, 1892, pp. 34-82. Eskimo Songs and Tales. Jour. Am. Folk-Lore, 1894, pp. 45-50. Correlation of Anatomical and Physiolog- ical Measurements. American Anthro- pologist, 1894, pp. 313-324. Linguistische Resultate einer Reise in Baffin Land. Mittheilungen der An- thropologischen Gesellschaft, Vienna, 1894, pp. 97-114. Anthropology of the North American Indians. Intern^ Wong. Anth. , Chicago, 1894, pp. 37-49. Classification of Languages of the North Pacific Coast. Ibid., pp. 339-346. Omaha Music. Review. Jour. Am. Folk-Lore, 1894, pp. 169-170. Remarks on the Theory of Anthropome- try. International Statistical Con- gress, Chicago. Quar. Jour. Amer. Stat. Soc, 1893. The Halt-blood Indian. Pop. Sci. Man., October, 1894. Human Faculty as Determined by Race. A. A. A. S., 1894. Reprint, pp. 1-27. Chinook Texts. Bulletin, Bureau of Ethnology, Washington, D.C., 1894, pp. 1-278. Salishan Texts. Am. Fhilos. Soc, 1896, pp. 31-48. Published Papers. 469 Notes on the Eskimo of Port Clarence, Alaska. Jour. Avi. Folk-Lore, 1894, pp. 205-208. Zur Mythologie der Indlaner von Wash- ington und Oregon. CHobus, 1893, Nos. 10-12. Dr. W. T. Porter's Investigations on the Growth of the School Children of St. Louis. Science, March 1, 1895, pp. 225-230. Oorrespondenzblatt der deut- schen Anth. Ges., 1895. The Grovfth of Pirst-horn Children. Science, April 12, 1895. Zur Ethnologic von Britisch Columbien. Verh. d. ffes. fur Erdkunde, Berlin, May 4, 1895. Indianisohe Sagen von der Nordpaoiflschen Kiiste. A. Asher, Berlin, 1895. vi. + 364 pp. The Relations Betvreen Length-hreadth and Length-height Index of the Skull. Verh. Berliner Oes. fur Anthropologic. The Growth of United States Naval Cadets. Science, N. S., Vol. 2, pp. 344-346. Anthropometry of the Indians of Southern California. Am. Ass''n for the Adv. Sci., 1895, pp. 261-269, 9 tables. Zur Anthropologic der Indlaner Nord Amerikas. Verh. der Berliner Anth. Ges., 1895, pp. 366-411. Spraohen Karte von Britisch Columbien. Petermann's Mittheilungen, 1896, No. 1, 2 plates. The Growth of Indian Mythologies. Jour. Am. Folk-Lore, 1896, pp. 1-12. Livi. Antropometria Militare. Beview. Science, N. S., Vol. 3, pp. 929 ff. The Growth of the Head. Ibid., N. S., Vol. 4, No. 80. Songs of the Kwakiutl Indians. Jnt. Archiv fur Ethnographic, IX., 1896, pp. 1-9. Hie Limitations of the Comparative Method of Anthropology. Science, Dec. 18, 1896, pp. 901-908. Traditions of the T'sets'a' ut. Jour. Am. Folk-Lore, Vol. 9, pp. 257-268 ; Vol. 10, pp. 35-48. The Growth of Children. Science, Vol. 5, pp. 570-573. The Decorative Art of the Indians of the North Pacific Coast. Bull. Amer. Mus. Nat. His., 1897, pp. 123-176. Eskimo Songs. Jour. Am. Folk-Lore, 1897, pp. 109-115. Northern Elements in the Mythology of the Navaho. American Anthropolo- gist, 1897, pp. 371-376. Social Organization and Religious Cere- monials of the Kwakiutl Indians. Report of the U. S. National Museum for 1895. Washington, 1897, pp. 311- 736. Traditions of the Tillamook. Jour. Am. Folk-Lore, 1898, pp. 23-38, 133-150. Bhrenreich ; Die Ureinwohner Brasiliens. Science, N. S., Vol. 6, pp. 880-883. Introduction to James Teit. Traditions of the Thompson River Indians of British Columbia, 1898, pp. 1-18. The Growth of the School Children of Toronto. Annual Meport of the Com- missioner of Education, 1896-97. Washington, 1898, Vol. 2, pp. 1541- 1599. Cathlamet Texts. Nineteenth Annual Beport of the Bureau of Ethnology, 200 pp. Nisqa Texts. Ibid., 100 pp. Facial Paintings of the Indians of North- ern British Columbia. Memoirs Am. Mus. Nat. His., Vol. 2, pp. 1-24. Mythology of the Bella Coola Indians, Ibid., pp. 25-127. A Precise Criterion of Species. Science, Vol. 7, No. 182, pp. 860-861. Twelfth Report of the Committee of the British Association for the Advance- ment of Science on the Northwestern Tribes of Canada (with Dr. Living- ston Farrand) . Proc. of the B. A. A. S., Bristol Meeting, 1898, pp. 1-61, 12 tables. Anthropologie in Nord Amerika. Cor- respbl. der dents. Ges. f. Anthrop., 1898. Mittheilungen aus Amerika. Ibid., 1898, Jahrg. 29, pp. 121-123. Some Recent Criticisms of Physical An- thropology. American Anthropologist, Jan., 1899, N. S., Vol. 1, pp. 98-106. 4T0 Titles of The Cephalic Index. Ihid., July, 1899, N. S., Vol. 1, pp. 448-461. ZiUGENE W. BOHANNON: — Graduate, Indiana State Normal School, 1887; Superintendent of Schools, Browns- hurg, Ind., 1887-88; A.B., Indiana Uni- versity, 1890 ; Superintendent of Schools, Plainfield, Ind., 1889-91 ; Principal, High School, Pekin, HI., 1891-92; A.M., In- diana University, 1892; Superintendent of Schools, Kensselaer, Ind., 1892-95; Scholar in Pedagogy, Clark XJniver- Bity, 1895-96 ; Fellow in Psychology, 1896-98 ; Professor of Psychology, Pedagogy, and Practice, State Normal School, Mankato, Minn., 1898-. Author of : — Peculiar and Exceptional Children. Fed- agogical Seminary, Oct., 1896, Vol. 4, pp. 3-60. The Only Child in a Family. Tbid., April, 1898, Vol. 6, pp. 475-496. The Undue Emphasis of Method. Ind. School Jour., Jan., 1899, pp. 1-7. FREDKRICK E. BOLTON: — Graduate, State Normal School, Milvfau- kee, Wis., 1890; Principal, High School, Pairchild, Wis., 1890-91 ; B.S., Univer- sity of Wisconsin, 1893 ; Principal of Schools, Kaukanna, Wis., 1893-95; M.S., University of Wisconsin, 1896 ; Univer- sity of Leipzig, Germany, 1896-97 ; Hon- orary Fellow in Psychology, Clark University, 1897-98; Ph.D., Clark TJniverBity, 1898 ; Professor of Psy- chology and Pedagogy, State Normal School, Milwaukee, Wis., 1898- ; Mem- ber, Wisconsin Educational Club; Past Vice President, Wisconsin Child Study Society ; Member, Wisconsin State Teach- ers' Association. Author of : — The Accuracy of Recollection and Obser- vation. Psychological Beview, May, 1896, Vol. 3, pp. 286-295. The Development of School Curricula in the United States. Thesis deposited in Library of University of Wisconsin, 1896, pp. 206. Apperception in the Study of Geography. Wis. Jour. Ed., Aug., 1896. The Importance of Higher Education to the Teacher. lUd., Sept., 1890. The Training of Elementary Teachers in Germany. Ibid., April, 1896. Elementary Schools in Germany. Ibid., June, 1897. A Contribution to the Study of Illusions. Am. Jour, of Psy., Jan., 1898, Vol. 9, pp. 167-182. Hydro-Psychoses (Doctorate Disserta^ tion). Ibid., Jan., 1899, Vol. 10, pp. 171-227. Scientific and Practical Child-study : The Province and the Limitations of Each. Wis. Jour. Ed., May, 1899, and Child Study Monthly, May, 1899, Vol. 5, pp. 7-24. The Secondary School System of Ger- many. The Internat. Ed. Series. D. Appleton & Co. (In press.) THADDEUS L. BOLTON: — A.B., University of Michigan, 1889; Principal, Public Schools, Vulcan, Mich., 1889-90; Scholar in Psychology, Clark TTniversity, 1890-91 ; Fellow and As- sistant, 1891-92 ; Fellow and Demon- strator, 1892-93 ; Assistant in Ethnol- ogy, World's Columbian Exposition, 1893 ; Teacher in Psychology, State Normal School, Worcester, Mass., 1893-1896; Ph.D., Clark University, 1895; Pro- fessor of Psychology and Pedagogy, State Normal School, San Jos6, Cal., 1896-97; Professor of Philosophy and Education, University of Washington, Seattle, Wash., 1897-98 ; University of Heidelberg, 1898- 99. Author of : — Brain Model on a Large Scale, by Dr. Azoux. Translation. (With H. H. Donaldson.) Am. Jour, of Psy., April, 1891, Vol. 4, pp. 132-141. The Size of the Several Cranial Nerves in Man, as indicated by the Areas of their Cross-sections. (With H. H. Published Papers. 471 Donaldson. {IhU., Dec, 1891, Vol. 4, pp. 224-229. The Growth of Memory in School Chil- dren. Ibid., April, 1892, Vol. 4, pp. 362-380. A Study of the Spinal Cord of a Spring- halt Horse. Jour, of Nervous and Mental Diseases, Jan., 1893, N. S., Vol. 18, pp. 7-12. On the Discrimination of Groups of Rapid Clicks. Am. Jour, of Psy., April, 1893, Vol. 5, pp. 294-310. Rhythm. Ibid., Jan., 1894, Vol. 6, pp. 145-283. Asymmetry of Body. Beport of Cal. State Teachers'' Ass''n, June, 1897. Modern Psychology in its Relation to Training of Teachers. Ibid., June, 1897. What is the New Psychology and what are its Claims ? Teacher and Student, San Jos6, Cal., June, 1897, Vol. 4, pp. 121-126. Knowledge from the Standpoint of Asso- ciation. (With E. M. Haskell.) Ed. Hev., Ma.y, 1898, Vol. 15, pp. 474- 499. Die Zuverlassigkeit einiger Methoden f iir die Messung des Ermiidungsrgades in Schulkiridern. Psychol. Arbeiten, herausg. v. E. Kraepelin. (In press.) OSKAR BOLZA. Ph.D., University of Gottingen, 1886; Reader in Mathematics, Johns Hopkins University, 1888-89 ; Associate in Mathematics, Clark University, 1889- 92 ; Associate Professor of Mathematics, University of Chicago, Jan., 1893-Jan., 1894 ; Professor of Mathematics, ibid., Jan., 1894-. Author of : — Ueher die Reduction HypereUiptischer Integrale auf EUiptisohe. Sitzungs- beriohte der Freiburger Naturf orschen- den Gesellschaft, 1885. Dissertation, GSttingen, 1886. Math. Annalen, 1887, Vol. 28, pp. 447-456. Darstellung der Invarianten der Binar- foim sechster Ordnung dnrch die Nullwerte der zugehorigen Theta- Punctlonen. Ibid., 1887, Vol. 30, pp. 478-495. On Binary Sextios with Linear Transfor- mations into Themselves. Am. Jour, of Math., 1888, Vol. 10, pp. 47-70. On the Construction of Intransitive Groups. Ibid., 1889, Vol. 2, pp. 185- 214. On the Theory of Substitution-Groups and its Applications to Algebraic Equa- tions. lUd., 1891, Vol. 13, pp. 1-86. Ueber Kronecker's Definition der Gruppe einer Gleichung. Math. Annalen, 1893, Vol. 42, pp. 253-256. Ueber die linearen Relationen zwischen den zu versohiedenen singularen Punc- ten gehorigen Fundamentalsystemen von Integralen der Riemannsohen Dif- ferentialgleichung. Ibid., 1893, Vol. 42, pp. 526-536. Netto's Theory of Substitutions, trans- lated by Dr. Cole. Bull, of the N. Y. Math. Soc, 1893, Vol. 2, pp. 83-106. On the Transformation of Linear Differ- ential Equations of the Second Order with Linear Coefficients. Am. Jour, of Math., 1893, Vol. 15, pp. 264-273. On Weierstrass' Systems of Hyperelliptio Integrals of the First and Second Kind. Chicago Math. Congress Papers, 1893, pp. 1-12. On the First and Second Logarithmic Derivatives of Hyperelliptio Sigma Functions. Am. Jour, of Math., 1895, Vol. 17, pp. 11-36. Die cul)ische Involution und die Dreithei- lung und Transformation dritter Ord- nung der ElUptisohen Funotionen. Math. Annalen, 1897, Vol. 50, pp. 68-102. Zur Reduction hyperelliptischen Integrale auf elliptische mittels einer Transfor- mation dritten Grades. Ibid., 1898, Vol. 50, pp. 314-324. The Partial Differential Equations for the Hyperelllptic — and 5 — Functions. Am. Jour, of Math., April, 1899, Vol. 21, pp. 107-125. Proof of Brioschi's Recursion Formula for the Expansion of the Even S — JFunc- 472 Titles of tions of Two Variables. Am. Jour, of Math., April, 1899, Vol. 21, pp. 175- 190. JAMBS W. BOYCE: — B.S., University of Vermont, 1896; Pel- lo-w in Mathematics, Clark Univer- sity, 1896-99. ■WILLIAM P. BOYNTON: — A.B., Dartmouth College (with honors in Physios), 1890 ; Professor of Physios and Chemistry, University of Southern Cali- fornia, 1890-93 ; A.M., Daitmouth College, 1893 ; Graduate Scholar and Assistant in Physics, ibid., 1893-94; Scholar in Physics, Clark University, 1894-9S ; Fellow, 1895-97 ; Ph.D., Clark Uni- versity, 1897 ; Instructor in Physios, University of California, 1897-. Author of : — A Quantitative Study of the High-Fre- quence Induotion-Coil. Physical He- view, July, 1898, Vol. 7, pp. 35-63 ; Philosophical Magazine, Sept., 1898, 5th ser.. Vol. 46, pp. 312-338. JOHN L. BRIDGE: — B.S., Wesleyan University, Middletown, Conn., 1888 ; Assistant in Chemistry, ibid., 1889-91 ; Fellow in Chemistry, Clark University, 1891-92 ; Fellow in Chemistry, University of Chicago, 1892- 93; Ph.D., Clark University, 1894; Instructor in Sciences, Connecticut Liter- ary Institution, 1893-96 ; Instructor in Sciences, Waterbury High School, 1896-. Author of : — The Ethers of Nitroso-phenol. Am. Chem. Jour., 1892, Vol. 14, pp. 276-284. Ueber die Aether des Chinonoximes. Ide- Mg's Annalen, Vol. 277, pp. 79-105. The Ethers of Toluchinonoxime and their bearing on the Space Isomerism of Nitrogen. (With Wm. Conger Mor- gan.) Am. Chem. Jour., Nov., 1898, Vol. 20, pp. 761-776. CHABLES L. B.S., New Teacher of Natural Sciences, Rivervlew BRISTOL : — York University, 1883 ; Academy, Poughkeepsie, N. Y., 1883-87; M.S., New York University, 1888 ; Pro- fessor of Zobiogy, State University, South Dakota, 1888-91 ; Fellow in Morphology, Clark University, 1891- 92 ; Fellow in Biology, University of Chicago, 1892-93 ; Associate Professor of Biology, New York University, 1893-98 ; Professor of Biology, Ibid., 1898- ; Ph.D., University of Chicago, 1894; Member of American Naturalists ; Member of Mor- phologists' Society ; Member of New York Zoological Society ; Fellow of New York Academy of Sciences. Author of: — The Metamerism of Nephelis, a contribu- tion to the morphology of the nervous system, with a description of Nephelis Lateralis. Journal of Morphology, Oct., 1898, Vol. 15, pp. 17-72. ERNEST NICHOLSON BROWN: — B.A., Dalhousie University, Halifax, N.S., 1889; Scholar in Psychology, Clark University, 1892 ; Assistant in Ethnology, World's Columbian Exposi- tion, 1893 ; Principal, Model School, Levis, Quebec, 1894-95; Principal, Model School, Lachine, Quebec, 1895- ; Con- vener of Committee on Child Study of the Provincial Association of Protestant Teachers of Quebec, 1897-. Author of : — Child Study. Educational Becord of the Province of Quebec, March, 1898, Vol. 18, pp. 51-63. The Spelling Problem. Ibid., May- June, 1899, Vol. 19, pp. 73-92. ELMER B. BRYAN : — Graduate of Indiana State Normal School, 1889 ; A.B., Indiana University, 1893 ; Principal of High School, Kokomo, Ind., 1893-94 ; Teacher of History, Industrial Training School, Indianapolis, 1894-96; Professor of Pedagogy, Butler College, 1896-97 ; Assistant Professor of Peda- gogy, Indiana University, 1897-99 ; Asso- ciate Professor, 1899- ; Graduate Student in Philosophy, Harvard University, Oct., Published Papers. 473 1898-Jan.,1899; Scholar In Philosophy, Clark University, Jan.-June, 1899. Author of : — School Hygiene. Indiana School Jour- nal, July, 1899, Vol. 44, pp. 393-396. School Diseases. Ibid., Aug., 1899, Vol. 44, pp. 465-469. The Hygiene of Instruction. Ibid. , Sept. , 1899, Vol. 44, pp. 533-536. The Care of the Senses. Ibid., Oct., 1899, Vol. 44, pp. 593-595. Child Life. Ibid., Nov., 1899, Vol. 44, pp. 647-649. ■WILLIAM LO"WE BRTAN : — A.B., Indiana University, 1884; A.M., 1886 ; Student, University of Berlin, 1886- 87 ; Instructor in Philosophy, Indiana University, 1885 ; Associate Professor in Philosophy, ibid., 1885-87 ; Professor in Philosophy, ibid., 1887 ; Fellow in Psy- chology, Clark University, Oct., 1891- Jan., 1893 ; Ph.D., Clark University, 1892 ; Vice-President, Indiana Univer- sity, 1893-. Author of : — Pscyhology at Indiana University. Am. Jour, of Psy., April, 1890, Vol. 3, pp. 283-284. On the Development of Voluntary Motor Ability. Ibid., Nov., 1892, Vol. 5, pp. 125-204. Auditory and Visual Memory in School Children. Proc. Internat. Ed. Ass^n, 1898. Suggestions on the Study of Children by Teachers. Pamphlet, 8 pp. Child Study : Systematic and Unsystem- atic. Proc. Dept. of Supt., 1895. Proc. JSr. E. A., 1895, pp. 412-418. On the Methods and Results of Child Study. Article in Johnson's Encyclo- Syllabus on Imitation of Teacher by Pupil. (With U. J. Griffith.) Handb. HI. Soc. for Child Study, May, 1895, Vol 1, pp. 44-45. Science and Education. Proc. N". E. A., 1895, pp. 161-165. Eeport on Work in Child Study in Indi- ana. Ibid., 1895, pp. 905-906. Scientific and Non-Scientific Methods of Child Study. Ibid., 1896, pp. 856-860. Studies on the Physiology and Psychology of the Telegraphic Language. (With Noble Harter.) Psychological Review, Jan., 1897, Vol. 4, pp. 27-53. Hygiene of Motor Development. Proc. Dept. of Supt., m E. A., 1897. Report of Special Committee on the Or- ganization of a Committee on School Hygiene. National Council of Educa^ tion, 1897. Plato the Teacher. Being Selections from the Apology, Euthydemus, Protagoras, Symposium, Phjedrus, Republic, and Phsedo of Plato. Edited with Intro- duction and Notes. (With Charlotte Lowe Bryan.) Charles Soribner's Sons, New York, 1897. xli. -f- 454 pp. The Republic of Plato. With Studies for Teachers (with Charlotte Lowe Bryan). Charles Scribner's Sons, New York, 1898. 318 pp. Studies on the Telegraphic Language. The Acquisition of a Hierarchy of Habits. (With Noble Harter.) Psy- chological Beview, July, 1899. Vol. 6, pp. 845-375. WARREN O. BULLARD: — A. B., Brown University, 1892; Instruc- tor in Mathematics, Pree Academy, Elmira, N.Y., 1892-93; Scholar in Mathematics, Clark University, 1893- 96; Ph.D., Clark University, 1896; Instructor in Mathematics, University of Vermont, 1896- ; Member of the Ameri- can Mathematical Society. Author of : — On the General Classification of Plane Quartic Curves. Math. Beview, Vol. L, pp. 193-208. (Preprint.) HERMON C. BUMPUS: — Ph.B., Brown University, 1884; Instruc- tor in Zoology, ibid., 1885-86; Professor in Zo81ogy and Geology, Olivet College, 1886-89 ; Fellow in Animal Morphol- 474 Titles of ogy, Clark University, 1889-90 ; Ph.D., Clark ITniverBity, 1891 ; Assistant Pro- fessor, 1890-91, and Associate Professor of Zoology, Brown University, 1891-92 ; Professor of ComparatiTe Anatomy, ibid. , 1892- ; Assistant Director, Marine Bio- logicaJ Laboratory, Woods HoU, Mass., 1893-95 ; Director Biological Laboratory of the XJ. S. Fish Commission, 1898- ; Secretary of the American Society of Natu- ralists, 1895-99 ; Vice-President American Society of Naturalists, 1899-. Author of : — Studies in Zoology. Am. Teacher, 1886. Keptiles and Batrachians of Rhode Island. Bandom Notes on Nat. Hist., 1885-86, Vols. 2, 3. Reptilia. Stand. Nat. Hist., 1885, Vol. 3. An Inexpensive Self-registering Anxan- ometer. Bot. Gaz., 1887, Vol. 12. The Embryology of the American Lob- ster. Jour, of Morph., 1891, Vol. 5, pp. 215-262. A New Method of using Celloidin for Serial Section Cutting. Amer. Nat., Jan., 1892, Vol. 26, pp. 80-81. A Laboratory Course in Invertebrate ZoSlogy. Henry Holt & Co., 1893. 157 pp. The Median Eye of Adult Crustacea. Zool. Anz., 1894, p. 447. Laboratory Teaching of Large Classes in Zoology. Science, March 8, 1895, N. S., Voll, pp. 260-263. Instinct and Education in Birds. Ibid., August 21, 1896, N. S., Vol. 4, pp. 213- 217. Report of the Fourteenth Annual Meeting of the American Society of Naturalists. Ibid., Feb. 28, 1896, N. S., Vol. 3, pp. 297-299. A Review of "The American Lobster, a Study of its Habits and Development," by F. H. Herrick. Ibid., Oct. 9, 1896, N. S., Vol. 4, pp. 536-537. A Contribution to the Study of Variation. Jour, of Morph., Feb. 1897, Vol. 12, pp. 455-484. Records of the American Society of Naturalists for the Meeting of 1896. A Review of Lloyd Morgan's " Habit and Instinct." Science, Dec. 17, 1897, N. S., Vol. 6, pp. 918-920. Report of the Fifteenth Annual Meeting of the American Society of Naturalists. Ibid., Jan. 7, 1898, N. S., Vol. 7, pp. 21-23. The Result of the Suspension of Natural Selection as illustrated by the Intro- duced English Sparrow. Ibid., March 12, 1897, N. S., Vol. 5, pp. 423-424. A Recent Variety of the Flatfish, and its Bearing upon the Question of Discon- tinuous Variation. Ibid., Feb. 11, 1898, N. S., Vol. 7, pp. 197-198. Certain Results from a Study of the Varia- tion of Littorina. Ibid., Feb. 11, 1898, N. S., Vol. 7, p. 198. The Breeding of Animals at Woods Holl during the Month of March, 1898. Science, April 8, 1898, N. S., Vol. 7, pp. 485-487. The Breeding of Animals at Woods Holl during the Month of May, 1898. Ibid., July 15, 1898, N. S., Vol. 8, pp. 58-61. The Breeding of Animals at Woods Holl during the Months of June, July, and August, 1898. Ibid. Dec. 16, 1898, N. S., Vol. 8, pp. 850-858. The Variations and Mutations of the Introduced Sparrow {Passer domesti- cus). Biological Lectures of the Ma- rine Biological Laboratory. 1896-97. Ginn & Co., Boston, 1898, pp. 1-15. The Variations and Mutations of the In- troduced Littorina. Zoological Bul- letin, Feb., 1898, Vol. 1, pp. 247-259. A Possible Case of Mutation. Jour. Bos- ton Soc. Med. Sci., Dec. 21, 1897, Vol. 2, pp. 25-26. The Work of the Biological Laboratory of the XJ. S. Fish Commission at Woods Holl. Science, July 22, 1898, N. S., Vol. 8, p. 96. The Identification of Adult Fish that have been Artificially hatched. Proceed- ings American Fisheries Society for 1898. American Naturalist, June, 1898, Vol. 32, pp. 407-412. Professor James Ingraham Peck. (An Account of his Life and Work.) ^cf- Published Papers. 475 ence, Dec. 2, 1898, N. S., Vol. 8, p. 783. The Elimination of the Unfit as illustrated by the Introduced Sparrow {Passer domestieus'). Biological Lectures of the Marine Biological Laboratory. (In press.) The Return of the Tileflsh. BuUettn U. S. Fish Commission. (In press.) FREDERIC BURK: — B.L., University of California, 1883; Instructor in Literature and History, California Military Academy, 1889-90 ; Graduate Student in Literature, Univer- sity of California, 1890-91 ; Instructor in Mathematics, Berkeley Gymnasium, 1890- 91 ; Graduate Student in Philosophy, Stan- ford University, 1891-92, and A. M., 1892 ; Supervising Principal of Schools, Santa Eosa, Cal., 1892-96; Fellow in Psy- chology, Clark University, 1896-97 ; Honorary Fellow, 1897-98; Ph. D., Clark University, 1898; Supt. of Schools, Santa Barbara, Cal., 1898-99 ; President, State Normal School, San Francisco, 1899- ; President of the Cal. State Teachers' Ass'n, 1899 ; Chairman of the Department of Child Study of the N. E. A., 1899. Author of : — gic Wand. (Alumni Address at Stan- ford University, 1894, pamphlet). Report upon the Pedagogical Methods in the Schools of Santa Rosa (pam- phlet), 1894. Modern Changes in Superintendency. Pacific Ed. Jour., March and April, 1896. Teasing and Bullying. Pedagogical Seminary, AprU, 1897, Vol. 4, pp. 336-371. The Training of Teachers; "The Old View of Childhood and the New." Atlantic Monthly, Oct., 1897, Vol. 80, pp. 547-561. The Graded System vs. Individual Pupils. Northwestern Monthly, March, 1898, Vol. 8, pp. 481-484. Growth of Children in Height and Weight. Am. Jour, of Psy., April, 1898, Vol. 9, pp. 253-326. Normal Schools and the Training of Teachers. Atlantic Monthly, June, 1898, Vol. 81, pp. 769-779. From Fundamental to Accessory in the Development of the Nervous System and of Movements. Pedagogical Sem- inary, Oct., 1898, Vol. 6, pp. 5-64. The Evolution of Music and the Pedagogi- cal Application. Proc. Cal. Teachers' Ass'n, 1898. A Curriculum for the Kindergarten from a Child's Standpoint. J6iU, 1898. A Study of the Kindergarten Problem. (With Caroline Frear Burk.) The Whitaker and Ray Co., San Francisco, 1899. 123 pp. The Kindergarten Child Physically. Proc.N. E. A, 1899. Child Study Application to the Curricula of the Primary School and Kinder- garten. Ibid., 1899. The Influence of Exercise upon Growth. Am. Phys. Ed. Sev., Dec, 1899, Vol. 4, and Pro. N. E. A., 1899. 'WILLIAM H. BURNHAM: — A.B., Harvard University (with Honors in Philosophy), 1882 ; Instructor in Witen- berg College, 1882-83 ; Instructor in State Normal School, Potsdam, N. Y., 1883-85; Fellow, Johns Hopkins University, 1885- 86 ; Ph.D., Johns Hopkins University, 1888; Instructor in Psychology, ibid., 1888-89; Docent in Pedagogy, Clark TTniversity, 1890-92 ; Instructor, 1892- ; Member of American Psycho- logical Association. Author of : — Memory, Historically and Experimentally Considered. I. The Older Conceptions of Memory; II. Modern Conceptions of Memory; III. Paramnesia; IV. Re- cent Theories. Am. Jour, of Psy., Nov., 1888, Feb., May, Aug., 1889, Vol. 2, pp. 39-90 ; 225-270 ; 431-464 ; 568-622. The Stage and the Pulpit. Christian Union, AprU 19, 1888, Vol. 37, pp. 486-487. 476 Titles of Training the Memory. Nation, Dec. 13, 1888, Vol. 47, pp. 480-481. Economy in Intellectual Work. Scribner^s Magazine, March, 1889, Vol. 5, pp. 306-314. Examination and Education. Nineteenth Century, Am. Suppl., March, 1889, Vol. 25, pp. 32-35. Recent Educational Literature. Nation, Aug. 15, 1889, Vol. 49, pp. 132-133. The New German School. Pedagogical Seminary, Jan., 1891, Vol. 1, pp. 13-18. The Study of Adolescence. Ibid., June, 1891, Vol. 1, pp. 174-195. Observation of Children at the Worcester Normal School. Ibid., June, 1891, Vol. 1, pp. 219-223. Higher Pedagogical Seminaries in Ger- many. Ibid., Dec. 1891, Vol; 1, pp. 390-408. Illusions of Memory. Scribner's Maga- zine, Feb., 1892, Vol. 11, pp. 185-195. Outlines of School Hygiene. Pedagogical Seminary, June, 1892, Vol. 2, pp. 9-71. La nuova scuola tedesca. (Translation of "The New German School" by Paolo Vecchia). Saggi Pedagogici, Turin, 1893, pp. 123-129. A Scheme of Classification for Child-study. Pedagogical Seminary, March, 1893, Vol. 2, pp. 191-198. Individual Differences in the Imagination of Children. Ibid., pp. 204-225. Some Recent German Literature on Physi- cal Education. Ibid., pp. 282-298. Child-study as the Basis of Pedagogy. Proc. Int. Cong, of Ed., Chicago, 1893, pp. 718-720. Motor Ability in Children : Development and Training. Proc. Am. Inst, of Instruction, Boston, 1894, pp. 127-140. Un esquema de classificaciSn para el estudio del niiio. (Translation of "A Scheme of Classification for Child- study). Soletin de la Institucidn libre de Ensehanza, Madrid, April 30, 1894, Vol. 18, pp. 107-112. Bibliographical Notes to Lectures in School Hygiene. Worcester, Mass., 1897. 11pp. Impurities in the Air of Schoolrooms. Northwestern Monthly, July, 1897, Vol. 8, pp. 75-80. Suggestions from the Psychology of Ado- lescence. School Beview, Dec. 1897, Vol. 5, pp. 14-27. Some Aspects of the Teaching Profession. The Forum, June, 1898, Vol. 25, pp. 481-495. Bibliography of School Hygiene. Proc. N. E. A., 1898, pp. 505-523. El estudio del nifio como base de la peda- gogfa. (Translation of " Child-study as the Basis of Pedagogy" by Manuel Valdes Rodriguez). Ensayos sobre Educaci6n Tedrica Prdctica y Experi- mental, Tomo Secunda, Habana, 1898, pp. 159-162. Mental Hygiene. Johnson's Universal Cyclopcedia, New Edition, 1C99, Vol. 10. School Diseases. Ibid. School Hygiene. Ibid. The Child in Education. Nation, Jan. 26, 1899, Vol. 68, pp. 72-73. B. C. BUHT: — A.B., University of Michigan, 1875 ; Pro- fessor, Indiana State Normal School, 1875- 78 ; A.M., University of Michigan, 1879 ; Fellow in Philosophy, Johns Hopkins University, 1881 ; Assistant Professor, University of Michigan, 1881-87 ; Pellow by Courtesy, Johns Hopkins University, 1887 ; Docent in Philosophy, Clark University, 1889-90 ; Ph.D., University of Michigan, 1894 ; Professsor (ad in- terim) of Philosophy and Pedagogy, University of Colorado, 1894-95 ; Agent, "Northwestern Line" and "Santa F^ Route," Superior, Nebraska, 1896-. Author ot: — Shakespeare in the Opinion of the 17th Century. New Englander, 1881. Watson's Kant and his English Critics. Unitarian Beview, 1882. Series of Articles on Greek Philosophy. Unity, Chicago, 1885-86. Some Relations between Philosophy and Literature. Pub. of Phil. Soo., Uni- versity of Michigan, 1886. Published Papers. 477 Eeferenoes for Students in English Litera- ture. Pamphlet, 1887. Philosophical Works of Professor George S. Morris. Chronicle, 1889. A Brief History of Greek Philosophy. Ginn & Co., Boston, 1889. xiv. + 296 pp. Translation of Erdmann's History of Philosophy from Kant to Hegel. Swan, Sonnenschein & Co., London. German Philosophy since Hegel. Educa- tion, April and May, 1890. Natural Science and the Philosophy of Nature. Philosophical Beview, May, 1892, Vol. 1, pp. 284-291. History of Modern Philosophy. 2 vols. MoClurg & Co., Chicago, 1892, 368, 321 pp. Translation of Hegel's Reohts-Pflichten und Beligionslehre. Translation of Erdmann's Logik und Metaphysik. Macmillau & Co., New York. JOHN CREAN CARD-WEiLL: — M.D., University of the City of New York, Medical Department, 1888 ; Assistant in the Physiological Laboratory, ibid., 1888- 89 ; Fellov7 in Physiology, Clark XTni- versity, 1889-91 ; Instructor in Physi- ology, Harvard Medical School, 1891-93 ; Lecturer on Physiology, Brooklyn College of Pharmacy, 1894-98 ; Assistant to the Chair of Nervous Diseases, Long Island College Hospital, 1897- ; Chief of Clinic for Nervous Diseases, Polhemus Clinic, Brooklyn, N. Y., 1898- ; Demonstrator of Physiology, Long Island College Hospital, 1899- ; Associate Director of Department of Physiology, Hoagland Laboratory, 1899-. ALEXANDER F. CHAMBERLAIN :— A.B., University of Toronto (with Honors in Modern Languages and Ethnology), 1886 ; A.M., University of Toronto, 1889 ; Fellow in Modern Languages, University College, Toronto, 1887-90 ; Examiner in French and German, Department of Ed- ucation, Toronto, 1888-89; Librarian Canadian Institute, Toronto, 1889-90; Examiner in German, University of To- ronto, 1888-91 ; Examiner in Modern Languages, Trinity University, Toronto, 1890-91 ; Anthropological Researches in British Columbia, under the auspices of the British Association for the Advance- ment of Science, Summer of 1891 ; Secre- tary Anthropological Section, American Association for the Advancement of Sci- ence, 1894; Secretary Anthropological Section, British Association for the Ad- vancement of Science, 1897 ; Fellovir in Anthropology, Clark TTniverBity, 1890-92; Ph.D., Clark University, 1892 ; Lecturer in Anthropology, 1892-. Author of : — The Relationship of the American Lan- guages. Proc. Oanad. Inst. (Toronto), 3d ser.. Vol. 5, 1886-87, pp. 57-76. Prehistoric Ethnology. [Brief Abstract.] Ibid., Vol. 5, 1886-87, p. 144. The Catawba Language. [Abstract.] Ibid., Vol. 6, 1887-88, p. 26. The Eskimo Race and Language. Ibid., Vol. 6, 1887-88, pp. 261-337. A First Contribution to the Bibliography of the Archaeology of the Dominion of Canada and Newfoundland. Ann. Bep. Canad. Inst., 1887-88, pp. 54- 59. The Catawba Language. Toronto, 1888. 4 pp., 8vo. The Mississaguas of Scugog. [Abstract.] Proc. Canad. Inst., 3d ser., Vol. 7, 1888-89, pp. 2-3. Deluge Myths of Canadian Indians. [Ab- stract.] Ibid., pp. 11-12. Arohseology of Scugog Island. [Abstract.] Ibid., pp. 14-16. The Language of the Mississaguas of Scugog. [Abstract.] Ibid., pp. 213- 215. The Origin and Development of Gram- matical Gender. [Abstract.] Ibid., pp. 216-217. A Second Contribution to the Bibliography of the Archaeology of Canada. Ann. Bep. Canad. Inst., 1888-89, pp. 102- 118. 478 Titles of Notes on the Negro Words lagniappe, buccra, goober. Science, July 13, 1888, p. 23. Mississagua Etjrmology. Ibid., Sept. 14, p. 132. The Archaeology of Scugog Island. Port Perry, 1889. 4 pp., 8to. Notes on the History, Customs, and Be- liefs of the Mississagua Indians. Jour. Am. Folk-Lore, Vol. 1, 1888, pp. ISO- ISO. Tales of the Mississaguas. I. Ibid., Vol. 2, pp. 141-147. A Mohawk Legend of Adam and Eve. Ibid., Vol. 2, pp. 228, 311. Algonliin Onomatology, with some Com- parisons with Basque. [Abstract.] Proc. Am. Ass^n Adv. Sci., Vol. 38, 1889, pp. 361-352. The Two Brothers : A Mississagua Leg- end. [Abstract.] Ibid., pp. 352-353. Words of Indian Origin in the French Canadian Dialect and Literature. Am. Notes and Queries (Philadelphia), Vol. 1, 1888, pp. 220-221, 232-233, 258-259, 270-271, 278-279, 293-294, 305-306; Vol. 2, 1888-89, pp. 2-3, 16-17, 30-31, 52-53, 62-63, 76-77, 87-88, 99-100, 124-125 ; Vol. 4, 1889, pp. 77-78. Who was "Etowokoam," mentioned in Spectator, No. 50 ? Ibid., Vol. 2, pp. 287-288. The Etymology of Terrapin. Ibid., Vol. 3, pp. 210-211. The Etymology of Tucquan. Ibid., Vol. 3, pp. 262-263 ; Vol. 4, p. 324. The Derivation of Chicago. Ibid. , Vol. 4, pp. 36, 91-92. The Names of the Humming Bird. Ibid., Vol. 4, pp. 206-208. New York Dialect Forms. Ibid., Vol. 3, pp. 295-296. Slav Proverbs. ' Varsity (University of Toronto), April 7, 1888. Etymology of Horse-Badish. Am. Notes and Queries, Vol. 2, 1889, pp. 119-120. Etymologies of Acadia, gore, undem, goober, Saginaw, Key West, cockle. Gal, elfetrioh, Manhattan, moonack, hurrah, chipmunk, plaquemine. Ibid., Vol. 1, p. 285 ; Vol. 2, pp. 69, 310, 311 ; Vol. 3, pp. 8, 9, 10, 103, 107 ; Vol. 4, pp. 34, 164, 155, 214. Hiawatha in Flemish. Ibid., Vol. 3, pp. 85-87. Etymology of Fad. Ibid., Vol. 3, pp. 154^155. Mississagua Place Names. Jour. Am. Folk-Lore, Vol. 3, 1890, p. 74. Tales of the Mississaguas. U. Ibid., pp. 149-154. A Negro Creation Legend. Ibid., p. 302. The Indians of Canada. [Abstract.] Trans. Canad. Inst., Vol. 1, 1890-91, pp. 18-19. The American Indian in Literature. [Ab- stract] Ibid., pp. 33-34. Mohawk Folk-Lore. Science, Vol. 16, 1890, p. 289. The Prehistoric Naturalist. Univ. Quart. Bev. (University of Toronto), Vol. 1, 1890, pp. 179-197. Dialect Research in Canada. Dialect Notes, Vol. 1, 1890, pp. 43-56. Contributions toward a Bibliography of the Archaeology of the Dominion of Canada and Newfoundland. III. Ann. Rep. Canad. Inst., 1890-91, pp. 78-82. The Algonkian Indians of Baptiste Lake. Ibid., pp. 83-89. The Aryan Element in Indian Dialects. I. Canadian Indian, Vol. 1, 1890-91, pp. 148-153. The Thunder-Bird amongst the Algonkins. American Anthropologist, Vol. 3, 1890, pp. 51-54. Note on the Os Inoae. Ibid., Vol. 3, p. 104. Notes on Indian Child Language. Ibid., Vol. 3, pp. 237-241. The Maple amongst the Algonkian Tribes. Ibid., Vol. 4, 1891, pp. 39-43. Maple Sugar and the Indians. Ibid., Vol. 4, pp. 381-383. Folk-Etymology in Canadian French. Modern Language Notes, Vol. 6, 1891, 202-205. Notes of French Canadian Folk-Lore. Dominion Illustrated (Montreal), Vol. 4, 1891, pp. 12-13. Nanibozhu amongst the Otchipw^, Mis- sissagas, and other Algonkian Tribes. Published Papers. 479 Jour. Am. Folk-Lore, Vol. 4, 1891, pp. 193-213. Words of Algonkian Origin in the Chinook Jargon. Science, Vol. 18, 1891, pp. 260-261. African and American. The Contact of the Negro and the Indian. Ibid., Vol. 17, 1891, pp. 85-90. Classics and Modern Languages in Europe and America since 1880, or Ten Years of the New Learning. Toronto, 1891, 60 pp. Some Points in Linguistic Psychology. Am. Jour, of Psy., Vol. 5, 1892-93, pp. 116-119. Notes on the Canadian French Dialect of Granhy, P. Q. I. Vocabulary. Mod- ern Language Notes, Vol. 7, 1892, pp. 324-327. Der Wettlauf: Eine Sage der Kftoniqa. Am Ur- Quell, III. Bd., 1892, S. 212- 213. A Mississaga Legend of NftnibSzhft. Jour. Am. Follc-Lore, Vol. 5, 1892, pp. 291- 292. The Use of Diminutives in -ing by Some Writers in Low German Dialects. Pub. Mod. Lang. Ass'n Am., Vol. 7 1892, pp. 212-217. The Language of the Mississagas of Skugog. A Contribution to the Lin- guistics of the Algonkian Tribes of Canada. [Thesis.] Philadelphia, 1892. 84 pp., 8to. British Association for the Advancement of Science. Edinburgh Meeting, 1892. Eighth Report on the Northwestern Tribes of Canada. Report on the Kootenay Indians of Southeastern British Columbia. (With introduc- tion by Horatio Hale.) London, 1892. 71 pp., 8vo. Human Physiognomy and Physical Char- acteristics in FoIk-Lore and Eolk- Speech. Jour. Am. Folk-Lore, Vol. 6, 1893, pp. 13-24. The Canadian-French Dialect of Granby, Province of Quebec. II. Phonetics. Modern Language Notes, Vol. 8, 1893, 31-35. Einige Wurzeln aus der Sprache der Ki- tSnaqa-Indianer von Britisoh-Colum- bien. Verh. der Berl. Gesellsch. f. Anthr., Ethn. u. Urgesch., 1893, S. 419-425. Ueber den Zauber mit menschlichem Blut und dessen Ceremonial-Gebrauch bei den Indianern Amerikas. Am Ur- Quell, IV. Bd., 1893, L, S. 1-3, IL, S. 34^7, III., S. 64-65. Sagen vom XTrsprung der Pliegen und Moskiten. Ibid., S. 201-202. Die Natur und die Naturerscheinungen in der My thologie und Volkkunde der In- dianer Amerikas. I. Der. Regenbo- gen. Ibid., S. 261-262. The Physical Education of Woman. By Prof. Mosso. [Translation.] Peda- gogical Seminary, Vol. 2, 1892-93, pp. 226-235. Notes on the Kootenay Indians. I. The Name. Am. Antiq. and Orient. Jour., Vol. 15, 1893, pp. 292-294. Further Notes on Indian Child Language. American Anthropologist, Vol. 6, 1893, pp. 321-322. Colour-Comparisons in the Low-German Poets. [Abstract.] Trans. Canad. Inst., Vol. 3, 1892-93, pp. 43-44. " Ch'nai-Sny." Nation, Vol. 56, p. 82. SuUe significazioni nella lingua degli in- digeni amerioani detti Kftonaqa (Koo- tenay) dei termini che denotano gli stati e le condizioni del corpo e dell' animo. Saggio di psicologia filologica. Arch, per V antrop. e la etnol. Firenze, Vol. 23, 1893, pp. 393-399. Primitive Woman as Poet. [Abstract.] Proc. Am. Ass''n Adv. Set., Vol. 42, 1893, p. 317. Syllabus of Lectures on the Mythology of the North American Indians. Report of President Clark Univ., 1893, pp. 123-125. Bibliography to accompany a Syllabus of Lectures on the Mythology of the North American Indians. Ibid., pp. 141-158. The Coyote and the Owl (Tales of the Kootenay Indians). Mem. Intern. Cong. Anthrop., Chicago, 1894, pp. 282-284. 480 Titles of A Kootenay Legend : The Coyote and the Mountain Spirit. Jour. Am. Folk- Lore, Vol. 7, 1894, p. 195. Words Expressive of Cries and Noises in the Kootenay Language. American Anthropologist, Vol. 7, 1894, pp. 68- 70. New Words in the Kootenay Language. Md., pp. 186-192. Life and Growth of Words in the French Dialect of Canada. L Modern Lan- guage Notes (Baltimore), Vol. 9, 1894, pp. 78-87. Life and Growth of Words in the French Dialect of Canada. II. Ibid., pp. 135-141. Ueber die Benennung des Pferdes in den Sprachen amerikanischer Indianer, Am Ur- Quell, V. Bd., 1894, S. 5-6. Notes on the Kootenay Indians. Second Paper. Linguistic Data. American Antiq., Vol. 17, 1894, pp. 271-274. Anthropology in Universities and Colleges. Pedagogical Seminary, Vol. 3, Oct., 1894, pp. 48-60. Primitive Anthropometry and its Folk- Lore. [Abstract.] Proc. Am. Ass^n Adv. Set, Vol. 43, 1894, pp. 348-349. Incorporation in the Kootenay Language. [Abstract.] Ibid., pp. 346-348. Translation into Primitive Languages ; Errors and Pitfalls ; with illustrations from Algonkian dialects. [Abstract.] Ibid., p. 346. Bayou (Etymology). Nation, Nov. 22, 1894, Vol. 59, p. 381. La Belle Nivemaise, par Alphonse Daudet, and Le Chien du Capitaine, par Louis :fenault. Edited, with Lives of the Authors, Notes, and Vocabulary, by John Squair, B.A., and A. F. Cham- berlain, M.A. Toronto, 1890, 6 + 184, and 198 + 132 pp. Notes on the Kootenay Indians. III. Mythology and Folk-Lore. Am. An- tiq. and Orient. Jour., Vol. 17, 1895, pp. 68-72. On Words for "Anger" in Certain Lan- guages. A Study in Linguistic Psy- chology. Am. Jour, of Psy., Vol. 6, 1894-95, pp. 585-592. Mutation of Gender in the French Dialect of Canada. Modern Language Notes, Vol. 10, pp. 232-236. The Child and Childhood in Folk-Thought (The Child in Primitive Culture). Macmillan's, N. Y., 1896, x. + 474 pp., 8vo. Indian Legends and Beliefs about the Squirrel and the Chipmunk. Jour. Am. Folk-Lore, Vol. 9, 1896, pp. 48- 50. The Poetry of American Aboriginal Speech. Ibid., pp. 43-47. Record of American Folk-Lore. Ibid., pp. 204-209. Beitrag zur Pflanzenkunde der NaturvSlker America's. Verh. d. Berl. Ges. f. Anthr., 1895, S. 551-556. Childhood. Address before Conference of Lend-a-Hand Clubs, Lowell, Mass., Feb. 1, 1896. Ten Times One Becord (Boston), Vol. 3, 1896, pp. 7-8. Anthropology at the Toronto Meeting of the British Association. Science, N. S., Vol. 6, 1897, pp. 575-683. Becord of American Folk-Lore. Jour. Am. Folk-Lore, Vol. 10, 1897, pp. 67-75. In Memoriam : Horatio Hale. Ibid., pp. 60-66. The Mythology and Folk-Lore of Inven- tion. Ibid., pp. 89-100. Becord of American Folk-Lore. Ibid., pp. 149-154. The Unitarian Church as a Social Institu- tion versus Alcoholism. Boston, 1897, 15 pp. The Lesson of the " Little Child." North- western Monthly (Lincoln, Neb.), Vol. 7, 1898, pp. 436-439. Becord of American Folk-Lore. Jour. Am. Folk-Lore, Vol. 10, 1897, pp. 233-239. Darwin and Lincoln. An Anniversary Address. Worcester (Mass.) Gazette, Feb. 8, 1898. Becord of American Folk-Lore. Jour. Am. Folk-Lore, Vol. 11, 1898, pp. 61-66. The Kootenays and their Salishan Neigh- bours. Hep. Brit. Ass'n Adv. Sci. Published Papers. 481 (Toronto, 1897), Vol. 47, London, 1898, p. 792. Kootenay Indian- Drawings. Ibid., pp. 797-798. Eecord of American Folk-Lore. (Jointly with I. C. C.) Jour. Am. Folk-Lore, Vol. 11, 1898, pp. 151-158. Record of American Folk-Lore. (Jointly with I. C. C.) Ibid., pp. 293-297. On the Words for Fear in Certain Lan- guages. A Study in Linguistic Psy- chology. Am. Jour. Psy., Vol. 10, 1898-99, pp. 302-305. Ethnology of the Aborigines. In British Association for the Advancement of Science (Toronto Meeting, 1897). Handbook of Canada (Toronto, 1897), pp. 106-126. American Indian Names of White Men and Women. Jour. Am. Folk-Lore, Vol. 12, 1899, pp. 24-31. The Child. A Study in Human Evolu- tion. (Volume of about 400 pages. In press.) Art of the Kootenay Indians. (In prep- aration.) Mythology of the Kootenays. (In prep- aration.) Dictionary of the Kootenay Indian Lan- guage. I. Kootenay-English. II. Eng- lish-Kootenay. (In preparation.) Three Shapers of Childhood's Genius — Society, Opportunity, Travel. North- western Monthly, June, 1899, Vol. 9, pp. 439-443. Record of American Folk-Lore. (With I. C. C.) Jour. Am. Folk-Lore, Vol. 12, 1899, pp. 136-143. Numerous reviews of books and articles in Journal of American Folk-Lore, Be- view of Historical Publications relat- ing to Canada, American Journal of Psychology, Pedagogical Seminary, etc. WILL GRANT CHAMBERS: — Graduate, Pennsylvania State Normal School, Look Haven, 1887 ; Instructor in Mathematics, ibid., 1887-90; A.B., La- fayette College (Honors in English and Philosophy), 1894 ; Instructor in Mathe- matics, State Normal School, Indiana, Pa., 2i 1894-97 ; B.S., State Normal School, Indi- ana, Pa., 1895 ; M.S., i6id., 1897 ; A.M., Lafayette College, 1897 ; Scholar in Payoholoey, Clark University, 1897- 98 ; Instructor in Mathematics and Peda- gogy, State Normal School, Indiana, Pa., 1899-. WALTER CHAINING: — Student, Massachusetts Institute of Tech- nology, 1867-68 ; M.D., Harvard Univer- sity, 1872 ; Honoraury Scholar, Clark University, 1889-90 ; Honorary Fel- low, 1890-92 ; Professor of Mental Diseases, Tufts College Medical School, 1895- ; Assistant Physician Asylum for In- sane Criminals, New York, 1873-75 ; First Assistant Pliysician, Insane Hospital, Danvers, Mass. 1876-78 ; Superintendent, Private Hospital Mental Diseases, Brook- line, Mass., 1879- ; Chief, Department Mental Diseases, Boston Dispensary ; Consulting Physician, Boston Aid Soci- ety ; Member of : American Medical Asso- ciation, Massachusetts Medical Society, American Medico-Psychological Society, American Neurological Society, New England Psychological Society, Boston Medical Improvement Society, Boston Medical Library Association, Corporation Massachusetts School for Feeble-minded ; Honorary Member, Association Institu- tions for Feeble-minded ; Member of : Council American Association Advance- ment Physical Education, Boston Society of Physical Education, Massachusetts Prison Association, National Conference of Charities ; Ex-president, Brookline Education Society, and Boston Medico- Psychological Society ; Trustee, New Eng- land Conservatory of Music ; Member, Brookline School Board. Author of: — Case of Helen Miller. Self-mutilation. Tracheotomy. Am. Jour, of Insanity. A Case of Feigned Insanity. Boston Med. and Surg. Jour., 1878, Vol. 98, p. 655. Buildings for Insane Criminals. Proc. of Conference of Charities, Chicago, June, 1879. 482 Titles of Care of the Insane in Massachusetts. Boston Med. and Surg. Jour. 1879, Vol. 101, p. 760. The Study of Psychological Medicine. Ibid., 1880, Vol. 102, p. 315. Note on the Construction of Hospitals for Insane Paupers. Proc. of Conference of Charities, Cleveland, June, 1880. Recent Progress in Insane Asylum Man- agement. Boston Med. and Surg. Jour., 1880, Vol. 102, p. 243. The Treatment of Insanity in its Economic Aspect. Proc. of Am. Social Sci. Ass^n, Saratoga, N. Y., Sept. 8, 1880. The Use of Mechanical Restraint in Insane Hospitals. Boston Med. and Surg. Jour., 1880, Vol. 103, p. 173. Recent Progress in Insane Asylum Man- agement and Care of the Insane. Ibid., 1881, Vol. 104, p. 272. The Care of Insane Criminals. Ibid., 1881, Vol. 104, p. 172. Medical Expert Testimony. Ibid., 1881, Vol. 105, p. 1. The Mental Status of Guiteau, the Assassin of President Garfield. Ibid., 1882, Vol. 106, p. 290. Recent Progress in Insane Asylum Man- agement and Construction. Ibid., 1882, Vol. 106, p. 267. Recent Progress in the Management of Lunatic Asylums and Care of the In- sane. Ibid., 1882, Vol. 107, p. 441. Non-Restraint in Lunatic Asylums. Ibid., 1882, Vol. 107, p. 282. Medical Treatment of the Insane -with Special Reference to Opium. Ibid., 1883, Vol. 108, p. 86. Report on Recent Progress in the Con- struction of Insane Hospitals and Management of the Insane. Ibid., 1883, Vol. 109, p. 462. A Consideration of the Causes of Insanity. Fifth Ann. Bep. Mass. Board of Health, Lunacy, and Charity, 1884. Recent Progress in the Construction of Insane Hospitals and Management of the Insane. Boston Med. and Surg. Jour., 1884, Vol. 110, pp. 295 and 321. Report on the Care of the Insane. Ibid., 1885, Vol. 112, p. 342. Temperature of the Insane, Especially In Acute Mania and Melancholia. Ibid., 1885, Vol. 113, pp. 1 and 29. The Connection between Insanity and Crime. Rep. of the Com. on Biblio- graphy of Insanity. Proc. of Am. Ass'n of Med. Supts. of Am. InstitUr- tions for the Insane, Saratoga, N. Y., June, 1885. Recent Progress in the Care of the Insane. Boston Med. and Surg. Jour. 1886, Vol. 114, pp. 291 and 318. Report of a Case of Epilepsy of Eorty-five Years' Duration, with Autopsy. Ibid., 1886, Vol. 115, p. 4. Recent Progress in Care of the Insane. Ibid., 1887, Vol. 116, pp. 351-^72. Progress in the Care of the Insane. Ibid., 1888, Vol. 118, p. 424. An International Classification of Mental Diseases. Am. Jour, of Insanity, Jan., 1888. Massachusetts Lunacy Laws. Boston Med. and Surg. Jour., 1888, Vol. 119, p. 97. Lunacy Legislation as Proposed by Dr. Stephen Smith and Others. Am. Jour. of Insanity, Jan., 1889. Physical Training of the Insane. Ibid., Oct., 1889. Physical Education. Boston Med. and Surg. Jour., 1891, Vol. 125, p. 4. Physical Education of Children. Proc. of the Ann. Meeting of the Social Sci. Ass^n, Sept. 1891. Evolution of Paranoia. (Rep. of a Case.) Jour, of Nervous and Mental Diseases, 1892, p. 192. Some Remarks on the Address Delivered to the American Medico-Psychological Association by S. Weir Mitchell, M.D., May 16, 1894. Am. Jour, of Insanity, Oct. 1894. Tuberculosis in Mental Disease. Boston Med. and Surg. Jour., 1894, Vol. 131, p. 62. Physical Training in Childhood. Educa- tional Beview, Oct., 1895, Vol. 10, pp. 262-272. The Importance of Frequent Observations of Temperature in the Diagnosis of Published Papers. 483 Chronic Tuberculosis. Boston Med. and Surg. Jour., Oct. 21, 1895. A Case of Tumor of the Thalamus, with Kemarks on the Mental Symptoms. Jour, of Nervous and Mental Diseases, Aug., 1896. The Significance of the Palatal Deformities of Idiots. Jour. Mental Sci., London, Jan., 1897. Beginnings of an Education Society. Educational Beview, Nov., 1897. Characteristics of Insanity. Boston Med. and Surg. Jour., Dec. 9 and 16, 1897. The Relation of the Medical Profession to School Education. Annals of Gynoe- cology and Fmdiatry, Jan. 26, 1897. Physical Training in the Boston Public Schools. Am. Physical Ed. Review, June, 1897. Medical Expert Testimony in the Kelly Murder Trial. Am. Jour, of Insanity, No. 3, 1898, Vol. 54. The New Massachusetts Board of Insanity. Charities Beview, Oct., 1898. OSCAR CHRISMAN: — Teacher and Principal in Public Schools, (Owen County, Gosport, Peru, Xenia, Logansport), Indiana, 1876-85 ; Graduate, Indiana State Normal School, 1887 ; A.B., Indiana University, 1888 ; Principal (Third Ward), Public School, Houston, Texas, 1888-89 ; Supt. Public Schools, Gonzales, Texas, 1889-92 ; Fellow in Pedagogy, Clark University, 1892-94; A.M., Indiana University, 1893 ; Student in Philosophy and Pedagogy, University of Jena, 1894-95 ; Ph.D., University of Jena, 1895 ; Professor of History of Education and Child-study, Kansas State Normal School, 1896- ; Secretary, 1898, and Presi- dent, 1899, of the Kansas Society for Child-study. Author of : — The Hearing of Children. Pedagogical Seminary, Dec, 1893, Tol. 2, pp. 397- 441. Secret Language of Children. Science, 1893, Vol. 22, p. 303 ; 1894, Vol. 23, p. 18. The Science of the Child. South Dakota Educator, Feb., 1894, p. 11. Vertical Writing. Texas School Jour., 1894. Child-study, a New Department of Edu- cation. Forum, Feb., 1894, Vol. 16, pp. 728-736. Contribution to a Symposium on Child- study. Interstate School Bevieiv, Illinois, June, 1894, p. 225. One Year with a Little Girl. Educational Beview, Jan., 1895, Vol. 9, pp. 52-71. Paidologie, Entwurf zu einer Wissenschaft des Kindes. Inaugural-Dissertation der philosophischen Fakultat der Uni- verstat Jena zur Erlangung der Doktor- vriirde. Jena, 1896. 96 pp. Children's Secret Language. Child-study Monthly, Sept., 1896, Vol. 2, pp. 202- 210. How a Story Affected a Child. Ibid., April, 1897, Vol. 2, pp. 650-661. The Hearing of School Children. North- western Monthly, July, 1897, Vol. 8, pp. 31-35. Motor Control : Its Place in the Physical and Psychical Life of the Child. State Normal Monthly, Oct., 1897, Vol. 10, p. 3. Child-study in Texas. Child-study Monthly, Nov., 1897, Vol. 3, p. 287. (Report of the Child-study Section of the Texas State Teachers' Association held at Waco, June 29-July 2, 1897.) The Secret Language of Children. North- western Monthly, Vol. 8, Oct., 1897, p. 187 ; June, 1898, p. 649; and Jan., 1899, p. 375. Exceptionals. State Normal Monthly, Jan., 1898, Vol. 10, p. 51. Results of Child-study. Education, Feb., 1898, Vol. 18, pp. 323-332. Religious Ideas of a Child. Child-study Monthly, March, 1898, Vol. 3, pp. 516- 628. How to use the Library. Western College Magazine, March, 1898, Vol. 19, p. 502. Paidology, the Science of the Child. Edu- cational Beview, March, 1898, Vol. 15, pp. 269-284. 484 Titles of The Secret Language of Childhood. Cen- tury, May, 1898, Vol. 56, pp. 54-68. Religious Periods of Child-growth. Edu- cational Beview, June, 1898, Vol. 16, pp. 40-48. Child and Parent. Northwestern Monthly, Vol. 9, Nov., 1898, p. 135 ; Dec, 1898, p. 180. The Pubescent Period. Education, Feb., 1899, Vol. 19, pp. 342-347. Opening Remarks as President of the Kansas Society for Child-study. Child- study Monthly, Feb., 1899, Vol. 4, p. 451. Editorial for the Child-study Department. Northwestern Monthly, Feb., 1899, Vol. 9, p. 275. Child and Teacher. Jour, of Pedagogy, May, 1899, Vol. 12, pp. 112-125. Courses of Study for Normal Schools. Arena, July, 1899. ARTHUR L. CLARE: — S.B., Worcester Polytechnic Institute, 1894 ; Instructor in Mathematics and Physics, Bridgeton Academy, Me., 1895- 96 ; Scholar in Pbysics, Clark Uni- versity, 1896-97; Fellow, 1897-98; Instructor in Science, Worcester Academy, 1898-. Author of : — A Method of Determining the Angle of Lag. Phil. Mag., April, 1896, Vol. 41, pp. 369-372. On the Specific Inductive Capacity of Cer- tain Oils. Physical Beview, Feb. , 1898, Vol. 6, pp. 120-125. ROBERT CLARE:— A.B., Amherst College, 1892 ; Teaching, 1892-97 ; Scholar, Clark University, 1897-99. THOMAS H. CLARE: — B.S., Worcester Polytechnic Institute, 1880 ; Assistant Superintendent Pennsyl- vania Lead Co., 1881-84 ; Student, Johns Hopkins University, 1884-85; Assistant in Chemistry, Wesleyan University, 1886- 89 ; Fellow in Chemistry, Clark Uni- versity, 1889-92 ; Ph.D., Clark Uni- versity, 1892 ; Assistantin Chemistry, 1892-93 ; Instructor in Quantitative Analysis, Tufts College, 1894-95; In- structor in Chemistry and Physics, Clinton Liberal Institute, 1895-97 ; Instructor in Chemistry and Physics, State Normal School, Plymouth, N. H., 1897- ; Member Am. Institute of Mining Engineers, and German Chem. Society. Author of : — The Addition-Products of Benzo- and of Toluquinone. Am. Chem. Jour. , Dec, 1892, Vol. 14, pp. 553-576. Relative Leichtigkeit der Eohlendiozyd- abspaltung aus den Silbersalzen der /3-Chlorcrotonsauren. (With Professor Arthur Michael.) Jour, fur prakt. Chemie, 1895, N. F., Bd. 52, pp. 326- 329. CHARLES W. CLINTON: — Principal of Public Schools in Wisconsin and Minnesota ; County Superintendent, Wisconsin ; Visitor to the State Normal Schools, Wisconsin ; Professor, Shattuck School, Faribault, Minn., 1880-88 ; Prin- cipal, St. John's Military Academy, Kan- sas, 1888-90; Head Master, Peekskill Military Academy, 1891-93 ; Principal, Marmaduke (Mo.) Military Academy, 1893-94; Ph.D., Ottawa University, 1895; Principal, Clinton Classical School, 1895- 97 ; Fellow in Psychology, Clark University, 1897-98 ; Professor of Mathematics and Latin, Stamford (Ct.) Preparatory School, 1899. HERBERT OTIS CLOUGH:- A.B., Bowdoin College, 1896 ; Scholar in Mathematics, Clark University, 1896-97; Assistant in Mathematics, Bowdoin College, 1897-98; Principal Kennebunkport (Me.) High School, 1898-. PRBDERICE W. COLEQROVE:- A.B., Colgate University, 1882; A.M., ibid., 1885 ; Student, Hamilton Theological Seminary, 1882-84 ; Principal, Collegiate Institute, Maiion, N. Y., 1884-89; Pro- fessor of Latin, Colgate University, 1889- 92 ; President, Ottawa University, Kansas, Published Papers. 485 1892-06; D.D., University of Rochester, 1893 ; Honorary Fellow in Psychology, Clark University, 1896-98; Ph.D., Clark University, 1898 ; Honorary Fellow in Psychology, Oct. -Dec, 1898 ; Student in Universities of Europe, 1899; Professor of Philosophy, Univer- sity of Washington, Seattle, Sept., 1899- ; Member of the American Philological Association, and Kansas Historical So- ciety. Author of : — Freedom of Worship. Our Young Peo- ple, April, 1897. Individual Memories. Am. Jour, of Psy., Jan., 1899, Vol. 10, pp. 228-255. The Time required for Recognition. lUa., pp. 286-292. Notes on Mental Standards of Length. Ibid,, pp. 292-295. LEVI L. CONANT: — A.B., Dartmouth College, 1879; Princi- pal of High Schools, Minnesota and Indiana, 1880-83; Superintendent of Schools, Deadwood and Rapid City, So. Dak., 1883-87; A.M., Dartmouth College, 1887 ; Professor of Mathematics, Dakota School of Mines, 1887-90 ; Scholar in Mathematics, Clark University, 1890- 91 ; Assistant Professor of Mathematics, Worcester Polytechnic Institute, 1891-92 ; A.M. and Ph.D., Syracuse University, 1893 ; Associate Professor of Mathematics, Worcester Polytechnic Institute, 1892-98 ; Professor of Mathematics, ibid., 1898-. Author of : — Historical Development of Arithmetical Notation; and Text Books in Arith- metic. Pedagogical Seminary, June, 1892, Vol. 2, pp. 149-163. Primitive Number Systems. Smithsonian Beport, 1892, pp. 583-594. The Teaching of Mathematics. School Beview, April, 1893, Vol. 1, pp. 210- 217. Note on the Translation of Certain Me- moirs on Infinite Series. Bull, of the N.Y. Math. /Soc, 1894. The Origin of Numeral Words. Proc. A. A. A. S., 1894. English Folk Tales in America. Jour, of Am. Folk-Lore, April-June, 1895, Vol. 8, pp. 143-144. The Number Concept. Macmillan and Company, New York, 1896. vi. + 218 pp. An Application of the Theory of Substi- tutions. Am. Math. Soc, Aug., 1898. ALFRED COOK:— A.B., Northwestern University, 1877 ; Ph.D., University of Halle, 1886 ; FeUow by courtesy, Johns Hopkins University, 1887 ; Superintendent of Schools, Nimonk, HI., 1887-88; Instructor in Philosophy, Bryn Maver College, 1888-89; Decent and Lecturer on History of Philoso- phy, Clark University, 1889-90 ; Inde- pendent University Extension Lecturer on Psychology and on the Philosophy of History, 1896-. Author of : — Ueber die Berkeleysohe Philosophie. C. A. Kaemmerer & Co., Halle, 1886. 48 pp. Harmony of Natural Law and Free Will, a Dissertation on the Kantian Philoso- phy. Bloomington, HI., 1888. 16 pp. L. P. CRAVEN'S : — A.B., Carthage College, 1878; A.M., ibid., 1879 ; Professor of Mathematics, Mt. Morris Academy, 1880-84 ; Professor of Mathematics, Carthage College, 1884-86 ; Superintendent of Schools, Carthage, lU., 1886-89; Scholar in Mathematics, Clark University, 1889-90 ; Professor of Mathematics, Slate Normal School, Winona, Minn., 1890-91; Student in Mathematics, University of Halle, 1891- 92 ; Professor of Mathematics, Fort Worth University, Texas, 1892-94; Student in Mathematics, University of Chicago, 1894- 95 ; Principal of Academic Department of Coe College, 1895-96 ; Principal of High School, Lake City, Minn., 1896-97 ; Super- intendent of Schools, Lake City, Minn., 1897-. 486 Titles of T. R. CROSWELL: — A.B., Bowdoin College, 1891; Principal, Wilton Academy, 1891-94; Student in Pedagogy, Columbia College, 1894-95 ; Scholar in Pedagogy, Clark TTniver- Bity, 1895-97 ; Teacher in Public Schools of Chicago, 1897-98; Teacher in Stevens Point (Wis.) Normal School, 1899. Author of : — Courses of Study in the Elementary Schools of the United States. Peda- gogical Seminary, April, 1897, Vol. 4, pp. 294-335. A Study of the Ungraded Schools of Maine. Maine School Report, 1897, Appendix II. , pp. 1-15. Amusements of Worcester School Chil- dren. Pedagogical Seminary, Sept., 1899, Vol. 6, pp. 314-371. HENRY S. CURTIS: — A.B., Olivet College, 1894; A.B., Tale University, 1896 (Honors in Philosophy) ; Fellow in Psychology, Clark Uni- versity, 1895-97; Ph.D., Clark TTni- versity, 1898 ; Teacher, N. Y. Public Schools, 1898-. Author of : — Learning without Books. Jour, of Peda- gogy, Jan., 1898, Vol. 11, pp. 86-90. Inhibition. Pedagogical Seminary, Oct., 1898, Vol. 6, pp. 65-118. Child-study in Connection with the Vaca- tion Schools. (With G. E. Partridge.) Report on the Vacation Schools and Playgrounds, N. Y. City, Boroughs of Manhattan and the Bronx, 1898, pp. 51-97. Child-study in Vacation Schools. Educa- tional Foundations, May, 1899. Child-study in the Playgrounds. Ibid., June, 1899. Plays and Playgrounds. (In press). ARTHUR HILIi DANIELS: — B.A., Olivet College, 1887 ; Student, Tale Divinity School, 1887-90; B.D., Yale University, 1890 ; Student in Philosophy and Psychology, Yale University, 1890- 92; Fellow in Psychology, Clark University, 1892-93 ; Ph.D., Clark University, 1893 ; Instructor in Phi- losophy, University of Illinois, 1893-95 ; Assistant Professor of Philosophy, ibid., 1895-99; Professor of Philosophy, ibid., 1899-. Author of : — The New Life : A Study of Regeneration. Am. Jour, of Psy., Oct., 1893, Vol. 6, pp. 61-106. The Memory After-image and Attention. Ibid., Jan., 1895, Vol. 6, pp. 568-564. SCHUYLER C. DAVISSON: — A.B., Indiana University, 1890 ; A.M., ibid., 1892; Instructor in Mathematics, ibid., 1890-93; Associate Professor in Mathematics, ibid., 1893-. Fellow in Mathematics, Clark University, 1895- 96 ; Student, University of Tiibingen, Germany, 1898-99. GEORGE E. DA-WSON: — A.B., University of Michigan, 1887; Pro- fessor of Greek and English Literature, Carleton Institute, Farmington, Mo., 1887-88 ; Student, University of Leipzig, 1888-89; Principal, OU City, Pa., High School, 1889-91 ; Professor of English and Literature, State Agricultural College, So. Dak., 1891-93 ; Instructor in English, University of Michigan, 1893-95 ; Fellow in Psychology, Clark University, 1895-97, Ph.D., Clark University, 1897 ; Professor of Psychology, Bible Normal College, Springfield, Mass., 1897-. Author of : — A Study in Youthful Degeneracy. Peda- gogical Seminary, Dec, 1896, Vol. 4, pp. 221-258. Series of Twelve Papers on Child-study. International Evangel, Sept., 1897- Sept., 1898. The Study of Man as Related to Religious Work. Biblical World, March, 1899. Interest, the Material of Instruction. Biblical World, June, 1899. Suggestions as to the Basis of a Sunday School Curriculum. Trans. III. Soc. Published Papers. 487 for Child-Study, Apr.-July, 1899, Vol. 4, pp. 10-17. Psychic Rudiments and Morality. Am. Jour, of Psychology. (In press.) ALFRED T. DE LURY: — B.A., University of Toronto (with Honors and Medal in Mathematics), 1890 ; PeUow in Mathematics, Clark TTniveraity, 1890-91; Mathematical Master, Whet- ham College, Vancouver, 1891 ; Mathemat- ical Master, Collegiate Institute, Toronto, 1892 ; Leotarer in Mathematics and Dean of the Residence, University of Toronto, 1892- ; Member of the American Mathe- matical Society. Author of ; — On Certain Deductions from the Theorem of Dr. Graves. Papers Math, and Phys. Soc, Toronto Univ., Tear 1890-91, pp. 22-30. Clark University. The Varsity, Toronto, Jan. 27, 1891, Vol. 10, pp. 150-151. HENRY H. DONALDSON: — A.B., Yale University, 1879; Sheffield Scientific School, 1880 ; College of Physi- cians and Surgeons, N. Y. City, 1881 ; Fellow, Johns Hopkins University, 1881- 83 ; Ph.D., Johns Hopkins University, 1885; Associate in Psychology, ibid., 1887-88 ; Assistant Professor of Neu- rology, Clark University, 1889-92; Professor of Neurology, University of Chicago, 1892-. Author of : — On the Detection and Determination of Arsenic in Organic Matter. (Under Prof. R. H. Chittenden.) Am. Chem. Jour., Oct., 1880, Vol. 2, pp. 235- 244. The Influence of Digitaline on the Work of the Heart and on the Flow through the Blood Vessels. (With Dr. L. T. Stevens.) Jour, of Phys., Jan., 1888, Vol. 4, pp. 165-197. (See also note in Vol. 5, p. 45.) On the Temperature-Sense. Mind, July, 1885, Vol. 10, pp. 399-416. Motor Sensations of the Skin. (With Dr. G. Stanley Hall.) Ibid., Oct., 1885, Vol. 10, pp. 557-572. On the Relation of Neurology to Psy- chology. Am. Jour, of Psy., Feb., 1888, Vol. 1, pp. 210-221. Anatomical Observations on the Brain and Several Sense-Organs of the Blind Deaf-Mute, Laura Dewey Bridgman. Part I. Ibid., Sept., 1890, Vol. 3, pp. 293-342. Part II. Dec, 1891, Vol. 4, pp. 248-294. Cerebral Localization. Ibid., April, 1891, Vol. 4, pp. 113-130. Notes on Models of the Brain. Ibid., April, 1891, Vol. 4, pp. 130-131. The Size of Several Cranial Nerves in Man as Indicated by the Areas of their Cross-sections. (With T. L. Bolton.) Ibid., Dec, 1891, Vol. 4, pp. 224-229. The Extent of the Visual Area of the Cor- tex: in Man as deduced from the Study of Laura Bridgman's Brain. Ibid., Aug., 1892, Vol. 4, pp. 503-513. Preliminary Observations on Some Changes catised in Nervous Tissues by Reagents, commonly used to harden them. Jour, of Morph., Jan., 1894, Vol. 9, pp. 123-166. The Education of the Nervous System. Educational Review, Feb., 1895, Vol. 9, pp. 105-121. The Growth of the Brain. (Contem- porary Science Series.) Walter Scott, London. Chas. Scribner's Sons, New York, 1895. 374 pp. Central Nervous System. Chapter X., Howell's Am. Text-Book of Physiol- ogy, W. B. Saunders, Philadelphia, 1896, pp. 605-743. Observations on the Weight and Length of the Central Nervous System and of the Legs in Bull-frogs of Different Sizes. Jour, of Comp. Neurol., Dec, 1898, Vol. 8, pp. 314-335. D. ELLIS DOUTY: — B.S., University of Washington, 1892; Assistant in Physics Laboratory, ibid., 1895-96 ; Tutor in Physics, ibid., 1896- 488 Titles of 98; Scholar in Physics, Clark Uni- versity, 1898-99. L. -WAYLAND DO"WLING : - Adrian College, 1889-90; Principal of Schools, Clayton, Mich., 1891-92; Pel- lo'w in Mathematics, Clark Univer- sity, 1892-95; Ph.D., Clark Univer- sity, 1895 ; Instructor In Mathematics, University of Wisconsin, 1895-98 ; Assist- ant Prof essor of Mathematics, ibid., 1898-; Member of the American Mathematical Society ; Member of the Wisconsin Acad- emy of Sciences, Arts, and Letters. Author of: — On the Forms of Plane Quintic Curves. Mathematical Beoiew, April, 1897, Vol. 1, pp. 97-119. FLETCHER B. DRESSLAR: — Instructor, Vincennes University, 1888 ; A.B., Indiana University, 1889 ; Princi- pal, High School, Princeton, Ind., 1889- 90 ; Superintendent of Schools, Princeton, Ind., 1890-91 ; Scholar in Psychology, Clark University, 1891-92 ; Instruc- tor in Psychology, Indiana University, Sept. -Dec, 1892; Fellow in Psychol- ogy, Clark University, Jan., 1893-July, 1894 ; Ph.D., Clark University, 1894 ; Professor of Psychology and Pedagogy, State Normal School, Los Angeles, Cal., 1894-97 ; Assistant Professor of the Sci- ence and Art of Education, University of California, 1897-. Author of : — A Review of the Genus Simotilus. (With Ernest P. Bioknell.) Proa. Acad, of Nat. Sci., Philadelphia, 1884. A Review of the Family Scombrinss (Illinois). (With Bert Fesler.) Bull, of U. S.Msh Com., 1887. Temperance Legislation in Indiana. (Prize Essay, University of Indiana.) In- diana Student, March, 1887. Evils of Modern Immigration. (Prize Oration, University of Indiana. ) B)id. , Dec, 1889. Fatigue. Pedagogical Seminary, June, 1892, Vol. 2, pp. 102-106. ' A Sketch of Old Sohoolhouses. Ibid., June, 1892, Vol. 2, pp. 115-125. Some Influences which afiect the Rapid- ity of Voluntary Movement Am. Jour, of Psy., Aug., 1892, Vol. 4, pp. 514-527. On Facial Vision and the Pressure Sense of the Drum of the Ear. Ibid., April, 1893, Vol. 5, pp. 344-350. A New Illusion for Touch and an Ex- planation for the Illusion of Displace- ment of Certain Cross Lines in Vision. Ibid., Vol. 6, pp. 275-276. A New and Simple Method for Comparing the Perception of Rate of Movement in the Direct and Indirect Fields of Vision. Ibid., Vol. 6, p. 312. Psychology of Touch. i6td!., June, 1894, Vol. 6, pp. 50-54. Outline for a Study of Habit-Degenera- tion. Teachers^ Handbook for Child- Study. Published by Illinois Society for Child-Study, May, 1895, Vol. 1, pp. 21-23. Preparation for History in the Grades. Normal Exponent, 1895. The New Psychology and Its Pedagogical Significance. JVoc. Cal. Teachers^ Ass'n, Dec, 1896. Experiments in Psychology. Overland Monthly, Aug., Sept., Nov., Dec, 1896 ; Feb., March, April, June, 1897. Education in Hawaii. Educational Be- view, Jan., 1898, Vol. 15, pp. 50-54. Genetic Psychology. Northwestern Monthly, April, 1899, Vol. 9, pp. 355-358. Guessing, as influenced by Number Pref- erences. Pop. Sci. Mo., April, 1899, Vol. 54, pp. 781-786. FRANK DREW: — Superintendent of Schools, Genoa, 111., 1887-89; A.B., Indiana University, 1890; A.M., ibid., 1891; Scholar in Psychology, Clark University, 1892- 93; Fellow, 1893-95; Ph.D., Clark University, 1895 ; Instructor in Psy- chology, Indiana University, 1895-96; Teacher in State Normal School, Worces- ter, Mass., 1896-. Published Papers. 489 Author of; — Adenoids in Cliildren. Pedagogical Sem- inary, March, 1893, Vol. 2, pp. 307- 309. Love Poems of College Students. Ibid. Dec. 1893, Vol. 2, pp. 504-505. Attention: Experimental and Critical. Am. Jour, of Psy., July, 1896, Vol. 7, pp. 533-672. LINDSAY DUNCAN: — B.S., University of Maine, 1897 ; Scholar in Mathematics, Clark University, 1897-99 ; Instructor in Mathematics and Engineering, Union College, Schenectady, N. Y., 1899-. ROBERT K. DUNCAN: — A.B., University of Toronto, 1892 ; Fel- low in Chemistry, Clark University, 1892-93; Instructor in Physics and Chemistry, Auburn, N. Y., High School, 1893-95 ; Instructor in Physics and Chem- istry, Dr. Julius Sach's Collegiate Insti- tute, New York, 1895-98 ; Non-Kesident Student, Columbia University, 1897-98 j Instructor in Physics and Chemistry, The Hill School, Pottstown, Pa., 1898-. VTILLIAM FREDERICK DURAND: — Graduate, U. S. Naval Academy, 1880; Graduate, Course at Sea, 1882; Assistant Engineer, U. S. Navy, 1882-87 ; Graduate Student, Lafayette College, 1883-85 ; Ph.D., Lafayette College, 1888 ; Profes- sor of Mechanics, Michigan State Agri- cultural College, 1887-91 ; Scholar in Physics, Clark University, Nov. and Dec, 1889; Professor of Marine Engi- neering, Cornell University, 1891-. Author of : — A Practical Method of Finding the Opti- cal Centre of an Objective and its Po- cal Length. Am. Mo. Micro. Jour. Aug., 1885, Vol. 6, p. 141. The Tundamental Conceptions of Me- chanics. Privately published, 1890. The Path of the Point of Contact of the Teeth of Gear Wheels. Sci. Am. Sup- plement, April 26, 1890, Vol. 29. An Interesting Experiment with the Mi- croscope. Am. Mo. Micro. Jour., June, 1890, Vol. 2, p. 136. The Behavior of Wood under Repeated and Varying Stress. Trans. Mich. Eng. Soc, 1891, p. 57. A New Porm of Contour Caliper. Ibid. 1891, p. 62. Decimal Subdivision by the Eye. Sibley Jour, of Eng., Jan., 1892, Vol. 6, p. 138. Study of the Element of a Screw Propel- ler. Jour, of Am. Soc. of Naval En- gineers, 1892, Vol. 4, p. 73. Treatment of Non-Algebraic Curves for Maxima and Minima by Use of Ordi- dinates. Ibid. p. 71. The Influence of Shook on Propeller Efll- ciency. Ibid. p. 611. Some Points in the Philosophy of the Steamship. Gassier' s Magazine, Nov., 1892, Vol. 5, p. 35. Marine Engine Design. Marine Heview, 1892, Vol. 6, Dec. 1, p. 6, and Dec. 8, p. 12. Eelative Weight of Water and Eire Tube Boilers. American Shipbuilder, June 20 and 27, 1893. Planning and Equipment of Modem Ship and Engine Building Plants. Sep. of Internat. Eng. Cong., Columbian Ex- position, Div. of Marine Eng., Vol. 2, No. 28. The Limit of Propeller EfBoiency as De- pendent on the Surface Form of the Propeller. Trans. Am. Soc. of Me- chanical Engineers, 1893, Vol. 14, p. 65. The Analysis of Certain Curves arising in Engineering Investigation. Jour, of Am. Soc. of Naval Engineers, 1893, Vol. 5, p. 543. On the Law of Prictional Resistance. Trans, of Am. Soc. of Naval Architects and Marine Engineers, 1893, Vol. 1, p. 210. A Planimeter for Averaging Radial Ordi- nates. Sibley Jour, of Eng. 1893, Vol. 7, p. 64. Uses of Logarithmic Paper. Engineering News, Sept. 28, 1893. New Rules for Approximate Integration. Ibid., Jan. 18, 1894. 490 Titles of Mathematical Tieatment of Continuous Functions by Approximate Methods. Sibley Jour, of Eng., Jan., 1894, Vol. 8, p. 135. An Approximate Formula for the Wetted Surface of Ships. (With G. R. MoDer- mott). Trans. Am, Soc. of Naval Architects and Marine Engineers, 1894, Vol. 2, p. 297. Water Tube Boilers for Marine Purposes. SiUey Jour, of Eng., Feb., 1895, Vol. 9, p. 181. Electricity for Marine Propulsion. Gas- sier^ s Magazine, Jan., 1895, Vol. 8, p. 143. Curves showing the Relation between Equivalent Hollow and Solid Shafts. Jour, of Am. Soc. of Naval Engineers, 1895, p. 507. The Number of Longitudinal Intervals in Ship Computations as Affecting the Accuracy of Integration for Displace- ment. Trans. Am. Soc. of Naval Architects and Marine Engineers, 1895, Vol. 3, p. 129. Note on Different Forms of the Entropy Function. Physical Review, Vol. 4, p. 343. Determination of the Current Curve Cor- responding to any Form of Alternating Electromotive Force in a Circuit with- outlron. Sibley Jour, of Eng., 1897, p. 182. Method of Determining a Continuous Record of the Performance of a Marine Engine. Jour. Am. Soc. of Naval Engineers, 1897, p. 1. Graphical Determination of the Index of the Power according to which one quantity varies relative to another. Jour, of Franklin Inst., March, 1897. An Experimental Study of the Influence of Surface on the Performance of Screw Propellers. Trans. Am. Soc. of Naval Architects and Marine Engineers, Vol. 5, p. 107. Steamship Vibrations and the Balancing of Marine Engines. Marine Engineer- ing, June, July, August, 1897. Resistance and Propulsion of Ships. J. Wiley & Sons, New York, 1898. ix. -1-431 pp. The Approximate Treatment of Differen- tial Equations. Annals of Math., July, 1898, p. 110. Entropy and Temperature Entropy Dia^ grams. Jour. Soc. Naval Engineers, 1898, p. 329. Electrical Propulsion for Torpedo Boats. Ibid., 1899, p. 53. PHEDERICK EBY: — A.B., McMaster University, 1895; Gradu- ate Student, University of Chicago, 1895- 97 ; Assistant Instructor, Morgan Park Academy, Morgan Park, 111., 1897-98; Scholar in Pedagogy, Clark Univer- sity, 1898-99. Author of : — Suggestions for Work which can be done by Teachers. 4:Zd. Annual Meport State Supt. of Ed., Albany, N. T., 1897, Vol. 2, pp. 968-972. Study of the Use of Secret Languages (Syllabus). Ibid., pp. 972-973. Preliminary Study of Child-.S!sthetics (Syllabus). Ibid., p. 976. Educational Value of Manual Construc- tive Work. Education, April, 1898, Vol. 18, pp. 491-495. Translation of Pestalozzi's "Meine Nach- forschungen." (With Dr. Julia E. Bulkley.) (In press.) THOMAS TW. EDMONDSON: — B.A., London, Eng., 1888 (first in Honors and Senior Exhibitioner at Matriculation, June, 1886) ; Akroyd Scholar, 1888-90 ; Senior Mathematical Scholar, Pembroke College, Cambridge University, Eng., 1888-91; B.A., Cambridge University (18th Wrangler in Mathematical Tripos), 1891 ; Graduate Student in Chemistry, Physics, and Botany, ibid., 1891 ; Assist- ant Tutor in Mathematics and Physics, University Corr. College, Cambridge, Eng., 1889-93 ; First Class m Intermediate Science Examination, London, 1893 ; Pellovr in Physics, Clark University, 1894-96; Ph.D., Clark University, Published Papers. 491 1896; Assistant Professor of Physios, New York University, 1896- ; Member of the American Mathematical Society, and American Physical Society. Author of : — Key to Briggs and Bryan's Coordinate Geometry. W. B. Clive & Co., London, New York, and Sydney, 1891. 192 pp. Worked Examples in Coordinate Geome- try. W. B. Clive & Co., London, New York, and Sydney, 1891 ; 18 Exam. Papers + 62 pp. Mensuration and Spherical Geometry. (In collaboration -with W. Briggs, M.A., LL.B., etc.) "W. B. Clive & Co. , London, New York, and Sydney, 1893. vi. + 112, ii. + 48 pp. Key to Briggs and Bryan's Elementary Text-book of Mechanics. (In collab- oration with Bion Reynolds, M.A.) W. B. Clive & Co. , London, New York, and Sydney, 1895. viii. -|- 172 pp. On the Disruptive Discharge in Air and Liquid Dielectrics. Physical Beview, Feb., 1898, Vol. 6, pp. 65-97. CHARLES L. EDWARDS: — B.S., Lombard University, 1884; B.S., Indiana University, 1886; A.M., ibid., 1887 ; Student, Johns Hopkins University, 1887-89; Ph.D., University of Leipzig, 1890; Fellow in Morphology, Clark University, 1890-91 ; Honorary Fel- low, Clark University, 1891-92; Assistant Professor of Biology, University of Texas, 1892-93 ; Adjunct Professor of Biology, ibid., 1893-94; Professor of Biology, University of Cincinnati, 1894- ; Member of the American Society of Natu- ralists ; Morphological Society ; President of the American Eolk-Lore Society, 1899 ; Socio Corresponsal, La Sociedad de Geo- graiia y Estadistica, Mexico ; Socio Honorario, La Sociedad Mexicana de Historia Natural; Socio Honorario, La Sociedad Antonio Alzate. Author of : — The Relation of the Pectoral Muscles in Birds to the Power of Plight. Amerir can Naturalist, Jan., 1886, Vol. 20, pp. 25-29. A Review of the American Species of the Tetraodontidse. (With President David S. Jordan.) Froc. of U. S. Nat. Mus., 1886, p. 232. The Influence of Warmth upon the Irrita- bility of Frog's Muscle and Nerve. Studies from Biol. Lab., Johns Sop- kins University, July, 1887. Winter Roosting Colonies of Crows. Am. Jour, of Psy., May, 1888, Vol. 1, pp. 436-459. Notes on the Embryology of Mlilleria Agassizli Sel. , a Holothurian common at Green Turtle Bay, Bahamas. Johns Hopkins University Circular, 1889, Vol. 8, p. 37. Folk-Lore of the Bahama Negroes. Am. Jour, of P^., Aug., 1889, Vol. 2, pp. 519-542. Beschreibung einiger neuen Copepoden und eines neuen copepodenShnlichen Krebses, Leuckertella paradoxa. Archiv f. Naturgeschichte, Berlin, 1891, Jahrg. 57, Bd. 1, 35 pp. Some Tales from Bahama Folk-Lore. Jour, of Am. Folk-Lore, 1891, Vol. 4, pp. 47-54. Some Tales from Bahama Folk-Lore. Fairy Tales. Ibid., pp. 247-252. Bahama Songs and Stories. (Vol. 3 of Memoirs of the Am. Folk-Lore Society.) Houghton, Mifflin & Co., Boston, 1895. Ill pp. Notes on the Biology of Phrynosoma Cor- nutum Harlan. Zool. Anzeiger, 1896. STAFFORD C. EDWARDS : — Classical Graduate, Oneonta, N. Y., Normals 1891 ; A.B., Brown University, 1895 ; A.M., Philosophy and Pedagogy, ibid., 1896 ; Student Teacher of History and English, High School, Providence, R. I., 1895-96; Principal of Greenport, N. Y., Union School, 1896-97; Scholar in Pedagogy, Clark University, Oct., 1897-March, 1898 ; Teacher of Mathe- matics, Jamaica, N. Y., Normal School, March-June, 1898 ; Principal Union School, Schuylerville, N. Y., 1898-. 492 Titles of ALIiXANDER CASWKLI. ELLIS: — Head Master, Classical High School, Chapel Hill, N. C, 1891-92; A.B., University of North Carolina, 1894 ; Scholar in Pedagogy, Clark TTniver- sity, 1894-95 ; Fellow in Psychology, 1895-97; Ph.D., Clark University, 1897 ; Adjunct Professor of Pedagogy, University of Texas, 1897- ; Member of American Association for the Advance- ment of Physical Education; Member of Illinois Child-Study Society; Fellow, Texas Academy of Science. Author ol : — Sunday School Work and Bible Study In the Light of Modern Pedagogy. Pedor gogical Seminary, June, 1896, Vol. 3, pp. 363-412. A Study of Dolls. (With G. Stanley Hall. ) Ibid., Dec, 1896, Vol. 4, pp. 129-175. Suggestions for a Philosophy of Education. Ibid., Oct., 1897, Vol. 5, pp. 159-201. Play in Education. Northwestern Monthly, Nov., 1898 ; and Sep. of Ad. and Proc. Texas State Teachers' Ass'n, 1898. Reading and Literature in the Schools. Bep. of Ad. and Proc. Texas State Teachers' Ass'n, 1898. The Science of Education in the Univer- sity of Texas, and Some of Its Prob- lems. University Becord, University of Texas, Vol. 1, No. 2. BENJAMIN F. ELLIS: — A.B., Dartmouth College, 1889; Instruc- tor in Physics and Mathematics, High School, Peoria, 111., 1889-92 ; Scholar in Physics, Clark University, 1892-93 ; Instructor, High School, Peoria, 111., 1893-. PERCY NORTON EVANS: — B.A.Sc, McGill University, Montreal, 1890 ; Assistant in Chemistry, Hid., 1890- 91 ; Student, University of Leipzig (McGill Exhibition of 1851 Science Scholar), 1891- 93 ; Ph.D., University of Leipzig, 1893; Honorary Fellow in Chemistry, Clark University, 1894 ; Assistant in Chemis- try to Professor Atwater, Wesleyan Uni- versity, 1894-95 ; Instructor in Chemistry, Purdue University, 1895-96 ; Associate Professor of Chemistry, ibid., 1896- ; Member of the Indiana Academy of Science. Author of : — Condensation von ;8-Diketonen mit Ham- stoff und Thiohamstoff. Jour, fur praktische Chemie, Vol. 46, p. 352. Condensationsprodukte der /3-Diketone mit Hamstoff, Guanidin, und Thioham- stoff. Ibid., Vol. 48, pp. 489-517. Food Adulteration. Purdue University Monographs, 1896. 17 pp. An Introductory Coturse in Quantitative Analysis. Ginn & Co., Boston, 1897. iv.-|-88pp. Note on Some Combustion Products of Natural Gas. Proc. Ind. Acad, of Science, 1897, pp. 133-134. Note on the Iodine Number of Linseed OU. Ibid., 1898, pp. 160-163. H. L. EVERETT: — A.B., Brown University, 1886; A.M., Harvard University, 1889 ; Student, Berlin University, 1889-90; Professor, Utah Agricultural College, 1890-92; Scholar in Psychology, Clark University, 1896-97; Honorary Fellow in Psy- chology, 1897-98 ; Instructor, Macken- zie College, S. Paulo, Brazil, 1898-. ALBERT C. EYCLESHYMER: — Assistant in Animal Morphology, Uni- versity of Michigan, 1888-89; Assistant in Botany, ibid., 1889-90; Chief Assist- ant, AUis Lake Laboratory, 1890-91 ; B.S., University of Michigan, 1891 ; Fellow in Morphology, Clark Uni- versity, 1891-92 ; Fellow in Biology, University of Chicago, 1892-93 ; Assistant in Anatomy and Histology, ibid., 189.3- 95 ; Ph.D., University of Chicago, 1895 ; Tutor in Anatomy and Histology, ibid., 1896-. Author of : — Celloidin Imbedding in Plant Histology. Botanical Gazette, Vol. 15, pp. 272- 295. Published Papers. 493 Notes on Celloidin Technique. American Naturalist, Vol. 26, pp. 364-358. Club-root (Plasmodiophora brassloae Wor.) in the United States. Journal of Mycology, Vol. 7, pp. 79-90. Paraphysls and Epiphysis in Amblystoma. Anatomischer Ameiger, April 7, 1892, Vol. 7, pp. 215-217. The Cleavage of the Amphibian Ovum. (With E. O. Jordan.) Ibid. Sept. 15, 1892, Vol. 7, pp. 622-624. The Development of the Optic Vesicles in Amphibia. Jour, of Morph., April, 1893, Vol. 8, pp. 189-194 ; Figs. 1-6. On the Cleavage of Amphibian Ova. (With E. O. Jordan.) Ibid., Sept., 1894, Vol. 9, pp. 407-416 ; PI. xxvi. The Early Development of Amblystoma ■with Observations on some other Vertebrates. Ibid., Eeb., 1895, Vol. 10, pp. 343-418 ; Pis. xviii-xxii. FHBDBRICK C. FERRY: — A.B., Williams College, 1891; Instructor in Latin and Mathematics, ibid., 1891- 94; A.M., ibid., 1894 ; Graduate Student in Mathematics, Harvard University, 1894-95; A.M., ibid., 1895; FeUow in Mathematics, Clark University, 1895- 98; Ph.D., Clark tTniversity, 1898; Assistant Professor of Mathematics, Wil- liams College, 1899-. Author of : — Geometry on the Cubic Scroll of the First Kind. ArcMv for Mathematik og Na- turvidenskab, B. xxi, Nr. 2. DANIEL FOLKMAR: — A.B., Western College, 1884 ; A.M., ibid., 1888 ; Student, Harvard Divinity School, 1888-89 ; FeUow in Psychology, Clark TTniversity, 1889-90 ; Professor of Po- litical Science and Psychology, Indiana Normal University, 1890-91 ; President and Professor of Social Science, ibid., 1891-92; Professor of Social Science, Western Michigan College, 1892-93 ; Presi- dent, ibid., 1893 ; Lecturer in Sociology, University of Chicago, 1893-95 ; Professor of Psychology and Pedagogy, State Nor- mal School, Milwaukee, Wis., 1895-98 ; Student, University of Paris, 1898-99; Professor of Anthropology, University Nouvelle, Brussels, Belgium, 1898; Doc- teur 6s sciences sociales, ibid., June, 1899 ; Fellow of the Royal Statistical Society, London ; Member of : Anthropologische Gesellschaft in Wien, Anthropological So- ciety of Washington, American Associa- tion for the Advancement of Science, American Academy of Political and Social Science, American Statistical Association, American Institute of Sociology, Wisconsin Academy of Sciences, Arts, and Letters. Author of : — Instruction in Sociology in Institutions of Learning. Reprint from Proc. of Nat. Conf. of Charities and Correction, Boston, 1894. 19 pp. Also reprinted as Chapter XXVII of the Beport of U. 8. Com. of Ed. for 1894^95, Vol. 2, pp. 1211-1221. A Sociological Ideal View of Normal Schools. Proc. of Inter. Cong, of Ed. of the World's Columbian Exposition, 1893, pp. 422-428. Published by Am. Ed. Ass'n, New York, 1893. New Views in Social Science, etc. The Interrogator, Feb.-June, 1893. The Ideal in Professional Training. Edvr- cation, April, 1896. The Duration of School Attendance in Chicago and Milwaukee. Proc. Wis- consin Academy of Sciences, Arts, and Letters, 1897, Vol. 12, pp. 255-305. Anthropology, not Sociology, as an ade- quate Philosophy of Human Life. Proc. A. A. A. S., 1898. Sociology as based upon Anthropology. Am. Jour, of Soc. Sci., 1898. Anthropologie Philosophique. (In press.) CLEMENS JAMES FRANCE: — A.B., Hamilton College, 1898; Scholar in Psychology, Clark TTniversity, 1898-99. Author of: — The Psychology of Ownership. (With L. W. Kline.) Pedagogical Seminary. (In press.) 494 Titles of JOSEPH IHWIN PHANCE: — A.B., Hamilton College (Root Scientific Fellowship, with Honors in Biology), 1895 ; Student, University of Leipzig, 1895-96 ; Scholar in Psychology, Clark University, 1896-97 ; A.M. (honorary), Hamilton College, 1898 ; Supervisor and Instructor in Science, Jacob Tome Insti- tute, Port Deposit, Md., 1897- ; Student, College of Physicians and Surgeons, Balti- more, Md., 1898-99. Author of : — The Conservation of Cosmos. An Essay. Gressner & Schramm, Leipzig, 1896. 18 pp. Nature-Study. Mdueational Eeview, March, 1899, Vol. 17, pp. 292-295. ALEXANDER FRASER : — A.B., Dalhousie College, 1889; Graduate Student, Harvard University, 1889-90 ; Fellow in Psychology, Clark Uni- versity, 1891-92 ; Student in Medicine, Dalhousie University, 1893-97; M.D., CM., ibid., 1897 ; Lecturer in Psychology, Halifax Ladies' College, 1893-94; In- structor in Psychology, Halifax School for the Blind, 1894-95 ; House Surgeon, Vic- toria General Hospital, Halifax, N. S., 1897-98 ; Practising Physician and Sur- geon, New Glasgow, N. S., 1898-. Author of: — Visualization as a Chief Source of the Psy- chology of, Hohbes, Locke, Berkeley, and Hume. Am. Jour, of Fsy., Dec, 1891, Vol. 4, pp. 230-247. The Psychological Foundation of Natural Realism. Ibid., April, 1892, Vol. 4, pp. 429-450. The Psychological Basis of Hegelism. Ibid., July, 1893, Vol. 5, pp. 472-496. JOHN S. FRENCH: — A.B., Bowdoin College, 1895; Scholar in Mathematics, Clark University, 1895-96; Fellow, 1896-98; Ph.D., Clark University, 1898 ; Supervisor and Instructor in Mathematics, Jacob Tome Institute, 1898-. Author of: — On the Theory of the Pertingents to a Plane Curve. (In press.) JOHN PHELPS FRUIT : — A.B., Bethel CoUege, Ky.,1878; Instruc- tor of Latin and Mathematics, High School, Parker's Grove, Ky., 1878-79; Professor of Latin and Greek, Bardstown Institute, Ky., 1879-81; A.M., Bethel College, 1881 ; President, Liberty Female College, Glasgow, Ky., 1881-83 ; Professor of English Literature, Bethel College, 1883-97 ; Scholar in Psychology, Clark University, 1891 ; Graduate Student, University of Leipzig, 1894-95 ; Ph.D., University of Leipzig, 1895 ; Professor of English Language and Literature, William Jewell College, 1897- ; Member of : Modern Language Association, American Dialect Society, American Statistical Association, Southern History Association. Author of: — The Evolution of Figures of Speech. Modern Language Notes, Dec, 1888. Browning and Tennyson. Ibid., May, 1890. A Plea for the Study of Literature from the Esthetic Standpoint. jPitft. of the Modem Language Ass^n, 1891, Vol. 6, No. 1. Shakespeare's Egoism. Poet Lore, Sept., 1899, Vol. 1, pp. 406-407. The Destiny of Marriage : Portia and the Caskets. Ibid., Feb., 1891, Vol. 3, pp. 69-74. Uncle Remus in Phonetic Spelling. Dia- lect Notes, Boston, 1892, Part 4, pp. 196-198. The Ideal the Need of the People. South- ern Magazine, May, 1894. John Milton. Seminary Magazine (Louis- ville, Ky.), March, 1899. The Mind and Art of Poe's Poetry. A. S. Barnes & Co., New York, 1899. 144 pp. HOMER GAGE:— A.B., Harvard University, 1882; A.M., ibid., 1887; M.D., ibid., 1887; Physician and Surgeon, Worcester, Mass., 1888- ; Published Papers. 495 Honorary Scholar in Anatomy, Clark University, 1889-90; Surgeon to Me- morial, St. "Vincent, and Worcester City Hospitals ; Consulting Surgeon to BaJdwin- ville Cottage Hospital. BENJAMIN IVES GILMAN: — A.B., Williams College, 1872; A.M., ibid., 1880; Fellow, Johns Hopkins Uni- versity, 1881-83 ; Lecturer at Princeton, Harvard, and Columbia, 1890-91 ; In- stxuctor in Psychology, Clark Uni- versity, 1892-93 ; Curator, Museum of Fine Arts, Boston, Mass., 1893-. Author of: — On Propositions and the Syllogism. On Propositions called Spurious. J. H. U. Circular, Aug., 1882, pp. 240-241. On Operations in Relative Number. Johns Hopkins Studies in Logic, 1882. A Study of the Inductive Theories of Bacon, Whewell, and MUl. Colorado College Studies, 1890, pp. 17-26. Zuili Melodies. Jour, of Am. Arch, and Eth., Vol. 1, 1891, pp. 65-91. On some Psychological Aspects of the Chinese Musical System. Philosophi- cal Beview, Jan. and March, 1892, Vol. 1, pp. 64-71, 154-178. On the Properties of a One-dimensional Manifold. Mind, Oct., 1892, N. S., Vol. 1, pp. 518-526. Report on an Experimental Test of Musi- cal Expressiveness. Am. Jour, of Psy., Vols. 4 and 5, Aug. and Oct., 1892. Syllabus of Lectures on the Psychology of Pain and Pleasure. Ibid., Oct., 1893, Vol. 6, pp. 3-60. HENRY H. GODDARD:— - A.B., Haverford College, 1887; A.M., ibid., 1889 ; Instructor in Latin and His- tory, University of Southern California, 1887-88; Graduate Student, Haverford College, 1888-89 ; Principal, Damascus Academy, Ohio, 1889-91 ; Instructor in Latin and Greek, Oak Grove Seminary, Vassalboro, Me., 1891-93 ; Principal, ibid., 1893-96 ; Scholar in Psychology, Clark University, 1896-97 ; Fellow, 1897- 99; Ph.D., Clark University, 1899; Professor of Psychology and Pedagogy, State Normal School, West Chester, Pa., 1899-. Author of : — The Effects of Mind on Body as evidenced by Faith Cures. Am. Jour, of Psy., April, 1899, Vol. 10, pp. 431-502. JOHN H. GRAY, JR.: — B.S., University of California, 1887; As- sistant to State Analyst, California, 1887- 90; Assistant in Chemistry, University of California, 1889-90 ; Instructor in Chemistry, ibid, 1890-92; Fellow In Chemistry, Clark University, 1892- 94 ; Instructor in Physios and Chemistry, State Normal School, Chico, Cal., 1894- 95 ; Assistant in Chemistry, University of California, 1895-96 ; Instructor in Chem- istry, ibid., 1896-. CEPHAS GUHiLET: — A.B., Victoria University, Cobourg, Ont. (Honors in English, French and German Literature), 1887 ; Modern Lan- guage Master, Perth, Ont., 1887-90 ; Modern Language Master, Ottawa, Ont., 1890-94 ; Student at Law, Osgoode Hall, Toronto, 1894-95; Scholar in Psy- chology, Clark University, 1895-96; Fellow, 1896-98. H. R. GURLEY: — United States Naval Academy, 1877-79; Assistant Resident Physician, Children's Hospital, Washington, D. C, 1882-84 ; M.D. (First Honor), National Medical College, Washington, D. C, 1884; Resi- dent Physician, United States Soldiers' Home Hospital, Washington, D. C, 1884^ 85; Scientific Assistant, United States National Museum, Washington, D. C, 1886-90 ; Scientific Assistant, Biological Laboratory, United States Fish Com- mission, Washington, D. C, 1890-95 ; M. So., Columbian University, 1895 ; Fellow in Biology, Clark University, 1895- 96 ; Junior Assistant Physician, Worcester Insane Hospital, 1896-97 ; Assistant Phy- sician, ibid., 1897-. 496 Titles of Author of: — The Geologic Age of the Graptollte Shales of Arkansas. Ann. Bep. Geol. Survey, Arkansas, 1890, Vol. 3, pp. 401-418, PI. 9. Some Recent Graptolite Literature. American Geologist, 1891, pp. 35-43. The Classification of the Myxosporidia, a Group of Protozoan Parasites infest- ing Fishes. Bull. U. S. Msh Com., 1891, pp. 407-420. The Myxosporidia, or Psorosperms of Fishes, and the Epidemics produced by them. Sep. U. S. Fish. Com., 1892, pp. 65-304, PI. 1-47. The North American Graptolites. Journal of Geology, 1896, Vol. 4, pp. 63-102 ; 291-311. PI. 4-5. G. STANLEY HALL: — A.B., Williams College, 1867; A.M., 1870 ; Union Theological Seminary, N. Y., 1867-68 ; Universities Berlin and Bonn, 1869-70 ; Union Theological Seminary, N. Y., 1870-71 ; Universities of Berlin and Heidelberg, 1871-72 ; Professor of Philosophy, Antioch College, 1872-76; Instructor, Harvard University, 1876-78; Ph.D., Harvard University, 1878; Uni- versities of Berlin and Leipzig, 1878-80 ; Lecturer in Harvard University and Williams College, 1880-81 ; Professor of Psychology, Johns Hopkins University, 1881-88 ; LL.D., University of Michigan, 1888, and Williams College, 1889 ; Presi- dent, and Professor of Psychology, Clark University, 1888- ; Editor and Founder of American Journal of Psychol- ogy (Founded in 1887), and Pedagogical Seminary (Founded in 1891) ; Resident Fellow of the American Academy of Arts and Sciences ; Resident Member of the Massachusetts Historical Society ; Mem- ber of American Antiquarian Society. Author of : — John Stuart Mill. Williams Quarterly, Williamstown, Mass., Aug., 1867. Digest of Dorner's Theology. Presby- terian Beview, Jan., 1873, pp. 60-93. Hegel as the National Philosopher of Ger- many. (Translated from the German of Dr. Carl Rosenkranz. ) Gray, Baker, & Co., St. Louis, 1874. 159 pp. Hegel : His Followers and Critics. Jour, of Spec. Philos., 1878, Vol. 12, pp. 93- 103. Color Perception. Proc. Am. Acad, of Arts and Sciences, March, 1878, Vol. 3, pp. 402-413. The Muscular Perception of Space. Mind, Oct., 1878, Vol. 3, pp. 433-450. The Philosophy of the Future. Nation, Nov. 7, 1878, Vol. 27, pp. 283-284. Philosophy in the United States. Mind, Jan., 1879, Vol. 4, pp. 89-105; also Pop. Sci. Mo., Suppl. No. 1, 1879, p. 57. Ueber die Abhangigkeit der Reactions- zeiten vora Ort des Reizes. (With J. v. Kries.) Archiv f. Physiol. (Du Bois-Reymond), Suppl. Band, 1879, pp. 1-10. Die willkiirliche Muskelaction. (With Hugo Kronecker.) Ibid., pp. 11-47. Laura Bridgman. Mind, April, 1879, Vol. 4, pp. 149-172. Recent Researches in Hypnotism. Ibid., Jan., 1881, Vol. 6, pp. 98-104. Aspects of German Culture. James R. Osgood & Co., Boston, 1881. 320 pp. Moral and Religious Training of Children. Princeton Beview, Jan., 1882, Vol. 10, pp. 26-48. Chairs of Pedagogy in our Higher Institu- tions of Learning. iV. E. A., March, 1882 ; U. S. Bur. of Ed., Circular of Information, No. 2, 1882, pp. 35-44. Optical Illusions of Motion. (With Dr. H. P. Bowditch.) Jour. ofPhys., Aug., 1882, Vol. 3, pp. 297-307. The Education of the Will. Princeton Beview, Nov., 1882, Vol. 10, pp. 306- 325. Reprinted in Pedagogical Semi- nary, June, 1892, Vol. 2, pp. 72-89. Methods of Teaching History. (Edited.) Ginn, Heath & Co., Boston, 1883. xii. + 296 pp. Educational Needs. iV. A. Bev., March, 1883, Vol. 136, pp. 284-290. Reaction-Time and Attention in the Hyp- notic State. Mind, April, 1883, Vol. 8, pp. 170-182. Published Papers. 497 Contents of Children's Minds on entering Scliool. Princeton Review, May, 1883, Vol. 11, pp. 249-272 ; Pedagogical Seminary, June, 1891, Vol. 1, pp. 139- 173. Issued in pamphlet form by E. L. Kellogg & Co., New York, 1893. 56 pp. Education and Theology. Nation, July 26, 1883, Vol. 37, pp. 81-82. The Study of Children. (Privatelyprinted.) N. Somerville, Mass., 1883, 13 pp. Eeport of the Visiting Committee of the Alumni of "Williams College, WiUiams- town, Mass., 1884. 11 pp. Bilateral Asymmetry of Function. (With E. M. Hartwell.) Mind, Jan., 1884, Vol. 9, pp. 93-109. New Departures in Education. JV. Am. Bev., Feb. 1885, Vol. 140, pp. 144- 162. The New Psychology. Andover Beview, Feb. and March, 1885, Vol. 3, pp. 120- 135, 239-248. Opening lecture, Johns Hopkins University, Oct. , 1884. Experimental Psychology. Mind, April, 1885, Vol. 10, pp. 245-249. Children's Collections. Nation, Sept. 3, 1885, Vol. 41, p. 190; reprinted in Pedagogical Seminary, June, 1891, Vol. 1, pp. 234-237. Overpressure in Schools. Nation, Oct. 22, 1885, Vol. 41, pp. 338-339. Motor Sensations of the Skm. (With Dr. H. H. Donaldson.) Mind, Oct., 1885, Vol. 10, pp. 557-572. Studies of Rhythm. (With Joseph Jas- trow.) Ibid., Jan., 1886, Vol. 11, pp. 55-62. Hints toward a Select and Descriptive Bibliography of Education. (With John M. Mansfield.) D. C. Heath & Co., Boston, 1886. 309 pp. Psychical Research. Am. Jour, of Psy., Nov., 1887, Vol. 1, pp. 128-146. Psychology. (Reviews.) Am. Jour, of Psy., Nov., 1887, Vol. 1, pp. 146-164. Dermal Sensitiveness to Gradual Pressure- Changes. (With Y. Motora.) Ibid., Nov., 1887, Vol. 1, pp. 72-98. The Story of a Sand Pile. Scribner's Magazine, June, 1888, Vol. 3, pp. 2k 690-696. Reprint, E. L. Kellogg & Co., N. Y., 1897. 20 pp. Introduction to American Edition of Preyer's Senses and Will. (Translated by H. W. Brown.) New York, 1888. Address Delivered at the Opening of Clark University, Opening Exercises, pp. 9- 32, Worcester, Mass., Oct. 2, 1889. (Published by the University.) A Sketch of the History of Reflex Action. Am. Jour, of Psy., Jan., 1890, Vol. 3, pp. 71-86. How to teach Reading, and What to Read in School. D. C. Heath & Co., Boston, 1890. 40 pp. (First edition, 1886.) Children's Lies. Am. Jour, of Psy. , Jan. , 1890, Vol. 3, pp. 59-70. Reprinted in Pedagogical Seminary, June, 1891, Vol. 1, pp. 211-218. The Training of Teachers. Forum, Sep- tember, 1890, Vol. 10, pp. 11-22. First Annual Report to the Board of Trustees of Clark University, Worces- ter, Mass., Oct. 4, 1890. 53 pp. University Study of Philosophy. Discus- sion. Begents^ Bep. Univ., State of New York, 1891, Vol. 105, pp. 335-338. Boy Life in a Massachusetts Country Tovni Thirty Years Ago. Proc. Am. Antiq. Soc, Worcester, Mass., 1891, N. S., Vol. 7, pp. 107-128. Educational Reforms. Pedagogical Semi- nary, Jan., 1891, Vol. 1, pp. 1-12. Appeared also as Rif orme Pedagogiche in H Bisveglio Educativo, Aprile 13- 16, 1892, Anno 8, pp. 207-208, 210-211. The Principles of Psychology. By William James. (Review.) Am. Jour, of Psy., Feb., 1891, Vol. 3, pp. 578-591. Contemporary Psychologists. I. Edward Zeller. Ibid., April, 1891, Vol. 4, pp. 156-175. Enseignement des Sciences. Bevue Sci- entifique, April 4, 1891, Vol. 47, pp. 430-433. Notes on the Study of Infants. Peda- gogical Seminary, June, 1891, Vol. 1, pp. 127-138. The Moral and Religious Training of Children and Adolescents. Ibid., pp. 196-210. 498 Titles of Second Annual Report to the Board of Trustees of Clark University, Worces- ter, Mass., Sept. 29, 1891. 56 pp. The New Movement in Education. An address delivered before the School of Pedagogy of the University of the City of New York, Dec. 29, 1891. Pub- lished by the Women's Advisory Com- mittee, New York, 1891. 20 pp. The Outlook in Higher Education. Acad- emy, Boston, Mass., Jan., 1892, Vol. 6, pp. 543-562. Health of School Children as affected by School Buildings. Report of Froc. Dept. of Superintendence, held in Brooklyn, N. Y., Feb., 1892, pp. 163- 172. Also Proc. JST. E. A., 1892, pp. 682-691. Moral Education and Will Training. Pedagogical Seminary, June, 1892, Vol. 2, pp. 72-89. Child-study as a Basis for Psychology and Psychological Teaching. Report of Com. of Ed., 1892-93, Washington, D.C., 1895, Vol. 1, pp. 357-358, 366-370. Third Annual Report to the Board of Trustees of Clark University, Worces- ter, Mass., April, 1893. 168 pp. Psychological Progress. The Liberal Club, BufEalo, N. Y., Nov. 16, 1893. Child-study : The Basis of Exact Educa- tion. Forum, Dec, 1893, Vol. 16, pp. 429-441. American Universities and the Training of Teachers. Ihid., April, 1894, Vol. 17, pp. 148-159. Universities and the Training of Pro- fessors. Ibid., May, 1894, Vol. 17, pp. 297-309. Scholarships, Fellowships, and the Train- ing of Professors. Ibid., June, 1894, Vol. 17, pp. 443-454. Research the Vital Spirit of Teaching. Ibid., July, 1894, Vol. 17, pp. 558-570. Child-study in Summer Schools. Regents^ Bulletin, University of the State of NewYork,No. 28, July, 1894. Albany, N. Y., 1895, Vol. 1, pp. 333-336. The New Psychology as a Basis of Edu- cation. Forum, August, 1894, Vol. 17, pp. 710-720. Address at the Bryant Centennial, Aug. 16, 1894. Bryant Memorial, Cum- mington, Mass., 1894, pp. 67-69. Address. Dedication of the Haston Free Public Library Building, North Brook- field, Mass., September 20, 1894. pp. 11-21. On the History of American College Text- Books and Teaching in Logic, Ethics, Psychology, and Allied Subjects. Proc. Am. Antiq. Soc, Worcester, Mass., 1894, N. S., Vol. 9, pp. 137-174. Remarks on Rhythm in Education. Proc. N: E. a., 1894, pp. 84-85. Child-study. Ibid., 1894, pp. 173-179. Practical Child-study. Jour, of Ed. , Deo. 13, 1894, Vol. 40, pp. 391-392. Topical Syllabi for 1894^-1895. These were one- or two-page leaflets, pre- pared by Dr. Hall, and privately printed at Worcester, Mass. They covered : L Anger ; II. Dolls ; III. Crying and Laughing; IV. Toys and Playthings; V. Folk-Lore Among Children ; VI. Early Forms of Vocal Expres- sion; Vn. The Early Sense of Self; VIII. Fears in ChUdhood and Youth; IX. Some Common Traits and Habits; X. Some Common Automatisms, Nerve Signs, etc. ; XI. Feeling for Ob- jects of Inanimate Nature ; XII. Feel- ing for Objects of Animate Nature ; Xin. Children's Appetites and Foods; XIV. Affection and its Opposite States in Children ; XV. Moral and Religious Experiences. Laboratory of the McLean Hospital, Somerville, Mass. Am. Jour, of In- sanity, Jan., 1895, Vol. 51, pp. 358- 364. Psychic Research. Am. Jour, of Fsy., Oct., 1895, Vol. 7, pp. 135-142. Results of Child-study applied to Educa- tion. Trans. III. Soc. for Child-study, 1895, Vol. 1, No. 4, p. 13. Introduction to the Psychology of Child- hood. By Frederick Tracy. Boston, 1895. Address at Union College Centennial An- niversary, June 24, 1895. Printed by the College. N. Y., 1897, pp. 230-244. Published Papers. 499 Topical Syllabi for 1895-96. I. Peculiar and Exceptional Children, with E. W. Bohannon ; II. Moral Defects and Perversions, with G. E. Dawson ; III. The Beginnings of Reading and "Writ- ing, with Dr. H. T. Lukens; IV. Thoughts and Eeelings about Old Age, Disease, and Death, with C. A. Scott ; V. Moral Education, with N. P. Avery ; VI. Studies of School Read- ing Matter, with J. C. Shaw; VII. Courses of Study in Elementary Gram- mar and High Schools, with T. R. Crosswell ; VIII. Early Musical Mani- festations, with Florence Marsh; IX. Fancy, Imagination, Reverie, with E. H. Lindley; X. Tickling, Fun, Wit, Humor, Laughing, with Dr. Arthur Allin; XI. Suggestion and Imitation, with M. H. Small; XII. Religious Experience, with E. E. Starbuck; Xm. Kindergarten, with Miss Anna E. Bryan and Miss Lucy Wheelock; XIV. Habits, Instincts, etc., in Ani- mals, with Dr. R. R. Gurley; XV. Number and Mathematics, vrith D. E. Phillips; XVI. The Only Child in the Family, with E. "W. Bohannon. The Case of the Public Schools. Atlantic Monthly, March, 1896, Vol. 77, pp. 402-413. Psychological Education. Froo. of the Am. Medico-Psychological Ass'n. 52d Annual Meeting, Boston, May 26-29, 1896, Transactions, Vol. 3, pp. 87- 100 ; also, Am. Jour, of Insanity, Oct. 1896, Vol. 53, pp. 228-241. Generalizations and Directions for Child- study. Northwestern Jour, of Ed., July, 1896, Vol. 7, p. 8- Address at Mount Holyoke College, Founder's Day, Nov. 5, 1896. Mount Molyoke, S. Hadley, Mass. Nov., 1896, Vol. 6, pp. 64-71. A Study of DoUs. (With A. C. ElUs.) Pedagogical Seminary, Dec, 1896. Vol. 4, pp. 129-175. Reprint, E. L. Kellogg & Co., N. Y., 1897. 69 pp. Nature Study. Proe. N. E. A., 1896. pp. 156-158. The Methods, Status, and Prospects of the Child-study of To-day. Trans. III. Soe. for Child-study, May, 1896, Vol. 2, pp. 178-191. Topical Syllabi for 1896-97. I. Degrees of Certainty and Conviction in Children, with Maurice H. Small; II. Sabbath and Worship in General, with J. P. Hylan; HI. Migrations, Tramps, Truancy, Running" Away, etc., vs. Love of Home, with L. W. Kline ; IV. Adolescence, and its Phenomena in Body and Mind, with E. C. Lancaster ; V. Examinations and Recitations, with John C. Shaw ; VI. Stillness, Solitude, Restlessness, with H. S. Curtis ; VII. The Psychology of Health and Disease, with Henry H. Goddard ; VIII. Spon- taneously Invented Toys and Amuse- ments, with T. R. CrossweU; IX. Hymns and Sacred Music, with Rev. T. R. Peede ; X. Puzzles and their Psychology, with Earnest H. Lindley ; XI. The Sermon, with Rev. Alva R. Scott ; XII. Special Traits as Indices of Character and as Mediatuig Likes and Dislikes, with E. W. Bohannon ; Xin. Reverie and Allied Phenomena, with G. E. Partridge ; XIV. The Psy- chology of Health and Disease, with H. H. Goddard. A Study of Fears. Am. Jour, of Psy., Jan., 1897, Vol. 8, pp. 147-249. Some Practical Results of Child-study. First National Congress of Mothers, Washington, D. C, 1897. D. Apple- ton and Co., New York, 1897. pp. 165-171. The Psychology of Tickling, Laughing, and the Comic. (With Arthur Allin.) Am. Jour, of Psy., Oct., 1897, Vol. 9, pp. 1-41. Topical Syllabi for 1897-98. I. Immortal- ity, with J. Richard Street ; 11. Psy- chology of Ownership vs. Loss, with Linus W. Kline ; III. Memory, with F. W. Colegrove ; IV. Humorous and Cranky Side in Education, with L. W. Kline ; V. The Psychology of Short- hand Writing, with J. O. Quantz ; VI. The Teaching Instinct, with D. E. Phillips ; VII. Home and School Pun- 500 Titles of ishments and Penalties, with Chas. H. Sears; VIII. Straightness and Uprightness of Body ; IX. Conven- tionality, with Albert Schinz; X. Local Voluntary Association among Teachers, with Henry D. Sheldon ; XI. Motor Education, with E. W. Bohannon ; XII. Heat and Cold ; Xin. Training of Teachers, with W. G. Chambers; XIV. Educational Ideals, with Lewis Edwin York ; XV. Water Psychoses, with Frederick B. Bolton; XVI. The Institutional Ac- tivities of Children, with Henry D. Sheldon ; XVII. Obedience and Obsti- nacy, with Tilmon Jenkins; XVIII. The Sense of Honor Among Children, with Robert Clark. Some Aspects of the Early Sense of Self. Am. Jour, of Psy., April, 1898, Vol. 9, pp. 351-395. Initiations into Adolescence. Proc. of Am. Antiq. Soc, Worcester, Mass., Oct. 21, 1898, N. S. Vol. 12, p. 367- 400. The Love and Study of Nature : A Part of Education. Agriculture of Massachu- setts, for 1898, pp. 134-154. Topical Syllabi for 1898-99. L The Organ- izations of American Student Life, with Henry D. Sheldon ; II. Mathematics in Common Schools, with E. B. Bryan ; m. Mathematics in the Early Years, with E. B. Bryan; IV. Unselfishness in Children, with Willard S. Small ; V. The Fooling Impulse in Man and Animals, with Normal Triplett; VI. Confession, with Erwin W. Eunkle ; VIL Pity; VHL Perception of Rhythm by Children, with Chas. H. Sears. R&um6 of Child-study. Norihwestern Monthly, March-April, 1899, Vol. 9, pp. 347-349. Paidologist, Chelten- ham, Eng., April, 1899, Vol. 1, pp. 6-8. The Kindergarten. School and Some Education, Bloomington, HI., June, 1899, Vol. 18, pp. 507-509. A Study of Anger. Am. Jour, of Psy., July, 1899, Vol. 10, pp. 516-591. The Line of Educational Advance. Out- look, Aug. 5, 1899, Vol. 62, pp. 768- 770. T. PROCTOH HALL: — B. A., University of Toronto, 1882 ; Fel- low and Instructor in Chemistry, ibid., 1883-84; B.A., McMaster University, Toronto, 1894; M.A., and Ph.D., Illi- nois Wesleyan University, 1888 ; Science Master, Woodstock College, Woodstock, Ont, 1885-90 ; Fellow in Physios, Clark TTniversity, 1890-93 ; Ph.D., Clark XTniversity, 1893; Professor of Natural Sciences, Tabor College, Iowa, 1893-96 ; Professor of Physics, Kansas City University, 1898- ; President Society of Economics, Kansas City ; Vice-Presi- dent Ez-Canadian Society, Kansas City. Author of: — The Projection of Four-fold Figures upon a Three-flat. Am. Jour, of Math., April, 1893, Vol. 15, pp. 179-189. The Possibility of a Realization of Four- fold Space. Science, May 13, 1892. New Methods of Measuring the Surface Tension of Liquids. Philosophical Magazine, Nov., 1893, Vol. 36, pp. 385-413. Graphic Representation of the Properties of the Elements. Proe. Iowa Acad, of Set, 1894. A Mad-Stone. Ibid., 1895. Physical Theories of Gravitation. Ibid., 1895. Unit Systems and Dimensions. Electrical World, Feb. 7, 1896. A Physical Theory of Electricity and Magnetism. Ibid., July 3, 1897, Vol. 30, pp. 10-12. The Vortex Theory of Electricity and Magnetism. Home Study for Elec- trical Workers, Sept., 1898, pp. 34-36. Complex Algebra of the Plane Extended to Three-fold Space.' Proc. Iowa Acad, of Sci., 1898, Vol. 6. JOHN A. HANCOCK: — B.S., Baker University, 1877; Principal of Schools, Indiana and Wisconsin, 1877- 89 ; Graduate Student in Pedagogy, Uni- Published Papers. 501 Tersity of ■Wisconsin, 1889-90; M.L., ibid.., 1890; City Superintendent, Green Bay, Wis., 1890-92 ; Graduate Student in Pedagogy, Leland Stanford Jr. Univer- sity, 1892-93 ; M.A., ibid., 1893 ; FeUow in Pedagogy, Clark University, 1893- 94 ; Superintendent of Schools, Durango, Col. , 1894-97 ; Temporary Assistant Pro- fessor of Psychology, University of Colo- rado, 1897-98 ; Superintendent of Schools, Santa Barbara, Cal., 1899-. Author of : — Secularization of Education. Wis. Jour. of Ed., March, 1890. Preliminary Study of Motor Ability. Pedagogical Seminary, Oct., 1894, Vol. 3, pp. 9-29. The Kindergarten and Child Study. Col. School Jour., Feb., 1895. The Relation of Strength to Flexibility in the Hands of Men and Children. Peda- gogical Seminary, Oct., 1895, Vol. 3, pp. 308-313. Children's Ability to Reason. Educa- tional Beview, Oct., 1896, Vol. 12, pp. 261-268. An Early Phase of the Manual Training Movement — the Manual Labor School. Pedagogical Seminary, Oct., 1897, Vol. 5, pp. 287-292. Mental Differences of School Children. Proc. JV. E. A., 1897, pp. 851-857. Children's Tendencies in the Use of Writ- ten Language Forms. Northwestern Monthly, June, 1898, Vol. 8, pp. 646- 649. ROLLIN A. HARRIS: — Ph.B., Cornell University, 1885; Fellow in Mathematics, ibid., 1886-87 ; Ph.D., ibid., 1888; Fellow in Mathematics, Clark University, 1889-90 ; Computer, United States Coast and Geodetic Survey, Washington, D.C., 1890-. Author of: — The Theory of Images in the Representa- tion of Functions. Annals of Math., 1888, Vol. 4, pp. 65-86, 128. On the Expansion of snj. Ibid., Vol. 4, pp. 87-90. Design for a Conicograph. Scien. Am. Supp., 1890, No. 740. On the Invariant Criteria for the Reality of the Roots of the Quintic. Annals of Math., 1891, Vol. 5, pp. 219-228. On Certain Bicircular Quartios Analogous to Cassini's Oval. Mathematical Maga- zine, Vol. 2, pp. 77-79. Note on Isogonal Transformations ; Par- ticularly on obtaining Certain Systems of Curves which Occur in the Statics of Polynomials. Annals of Math., 1891, Vol. 6, pp. 77-80. Note on the Use of Supplementary Curves in Isogonal Transformation. Am. Jour, of Math., 1892, Vol. 14, pp. 291- 300. Some Connections between Harmonic and Non-harmonic Quantities,Including Ap- plications to the Reduction and Predic- tion of Tides. U. S. Coast and Geod. Sur. Beport, 1894, Appendix, No. 7 (Manual of Tides, Part III.). Introduction and Historical Treatment of the Subject, Ibid., 1897, Appendix, No. 8 (Manual of Tides, Part I.). Tidal Observation, Equilibrium Theory, and the Harmonic Analysis, Ibid., 1897, Appendix, No. 9 (Manual of Tides, Part II.). A Proposed Tidal Analyzer. Physical Beview, 1899, Vol. 8, pp. 54-60. JAMES N. HART: — B.C.E., Maine State College, 1885 ; Prin- cipal of High School, Dennysville, Me., 1885 ; Instructor in Mathematics and Drawing, Maine State College, 1887-90; C.E., ibid., 1890 ; Scholar in Mathe- matics, Clark University, 1890-91; Professor of Mathematics and Astronomy, University of Maine, 1891-; Graduate Stu- dent in Mathematics and Astronomy, Uni- versity of Chicago, 1894-95; M.S., ibid., 1897 ; Member of American Mathematical Society. S. B. HASLETT: — Graduate, Edinboro, Pa., State Normal School, 1885 ; Principal, Creighton Pub- lic Schools, 1887-88; A.B., Grove City 602 Titles of College, Pa., 1889; Principal, Braddoek High School, 1891-92; Graduate, Alle- gheny Theological Seminary, 1892 ; Pres- byterian Ministry, 1892-; A.M., Grove City College, 1896 ; Scholar in Psy- chology, Clark University, 1898-99. N. B. HELLER: — B.S., University of Pennsylvania, 1884; Professor of Mathematics, Boys' High School, Eeadmg, Pa., 1887-91; Scholar in Mathematics, Clark TTniversity, 1891-92 ; Fellow in Mathematics, Uni- versity of Chicago, 1892-93 ; Assistant Professor in Mathematics, Drexel Insti- tute, Philadelphia, 1893-. CLARE -WILSON HETHERINGTON : A.B., Leland Stanford Jr. University, 1895 ; Instructor, Encina Gymnasium, Stanford University, 1893-96 ; Statistician and Director of Physical Training, Whil^ tier State Reform School, 1896-98 ; Fel- low in Psychology, Clark University, 1898-99. JOHN E. HILL : — Ph.B., Sheffield Scientific School (Yale"), 1885 ; Resident Engineer, C. M. and St. Paul E.R., 1885-88; Professor of Mathe- matics, Military Academy, Louisville, Ky., 1888-89 ; Superintendent of Schools, Pleasantville, N. T., 1889-90 ; Professor of Mathematics and Civil Engineering, Highland Park College, 1890-92 ; Fellow in Mathematics, Clark University, 1892-95; Ph.D., Clark University, 1895; Tutor in Mathematics, Columbia University, 1895-97 ; Teacher of Mathe- matics, Manual Training High School, Brooklyn, N. Y., 1897-98 ; Teacher of Science, High School, Stamford, Ct., 1898-99. AilthoT of : — On Quintic Surfaces. Mathematical JJ«- ■eiew, July, 1896, Vol. 1, pp. 1-59. Bibliography of Surfaces and Twisted Curves. Bull. Am. Math. Soc, Jan., 1897, Vol. 3, pp. 133-146. On Three Septic Surfaces. Am, Jour, of Math., Oct., 1897, Vol. 19, pp. 289-311. BENJAMIN C. HINDE : — A.B., Central College, Missouri, 1881 ; A.M., ibid., 1882; Instructor in Physical Sciences, Howard College, 1882-88 ; Grad- uate Student, Johns Hopkins University, 1888-90 ; Professor of Physics and Chem- istry, State Normal College, Mo., 1890-91 ; Professor of Physics, Trinity College, N. C, 1891-92; Fellow and Assistant in Physics, Clark University, 1892-93 ; Professor of Physios, Trinity College, N. C, 1893-94. Died Feb. 6, 1894. CLIFTON F. HODGE: — A.B., Ripon College, 1882; Civil En- gineer, Montana, 1882-86 ; Graduate Stu- dent, Johns Hopkins University, 1886-88 ; Fellow in Biology, ibid., 1888-89 ; Ph.D., Johns Hopkins University, 1889 ; Fellow in Psychology and Assistant in Neu- rology, Clark University, 1889-91 ; Instructor in Biology, University of Wis- consin, 1891-92 ; Assistant Professor of Physiology and Neurology, Clark University, 1892- ; Member of : Ameri- can Physiological Society, Society Ameri- can Naturalists, Massachusetts Forestry Association, Boston Society of Medical Sciences. Author of : — Some Effects of Stimulating Ganglion Cells. Am. Jour, of Psy., May, 1888, Vol. 1, pp. 479-486. Some Effects of Electrically Stimulating Ganglion Cells. Ibid., May, 1889, Vol. 2, pp. 376-402. A Study of the Oyster Beds of Long Island Sound with Reference to the Ravages of Starfish. J. H. U. Circular, Sept., 1889, No. 75, Vol. 8, p. 102. A Sketch of the History of Reflex Action. Am. Jour, of Psy., April and Sept., 1890, Vol. 3, pp. 149-167, 348-363. The Process of Recovery from the Fatigue occasioned by the Electrical Stimula- tion of Cells of the Spinal Ganglia. Ibid., Feb., 1891, Vol. 3, pp. 530- 543. Homing Pigeons, ^gis, June, 1892. Published Papers. 503 A Microscopical Study of Changes due to Functional Activity in Nerve Cells. Jour, of Morph., Nov., 1892, Vol. 7, pp. 95-168. The Method of Homing Pigeons. Pop. Set Mo., AprU, 1894, Vol. 44, pp. 758-775. Changes in Ganglion Cells from Birth to Senile Death. Observations on Man and Honeybee. Jour, of Phys., 1894, Vol. 17, pp. 12&-134. Botanical Gardens. Wor. Co. Hort. Soc. Hep., 1894-95, pp. 102-117. Die Nervenzelle bei der Geburt und beim Tode an Alterschwache. Anat. An- zeiger, Aug. 1, 1894, Vol. 9, pp. 706- 710. A Microscopical Study of the Nerve Cell during Electrical Stimulation. Jour, of Morph., Sept., 1894, Vol. 9, pp. 449-463. The Daily Life of a Protozoan : A Study in Comparative Psycho-Physiology. (With H. A. Aikins.) Am. Jour, of Psy., Jan., 1895, Vol. 6, pp. 524-533. The Vivisection Question. Pop. Set. Mo., Sept. and Oct., 1896, Vol. 49, pp. 614- 624, 771-785. Experiments on the Physiology of Alcohol, made under the Auspices of the Com- mittee of Fifty. Ibid., March and AprU, 1897, Vol. 50, pp. 594-603, 796-812. Horticultural Interests in Relation to Public Education. Wor. Go. Hort. Soc. Bep., 1898, pp. 62-81. The Common Toad. Nature Study Leaf- let. Biology Series, No. 1, 1898. Worcester, Mass. 15 pp. Our Common Birds. Biology Series, No. 2, 1899. Worcester, Mass. 34 pp. FREDERICK H. HODGE: — A.B., Boston University, 1894; A.M., ibid., 1899 ; Special Student, Bridgewater Normal School, 1894-95; Professor of Mathematics, J. B. Stetson University, 1895-96 ; Graduate Student in Mathe- matics, University of Chicago, 1896-97 ; Scholar in Mathematics, Clark Uni- versity, 1897-98 ; Fellow, 1898-99 ; Professor of Mathematics and History, Bethel College, Eussellville, Ky., 1899-. THOMAS FRANKLIN HOLGATB: — B.A., Victoria University, Toronto, 1884 ; Mathematical Master, Albert College, Belleville, Ont., 1884-90; M.A., Victoria University, 1889; Fellow in Mathe- matics, Clark University, 1890-93 ; Ph.D., Clark University, 1893; In- structor in Mathematics, Northwestern University, 1893-94; Professor of Ap- plied Mathematics, ibid., 1894- ; Member of the American Mathematical Society. Author of : — On the Cone of the Second Order which is Analogous to the Nine Point Conic. Annals of Math., 1893, Vol. 7, pp. 73-76. On Certain Ruled Surfaces of the Fourth Order. Am. Jour, of Math., Oct., 1893, Vol. 15, pp. 344-386. Addi- tional Note on same. Ibid. (In press.) Correction of an Error in Salmon's " Ge- ometry of Three Dimensions." Bull. N. T. Math. Soc, 1894, Vol. 3, p. 224. A Geometrical Locus connected with a System of Coaxial Circles. Bull. Am. Math. Soc, Nov., 1897, 2d ser.. Vol. 4, pp. 63-67. A Second Locus connected with a System of Coaxial Circles. Ibid., Dec, 1898, Vol. 5, pp. 135-143. Reye's "Lectures on the Geometry of Position" (translation). Part I. Mac- millan Company, New York, 1898. 248 pp. RICHARD J. HOLLAND: — B.A., Victoria College, Toronto, 1887 ; Certificate Specialist in Science, Teachers' Training Institute, Kingston, Ont., 1887- 88 ; Science Master, Morrisburg Collegiate Institute, 1888-90 ; Graduate Student, Uni- versity of Leipzig, 1890-93 ; Ph.D., Uni- versity of Leipzig, 1893 ; Honorary Fellow in Physics, Clark University, 1893-94 ; with Westinghouse Electric Company, Pittsburg, Pa., 1894-95 ; with 504 Titles of Electric Power Storage Company, N. Y. City, April, 1896-. Author of: — Ueber die Aenderung der electrisohen Leitfahigkeit einer Lbsung durch Zu- satz Ton Ideinen Mengen eines Niolit- leiters. Wied. Annalen, Sept., 1893, Vol. 50, pp. 261-292. Ueber die eleotrisohe LeltfShigkeit von Kupferchloridlosungen. Ibid., pp. 349- 360. R. C. HOLLENBAITGH: — A.B., Bucknell University, 1888; Princi- pal, Cross Creek Academy, 1888-89; A.M., Bucknell University, 1891; Ph.D., Wooster University, 1891 ; Graduate Stu- dent, Johns Hopkins University, 1891-92 ; Scholar in Psychology, Clark TTniver- sity, 1892. Died July 6, 1893. WILLIAM A. HOYT: — A.B., Bates College, 1880; Principal High School, Rockport, Me., 1881-82; Principal Greeley Institute, Cumberland, Me., 1882-83 ; Cornwall Heights School, Cornwall, N. Y., 1883-86; A.M., Bates College, 1884; Principal High School: Med- way, Mass., 1886-88, North Brookfield, Mass., 1888-92, Augusta, Me., 1892-93; Scholar in Pedagogy, Clark Universi- ty, 1893-94 ; Superintendent of Schools, Brookfield, Mass. (District), 1894-. Author of: — The Love of Nature as the Root of Teach- ing and Learning the Sciences. Peda- gogical Seminary, Oct., 1894, Vol. 3, pp. 61-86. EDMUND B. HUBY: — A.B., Lafayette College (First Honors in Philosophy and Anglo-Saxon), 1895; In- structor in Latin, Harry Hillman Academy, Wilkesbarre, Pa., 1896-97; Scholar in Psychology, Clark University, 1897- 98; Fellov7, 1898-99; Prof essor of Psy- chology, State Normal School, Moor- head, Minn., 1899-. Author of: — Preliminary Experiments in the Physi- ology and Psychology of Reading. Am. Jour, of Fsy., July, 1898, Vol. 9, pp. 575-586. D. D. HUGH: — A.B., Dalhousie College, 1891 ; A.B., Harvard University, 1892 ; A.M., Cornell University, 1893 ; Fellow in Psychol- ogy, Clark University, 1895-96 ; Prin- cipal of High School, La Junta, Col., 1896-98; Professor of Psychology, Colo- rado State Normal School, Greeley, Col., 1898-99 ; Professor of Pedagogy and Eng- lish, State Agricultural College, Logan, Utah, 1899-. Author of : — Formal Education fiom the Standpoint of Physiological Psychology. Pedagogi- cal Seminary, April, 1898, Vol. 5, pp. 599-605. The Animism of Children. Northwestern Monthly, June, 1899, Vol. 9, pp. 450- 453. LORRAIN S. HULBURT: — A.B., University of Wisconsin, 1883 ; A.M., ibid., 1888; Professor of Mathematics, University of So. Dakota, 1887-91 ; Grad- uate Student, University of G5ttingen, 1889-90 ; Fellow inMathematics, Clark University, 1891-92 ; Instructor in Mathematics, Johns Hopkins University, 1892-94 ; Ph.D., Johns Hopkins Univer- sity, 1894 ; Associate in Mathematics, ibid., 1894^97; Collegiate Professor of Mathematics, ibid., 1897- ; Member of American Mathematical Society. Author of: — Theorems on the Number and Arrange- ment of the Real Branches of Plane Algebraic Curves. Am. Jour, of Math. , July, 1892, Vol. 14, pp. 246-260. Topology of Algebraic Curves. Bull, of the N. Y. Math. Soc, 1892, Vol. 1, pp. 197-202. JOHN L HUTCHINSON : — A.B., Bates College, 1889; Scholar In Mathematics, Clark University, 1890- Published Papers. 505 91 ; Fellow, 1891-92 ; Fellow in Mathe- matics, University of Chicago, 1892-94 ; Instructor in Mathematics, Cornell Uni- versity, 1894- ; Ph.D., University of Chicago, 1896 ; Member of American Mathematical Society. Author of : — A Special Form of a Quartio Surface, Annals of Math., June, 1897, Vol. 2, pp. 158-160. On the Reduction of Hyperelliptio Func- tions, (p = 2) to Elliptic Functions by a Transformation of the Second Degree. (Dissertation.) Gottingen, 1897. 40 pp. Note on the Tetrahedroid. Bull, of the Am. Math. Soc, April, 1898, 2d ser.. Vol. 4, pp. 327-329. The Hessian of the Cubic Surface. Ibid., March, 1899, 2d ser., Vol. 5, pp. 282- 292. The Asymptotic Lines of the Kummer Surface. Ibid., July, 1899, 2d ser.. Vol. 5, pp. 465-467. JOHN P. HTLAN : — Student, Harvard University, 1891-95; Fellow in PByohology, Clark Univer- sity, 1895-97 ; Instructor in Psychology, University of Illinois, 1897-98 ; Assistant Professor, ibid., 1898-99; Member of Executive Commission of Illinois Society of Child Study. Author of : — Fluctuation of Attention. (Studies from the Harvard Psy. Lab.) Psychological Bemew, Jan., 1896, Vol. 3, pp. 56-63. The Fluctuation of Attention. Psycho- logical Beview, Monograph Supple- ment, March, 1898, Vol. 2, No. 2. 78 pp. MASSUO IKUTA: — Student, University of Tokio, Japan, 1880- 85 ; University of Berlin, 1886 ; University of Erlangen, 1887-88 ; Ph.D., University of Erlangen, 1888 ; Consulting Chemist, Tokio, Japan, 1889-90; Assistant in Chemistry, Clark University, 1890- 92 ; Assistant in Chemistry, University of Chicago, 1892-95 ; Instructor, ibid., 1895-. Author of : — Ueber die Einwirkung von Acetessigather auf Chinone ; Synthese von Benzofur- furan-Derivaten. Jour, fur praktische Chemie, 1892, Vol. 45, pp. 65-83. Metamidophenol and its Derivatives, Am. Ghem. Jour., Jan., 1893, Vol. 15, pp. 39-44. JAMES EDMUND IVES: — Jessup Student, Academy of Natural Sciences, 1887-91 ; Assistant Curator, ibid. , 1887-93 ; Instructor in Physics, Drexel Institute, 1893-97; Student in Histology and Embryology, University of Pennsylvania, 1888-89 ; Student in Mathe- matics, ibid., 1893-95 ; Student in Physios, Cavendish Laboratory, Cambridge, Eng., 1896 ; Scholar in Physics, Clark Uni- versity, 1897-98 ; Fellow, 1898-99. Author of : — On Two New Species of Starfishes. Proc. Acad. Nat. Sci. of Phila., 1888, pp. 421-424. Linguatula Diesingii, from the Sooty Mangabey. Ibid., 1889, p. 31. Variation in Ophiura Panamensis and Ophiura teres. Ibid., 1889, pp. 76- 77. On a New Genus and Two New Species of Ophiurans. Ibid., 1889, pp. 143-145. Catalogue of the Asteroidea and Ophiuroi- dea in the Collection of the Academy of Natural Sciences of Philadelphia. Ibid., 1889, pp. 169-179. Mimicry of the Environment in Ptero- phryne histrio. Ibid., 1889, pp. 344- 345. On Arenicola cristata and Its Allies. Ibid., 1890, pp. 73-75. Echinoderms from the Northern Coast of Yucatan and the Harbor of Vera Cruz. Ibid., 1890, pp. 317-340. Crustacea from the Northern Coast of Yucatan, the Harbor of Vera Cruz, the "West Coast of Florida and the Bermuda Islands. Ibid., 1891, pp. 176-207. Echinoderms and Arthropods from Japan. Ibid., 1891, pp. 210-223. 506 Titles of Echinoderms from the Bahama Islands. lUd., 1891, pp. 337-341. Reptiles and Batrachians from Northern Yucatan and Mexico. Ibid., 1891, pp. 458-463. Echinoderms and Crustaceans collected by the West Greenland Expedition of 1891. lUd., 1891, pp. 479-481. A New Species of Pycnogonum from Cali- fornia. Ihid., 1892, pp. 142-144. TILMON JENKINS : — B.A., National Normal University, 1882; Professor of Didactics, Salina, Kan., Normal University, 1883-85 ; Superin- tendent of Schools, Kingman, Kan., 1885- 87; M.A., National Normal University, 1891 ; Educational work in Colorado, 1887-96; Assistant State Superintendent of Public Instruction, Colorado, 1894 ; Superintendent of Schools, Santa F6, New Mexico, 1896-97 ; Scholar in Pedagogy, Clark TTniversity, 1897-98 ; Special Student, University of Colorado, 1898-99. GEORGE ELLSTATORTH JOHNSON: — A.B., Dartmouth College, 1887; A.M., ibid. 1891 ; Principal, Colebrook Acad- emy, N. H., 1887-88 ; Principal of Schools, Springfield, Vt., 1888-92 ; Student, Hart- ford Theological Seminary, 1892-93; Scholar in Pedagogy, Clark TTniver- sity, 1893-94 ; FeUow, 1894-95 ; Su- perintendent of Schools, Andover, Mass., 1895-. Author of : — Education by Plays and Games. Peda- gogical Seminary, Oct., 1894, Vol. 3, pp. 97-133. Contribution to the Psychology and Peda- gogy of Feeble-minded Children. Ibid., Oct., 1895, Vol. 3, pp. 246-301. Play in Education. Northwestern Monthly, July, 1897, Vol. 8, pp. 3-8. Games and Play. First of Series of Twelve Monographs on Social Work. Issued by Lincoln House, Boston, Mass., and The Commons, Chicago, ni. The Co-operative Press, Cam- bridge, 1898. 22 pp. Play in Physical Education. Am. Phys. Ed. Bev., Sept., 1898, Vol. 3, pp. 179- 187. The New Education. Address delivered before the Andover Burns Club, March 19, 1898. The Andover Press, Andover, Mass., 1898. 15 pp. HERBERT F. JOHNSON: — A.B., Harvard University (with Honors in Natural History), 1889; A.M., ibid., 1890 ; Assistant in Biology, Williams Col- lege, 1890-91 ; Fellow in Morphology, Clark University, 1891-92 ; Fellow in Morphology, University of Chicago, 1892- 94 ; Ph.D., University of Chicago, 1894 ; Instructor in Biology, Des Moines Col- lege, 1894 ; Assistant Professor of Zo- ology, University of California, 1894- ; Member of : American Society of Natu- ralists; California Academy of Sciences; San Francisco Microscopical Society. Author of : — Amitosis in the Embryonal Envelopes of the Scorpion. Bull. Museum Com- parative Zool., Harvard College, 1892, Vol. 22, pp. 127-161 ; 3 pis. A Contribution to the Morphology and Biology of the Stentors. Jour, of Morph., Aug., 1893, Vol. 8, pp. 468- 562 ; 4 pis. The Plastogamy of Actinosphserium. Ibid. April, 1894, Vol. 9, pp. 269-276. A Preliminary Account of the Marine Annelids of the Pacific Coast, with Descriptions of New Species. Proc. California Academy of Sciences, Third Series. Zoology, 1897, Vol. 1, pp. 153-198 ; 6 pis. EDWIN O. JORDAN: — S.B., Massachusetts Institute of Tech- nology, 1888 ; Chief Assistant Biologist, Massachusetts State Board of Health, 1888-90 ; Lecturer in Biology, Massachu- setts Institute of Technology, 1889-90 ; Fellovir in Morphology, Clark Uni- versity, 1890-92 ; PhJ3., Clark Uni- versity, 1892 ; Associate in Biology, University of Chicago, 1892-93 ; Instructor Published Papers. 507 in Biology, ibid., 1893-95 ; Assistant Pro- fessor of Bacteriology, ihid., 1896-. Author of : — Phagocytosis and Immunity, Boston Med. and Surg. Jour., 1890, Vol. 122, p. 406. Recent Theories on the Function of the White Blood-Cell. Technology Quar- terly, 1890, Vol. 3, p. 170. Certain Species of Bacteria observed in Sewage. Report of the Mass. State Board of Health on Water Supply and Sewage, 1889-90, Vol. 2, p. 821. Investigations on Nitrification and the Nitrifying Organisms. (With Mrs. Ellen H. Richards.) Ibid., Vol. 2. Volume on Water Supply and Sewage, 1890, p. 865. The Spermatophores of Diemyctylus. Jour, of Morph., Sept., 1891, Vol. 5, pp. 263-270. The Cleavage of the Amphibian Ovum. (With A. C. Eycleshymer.) Anat. Anzeiger, Sept. 15, 1892, Vol. 7, pp. 622-624. The Habits and Development of the Newt. Jour, of Morph., May, 1893, Vol. 8, pp. 270-366, 5 Plates. On the Cleavage of Amphibian Ova. (With A. C. Eycleshymer.) Ibid., Sept., 1894, Vol. 9, pp. 407-416, 1 Plate. The Identification of the Typhoid Fever Bacillus. Jour. Am. Med. Ass'n, Dec. 22, 1894. On Some Conditions affecting the Be- havior of the Typhoid Bacillus in Water. Medical News, Sept. 28, 1895. The "Inheritance" of Certain Bacterial Diseases. Chicago Med. Recorder, Aug., 1898, Vol. 15, p. 82. The Production of Fluorescent Pigment by Bacteria. Botanical Gagette, Jan., 1899, Vol. 27, p. 19. Translation of the Principles of Bacteri- ology by Professor F. Hueppe. Open Court Publishing Co., Chicago. 467 pp. The Death-rate from Diphtheria in the Large Cities of the United States. Philadelphia Med. Jour., Feb. 18, 1899. P. C. KENYON: — B.Sc, University of Nebraska, 1892 ; In- structor in ZoSlogy, ibid., 1891-93 ; Assist- ant and Fellow in Biology, Tufts College, 1893-95 ; A.M. and Ph.D., Tufts College, 1895; Fellow in Biology, Clark Uni- versity, 1895-96 ; Fellow, American Association for the Advancement of Science ; Member of : American Morpho- logical Society, American Society of Naturalists, National Geographic Society. Author of : — The Morphology and Classification of the Pauropoda. Tufts College Studies, 1895. In the Region of the New Fossil ; Ds- mouelix. American Naturalist, 1895. Formal as a Preserving Agent. Ibid., 1895. The Meaning and Structure of the So- called Mushroom Bodies of the Hexa- pod Brain. Ibid., 1896. The Brain of the Bee. Jour. Comp. Neur- rology, 1896. The Optic Lobe of the Bee's Brain in the Light of Recent Neurological Methods. 1897. Delarvation. American Naturalist, 1897. The Chartognaths of American Waters. Ibid. The Regeneration of an Antenna-like Structure instead of an Bye. Ibid. The Regeneration of the Lens of the Eye of Tritan. Ibid. Formol or Formalin. Ibid. Effect of Lithium Chloride upon the De- velopment of the Frog and Toad Egg. Ibid., 1896. The Terminology of the Neurocytes. Science, 1897. HERBERT G. KEPPEL: — A.B., Hope College, Holland, Mich., 1889 ; Instructor in Mathematics, North- western Classical Academy, Orange City, la., 1891-92; Scholar in Mathematics, Clark University, 1892-93; Fellow, 1893-95 ; Instructor in Mathematics, Academy of Northwestern University, Evanston, 111., 1895-96; Instructor in 508 Titles of Mathematics, Northwestern University, Evanston, HI., 1896- ; Member of the American Mathematical Society ; Member of Het Wiskondig Genootschap, Amster- dam. E. A. KIREFATRICK : — B.Sc, Iowa Agricultural College, 1887; M.Ph., Ibid., 1889; Scholar in Psy- chology, Clark University, 1889-90 ; FeUow, 1890-91; Professor of Psy- chology and Pedagogy, State Normal School, Winona, Minn., 1892-97 ; Pro- fessor of Psychology and Child Study, State Normal School, Fitchburg, Mass., 1898- ; Member of American Psychologi- cal Association. Author of : — Observations on College Seniors and Elec- tives in Psychological Subjects. Am. Jour. ofPsy., April, 1890, Vol. 3, pp. 168-173. Number of Words in an Ordinary Vocabu- lary. Science, Aug, 21, 1891, Vol. 18, pp. 107-108. How Children learn to Talk. Ibid., Sept. 25, 1891, Vol. 18, pp. 175-176. Mental Images. Ibid. , Oct. 27, 1893, Vol. 22, pp. 227-230. An Experimental Study of Memory. Psy- chological Meview, Nov., 1894, Vol. 1, pp. 602-609. Inductive Psychology: An Introduction to the Study of Mental Phenomena. E. L. Kellogg & Co., New York, 1895. 208 pp. Child Study in the Training of Teachers. Meview of Beviews, Dec, 1896, Vol. 14, pp. 686-692. Handbook of Minnesota Child-Study As- sociation. James and Kroeger, Wi- nona, Minn., 1897. 60 pp. Continuous Sessions of Schools. Review of Beviews, July, 1897, Vol. 16, pp. ■ 190-191. Play as a Factor in Social and Educa- tional Reforms. Ibid., Aug., 1899, Vol. 20, pp. 192-196. Children's Reading. Northwestern Month- ly, June, 1898, Vol. 8. pp. 651-654; Dec, 1898, Jan., March-April, 1899, Vol. 9, pp. 188-191, 229-233, 838-342. Learning Voluntaiy Movements. School and Home Education, March, 1899, Vol. 18, pp. 337-344. The Development of Voluntary Move- ment. Psychological Beview, May, 1899, Vol. 6, pp. 275-281. MILTON S. EISTLER: — Graduate, West Chester, Pa., State Nor- mal School, 1888 ; Principal, High School, Honey Brook, Pa., 1888-89; Prmoipal, Blaine Normal Institute, Pa., 1889-90; Ph.B., Dickinson College, 1894; A.M., ibid., 1897 ; Professor of Latin and Eng- lish, Edinboro, Pa., State Normal School, 1894r-97 ; Scholar in Pedagogy, Clark University, 1897-98 ; Teacher, N. Y. City Schools, 1898-. Author of : — John Knox's Services to Education. Edu- cation, Boston, Mass., Oct. 1898, Vol. 19, pp. 105-116. LINUS W. KLINE: — Student, University of Virginia, 1886-87 ; L.I., Peabody Normal College, 1889; Principal, Hamilton Grammar School, Houston, Texas, 1891-93 ; B.S., Harvard University, 1896 ; Scholar in Psychol- ogy, Clark University, 1896-97 ; Fel- low, 1897-98 ; Ph.D., Clark Univer- sity, 1898 ; Honorary Fellow and Assistant in Psychology, 1898-99 ; Professor of Psychology and Pedagogy, State Normal School, Mankato, Minn., 1899-. Author of: — Truancy as Related to the Migrating In- stinct. Pedagogical Seminary, Jan., 1898, Vol. 5, pp. 381-420. The Migratory Impulse vs. Love of Home. Am. Jour, of Psy., Oct. 1898, Vol. 10, pp. 1-81. Methods in Animal Psychology. Ibid., Jan., 1899, Vol. 10, pp. 256-279. Suggestions toward a Laboratory Course in Comparative Psychology. Ibid^, April, 1899, Vol. 10, pp. 399-430. Published Papers. 509 The Psychology of Ownership. (With C. J. France.) Pedagogical Seminary. (In press.) WILLIAM O. KROHN: — A.B. , Western College, 1887; Ph.D., Yale University, 1889 ; Instructor in Phi- losophy and Psychology, Western Reserve University, 1889-91 ; Inspecting Psycho- logical liaboratories in German Universi- ties, July, 1891-Feb. 1892 ; FeUow in Psychology, Clark XTniversity, March- June, 1892; Professor of Psychology, University of Illinois, 1892-97 ; Psychol- ogist, Illinois Eastern Hospital, Kanka- kee, 111., 1897- ; Editor of Child-Study Monthly. Author of : — Facilities in Experimental Psychology at the Various German Universities. Am. Jour, of Psy., Aug., 1892, Vol. 4, pp. 585-594. Fseudo-Chromesthesia, or the Association of Colors with Words, Letters, and Sounds. Ibid., Oct., 1892, Vol. 5, pp. 20-41. An Experimental Study of Simultaneous Stimvdation of the Sense of Touch. Jour, of Nervous and Mental Disease, March, 1893 ; N. S., Vol. 18, pp. 169- 184. Practical Lessons in Psychology. The Werner Co., Chicago and New York. 400 pp. Laboratory Psychology as applied to the Study of Insanity. Psychiater, Vol. 1, No. 1. Minor Mental Abnormalities in Children as occasioned by Certain Erroneous School Methods. Proc. N. E. A. , 1898, pp. 162-172. ELLSWORTH G. LANCASTER: — B.A., Amherst College, 1885; M.A., ibid. 1888 ; Teacher, Elocution and Phys- ical Culture, Williston Seminary, East- hampton, Mass., 1885-86; Student, Auburn Theological Seminary, 1886-87 ; Teacher, Physical Culture, Latin, and German, Morgan Park Military Academy, 1887-88 ; Student, Chicago Baptist Semi- nary, 1887-88 ; Student, Andover Theo- logical Seminary, 1888-89; B.D., ibid., 1889 ; Pastor, Congregational Church, Ashby, Mass., 1889-90 ; Principal, South- ern Kansas Academy, 1890-96 ; Scholar in Psychology, Clark University, 1895-96; FeUow, 1896-97; Ph.D., Clark University, 1897 ; Instructor in Philosophy and Pedagogy, and President's Assistant, Colorado College, 1897-98; Assistant Professor, ibid., 1898-. Author of : — Psychology and Pedagogy of Adolescence. Pedagogical Seminary, July, 1897, Vol. 5, pp. 61-128. Warming Up. Colorado College Studies, Nov., 1898, Vol. 7, pp. 16-29. JAMES STEPHEN LEMON: — B.A., Wesleyan University, 1863; M.A., ibid., 1866; Principal of High School, Brownville, New York, 1862; Assistant on McClintook and Strong's Cyclopmdia of Biblical, Theological, and Ecclesiastical Literature, 1859-61 ; Assistant on Strong's Concordance of the Bible, 1859-65 ; Pro- fessor of Physics, Marion, N. Y. , Institute, 1863-65 ; Principal, Almond Collegiate In- stitute, 1866 ; Principal, Macedon, N. Y., Academy, 1867 ; Hector, Protestant Epis- copal Church, 1877-; Scholar in Psy- chology, Clark University, 1891-93; Student in Psychology, 1893-94 ; Lec- turer in Psychophysics, Columbian Uni- versity, Washington, D. C, 1894-; Ph.D., Columbian University, 1896 ; Lecturer in Physiological Psychology, Howard University, 1897- ; Member Society for Philosophical Inquiry, Washington, D. C; Member American Anthropological So- ciety. Author of: — Signalling by Flashlights. Troy, Pa. , 1874. 10 pp. The Body Considered in Its Relation to the Intellectual Processes. Union Springs, N. Y., 1875. Lists of Questions to be Asked as to Defectives, etc., admitted to Cottage 510 Titles of Hospitals for Children. Athol, Mass. 7 pp. Psychic Efleots of the Weather. Am. Jour. ofFsy., Jan., 1894, Vol. 6, pp. 277-311. Bequirements Demanded for Official Rec- ognition as Teachers. Templeton Press, Templeton, Mass., 1898. 13 pp. The Skin considered as an Organ of Sensa- tion. Journal Publishing Co., Gardner, Mass., 1898. 77 pp. The Weather Idea. Journal Publishing Co., Gardner, Mass., 1899. 60 pp. Numerous reviews and articles in Healthy Home, Cottager, and National Tribune, 1880-. JAMES E. LEROSSIGNOL : — B.A.,McGill University, 1888; Teacher in Berthelet School, Montreal, 1888-89 ; Stu- dent in Philosophy, University of Leipzig, 1889-92; Ph.D., University of Leipzig, 1892; FeUow in Psychology, Clark Uni- versity, May-July, 1892 ; Professor of Psychology and Ethics, Ohio University, Athens, 1892-94 ; Professor of History and Political Economy, University of Denver, 1894- ; Member of : American Economic Association, American Academy of Polit- ical and Social Science, American His- torical Association. Author of : — The Ethical Philosophy of Samuel Clarke. G. Kreysing, Leipzig, 1892. 97 pp. The Training of Animals. Am. Jour, of Psy., Nov., 1892, Vol. 5, pp. 205-213. Malevolence in the Lower Animals. Ohio University Bulletin, Sept., 1893, Vol. 1, pp. 1-9. The Expression of Anger. Transactions of the Ohio College Association, 1894, pp. 40-49. Spinoza as a Biblical Critic. Canadian Methodist Beview, Jan.-Peb., 1895, Vol. 7, pp. 52-60. JAMES H. LEUBA: — B.S., University of NeuchStel, Switzer- land, 1886 ; Ph.B., Ursinus College, 1888 ; Instructor in French and German, St. Mark's School, Southborough, Mass., 1891-92 ; Scholar in Psychology, Clark University, 1892-93; Fellow, 1893- 95 ; Ph.D., Clark University, 1895 ; Professor of Psychology and Pedagogy, Bryn Mawr College, 1897- ; Universities of Leipzig, Gottingen, Heidelberg, and Paris, 1897-98 ; Member of the American Psychological Association. Author of: — A New Instrument for Weber's Law ; with Indications of a Law of Sense Memory. Am. Jour, of Psy., April, 1893, Vol. 5, pp. 370-384. National Destruction and Construction in Prance as seen in Modem Literature and in the Neo-Christian Movement. Ibid., July, 1893, Vol. 5, pp. 496-539. A Study in the Psychology of Religious Phenomena. Ibid., April, 1896, Vol. 7, pp. 309-385. The Psycho-Physiology of the Moral Im- perative. Ibid., July, 1897, Vol. 8, pp. 528-559. On the Validity of the Griesbach Method of Determining Fatigue. Psychologi- cal Beview, Nov., 1899, Vol. 6, pp. 573-598. FRANK R. IiILLIE: — Assistant in Biology .University of Toronto, 1890-91; B.A., ibid., 1891 ; FeUow in Morphology, Clark University, 1891- 92; Fellow in ZoBlogy, University of Chi- cago, 1892-93 ; Reader in Embryology, ibid., 1893-94; Ph.D., University of Chi- cago, 1894; Instructor in Zoology, Uni- versity of Michigan, 1894-99; Professor of Biology, Vassar College, 1899-; Member American Society of Morphologists; Mem- ber Michigan Academy of Sciences. Author of: — Preliminary Account of the Embryology of Unio complanata. Jour. ofMorph., Aug., 1893, Vol. 8, pp. 569-578, 1 plate. The Embryology of the Unionidae, a Study in Cell-Lineage. Ibid., Jan., 1895 ; Vol. 10, pp. 1-100, 6 plates. On the Smallest Parts of Stentor Capable of Regeneration. A Contribution on Published Papers. 511 the Limit of Divisibility of Living Mat- ter. Ihid. , May, 1896, Vol. 12, pp. 239- 249. On the Efieot of Temperature on the De- velopment of Animals. ("With F. P. Knowlton.) Zoological Bulletin, Dec. , 1897, Vol. 1, pp. 179-193. On the Origin of the Centres of the First Cleavage Spindle in Unio complanata. Science, March 5, 1897, N. S., Vol. 5, pp. 389-390. Centrosome and Sphere in the Egg of Unio. Zoological Bulletin, May, 1898, Vol. 1, pp. 265-274. Hertwig's "Zelle und Grewehe," Vol. 2. Science, Oct. 14, 1898, N. S.,Vol. 8, pp. 517-520. Adaptation in Cleavage. Woods HoU Biological Lectures, 1898. Ginn & Co., Boston. (In press.) ERNEST H. LINDLE7: — A. B., Indiana University, 1893; AM.,ibid., 1894 ; Instructor in Philosophy, iftid., 1893- 95 ; Fellow in Psychology, Clark University, 1895-97; Ph.D., Clark University, 1897 ; Universities of Jena, Leipzig, and Heidelberg, 1897-98; Asso- ciate Professor of Psychology, Indiana University, 1898- ; Member American Psychological Association. Author of: — A Preliminary Study of Some of the Mo- tor Phenomena of Mental Effort. Am. Jour, of Fsy., July, 1896, Vol. 7, pp. 491-517. Some Mental Automatisms. (With G. E. Partridge.) Pedagogical Seminary, July, 1897, Vol. 5, pp. 41-60. A Study of Puzzles -with Special Reference to the Psychology of Mental Adapta- tion. Am. Jour, of Fsy., July, 1897, Vol. 8, pp. 431-493. Ueber Arbeit und Ruhe. Psychologische Arheiten, herausg. von E. Exaepelin. Heidelberg. (In press.) C. E. LINES ARGER : — A.B., Northvrestern University, 1888; Student, Chicago Medical College, 1888- 89 ; Student, Universities of Tubingen and Paris, 1889-91 ; Fellow In Chemistry, Clark University, 1891 ; Instructor in Chemistry, North Division High School, Chicago, 1891-93 ; Student, University of Gottingen, 1893-94; Student, School of Mines, Paris, 1894 ; Instructor in Chem- istry and Physics, South Division High School, Chicago, 1894-96 ; Instructor in Chemistry and Physios, Lake View High School, Chicago, 1896-99; Member of: American Chemical Society, Chemical Society of Paris, German Electro- chemical Society. Author of: — An Examination of Eusel Oil. (With J. H. Long.) Jour, of Anal. Chem., 1890, Vol. 4, p. 5. Sur I'Hydroxanthranol. Bull. d. I. Soc. Chimique, 1891, Vol. 6, p. 92. The Action of Benzene on Benzal Chloride in the Presence of Aluminium Chloride. Am. Chem. Jour., 1891,Vol. 13, p. 556. The Reaction between Triphenylmethane and Chloroform in the Presence of Aluminium Chloride. Ibid., p. 553. On Disulphotetraphenylene. Jour. Am. Chem. Soc, Vol. 13, p. 270. A Rapid Dialyzer. Jour, of Anal. Chem. , 1892, Vol. 6, p. 91. On the Nature of Colloid Solutions. Am. Jour, of Sci., 1892, Vol. 43, p. 218. The Molecular Masses of Dextrine and Gum Arabic as determined by their Osmotic Pressures. Ibid., p. 428. On the Formation of Layers in Solutions of Salts in Mixtures of Water and Organic Liquids. Am. Chem. Jour., 1892, Vol. 14, p. 380. On the Relations between the Surface Tensions of Liquids and their Chemi- cal Constitution. Am. Jour, of Sci., 1892, Vol. 44, p. 83. On the Influence of the Concentration of the Ions on the Intensity of Color of Solutions of Salts in Water. Ibid., p. 416. The Dissociation of Salts into their Ions by Water of Crystallization. Am. Chem. Jour., 1892, Vol. 14, p. 604. 512 Titles of On the Application of the rriedel-Craffts Reaction to Syntheses in the Anthra- cene Series. Ihid., p. 602. On the Preparation and Constitution of Paraanthracene. Ibid., p. 597. A Definition of Solutions. Science, 1892, Vol. 20, p. 352. The Solubility of Triphenylmethane in Benzene. Am. Chem. Jour., 1893, Vol. 15, p. 45. The Hydrates of Manganous Sulphate. Ibid., 1893, Vol. 15, p. 225. On the Existence of Double Salts in Solu- tion. Ibid., 1893, Vol. 15, p. 337. An Isothermal Curve of Solubility of Mercuric and Sodium Chlorides in Acetic Ether. Ibid., 1894, Vol. 16, p. 215. The Benzoyl Halogen Amides. Ibid., 1894, Vol. 16, p. 218. Ueber die Bestimmung kleiner Dissoola- tionsspannungen speciell Krystallwas- serhaltiger Salze. Zeits. f. phys. Chemie, 1894, Vol. 13, p. 500. Some Modifications of Beckmann's Ebul- liosoopio Apparatus. Chemical News, 1894, Vol. 69, p. 279. The Boiling Points of Dilute Solutions of Water in Alcohol and in Ether. Ibid. , p. 613. On the Application of the Schroeder-Le- Chatelier Law of Solubility to Solutions of Salts in Organic Liquids. Am. Jour, of Sci., 1895, Vol. 49, p. 48. The Combination of Sulphur with Iodine. Am. Chem. Jour., 1895, Vol. 17, p. 33. On Some Experiments in the Anthracene Series. Jour. Am. Chem. Sac, 1895, Vol. 17, p. 351. On the .Reaction between Zinc Sulphate and Potassium Hydroxide. Ibid., p. 358. On Some Relations between Temperature, Pressure, and Latent Heat of Vapor- ization. Am. Jour, of Sci., 1895, Vol. 49, p. 380. On the Vapor Tensions of Mixtures of Volatile Liquids. Jour. Am. Chem. Soc, 1895, Vol. 17, p. 580. On the Formation of Layers in Mixtures of Acetic Acid and Benzene. Ibid., p. 932. On the Heat Eflect of mixing Liquids. Physical Beview, 1896, Vol. 3, p. .418. On the Specific Gravities of Mixtures of Normal Liquids. Am. Chem. Jour., 1896, Vol. 18, p. 428. A Rapid Method of determining the Mo- lecular Masses of Liquids by Means of their Surface Tensions. Jour. Am. Chem. Soc, 1896, Vol. 18, p. 514. On the Reaction between Carbon Tetra^ chloride and the Oxides of Niobium and Tantalum. (In collaboration with M. Delafontaine.) Ibid., p. 32. Ueber die Dielektrioitatskonstanten von Flilssigkeitsgemischen. Zeitschr. f. phys. Chemie, 1896, Vol. 20, p. 131. An Apparatus for the Rapid Determina- tion of the Surface Tensions of Liquids. Am. Jour. Sci., 1896, Vol. 2, p. 108. On the Surface Tension of Mixtures of Normal Liquids. Ibid., p. 226. On the Viscosity of Mixtures of Liquids. Ibid., p. 331. The Phase Rule. By Wilder D. Bancroft. Review. Monist, 1897, Vol. 7, p. 634. GrundzUge einer thermodynamisohen Theorie el^trochemischer Krafte. By Alfred H. Buoherer. Review. Ibid., p. 635. The Phase Rule. By Wilder D. Bancroft. Review. Jour. Am. Chem. Soc, 1897, Vol. 19, p. 767. The Surface Tensions of Aqueous Solu- tions of Oxalic, Tartaric, and Citric Acids. Ibid., 1898, Vol. 20, p. 128. An Outline of the Theory of Solution and its Results. By J. Livingston R. Mor- gan. Review. Ibid., 1898, Vol. 20, p. 153. The Principles of Mathematical Chemis- try. By J. Livingston R. Morgan. Review. Ibid., 1898, Vol. 20, p. 155. On the Speed of Coagulation of Colloid Solutions. Ibid., 1898, Vol. 20, p. 375. Text-book of Physical Chemistry. By Clarence L. Speyers. Review. Ibid., 1898, Vol. 20, p. 389. On a Balance for Use in Courses in Ele- Published Papers. 513 mentary Chemistry, /ftid., 1899, Vol. 21, p. 31. The Surface Tension of Aqueous Solutions of Alkaline Chlorides. Ibid., 1899, Vol. 21, p. 327. A Simple Volumihometer. Ihid., 1899, Vol. 21, p. 435. The Elements of Differential and Integral Calculus. (In collaboration with J. W. A. Young.) 1899, D. Appleton & Co. SIDNEY J. LOCHNER: — A.B., Union College, 1890; A.M., ibid., 1892 ; First Assistant in Astronomy, Dud- ley Observatory, Albany, N. Y., 1889-92 ; Fellow in FbysicB, Clark TTniversity, Oct., 1892-May, 1893 ; Assistant, Har- vard Observatory, 1893 ; Admitted as At- torney at Law, Detroit, Mich., Dec, 1893; Professor of Physics and Mathe- matics, Delaware Literary Institute, Franklin, N.Y., 1894.-. Author of: — On the Elongation Produced in Soft Iron by Magnetism. Phil. Magazine, Dec. , 1893, Fifth Series, Vol. 36, pp. 498- 507. Modem Scientific Investigations. Union College Coneordensis, 1894. WILLIAM B. LOCKWOOD: — Ph.B., Sheffield Scientific School, Yale University, 1883; M.D., iftitf., 1885; in- structor in Chemistry, ibid., 1885-86 ; In- structor and Demonstrator in Physiology, ibid., 1887-91 ; PeUow in Physiology, Clark University, 1891-92. Died at Kedlands, Cal., June 23, 1897. Author of : — The New Haven Water Supply : A Criti- cism of the Results of Analyses of this Water, as given by Dr. Arthur J. Wolff, in the Report of the Connecticut State Board of Health for 1885. (With Herbert E. Smith, M.D.) New Haven. 6 pp. Report of the Analyses of One Hundred and Ten Well Waters, collected in New Haven. (With Herbert E. Smith, M.D.) Report of the Connecticut State Board of Health, 1886, pp. 259- 269. Some Hints for the Physician concerning Urinary Analysis. Medical Begister, Philadelphia, March 19, 1887, Vol. 1, pp. 169-174. MORRIS LOEB: — A.B., Harvard University, 1883; Ph.D., University of Berlin, 1887 ; Assistant to Professor Wolcott Gibbs, 1888-89; Do- cent in Physical Chemistry, Clark University, 1889-91 ; Professor of Chemistry, New York University, N. Y. City, 1891-. Author of: — Ueber die Einwirkung von Phosgen auf Aethenyldiphenyldiamin. Ber. d. deut. chem. Gesellschaft, Aug., 1885, Vol. 18, pp. 2427-2428. Ueber Amidinderivate. Ibid., Aug., 1886, Vol. 19, pp. 2340-2444. Das Phosgen und seine AbkSmmluige. Berlin, March 15, 1887. 51 pp. The Molecular Weight of Iodine in its Solutions. Jour, of Chem. Soc, Trans., 1888, Vol. 53, pp. 805-812. Also Zeits. f. physikalische Chemie, July, 1888, Vol. 2, pp. 606-612. The Use of Aniline for Absorbing Cyano- gen in Gas Analysis. Jour, of Chem. Soc, Trans., 1888, Vol. 53, pp. 812- 814. The Rates of Transference and the Con- ducting Power of Certain Silver Salts. (With W. Nernst. ) Am. Chem. Jour. , Feb., 1889, Vol. 11, pp. 106-121. Also Zeits. f. physikalische Chemie, Nov., 1888, Vol. 2, pp. 948-963. Is Chemical Action Affected by Magnet- ism? .4m. CAem. <7oMr., March, 1891, Vol. 13, pp. 145-153. WARREN P. LOMBARD : — A.B., Harvard University, 1878; M.D., Harvard Medical School, 1881 ; University of Leipzig, 1882-85; Assistant in Physi- ology, College of Physicians and Surgeons, New York City, 1888-89 ; Assistant Pro- fessor of Physiology, Clark Univer- 514 Titles of aity, 1889-92 ; Professor of Physiology, University of Michigan, 1892- ; Member American Physiological Society. Author of : — Beitrage zur Theorle der Warmeempfin- dung. Vorlaufige Mitteilung. Cen- tralbl. f. d. Med. Wissensch., 1883, Vol. 21, pp. 577-579. Bie raumllche und zeitliche Aufeinander- folge reflectorisch contrahirter Mus- keln. Arch. f. Anat. u. Physiologie, Physiol. Abthl., 1885, pp. 408-489. Is the "Knee-jerk" a Keflex Act? Am. Jour, of Med. Sciences, Jan., 1887. The Variations of the Normal "Knee- jerk." Am. Jour. ofPsy., Nov., 1887, Vol. 1, pp. 5-71. Die Variationen des normalen Kniestosses. Arch. f. Anat. u. Physiologic, Suppl. Band, 1889, pp. 292-335, 10 pis. On the Nature of the " Knee-jerk." Jour, of Physiology, Feb., 1889, Vol. 10, pp. 122-148. The Effect of Fatigue on Voluntary Mus- cular Contraction. Am. Jour. ofPsy., Jan., 1890, Vol. 3, pp. 24^2. EfEet de la fatigue sur la contraction mus- culaire volontaire. Arch. Ital. de Biol- ogic, 1890, Vol. 13, pp. 371-381. Alterations in the Strength which occur during Fatiguing Voluntary Muscular Work. Jour, of Physiology, Jan., 1893, Vol. 14, pp. 97-124. General Physiology of Muscle and Nerve. Chapter II., Howell's Am. Text Book of Physiology. W. B. Saunders, Phila- delphia, 1896. pp. 32-151. FRANK H. LOUD: — A.B., Amherst College, 1873 ; Walker In- structor in Mathematics, ibid., 1873-76; Professor of Mathematics, Colorado Col- lege, 1877- ; Director of State Weather Service, Colorado, 1889-90; Scholar in MathematicB, Clark University, 1890-91. Author of : — A Rigorous Elementary Proof of the Binominal Theorem. Col. College Studies, 1890, pp. 7-15. On Certain Cubic Curves. Ibid., 1890, p. 16. The Elliptic Functions Defined Indepen- dently of the Calculus. Ibid., 1891, pp. 48-81. ELWYN N. LOVEWELL: — Ph.B., University of Vermont, 1898 (Double Honors) ; Scholar in Mathe- matics, Clark University, 1898-99. GEORGE •W. A. LUCKEY: — Teacher in Public Schools of Indiana, 1874-78 ; Superintendent of Schools, Adams Co., Ind., 1878-82 ; Superinten- dent of Schools, Decatur, Ind., 1882- 87 ; Supervising Principal, Ontario, Cal., 1888-92 ; Non-Eesident Student, Univer- sity of City of New York, 1889-92 ; Stu- dent in Pedagogy and Psychology, Leland Stanford Jr. University, 1892-94 ; A.B., ibid., 1894 ; Fellow in Psychology, Clark University, 1894-95 ; Associate Professor of Pedagogy, University of Ne- braska, 1895-96 ; Professor of Pedagogy, ibid., 1896- ; Editor of the Child Study Department, Northwestern Monthly, 1895- 99. Author of : — Comparative Observations on the Indirect Color Range of Children, Adults, and Adults Trained in Color. Am. Jour, of Psy., Jan., 1895, Vol. 6, pp. 489- 504. Some Recent Studies of Pain. Ibid., Oct. , 1895, Vol. 7, pp. 108-123. Child Study in its Effects upon the Teacher. Child Study Monthly, Feb., 1896, Vol. 1, pp. 230-247. Children's Interests. Northw. Monthly, 1896-97, Vol. 7, pp. 67, 96, 133, 156, 221, 245, 306, and 335. Practical Results Obtained through the Study of Children's Interests. Proc. N. E. A., 1897, pp. 284-288 ; also Jour. of Ed., Apr. 8, 1897, Vol. 45, p. 222. Lines of Child Study for the Teacher. Educational Seview, Nov., 1897, Vol. 14, pp. 340-347 ; also I^oc. N. E. A., 1897, pp. 826-833. Published Papers. 515 A Brief Survey of Child Study. North- western Jour, of Ed., July, 1896, Vol. 7, pp. 2-9. Methods Pursued in Child Study. Ibid., pp. 33-35. The Best "Works on Child Study. Ibid., pp. 48-53. The Bevelopment of Moral Character. Proo. N: E. a., 1899. HERMAN T. LUKENS: — A.B., University of Pennsylvania, 1885; A.M., ifeid., 1888 ; Student in Halle, Jena, and Berlin, 1888-91 ; Ph.D., University of Jena, 1891 ; Instructor in Biology, N. W. Division High School, Chicago, 1891-94 ; Honorary Fellow in Psychology, Clark University, 1894-95 ; Docent in Pedagogy, 1895- ; Lecturer in Education, Bryn Mawr College, 1896-97 ; Visit to Europe to study Education, 1897-98 ; Head Training Teacher, S. W. State Normal School, California, Pa., 1898-. Author of : — ' Herbart's Psychological Basis of Teach- ing. Part n of Th. B. Noss's Outlines of Psychology and Pedagogy, Pitts- burg, 1890. Die Vorstellungsreihen und ihre padago- gische Bedeutung. Gutersloh, Prussia, 1892. A Portion of the Translation of Lange's Apperception. Edited by Charles De Garmo. D. C. Heath & Co., Boston, 1893. 279 pp. The Connection between Thought and Memory. Based on Dorpfeld's Den- ken und Geddchtnis. D. C. Heath & Co., Boston, 1895. 179 pp. The Correlation of Studies. Educational Beview, Nov., 1895, Vol. 10, pp. 364- 383. Correlation. Jour, of Ed., May 9 and June 20, 1895, Vol. 41, pp. 311-312 ; Vol. 42, p. 15. A Point of Difference between Race and Individual Development. Second Her- bartian Yearbook, 1896. Preliminary Report on the Learning of Language. Pedagogical Seminary, June, 1896, Vol. 3, pp. 424-460. A Study of Children's Drawings in the Early Years. Ibid., Oct. 1896, Vol. 4, pp. 79-110. Child Study for Superintendents. Edun cational Beview, Eeb., 1897, Vol. 13, pp. 105-120. Honorary Degrees in the United States, Ibid., June, 1897, Vol. 14, pp. 8-16. Language Defects. Northw. Monthly, July, 1897, Vol. 8, pp. 39-44. The Vital Question in the Curriculum, Education, Sept., 1897, Vol. 18, pp, 19-29. Die Entwiokelungsstufen beim Zeichnen, Kinderfehler, Dec, 1897, Vol. 2, pp, 166-170. Malendes Zeichnen. Aus dem pad. Univ.- Seminar Jena, VII., 1897. The School Patigue Question in Ger- many. Educational Beview, March, 1898, Vol. 15, pp. 246-254. The Method of Suggestion in the Cure of Paults. Northwestern Monthly, May, 1898, Vol. 8, pp. 592-595. The School and Real Life. JV. Y. School Jour., Oct. 1, 1898, Vol. 57, pp. 277- 279. Notes Abroad. Pedagogical Seminary, Oct., 1898, Vol. 6, pp. 114-125. A School-Garden in Thuringia. Educa- tional Beview, March, 1899, Vol. 17, pp. 237-241. Mental Patigue. Am. Phys. Ed. Beview. March and June, 1899, Vol. 4, pp, 19-29, 121-135. The Joseph Story. N. T. Teachers^ Magazine, April, 1899, Vol. 1, pp, 331-334. Drawing in the Early Years. Proc. N. E. A., 1899. ALEXANDER G. McADIE: — A.B., College of City of New York, 1881 ; A.M., ibid., 1884 ; Student, Harvard Uni- versity, 1882-85 ; A.M., i6id.,1885; Phys- ical Laboratory, U. S. Signal Oflce, 1886- 87 ; Fellow in Physics, Clark Univer- sity, 1889-90; U. S. Signal Office, Washington, 1890-91 ; U. S. Weather Bu- 516 Titles of reau, Washington, 1891-95; Hodgkins Medal and Honorable Mention, Smith- sonian Institution, 1895; Local Forecast Official, New Orleans, 1898-99 ; Forecast OfBcial, San Francisco, 1899-; Honorary Lecturer in Meteorology, University of California; Director, California Climate and Crop Service. Author of: — On the Aurora. U. 8. Signal Service Note, No. 18, pp. 21, 5 maps, 12 charts. Protection against Lightning. Am. Met. Jour., June, 1885, Vol. 2, pp. 60-66. Atmospheric Electricity at High Altitudes. Proc. Am. Academy, 1885, Vol. 13, pp. 129-134. Electrometer Work. Monthly Weather Beview, 1886-87, Vol. 14, pp. 166-167. Observations of Atmospheric Electricity. Am. Met. Jour., March, 1887, Vol. 3, pp. 523-531 ; April, 1887, Vol. 3, pp. 551-561 ; May, 1887, Vol. 4, pp. 21-31. WUUam Ferrell. Ibid., Feb., 1888, Vol. 4, pp. 441-449. Lightning and the Electricity of the At- mosphere. Ibid., May, 1889, Vol. 6, pp. 1-4. Tornadoes. Prize Essay. Ibid., Vol. 7, pp. 179-192. Mean Temperatures in the United States. Professional Paper, U. S. Signal Office, June, 1891. Washington, 1891. 45 pp. Franklin's Kite Experiment. Am. Met. Jour., July, 1891, Vol. 8, pp. 97-108. Shall We erect Lightning Rods ? Ibid., July, 1892, Vol. 9, pp. 60-66. Experiments in Atmospheric Electricity. Annals of Observatory of Harvard Col- lege, Vol. 40, Part 1, pp. 53-58. Experiments in Atmospheric Electricity at Blue Hill, 1892. Annals of Observa- tory of Harvard College, Vol. 40, Part 2, pp. 120-124. Energy of a Flash of Lightning. Proc. of the Internal. Met. Congress, Chicago, 1893, Paper 6, Part 1, pp. 18-21. Utilization of Cloud Observations. Ibid., Paper 6, Part 1, pp. 21-26. Protection from Lightning. U. S. Weather Bureau, Bulletin No. 15, 1894. A Colonial Weather Service. Pop. Sd. Mo., July, 1894, Vol. 45, pp. 331-337. The Storage Battery of the Air. Harper'' s Magazine, July, 1894, Vol. 89, pp. 216- 219. New Cloud Classifications. Proc. Phil. Soc. of Washington, March 2, 1895, Vol. 13, pp. 77-86. The Work and Equipment of an Aero- Physical Laboratory. Smithsonian In- stitution, 1895. 30 pp. Smithsonian Miscellaneous Collections, Vol. 39, No. 1077. Fog Possibilities. Harper^s Magazine, Jan., 1897, Vol. 94, pp. 263-266. What is an Aurora ? Century Magazine, Oct., 1897, Vol. 54, pp. 874r-878. Franklin's Kite Experiments. Pop. Sci. Mo., Oct. 1897, Vol. 51, pp. 739-747. Needless Alarm during Thunder-storms. Century Magazine, Aug., 1899, Vol. 58, pp. 604-605. FRANK H. MoASSE!7: — A.B., Eipon College, Ripon, Wis., 1897; Scholar in Psychology, Clark Univer- sity, 1898-99. J. F. MoCtJIiLOCH: — A.B., Adrian College, 1883; A.M., ibid., 1889; Ph.B., j6ic?.,1884; Assistant Pro- fessor of Mathematics, ibid., 1885-87 ; In- structor in Mathematics, University of Micliigan, 1887-88 ; Assistant Professor of Mathematics, Adrian College, 1888-89 ; Fellow in Mathematics, Clark XTniver- sity, 1889-90; President, Adrian Col- lege, 1890-93 ; Pastor of M. P. Church, Fairmont, W. Va., 1893-94; Editor, Our Church Becord, Greensboro, N. C, 1894-. Author of: — RoUe's Theorem extended. Annals of Mathematics, Vol. 4, p. 5. A Theorem in Factorials. Ibid., Vol. 4, p. 161. ARTHUR MacDONALD: — A.B., University of Rochester, 1879 ; A.M., ibid., 1883; Union Theological Seminary, 1880-83 ; Graduate Student, Harvard Uni- versity, 1883-86; Fellow, Johns Hopkins Published Papers. 617 University, 1885; Universities of Berlin, Leipzig, Paris, and Ztlricli, 1885-88 ; Do- cent in Ethics, Clark University, 1889- 91 ; Specialist in Education as related to the Abnormal and Weakling Classes, U. S. Bureau of Education, 1891- ; U. S. Dele- gate, International Criminal Congress, Brussels, 1892 ; International Psychological Congress, London, 1893 ; International De- mographioal Congress, Budapest, 1894. Author of: — Ethics as Applied to Criminology. Jour, of Mental Science, Jan., 1891, Vol. 37, pp. 10-16, and Open Court, July, 1891. Alcoholism. Medico-Legal Journal, June, 1891. Criminal Aristocracy, or the Maffia. Med- ico-Legal Journal, June, 1891, Vol. 9, pp. 21-26. Criminology. With an Introduction by C. Lombroso, with Bibliography. Eunk & Wagnalls Co. , New York, 1894. 416 pp. Abnormal Man. Being Essays on Educa- cation and Crime and Belated Subjects, with Digests of Literature and a Bibli- ography. U. S. Bureau of Education, Washington, 1893. 445 pp. Le Criminel-Type dans quelques formes graves de la Criminality Bibliographie de Sexualitfi Pathologique. Un volume in 8° iUustr6 de Portraits. A Storck, Lyon et G. Masson, Paris, 1895. 300 pp. Education and Patho-Social Studies. Re- print from Annual Beport of U. 8. Commissioner of Education for 1893- 94, Washington, D. C, 1896. 57 pp. Jimile Zola: a Psycho-Physical Study of Zola's Personality. Reprint from Open Court, August, 1898. 18 pp. Experimental Study of Children, including Anthropometrical and Psycho-Physical Measurements, with a Bibliography. Reprint from Annual Report of U. 8. Commissioner of Education for 1897- 98, Washington, D. C, 1899. 325 pp. Ueber Korpermessungen an Kindern. Deuts. Zeits. f. Auslandisches Vhter- richtswesen, July, 1899, Vol. 4, pp. 25.3-266. Abnormal Children. (In press.) JOHN McGOWAN: — B. A., University of Toronto, 1888 ; Pellow in Mathematics, ibid., 1888-91; Scholar in Mathematics, Clark University, 1891-92 ; Instructor in Mathematics, Princeton College, 1892-93; Graduate Student, University of Toronto, 1893-94 ; Lecturer in Mathematics and Physics, Toronto Technical School, 1894-95; B.S., University of Toronto (School of Practical Science), 1895. J. PLAYPAIH McMURRICH: — B. A., University of Toronto, 1879; M.A., ibid., 1882 ; Assistant in Biological Lab- oratory, ibid., 1880-81 ; Professor of Biol- ogy, Ontario Agricultural College, 1882-84 ; Instructor in Osteology, Johns Hopkins University, 1884-86; Ph.D., Johns Hop- kins University, 1885 ; Professor of Biology, Haverford College, 1886-89; Docent in Morphology, Clark University, 1889- 91 ; Assistant Professor, 1891-92 ; Professor of Biology, University of Cin- cinnati, 1892-94 ; Professor of Anatomy, University of Michigan, 1894-. Author of : — On the Origin of the So-oalled Test-cells in the Ascidian Ovum. Studies from Biol. Lab. J. H. TT. , 1882, Vol. 2. Ah- stractinjBio?.Ce»ira26to«<, 1882,Vol. 2; Arch, de Zool. exp. et gen., 1882, Vol. 10. Note on the Function of the " Test-cells " in Ascidian Ova. Zool. Anzeiger, 1882, Vol. 6. Abstract in Jour. Boy. Micros. Soc, 1882, Vol. 2. On the Osteology and Development of Syngnathus peokianus (Storer). Quart. Jour. Micros. Sci., 1883, Vol. 23. Abstract in J. H. XT. Circular, 1883, No. 27. The Osteology and Myology of Amiurus catus (L.) Gill. Proc. of the Canadian Inst., Toronto, 1884, Vol. 2. Pre- liminary Notice in Zool. Anzeiger, 1884, Vol. 7. On the Structure and Affinities of Phytop- tus. J. S. U. Circular, 1884, No. 35. Abstract in Jour. Boy. Micros. Soc, 1885, Vol. 5. 518 Titles of On the Tape-worm Epizootic among Lambs (Taenia expansa). 9th Ann. Bep. of the Ont. Agricultural College, Toronto, 1884. Tlie Cranial Muscles of Amia oalva (L.), ■with a consideration of the Post-occipi- tal and Hypoglossal Nerves in the various Vertebrate Groups. Studies from Biol. Lab. J. H. U., 1885, Vol. 3. Preliminary Notice in J. H. U. Circu- lar, 1885, No. 38. On the Existence of a Post-oral Band of Cilia in Gasteropod Veligers. J. H. U. Circular, 1885, No. 43. Abstract in Jour. Boy. Micros. Soc, 1886, Vol. 6. A Contribution to the Embryology of the Prosobranch Gasteropoda. Studies from Biol. Lab. J. H. U., 1886, Vol. 3. Preliminary Notice in J. H. TJ. Circular, 1886, No. 49. Abstract in Jour. Boy. Micros. Soc, 1886, Vol. 6. Notes on the Actiniae obtained at Beau- fort, N. C. Studies from Biol. Lab. J. H. U., 1887, Vol. 4. On the Occurrence of an Edwardsia Stage in the Eree-swimming Embryos of a Hexactinian. J. S. XI. Circular, 1899, No. 70. Abstract in Jour. Boy. Micros. Soc, 1889, Vol. 9. A Contribution to the Actinology of the Bermudas. Froc of the Acad, of Nat. Sciences, Philadelphia, 1889. Abstract in Jour. Boy. Micros. Soc, 1889, Vol. 9. Note on the Structure and Systematic Position of Lebrunea neglecta, Duch. and Mich. Zool. Anzeiger, 1880, Vol. 12. Abstract in Jour. Boy. Micros. Soc, 1889, Vol. 9. Article " Reproduction " in Buck's Befer- ence Handbook of the Medical Sciences, 1889, Vol. 8. The Actiniaria of the Bahama Islands, W. I. Jour, of Morph., 1889, Vol. 3. Abstract in Jour. Boy. Micros. Soc, 1890, Vol. 10 ; American Naturalist, 1889 ; Preliminary Notice in J. S. JJ. Circular, 1889, No. 70. Contributions on the Morphology of the Aotinozoa. I. The Structure of Ceri- anthus americanus. Jour, of Morph., Oct., 1890, Vol. 4, pp. 131-150. Contributions on the Morphology of the Actinozoa. II. On the Development of the Hexactinise. Ibid., Jan., 1891, Vol. 4, pp. 303-330. Contributions on the Morphology of the Actinozoa. III. The Phylogeny of the Actinozoa. Ibid., June, 1891, Vol. 5, pp. 125-164. The Gastraea Theory and its Successors. Biological Lectures, Marine Biological Laboratory, Woods HoU. Ginn & Co., Boston, 1891, pp. 79-106. The Formation of the Germ-layers in the Isopod Crustacea. Zool. Anseiger, Jahrg. 15, 1892. Keport on the Actiniae collected by the U. S. Eish Commission steamer Albatross during the winter of 1887-88. Proc. U. S. National Museum, 1893, Vol. 16, p. 119. A Text-book of Invertebrate Morphology. New York, 1894. Embryology of the Isopod Crustacea. Jour, of Morph., May, 1895, Vol. 11, pp. 63-154. Cell Division and Development. Biologi- cal Lectures, Marine Biological Labora- tory, Woods HoU. Ginn & Co. , Boston, 1895, pp. 125-147. Notes on Some Actinians from the Ba- hama Islands, collected by the late Dr. J. I. Northrop. Annals N. T. Acad, of Science, 1896, Vol. 9, p. 181. The Yolk-lobe and Centrosome of Eulgur carica. Anat. Anzeiger, 1896, Bd. 12, p. 534. Contributions on the Morphology of the Actinozoa. IV. On Some Irregulari- ties in the Number of the Directive Mesenteries in the Hexactinise. Zool. Bulletin, 1897, Vol. 1. The Epithelium of the So-called Midgut of the Terrestrial Isopods. Jour, of Morph., 1897, Vol. 14, p. 83. A Case of Crossed Dystopia of the Kid- ney with Fusion. Jour, of Anat. and Phys., 1898, Vol. 32, p. 652. Report on the Actiniaria collected by the Bahama Expedition of the State Uni- Published Papers. 519 versity of Iowa, 1893. Bull. Lab. of Nat. Hist. State Univ. of Iowa, 1898, Vol. 4, p. 225. The Present Status ol Anatomy. Amer- ican Naturalist, 1899, Vol. 33, p. 185. FRANKLIN P. MALL :— M.D., University of Michigan, 1883; University of Heidelberg, 1883-84; University of Leipzig, 1884-86 ; Fellow, Instructor, and Associate in Pathology, Johns Hopkins University, 1886-89 ; Ad- junct Professor ol Vertebrate Anat- omy, Clark University, 1889-92 ; Pro- fessor of Anatomy, University of Chicago, 1892-93 ; Professor of Anatomy, Johns Hopkins University, 1893-. Author of: — Entwickelung der Branohialbogen und -Spalten des Huhnchens. Arch. f. Anatomic (His u. Braune), 1887, pp. 1-34, 3 pis. Die Blut- und Lymphwege im Dunndarm des Hundes. Abhandl. d. K. S. Cfe- sellsch. der Wissenschaften, 1887, Vol. 24, pp. 153-189, 6 pis. The First Branchial Arch of the Chick. J. H. U. Circular, Feb., 1888, Vol. 7, p. 38. The Branchial Region of the Dog, Ihid., Feb., 1888, Vol. 7, p. 39. Development of the Eustachian Tube, Middle Ear, Tympanic Membrane, and Meatus of the Chick. Studies from Biol. Lab. J. H. U., June, 1888, Vol. 4, pp. 185-192, 1 pi. The Development of the Branchial Clefts of the Dog with Special Reference to the Origin of the Thymus Gland. Ibid., pp. 193-216, 3 pis. Reticulated and Yellow Elastic Tissues. Anat. Anzeiger, June 1, 1888, Vol. 3, pp. 397-401. Die motorischen Nerven der Portalvene. Du Bois-Beymond^s Arch. f. Fhysiolo- gie, 1890, Supp. Band, pp. 57-58. Development of the Lesser Peritoneal Cavity in Birds and Mammals. Jour. of Morph., June, 1881, Vol. 5, pp. 165-179. Das Reticulirte Gewebe. Abhandl. d. K. 8. Qesellsch. der Wissenschaften, 1891, Vol. 17, pp. 293-338, 11 pis. A Human Embryo Twenty-six Days Old. Jour, of Morph., Dec, 1891, Vol. 5, 459-480, 2 pis. Methods of preserving Human Embryos. American Naturalist, Dec, 1891, Vol. 25, pp. 1144^1146. Der Einfluss des Systems der Vena portae auf die Vertheilung des Blutes. Du Bois-Beymond's Arch. f. Physiologic, 1892, pp. 409-453. The Vessels and Walls of the Dog's Stom- ach. J. H. Hospital Beports, 1896, Vol. 1, pp. 1-36, 5 pis. A Study of the Intestinal Contraction. Ibid., pp. 37-75, 8 pis. Healing of Intestinal Sutures. Ibid., pp. 76-92. Reversal of the Intestine. Ibid., pp. 93- 110. A Human Embryo of the Second Week. Anat. Anzeiger, Aug. 5, 1893, Vol. 8, pp. 630-633. Histogenesis of the Retina in Amblystoma and Necturus. Jour, of Morph., Ma,y, 1893, Vol. 8, pp. 415-432. Coelom, pp. 184-189 ; Human Embryos, pp. 268-269 ; The Heart, pp. 391-395 ; Development of the Thymus Gland, pp. 875-877; Development of the Thyroid Gland, pp. 879-882. Bef. Handbook of Med. Sciences (Supp. Vol.). What is Biology? Chautauquan, Jan., 1894, Vol. 18, pp. 411-414. Early Human Embryos and the Mode of their Preservation. Bull, of J. H. Hospital, Dec, 1893, Vol. 4, pp. 115- 121. The Preservation of Anatomical Material for Dissection. Anat. Anzeiger, April 9, 1896, Vol. 11, pp. 769-775. The Contraction of the Vena Portse and its Influence upon the Circulation. J. H. Hospital Beports, 1896, Vol. 1, pp. 111-156. Reticulated Tissue and its Relation to the Connective Tissue Fibrils. Ibid. , 1896, Vol. 1, pp. 171-208, 9 pis. 520 Titles of The Anatomical Course and Latoratory of the Johns Hopkins University. Bull, of J. H. Hospital, May-June, 1896, Vol. 7, pp. 85-100, 6 pis. Development of the Human Coelom. Jour, of Morph., Feb., 1897, Vol. 12, pp. 395-453. Ueherdie Entwickelung des menschliohen Darmes und seiner Lage beim Erwach- senen. Sis.' s Arch. f. Anatomie, 1897, Supp. Band, pp. 403-434, 10 pis. Development of the Ventral Abdominal Walls in Man . Jour, of Morph. , June, 1898, Vol. 14, pp. 347-366, 6 pis. Development of the Human Intestine and its JPosition in the Adult. Bull, of J. H. Hospital, Sept.-Oct., 1898, Vol. 9, pp. 197-208, 5 pis. The Lobule of the Spleen. Ibid., pp. 218-219. Development of the Internal Mammary and Deep Epigastric Arteries in Man. Ihid., pp. 232-235. The Value of Embryological Specimens. Md. Med. Jour., Oct. 29, 1898, Vol. 40, p. 29. Liberty in Medical Education. Phila. Med. Jour., April 1, 1899, Vol. 3, p. 720. CHARLES W. MARSH: — Ph.B., Columbia College, School of Mines, 1879; Ph.D., Columbia College, 1882 ; Assistant in Chemistry, Green School of Science, Princeton, N. J., 1882- 85; University of Berlin, 1885-87; Assist- ant in Chemistry, Lehigh University, 1887-89 ; Honorary Fellow in Chemis- try, Clark Univeraity, 1889-90 ; Elec- trical Engineer, New York City, 1893-. Author of: — Note on the Ammoniar-Process for Water Analysis. Am. Chem. Jour., July, 1882, Vol. 4, pp. 188-192. A Method for the Detection of Chlorine, Bromine, Iodine, and Sulphur in Or- ganic Compounds. Ibid., April, 1889, Vol. 11, pp. 240-244. A New Form of Adapter. Am. Jour, of Anal. Chem., Jan., 1889. The Beduction of Barium Sulphate to Barium Sulphide on Ignition with Filter Paper. Ihid., April, 1889. ALFRED G. MAYER: — M.E., Stevens Institute, Hoboken, N. J., 1889 ; Assistant in Physics, Clark Uni- versity, 1889-90 ; Assistant in Physics, University of Kansas, 1890-92 ; Graduate Student in Zoology, Harvard University, 1892-95 ; Museum Assistant in Charge of Radiates, Echinoderms, and Polype, and Assistant to Dr. Alexander Agassiz, 1895- ; Sc.D., Harvard University, 1896 ; Member of : American Society of Natu- ralists, American Morphological Society, Boston Society of Natural History, Ameri- can Association for Advancement of Sci- ence ; President of the Cambridge Ento- mological Society. Author of : — Badiation and Absorption of Heat by Leaves. Am. Jour, of Sci., April, 1893, Vol. 45, pp. 340-346. Some New Medusae from the Bahamas. Bull. Mus.Comp. Zool, 1894, Vol. 25, pp. 235-242, 3 pis. Color and Color-Patterns of Moths and Butterflies. Ibid., 1897, Vol. 30, pp. 169-256, 10 pis. The Development of Wing Scales and their Pigment in Butterflies and Moths. Ibid., 1896, Vol. 29, pp. 209-236, 7 pis. A New Hypothesis of Seasonal Dimor- phism in Lepidoptera. Psyche, April- May, 1897, Vol. 8, pp. 47-50, 59-62. On Dactylometra. (With A. Agassiz.) Bull. Mus. Comp. Zo'ol., 1898, Vol. 32, pp. 1-11, 13 pis. On Some Medusse from Australia. (With A. Agassiz.) Ibid., 1898, Vol. 32, pp. 12-19, 3 pis. Acalephs from the Fiji Islands. (With A. Agassiz.) /6id., 1899, Vol. 32, pp. 151-189, 17 pis. On an Atlantic "Palolo" Worm. Ibid. (In press.) Medusae of the Atlantic Coast of North America. (With A. Agassiz.) Mem. Mus. Comp. Zool. Published Papers. 521 A. D. MEAD: — A.B., Middlebury College, 1890; A. M., Brown University, 1891 ; Fellow in Mor- phology, Clark University, 1891-92 ; Fellow in Biology, University of Chicago, 1892-95 ; Ph.D., University of Chicago, 1895 ; Instructor in Comparative Anatomy, Brown University, 1895-96 ; Associate Professor of Embryology and Neurology, ibid., 1897-. Author of : — Preliminary Account of the Cell-Lineage of Amphitrite and other Annelids. Jour, of Morph., Sept., 1894, Vol. 9, pp. 465-473. Some Observations on Maturation and Fecundation of Chjetopterus perga- mentaceus Cuvier. Ibid., Jan., 1895, Vol. 10, pp. 313-317. The Origin of the Egg Centrosomes. Ibid., Feb., 1897, Vol. 12, pp. 391-394. The Early Development of Marine Anne- lids. (Thesis.) Ifeid., May, 1897, Vol. 13, pp. 227-326. The Origin and Behavior of the Centro- somes in the Annelid Egg. Ibid., June, 1898, Vol. 14, pp. 181-218, 4 pis. The Rate of Cell Division and the Function of the Centrosome. Woods Hall Biol. Lectures, 1896-97. Gmn & Co., Bos- ton, 1898, pp. 203-218. The Breeding of Animals at Woods HoU during the Month of April, 1898. Science, May 20, 1898, N. S., Vol. 7, pp. 702-704. Habits and Life History of the Starfish. I. S8th Sep. of the Com. of Inland Fish- eries of B. I., 1898. Habits and Life History of the Starfish. XL S9th Bep. , ibid. , 1899. Peridinium and the "Eed Water" in Narragansett Bay. Science, Nov 18, 1898, N. S., Vol. 8, pp. 707-709. The Cell Origin of the Prototroch. Woods Soil Biol. Lectures, 1898. GEOROi: F. METZLER: — A.B., Albert College, Ontario, Can., 1880; Head Master, Port Dover High School, 1880-81; Professor of Mathe- matics, Albert College, 1881-84; A.M., Victoria College, 1888 ; Professor of Mathematics, Marietta College, 1889-90 ; Ph.D., Johns Hopkins University, 1891 ; Honorary Fellow in Psychology, Clark University, 1891-92 ; Decent in University of Chicago and Instructor in Mathematics, University of Michigan, 1892-93 ; University of Gottingen, 1893- 94; University of Berlin, 1894-95 ; Asso- ciate in Mathematics, Queens College, 1896-97 ; Assistant Pastor Methodist Church, Newburgh, Can., 1897-98 ; Pas- tor of Methodist Church, Wilberforoe, Canada, 1898-. Author of: — Equations and Variables Associated with the Linear Differential Equation . An- nals of Math., Vol. 9, pp. 171-178 ; Vol. 11, pp. 1-9. Surfaces of Rotation with Constant Meas- ure of Curvature and their Represen- tation on the Hyperbolic (Cayley's) Plane. Am. Jour, of Math., Jan. , 1898, Vol. 20, pp. 76-86. WILLIAM H. METZLER: — A.B., University of Toronto, 1888; Science Master, Collegiate Institute, Inger- soU, Ont., 1888-89 ; Fellow in Mathe- matics, Clark University, 1889-92; Ph.D., Clark University, 1893; In- structor in Mathematics, Massachusetts Institute of Technology, 1892-94 ; Pro- fessor of Mathematics, Genesee Wesleyan Academy, 1894-95; Associate Professor of Mathematics, Syracuse University, 1895-96 ; Professor of Mathematics, ibid., 1896-; Member of : American Association for the Advancement of Science ; Ameri- can Mathematical Society ; Deutsche Mathematiker-Vereinigung ; Mathemat- ical Association (England) ; British As- sociation for the Advancement of Science ; London Mathematical Society. Author of: — On the Roots of Matrices. Am. Jour, of Math., Oct., 1892, Vol. 14, pp. 326- 377. 522 Titles of On Certain Properties of Symmetric, Skew Symmetric, and Orthogonal Matrices. Ibid., July, 1893, Vol. 15, pp. 274-282. Homogeneous Strains. Annals of Math., Vol. 8, No. 5. On Compound Determinants. Am. Jour, of Math., AprU, 1894, Vol. 16, pp. 131-150. Matrices which Represent Vectors. Tech- nology Quarterly, Vol. 6. No. 4. Some Notes on Symmetric Functions. Proc. London Math. Soc, March 11, 1897, Vol. 28, pp. 390-393. Compound Determinants. Am. Jour, of Math., July, 1898, Vol. 20, pp. 253- 272. A Theorem in Determinants. Ibid. , July, 1898, Vol. 20, pp. 273-276. On the Excess of the Number of Combina- tions in a set which have an even number of inversions over those which have an odd number. (In press.) On the Roots of a Determinantal Equa- tion. Am. Jour, of Math., Oct., 1899, Vol. 21, pp. 367-^68. On a Determinant each of whose Elements is the Product of K Factors. (In press.) On a Theorem in Determinants related to Laplace's. (In press.) ADOLF MEYEH: — Maturitatsexamen, Gymnasium, Ziirich, 1885 ; Medical Staatsexamen, Ziirich, 1890 ; Graduate Student in Medicine, Paris, Edinburgh, and London, 1890-91 ; Neurological Work in the Laboratory of the Clinic of Psychiatry of Professor A. Forel, Ziirich, 1891 ; Neurological Student, Vienna, 1892 ; M.D., University of Ziirich, 1892 ; Docent in Neurology, University of Chicago, and Pathologist, Illinois Hospital for the Insane, 1893-95 ; Director of the clinical and laboratory work, Worcester Insane Hospital, 1895- ; Docent in Psy- chiatry, Clark University, 1895-. Author of : — Medicinische Studien in Paris, Edinburgh, und London. Oorrespondem-Blatt fur Schweizer Aerzte, June 1, 1891, Vol. 21, pp. 350-357 ; June 15, pp. 381-386 ; July 1, pp. 417-420. Ueber das Vorderhirn einiger Reptilien. Zeitschrift fur wissenschaftliche Zo- ologie, 1892, Vol. 55, pp. 63-133, 2 pis. Zur Homologie der Fornixcommissur und des Septum luoidum bei den Reptilien und Saugern. Anatomischer Anzeiger, March 15, 1895, Vol. 10, pp. 474-482. Neurological Work at Ziirich. Journal of Comparative Neurology, 1893, Vol. 3, pp. 1-6, 41-44, 114-118. How Can We Prepare Neurological Ma- terial to the Best Advantage ? Jour- nal of Nervous and Mental Diseases, May, 1894, Vol. 19, pp. 277-291. Considerations on the Findings in the Spinal Cord of Three General Para- lytics. Am. Jour, of Insanity, Jan., 1895, Vol. 51, pp. 374-379. Mental Abnormalities in Children during Primary Education. Ti-an. III. Soc. for Child Study, Dec, 1894, Vol. 1, No. 1, pp. 48-58. Schedule for the Study of Mental Abnor- malities in Children. Ibid., May, 1895, Vol. 1, No. 2, pp. 53-57. On the Observation of Abnormalities of ChEdren. Child Study Monthly, May, 1895, Vol. 1, pp. 1-12. Report to the Governor of Illinois on the Treatment of the Insane. Compila- tion of Special Reports, etc., Spring- field, 111., 1894, pp. 18-29. A Few Demonstrations of Pathology of the Brain and Remarks on the Prob- lems connected with Them. Am. Jour, of Insanity, Oct., 1895, Vol. 52, pp. 243-249, 3 pis. On the Diseases of Women as a Cause of Insanity in the Light of Observations in Sixty-nine Autopsies. Tran. of the ni. State Med. Soc, 1895. A Review of the Signs of Degeneration and of Methods of Registration. Am. Jour, of Insanity, Jan., 1896, Vol. 52, pp. 344-363. Pathological Report of the Illinois Eastern Hospital for the Insane at Kankakee, m. Chicago, 1896, pp. 1-236, 16 pis. Published Papers. 523 A Case of Landry's Paralysis, with Au- topsy. ("With Dr. Th. Diller.) Am. Jour, of the Medical Sciences, April, 1896, Vol. 115, pp. 404-413. Etiological, Clinical, and Pathological Factors in Diagnosis and Rational Classification of Infectious, Toxic, and Asthenic Diseases of the Peripheral Nerves, Spinal Cord, and Braiu. Medi- cine, Detroit, Mich., Aug. 1896, Vol. 2, pp. 639-652. A Short Sketch of the Problems of Psy- chiatry. Am. Jour, of Insanity, April, 1897, Vol. 53, pp. 538-549. Greneral Paralysis and Other Nervous and Mental Affections Following Syphilitic Infection. Tale Medical Journal, May, 1897, Vol. 3, pp. 311-317. Demonstration of Various Types of Changes in the Giant Cells of the Paracentral Lobule. Am. Jour, of Insanity, Oct. 1897, Vol. 54, pp. 221- 226, 3 pis. Anatomical Eludings in a Case of Facial Paralysis of Ten Days' Duration in a General Paralytic, with Eemarks on the Termination of the "Auditory" Nerves. Jour, of Experimental Medi- cine, Nov. 1897, Vol. 2, pp. 607-610, 2 pis. Special Report of the Medical Depart- ment of the "Worcester Lunatic Hos- pital. Annual Report, Oct. 1898, pp. 20-27. Critical Review of the Data and General Methods and Deductions of Modem Neurology. Jour, of Comp. Neurol- ogy, Nov.-Dec, 1898, Vol. 8, pp. 113- 148 ; 249-313, 7 pis. Critical Review of Recent Publications of Bethe and Nissl. Ibid., March, 1899, Vol. 9, pp. 38-45. Reviews in the Neurologisches Central- blatt, Psychological Beview, Am. Jour, of Insanity, Jour, of Nervous andMen- tal Disease. ARTHUR MICHAEIi: — University of Heidelberg, 1873-75 ; Uni- versity of Berlin, 1875-78 ; ]&cole de M6de- cuie, 1879-80; Professor of Chemistry, Tufts CoUege, 1881-89; Ph.D. (Honor- ary), Tufts College, 1889; Professor of Chemistry, Clark University, Sept.- Dec. , 1889 ; Research Work in England, 1890-94; Professor of Chemistry, Tufts College, 1894-. Author of : — Ueber die Einwlrkung von Kaliumsulfhy- drat auf Chloralhydrat. Ber. d. deuts. chem. Oesellschaft, 1876, Vol. 9, pp. 1267-1268. Ueber die Darstellung und Bigenschaften des Trijodresorcins. ("With T. H. Norton.) Ibid., Vol. 9, pp. 1752-1753. Ueber die Einwirkung von wasserentzie- henden Mitteln auf Saureanhydride. (With S. Gabriel.) Ibid., 1877, Vol. 10, pp. 391-393; 1551-1562, 2199- 2210; 1878, Vol. 11, pp. 1007-1021, 1679-1683. ZurDarstellungderParamidobenzoesaure. Ibid., 1877, Vol. 10, pp. 576-580. Ueber die Diamidosulfobenzid-Dicarbon- saure. (With T. H. Norton.) Ibid., Vol. 10, pp. 580-583. Zur Kenntniss der aromatischen Sulf one. (With A. Adair.) Ibid., Vol. 10, pp. 583-587. Ueber die Einwirkung des Broms auf Aethylphtalimid. Ibid. Vol. 10, pp. 1644-1645. Ueber die Einwirkung des Chlorjods auf aromatische Amine. (With L. M. Norton.) Ibid., 1878, Vol. 11, pp. 107-116. Zur Kenntniss der aromatischen Sulfone. (With A. Adair.) Ibid., Vol. 11, pp. 116-121. Ueber Benzylmethylglycolsaure. (With S. Gabriel.) Ibid., 1879, Vol. 12, pp. 814^816. On the Action of Iodine Monochloride upon Aromatic Acids. (With L. M. Norton.) Am. Chem. Jour., 1879, Vol. 1, pp. 255-267. On the Synthesis of Helicin and Phenol- glucoside. Ibid., Vol. 1, pp. 305-312. On a New Formation of Stilbene and some of its Derivatives. Ibid., Vol. 1, pp. 312-316. 524 Titles of On Mono-Ethylphthalate. IhU., 1880, Vol. 1, pp. 413-416. On a New Formation of Ethyl-Mustard Oil. Ibid., Vol. 1, pp. 416-418. On the Preparation of Methyl Aldehyde. Ibid., Vol. 1, pp. 418-420. On the " Migration of Atoms in the Mole- cule " and Reimer's Chloroform Alde- hyde Reaction. Ibid., Vol. 1, pp. 420-426. On a- and 6-Monohromcrotonic Acids. (WithL. M. Norton.) Ibid., Vol. 2, pp. 11-19. Preliminary Note on the Synthesis of Methylconine and Constitution of Co- nine. (With Charles Gundelach.) Ibid., Vol. 2, pp. 171-172. Ueher die Einwirkung von aromatisohen Oxysauren auf Phenole. Ber. d. deuts. chem. Gesellschaft, 1881, Vol. 14, pp. 656-658. Ueber die Synthese des Methylarbutins. Ibid. Vol. 14, pp. 2097-2102. Zur Kenntniss des Paraconiins. Ibid., Vol. 14, pp. 2105-2110. Ueber die Synthese des Saloins und des Anhydrosalicylglucosids. Ibid., 1882, Vol. 15, pp. 1922-1925. On the Action of Aromatic Oxy-aoids on Phenols. Am. Chem. Jour., 1883, Vol. 5, pp. 81-97. On Some Properties of Phenylsulphona- cetio Ethers. (With A. M. Comey.) Ibid., Vol. 5, pp. 116-119. Synthetical Researches in the Gluooside Group. Ibid., Vol. 5, pp. 171-182. On the Formation of Crotonio and 6-Oxy- butric Aldehydes from Ethyl Alde- hyde. (With Adolph Kopp.) Ibid., Vol. 5, pp. 182-191. On the Action of Sodium Ethyl Oxide on Bromethylidenebromide. Ibid., Vol. 5, pp. 192-197. A New Synthesis of Allantol'n and Some Suggestions on the Constitution of TJric Acid. Ibid., Vol. 5, pp. 198- 202. On a Convenient Method for Preparing Eromacetic Acid. Ibid., Vol. 5, pp. 202-203. On Several Cases of Intermolecular Re- arrangement. Ibid., Vol. 5, pp. 203^ 205. On a New Synthesis of Cinnamio Acid. Ibid., Vol. 5, pp. 205-206. On the Action of Aldehydes on Phenols. Ibid., Vol. 5, pp. 339-349. Action of Ethylaldehyde on Orcin and Resoroin. (With A. M. Comey.) Ibid., Vol. 5, pp. 349-853. Some Convenient Quantitative Lecture Apparatus. Ibid., Vol. 5, pp. 363- 359. Observations on the Action of Acetyl- chloride and Acetic Anhydride on Corn and Wheat Starch. Ibid., Vol. 5, pp. 359-360. On the Constitution of Resooyanin. Ibid. , Vol. 5, pp. 434.-440. Ueber die optisch-inactive Asparaginsaure. (With J. F. Wing.) Ber. d. deuts. chem. Gesellschaft, 1884, Vol. 17, p. 2984. On the Action of Sodium Phenylsulphin- ate on Methylene Iodide. (With G. M. Palmer.) Am. Chem. Jour., 1884, Vol. 6, pp. 253-257. On the Conversion of Organic Isocyanates into Mustard Oils. (With G. M. Palmer.) Ibid., Vol. 6, pp. 257-260. Synthetical Researches in the Glucoside Group. Ibid., Vol. 6, pp. 336-340. On the Action of Methyl Iodide on As- paragine. (With J. F. Wing.) Ibid., 1885, Vol. 6, pp. 419-422. On Some Properties of Phenylsulphona- cetio Ethers. (With G. M. Palmer.) Ibid., Vol. 7, pp. 65-71. Note on the Constitution of the Addition- Product of Chlorhydric Acid to Ethyl- cyanide. (With J. F. Wing.) Ibid., Vol. 7, pp. 71-74. On the Decomposition of Cinchonine by Sodium Ethylate. Ibid., Vol. 7, pp. 182-189. On Simultaneous Oxidation and Reduc- tion by Means of Hydrocyanic Acid. (With G. M. Palmer.-) Ibid., Vol. 7, pp. 189-194. On the Action of Alkyl Iodides on Amido Acids. (With J. F. Wing.) Ibid., Vol. 7, pp. 195-199. Published Papers. 525 On Resacetophenone. (With G. M. Palmer.) Ihid., Vol. 7, pp. 275-277. On Inactive Aspartic Acid. (With J. F. Wing.) Ihid., Vol. 7. pp. 278-281. Ueber die Einwirkung von Piinffach- Chlorphosphor auf die Aether organ- isoher Sauren. Ber. d. deuts. chem. Qesellschafi, 1886, Vol. 19, pp. 845- 847. Ueber einen Zusammenhang zwisohen Anilidbildung und der Constitution ungesattigter, mehrbasischer, organ- ischer Sauren. Ihid., Vol. 19, pp. 1372-1375. Ueber einen Zusammenhang zwischen Anilidbildung und der Constitution ungesattigter, mehrbasischer, organ- ischer Sauren. (With G. M. Palmer. ) lUd., Vol. 19, pp. 1375-1376. Ueber die Einwirkung des Anillns auf die Brommalein und Chlorfumarsaure. lUd., Vol. 19, pp. 1377-1378. Zur Isomerie in der Zimmtsaurereihe. (With G. M. Browne.) Ihid., Vol. 19, pp. 1378-1381. Zur Isomerie in der Eettreihe. Ihid., Vol. 19, pp. 1381-1386. Ueber die Nitrirung des Phenylhydrazins. Ihid., Vol. 19, pp. 1368-1388. Zur Kenntniss der Einwirkung von Alde- hyden auf Phenole. (With J. P. Ry- der.) Hid., Vol. 19, pp. 1388-1390. Die CitraoonsSure als Reagenz zur Erken- nung und Soheidung der aromatisohen Amine. Ihid., Vol. 19, pp. 1390-1392. Ueberftihrung der a-Bromzimmtather in Benzoylessigather. (With G. M. Browne.) Ihid., Vol. 19, pp. 1392- 1393. Zur Isomerie in der Zimmtsaurereihe. (With G. M. Browne.) Ibid., 1887, Vol. 20, pp. 560-556. Bemerkungen zu einer Abhandlung des Hrn. L. Claisen. Ihid., Vol. 20, pp. 1572-1573. On the Addition of Sodium Acetacetic Ether and Analogous Sodium Com- pounds to Unsaturated Organic Ethers. Am. Chem. Jour., 1887, Vol. 9, pp. 112-124. On Some New Reactions with Sodium Acetacetic and Sodium Malonic Ethers. Ibid., Vol. 9, pp. 124-129. On the Action of Aldehydes on Phenols. (With J. P. Ryder.) Ibid., Vol. 9, pp. 130-137. Researches on AUoisomerism. /6ia!., Vol. 9, pp. 180-183. A Relation between the Constitution of Polybasic Unsaturated Organic Acids and the Formation of their Anilides. Ibid., Vol. 9, pp. 183-197. A Relation between the Constitution of Polybasic Unsaturated Organic Acids and the Formation of their Anilides. (With G. M. Palmer.) Ibid., Vol. 9, pp. 197-204. On the Action of Phosphorus Pentachlo- ride on the Ethers of Organic Acids, and on some Derivatives of Acetic Acid. Ibid., Vol. 9, pp. 205-217. On the Action of Phosphorus Pentachlo- ride on Aoetanilide. Ibid., Yo\. 9, pp. 217-219. Preliminary Notes. Ibid., Vol. 9, pp. 219-222. Researches on AUoisomerism. (With G. M. Browne.) Ihid., Vol. 9, pp. 274- 289. Remarks on the Constitution of Levulinic and Maleic Acids. Ibid., Vol. 9, pp. 364-372. Ueber einebequeme Darstellungsweise von bromirten Fettsauren. Jour. f. prak- tische Chemie, 1887, Vol. 35, pp. 92-95. Das Verhalten von EssigsSure und einigen Derivaten derselben gegen Funffach- Chlorphosphor. Ibid., Vol. 35, pp. 95-96. Ueber die Constitution der Trimethylen- tricarbonsaure. Ibid., Vol. 35, pp. 132-136. Zur Kenntniss der Einwirkung des Funf- fach-Chlorphosphors auf Acetanilid. Ihid.,Yo\. 35, pp. 207-208. Ueber die Bildung des Indigblau aus Orthonitrophenylpropiolsaure mittelst Cyankalium. Ibid., Vol. 35, pp. 254- 256. Ueber AUoisomerie in der Crotonsaure- reihe. (With G. M. Browne.) Ibid., Vol. 35, pp. 267-259. 526 Titles of Ueber die Addition von Natriumacetessig- und Natriummalonsaureatliem zu den Aethem ungesattigter Sauren. Ihid., Vol. 35, pp. 349-356. Die Reduction von Alpha^ imd AUoalpha^ bromzimmtsauren zu Zimmtsaure. Ibid., Vol. 35, pp. 357-358. Ueber aromatische Hydroxylamine. (With G. M. Browne.) lUd., Vol. 35, pp. 358-359. Ueber neue Eeactioneu mit Natriumacet- essig- und Natriummalonsaureather. Ihid., Vol. 35, pp. 449-459. Ueber das Verhalten von Oxalsaureather zu Eesorcin. Ihid., Vol. 35, pp. 510- 512. Antwort auf eine Bemerkung von L. Claisen. Ihid., Vol. 36, pp. 113-114. Zur Isomerie in der Crotonsaurereihe. (With G. M. Browne. ) Ihid. , Vol. 36, pp. 174-176. Znr Constitution des Natriumacetessig- athers. Ihid., 1888, Vol. 37, pp. 473- 530. Ueber das Verhalten von Natriummalon- ather gegen Eesorcinol. Ibid., Vol. 37, pp. 469-471. Zur Alloisomerie in der Crotonsaurereihe. (With H. Pendleton.) /&iU, Vol. 38, pp. 1-5. Zur Kritik der Abhandlung von J. Wislicenus: "Ueber die raumliohe Anordnung der Atome in organisohen Molekiilen." Ihid., Vol. 38, pp. 6-39. Preliminary Note on the Constitution of Sodium Acetacetic and Malonic Ethers. Am. Chem. Jour., 1888, Vol. 10, pp. 158-160. Bemerkung zu der Abhandlung von Otto und Bossing iiber die Ersetzbarkeit des Natriums im Natriumphenylsulfones- sigather duroh Alkyle. Ber. d. deuts. chem. GeseUsehaft, 1890, Vol. 23, pp. 669-671. On the Constitution of Sodium Acetacetic Ether. Am. Chem. Jour., 1892, Vol. 14, pp. 481-544. On the Action of Acetic Anhydride on Phenylpropiolio Acid. (With J. E. Bucher.) Ibid., 1898, Vol 20, pp. 89- 120. On the Eormation of Imido-1, 2-Diazo. Derivatives from Aromatic Azimides and Esters of Aoetyleneoarboxylio Acids. (With F. Luehn and H. H. Higbee.) Ibid., Vol. 20, pp. 377- 395. Zur Schmelzpunktsbestimmung von hoch- schmelzenden und sogen. unschmelz- baren organischen Verbindungen. Ber. d. deuts. chem. Gesellschaft, 1895, Vol. 28, pp. 1629-1633. Ueber die Addition von Schwefel zu un- gesattigten organischen Verbindungen. Ibid., Vol. 28, pp. 1633-1637. Ueber die Einwirkung von Essigsaurean- hydrid auf Sauren der Aoetylenreihel. (With J. E. Bucher.) Ibid., Vol. 28, pp. 2511-2512. Einwirkung v. Aethyljodid u. Zink auf A a /3-Pettester. Ibid., Vol. 29, p. 1791. Zur Kenntniss der Additionsvorgange bei den Natriumderivaten von Formyl- und Acetessigestern, und Nitroathanen. Ihid., Vol. 29, pp. 1794-1799. Zur Constitution der Oxalessigsaure. (With J. E. Bucher.) Ibid., Vol. 29, pp. 1792-1793. Ueber die Eegehnassigkeiten bei der Anla- gerung von Halogenverbindungen auf ungesattigten Sauren. Jour. f. prakt. Chemie, 1889, Vol. 40, pp. 171-179. Ueber die Einwirkung von JodwasserstofE auf die Krotonsauren. Ihid., Vol. 40, pp. 95-96. Zur Kenntniss der Lavulinsaure und des Aoetondiessigsauredilaktons. Ibid., Vol. 43, pp. 113-130. Ueber die Addition vou Natriumacetessig- und Natriummalonsaureathem zu den Aethem ungesattigter Sauren. (With P. C. Freer.) Ibid., Vol. 39, pp. 390- 395. Zur Kenntniss der Halogenentziehung bei organischen a /3-Halogensaureathern. (With O. Schulthess.) Ihid., Vol, 39, pp. 587-596. Ueber die Addition von Brom zu Acetylen- dicarbonsaure und deren Althylather. Ihid., Vol. 46, pp. 210-283. Ueber die Einwirkung von Natrium- athylat auf DibrombemsteinsSure- Published Papers. 527 ather. (With C. C. Maisch.) Ihid., Vol. 46, pp. 233-236. CTeber die Crotonsaure und Derivate der- selben. (Witli O. Schulthess.) Ibid., Vol. 46, pp. 236-266. Ueber die BUdvmg von fester Crotonsaure bei der Keduotion von allo-a-Brom- und-clilorcrotoiisaure. Ihid., Vol. 46, pp. 266-272. Beitrage zur Kenntniss einiger Homologen der Aepfelsaure. ("With G. Tissot.) lUd., Vol. 46, pp. 285-304. TJeber die Addition von Chlor zu mehr- basisohen, ungesattigten Fettsauren. (With G. Tissot.) Hid., Vol. 46, pp. 381-427. Ueber die Addition von Natrinmacetessig- und Natriumaoetmalonather zu den Aethern ungesattigter Sauren. Ibid., Vol. 49, pp. 20-25. Beitrage zur Kenntniss der Eingbildung bei organisohen, stiokstoffhaltigenVer- bindungen. Ibid., Vol. 49, pp. 26-43. Untersuohungen iiber AUoisomerie. Ibid., Vol. 49, pp. 289-372. Ueber das Verhalten von Benzaldehyd gegen Phenol. Ibid., Vol. 57, 834- 336. Ueber einige Gesetze und deren Anwen- dung in der organisohen Chemie. Ibid., Vol. 60, pp. 286-470. ALBERT A. MICHELSON : — Midshipman, U. S. Naval Academy, 1873 Instructor in Physics and Chemistry, ibid. 1875-79 ; Nautical Almanac Office, Wash- ington, 1880 ; University of Berlin, 1880 University of Heidelberg, 1881 ; College de France, ^fecole Polytechnique, 1882 Professor of Physics, Case School of Ap- plied Science, Cleveland, O., 1883-89 Corresponding Member, British Associa^ tionforthe Advancement of Science, 1884 Associate Fellow of American Academy of Arts and Sciences, 1885 ; Ph.D (Honorary), Western Reserve University 1886 ; and Stevens Institute, 1887 ; Vice- President, American Association for the Advancement of Science, ibid. ; Member of National Academy of Sciences, 1888 ; Rumford Medal, 1889; Professor of Physios, Clark University, 1889-92 ; Head Professor of Physics, University of Chicago, 1892- ; Bureau International des Poids et Measures, 1892-93; Member, Soci^t^ Frangaise de Physique, 1893 ; Fel- low, Eoyal Astronomical Society, 1896; Foreign Member, Soci6t6 HoUandaise des Sciences, 1897 ; Honorary Member, Cam- bridge Philosophical Society, ibid. ; Mem- ber (for the United States) of the In- ternational Committee of Weights and Measures, ibid. ; Lowell Lecturer, 1899 ; ScD. (Honorary), University of Cambridge (England) ; Honorary Member Royal In- stitute, 1899. Author of : — Experimental Determination of the Veloc- ity of Light. Papers I. and II. Proc. A. A. A. S., 1879 and 1880. The Relative Motion of the Earth and the Luminiferous Ether. Am. Jour, of Sci., 1881, Vol. 22, pp. 120-129. A New Sensitive Thermometer. Jour, de Physique, 1882. Interference Phenomena in a New Form of Refractometer. Am. Jour, of Sci., May, 1882, Vol. 23, pp. 395-400. A Method of Determining the Rate of Tuning-Forks. Am. Jour, of iScL, Jan., 1883. Experimental Determination of the Veloc- ity of Light. Third Paper. Astron. Papers, Jffautical Almanac, Vol. 2. Velocity of Light in Carbon Disulphide and Velocity of Red and Blue Light in Same. Ibid. M. Wolf's Modification of Foucault's Apparatus for the Measurement of the Velocity of Light. Nature, May 7, 1885, Vol. 32, pp. 6-7. Influence of Motion of the Medium on the Velocity of Light. Am. Jour, of Sci., May, 1886, Vol. 31, pp. 377-386. On the Relative Motion of the Earth and the Luminiferous Ether. (With E. W. Morley.) Philosophical Magazine, 5th ser., Dec, 1887, Vol. 24, pp. 449-463. On a Method for Making the Wave Length of Sodium Light the Actual 528 Titles of and Practical Standard of Length. (With E. W. Morley.) Am. Jour, of Sci., Dec, 1887, Vol. 34, pp. 427-430. Fhilosophical Magazine, 5th ser., Dec, 1887, Vol. 24, pp. 463-466. On the Feasibility of Establishing a Light Wave as the Ultimate Standard of Length. (With E. W. Morley.) Am. Jour, of Sci., 8rd ser., Sept., 1889, Vol. 38, pp. 181-186. Measurement by Light Waves. Ibid., Feb., 1890, Vol. 39, pp. 115-121. A Simple Interference Experiment. Ibid. , March, 1890, Vol. 39, pp. 216-218. Application of Interference Methods to Astronomical Measurements. Philo- sophical Magazine, 5th ser., July, 1890, Vol. 30, pp. 1-21. Visibility of Interference Fringes in the Focus of a Telescope. Ibid., March, 1891, Vol. 31, pp. 256-259. Application of Interference Methods to Spectroscopic Measurements. Ibid., April, 1891, Vol. 31, pp. 338-346. Measurement of Jupiter's Satellites by Interference. Mem. Astr. Soc. of the Pacific, 1891. Les m^thodes interf6rentielles en m6trol- ogie et I'^tablissement d'une longueur d'onde comme unitfe absolue de longueur. Eev. Oin. des Sciences, 30 Juin, 1893. Translation in Nature, Nov. 16, 1893. Abstracts in Oomptes Bendus and Soc. de Physique. Determination exp^rimentale de la valeur du mfetre en longueur d'ondes lumi- neuses. Travaux et Memoires du Bureau International des Poids et Mesures, Paris, 1895, Vol. 11, pp. 3-85. On the Broadening of Spectral Lines by Temperature and Pressure. Astro- physical Journal, Nov., 1895. On the Conditions which Affect the Spec- trum Photography of the Sun. Ibid., Jan., 1895. On the Limit of Visibility of Fine Lines in a Telescope. Ibid., June, 1895. The Relative Motion of the Earth and the Ether. Am. Jour, of Sci., 4th ser., 1897, Vol. 3. pp. 475-478. Radiation in a Magnetic Field, Fhilo- sophical Magazine, 5th ser., July, 1897, Vol. 44, pp. 109-115. A New Harmonic Analyser. (With S. W. Stratton.) Am. Jour, of Sci., 4th ser., Jan., 1898, Vol. 5, pp. 1-13. A Spectroscope without Prisms or Grat- ings. Ibid., 4th ser., March, 1898, Vol. 5, pp. 215-217. Radiation in a Magnetic Field, Astro- physical Journal, Feb., 1898. The Echelon Spectroscope. Ibid., June, 1898. Nouvelle M^thode de tracer et d' observer des divisions de precision, formfes par des traits lumineux sur fond noir. Travaux et Memoires du Bureau International des Poids et Mesures, Paris, 1899. DICKINSON SERGEANT MILLER: University of Pennsylvania, 1885-88 ; Fellow in Philosophy, Clark Univer- sity, 1889-90 ; Morgan Fellow, Har- vard University, 1890-91 ; Walker Fellow, ibid., 1891-92; A.B. and A.M., ibid., 1892 ; University of Berlin, 1892-93 ; Ph.D., University of Halle, 1893 ; Asso- ciate in Philosophy, Bryn Mawr College, 1893-98 ; Instructor, Harvard Univer- sity, for the year 1899-1900 ; Member of American Psychological Association. Author of : — The Meaning of Truth and Error. Phil- osophical Beview, July, 1893, Vol. 2, pp. 408-425. The Confusion of Function and Content in Mental Analysis. Proc. Am. Psy. Ass^n, Dec, 1893, and Psychological Beview, Nov., 1895, Vol. 2, pp. 535- 550. The Relations of "Ought" and "Is." Internal. Jour, of Ethics, July, 1894, Vol. 4, pp. 499-512. Desire as the Essence of Pleasure. Proc. Am. Psy. Ass^n, Dec, 1894. Psycho- logical Beview, March, 1895, Vol. 2, pp. 164-165. "The Will to Believe" and the Duty to Doubt. Internat. Jour, of Mhics, Jan., 1899, Vol. 9, pp. 169-195. Published Papers. 529 Professor James on Philosophical Method. Philosophical Review, March, 1899, Vol. 8, pp. 166-179. •WILLIAM S. MILLEH: — M.D., Yale Medical School, 1879 ; Prac- tising Physician, ibid., 1879-86; College of Physicians and Surgeons, New York, 1886-87 ; Lecturer in Microscopical Tech- nique, Mt. Holyoke College, 1887-88; Pathologist, City Hospital and Memorial Hospital, Worcester, Mass., 1888-91; Scholar in Anatomy, Clark Univer- sity, 1889-91 ; Fellow, 1891-92 ; In- structor in Biology, University of Wis- consin, 1892-93 ; Instructor in Vertebrate Anatomy, ibid., 1893-96 ; on leave of absence. University of Leipzig, 1895-96 ; Assistant Professor of Vertebrate Anat- omy, University of Wisconsin, 1895- ; Pellow, Massachusetts Medical Society, Pellow, A. A. A. S. ; Member Anatomische Gesellschaf t, Member Wisconsin Academy of Arts and Sciences. Author of : — The Lobule of the Lung and its Blood- vessels. Anat. Ameiger, 1892, Vol. 7, pp. 181-190. The Structure of the Lung. Jour, of Morph., April, 1893, Vol. 8, pp. 165- 188. On the So-called Incas Eyes. (Science, J-eb. 10, 1893, Vol. 21, pp. 74-75. The Anatomy of the Lung. Bef. Hand- book of the Med. Sciences, 1893, Vol. 9, pp. 571-576. The Anatomy of the Heart of Cambarus. Trans. Wis. Acad, of Sciences, Arts, and Letters, 1895, Vol. 10, pp. 327- 338. The Relation between the Cortex and Medulla in the Cat's Kidney, and an Estimation of the Number of Glumer- uli. Ibid., pp. 525-538. The Lymphatics of the Lung. Anat. An- zeiger, June 4, 1896, Vol. 12, pp. 110- 114. HALCOTT C. MORENO: — A.B., University of Georgia, 1893 ; A.M., ibid., 1894; B.L., ibid., 1896; Tutor in 2m Mathematics, ibid., 1893-97 ; Scholar in Mathematics, Clark University 1897-98 ; Fellow, 1898-99. SAMUEL P. MULLIKEN: — S.B., Massachusetts Institute of Tech- nology, 1887 ; Assistant in Chemistry, University of Cincinnati, 1887-88 ; Gradu- ate Student, University of Leipzig, 1888- 90; Ph.D., University of Leipzig, 1890; Fellow in Chemistry, Clark Univer- sity, Jan.-June, 1891 ; Associate in Chemistry, Bryn Mawr College, 1891-92 ; Instructor in Chemistry, Clark Uni- versity, 1892-94 ; Besearch Assistant to Professor Wolcott Gibbs, Newport, R.I., 1894-95 ; Instructor in Organic Chemistry, Massachusetts Institute of Technology, 1895-. Author of : — Ueber die Konstitution der Chlorzimmt- sauren. (Inaugural-dissertation der Universitat Leipzig.) Leipzig, 1890. 57 pp. The Geometrical Isomerism of the Chlor- cinnamio Acids. Technology Quar- terly, 1891, Vol. 4, pp. 170-177. A New Class of Organic Electrosyntheses. Am. Chem. Jour., June, 1893, Vol. 15, pp. 323-333. Laboratory Experiments on the Class Re- actions of Organic Substances and their Identification. (With A. A. Noyes.) First edition, 17 pp., Maclachlan, Boston, 1896; second edition, 88 pp., 1897, and third edition, 30 pp., 1898. Chem. Publishing Company, Easton, Pa. A Simple Color Reaction for Methyl Al- cohol. (With H. Scudder.) Am. Chem. Jour., March, 1899, Vol. 21, pp. 266-271. Reactions for the Detection of the Nitro- group. (With E. R. Barker.) Ibid., pp. 271-276. F. "WILLIAM MUTHMANN: — Assistant in Analytical Chemistry, Uni- versity of Munich, 1884-86 ; Ph.D., Uni- versity of Munich, 1886; Instructor in 530 Titles of Chemistry and Crystallography, ibid., 1887-89 ; Docent in Chemistry, Clark University, 1889-91 ; Assistant in Chemistry, Academy of Science, Munich, 1891-94 ; Docent in Chemistry, UniTersity of Munich, 1894-95 ; Professor of Inor- ganic and Analytical Chemistry, ibid., 1895-. Author of : — Ueber niedere Oxyde des MolybdSns. (Inaugural dissertation. ) Liebig^s An- nalen, 1887, Vol. 238, pp. 108-137. Ueber Polymorphie und Mischkrystalle einiger organischer Substanzen. Zeits. f. Krystallographie, 1889, Vol. 15, pp. 60-79. Krystallographisch-chemische Notizen. Ibid., 1888, Vol. 15, pp. 387-403. Krystallographische Untersuchung der Phtalsaure, tind einigen Derivate der- selben. (With W. Bamsay.) Ibid., 1889, Vol. 17, pp. 73-84. Messelit, ein neues Mineral. Ibid., 1889, Vol. 17, pp. 93-94. Untersuohungen fiber den Schwefel und das Selen. Ibid., 1890, Vol. 17, pp. 336-367. Zur Prage der Silberoxydulverbindungen. Ber. d. deuts. chem. Gesellschaft, 1887, Vol. 20, pp. 983-990. Krystallographische Untersuchung einjger Derivate der Terephtalsaure. Zeits. f. Krystallographie, 1890, Vol. 17, pp. 460-483. Ueber Isomorphimus einiger organischer Substanzen. Ibid., 1891, Vol. 19, pp. 357-867. Bemerkung fiber den rothen Phosphor. Zeits. f. anorg. Chemie, 1893, Vol. 4, pp. 303-304. Untersuohungen fiber das Selen. (With Dr. J. Schafer.) Ber. d. deuts. chem. Gesellschaft, 1893, Vol. 26, pp. 1008- 1016. Eine bequeme Methode zur Darstellung von Baryumpermanganat. Ibid., pp. 1016-1018. Ueber die Reindarstellung von Eubidium- salzen. Ibid., pp. 1019-1020. Beriohtigung. Ibid., pp. 1425-1426. Beitrage zur Volumtheorie der Krystalli- sirten Korper. Zeits. f. Krystallogra- phie, 1894, Vol. 22, pp. 497-551. Ueber die LSsliohkeit der MischkrystaEe einiger isomorpher Salzpaare. (With Dr. O. Kuntze.) Ibid., 1894, Vol. 23, pp. 368-378. Ueber den sogenannten Schneebergit. Ibid., 1895, Vol. 24, pp. 583-586. Schwefelstickstoff. Ber. d. deuts. chem. Gesellschaft, 1896, Vol. 29, pp. 340- 343. Zur quant. Best, und Scheidung des Kup- fers. Zeits. f. anorg. Chemie, 1896, Vol. 11, pp. 268-271. Ueber einige Verbindungen des Phosphors und Selens. Ibid. , Vol. 13, pp. 191-199. StickstofEpentasulfid. Ibid., Vol. 13, pp. 200-208. Loslichkeit des Sohwefels Ceroxyduls in Wasser. Ibid. ,1897, Vol. 16, pp. 450- 462. Zusammensetzung einiger Tellurmrnera- len. Zeits. f. Krystallographie, 1898, Vol. 29, pp. 140-145. Ueber Permolydate. Zeits. f. anorg. Chemie, 1898, Vol. 17, pp. 73-81. Also Ber. d. deuts. chem. Gesellschaft, 1898, Vol. 31, pp. 1836-1844. Doppelthiosulfate von Kupfer und Ka- lium. Ber. d. deuts. chem. Gesell- schaft, 1898, Vol. 31, pp. 1732-1735. JOHN U. NBF: — A.B., Harvard University (with Honors in Chemistry), 1884 ; Kirkland Fellow, ibid., 1884-87 ; University of Munich, 1884-87 ; Ph.D., University of Munich, 1886 ; Professor and Director of Chemical Laboratory, Purdue University, 1887-89 ; Assistant Professor of Chemistry, Clark University, 1889-92 ; Professor of Chemistry and Director of the Kent Chemi- cal Laboratory, University of Chicago, 1892-96 ; Head Professor of Chemistry and Director of the Kent Chemical Lab- oratory, ibid., 1896-. Author of ; — The Volumetric Determination of Com- bined Nitrous Acid. (With Dr. Kin- Published Papers. 531 nicutt.) Am. Ohem. Jour., Nov. 1883, Vol. 5, pp. 388-389. Ueber einige Derivate des Durols. Ber. d. deuts. chem. Cfesellschaft, 1885, Vol. 18, pp. 2801-2807. Ueber Benzochinonoarbonsauren. Ibid., pp. 3496-3499. TJeber Benzocblnoncarbonsauren. Lie- big's Annalen, 1887, Vol. 237, pp. 1- 39. Ueber Py-3-Phenylobinaldlnsaure und Py-S-Phenylohinolin. (With Dr. Koe- nigs.) Ber. d. deuts. chem. Qesell- schaft, 1886, Vol. 19, pp. 2417-2432. Ueber des Py-3-Phenylchinolln und Py- 3-B-Dichiiiolyle. (WithDr. Koenigs.) Ibid., 1887, Vol. 20, pp. 622-636. Notlz tiber die Cinohoninsaure. (With W. Muthmann. ) Ibid. ,1887, Vol. 20, pp. 636-638. Nitranilsaure aus Chloranil. Ibid., 1887, Vol. 20, pp. 2027-2031. On Tautomeric Compounds. Part I. Am. Ohem. Jour., Jan., 1889, Vol. 11, pp. 1-17. The Constitution of the AnUic Acids. Ibid., pp. 17-26. Ueber tautomere K6rper. Liebig's An- nalen, 1890, Vol. 258, pp. 261-318. Die Constitution des Benzochinons. Jour. f. praktische Chemie, 1890, Vol. 42, pp. 161-188. On Tautomeric Compounds. Part 11. Am. Chem. Jour., June, 1890, Vol. 12, pp. 379-425. The Constitution of Benzoquinone. Part I. Ibid., JiUy, 1890, Vol. 12, pp. 463-488. Zur Kenntniss des Acetessigathers. Lie- big's Annalen, 1891, Vol. 266, pp. 52-138. The Constitution of Benzoquinone. Part II. Am. Chem. Jour., June, 1891, Vol. 13, pp. 422-428. Ueber das zweiwerthige Kohlenstoffatom. Erste Abh. Liebig's Annalen, 1892, Vol. 270, pp. 267-335. Also in Proe. of Am. Acad, of Arts and Sciences, on Bivalent Carbon, for 1892, Vol. 27, pp. 102-162. Zur Kenntniss des Acetessigathers. Lie- big's Annalen, 1893, Vol. 276, pp. 200-245. Ueber die 1.3 Diketone. lUd., 1893, Vol. 277, pp. 59-78. Ueber die Constitution der Salze der NitroparafBne. Ibid., 1894, Vol. 280, pp. 263-291. Also in Froc. of Am. Acad, of Arts and Sciences, 1894, Vol. 29, pp. 124-150. Ueber das zweiwerthige Kohlenstoffatom. Zweite Abh. Liebig's Annalen, 1894, Vol. 280, pp. 291-342. Also in Proc. of Am. Aead. of Arts and Sciences, 1894, Vol. 29, pp. 151-193. Ueber das zweiwerthige Kohlenstofiatom. Dritte Abh. Die Chemie des Cyans und des Isocyans. Liebig's Annalen, 1895, Vol. 287, pp. 265-359. Ueber das zweiwerthige Kohlenstoffatom. Vierte Abh. Die Chemie des Me- thyleus. Ibid., 1897, Vol. 298, pp. 292-374. Notiz iiber die Formhydroxamsaure. Ber. d. deuts. chem. Gesellschaft, 1898, Vol. 31, pp. 2720-2721. Ueber das Phenylacetylen, seine Salze, und seine Halogen Substitutions Pro- dukte. Liebig's Annalen der Chemie, 1899, Vol. 308, pp. 264-328. Ueber das Verhalten der tri- und tetra- balogen-substituirten Methane. Ibid., 1899, Vol. 308, pp. 329-333. Dissociationsvorgange bei den Alkyla- theon der Saltpetersaure, der Schwe- felsaure und der Halogenwassei'stoff- sauren. Ibid., 1899, Vol. 309, pp. 126-189. HERBERT NICHOLS:— B.S., Worcester Polytechnic Institute, 1871; Fellow in Psychology, Clark University, 1889-91; PhJ3., Clark University, 1891; Instructor in Psy- chology, Harvard University, 1891-93; Lecturer in Psychology, Johns Hopkins University, 1895-96; Member American Society of Naturalists, 1890; Member American Psychological Association, 1892. Author of : — The Psychology of Time. Am. Jour, of Psy., Feb., 1891, Vol. 3, pp. 453-529 ; 532 Titles of April, 1891, Vol. 4, pp. 60-112. Henry Holt & Co., N. Y., 1891, 140 pp. The Origin of Pleasure and Pain. PAt7o- sopfticaZ JJemew, July, 1892, Vol.1 .,pp. 403-432; Sept., 1892, Vol. 1., pp. 518- 534. Experiments upon Pain. Report First An. Mtg.Am.Psy.Assn.,T>60.,l?i^2. Mac- millan & Co., N. Y., 1894. Perceptions of Rotation. Ibid., Dec, 1892. Macmillan & Co., N. Y., 1894. Primary Education. Beport Special Cor- respondence, Feb., 1893. Educational Club, Philadelphia, 1893. The Harvard Psychological Laboratory. McClure^ s Magazine, Oct., 1893, Vol. 1, pp. 399-409. The Promise in Mental Science. Ibid., Jan., 1894, Vol. 2, pp. 202-203. Beitrage zur Psychologie des Zeitsinns, and Untersuchungen zur Psychologie und JEsthetik des Ehythmus. By Ernst Meumann. Review. Psycho- logical Beview, Nov., 1894, Vol. 1, pp. 638-641. Our Notions of Number and Space. Ginn & Co., Boston, 1894. 201 pp. The Motor Power of Ideas. Philosophical Beview, March, 1895, Vol. 4, pp. 174- 185. William James. (Biographical Sketch.) The Book Buyer, March, 1895, Vol. 12, pp. 61-63. The "Feelings." Philosophical Beview, Sept., 1895, Vol. 4, pp. 506-530. Pain Nerves. (Discussion.) Psychologi- cal Beview, Sept., 1895, Vol. 2, 487- 490. Psychology and Education. The Citizen, Dec, 1895, Vol. 1, pp. 229-230. Uni- versity Extension Study, Philadelphia. Pain Nerves. (Discussion.) Psychologi- cal Beview, May, 1896, Vol. 3, pp. 309- 313. Fear. By Angelo Mosso. Review. Ibid., July, 1896, Vol. 3, pp. 445-447. TJeber Raumwahmehmungen im Gebiete des Tastsinnes. By Chas. Hubbard Judd. Review. Ibid., Sept., 1896, Vol. 3, pp. 577-578. Professor Baldwin's New Factor in Evo- lution. The American Naturalist, Sept., 1896, Vol. 30, pp. 697-710. Further Comments on Professor Baldwin's New Factor in Evolution. Ibid., Nov., 1896, Vol. SO, pp. 951-954. The Biologic Origin of Mental Variety, or How We came to Have Minds. Ibid., Dec, 1896, Vol, 30, pp. 963-975; Jan., 1897, Vol. 31, pp. 3-16. The Psycho-Motor Problem. Am. Jour, of Insanity, July, 1897, Vol. 54, pp. 59- 80. Psychology and Physiology. Ibid., Oct., 1897, Vol. 54, pp. 181-200. The Psychology of the Emotions. By Th. Eibot. Review. Ibid., Oct., 1897, Vol. 54, pp. 266-270. Hallucinations and Illusions. By Ed- mund Parish. Review. Ibid., Jan., 1898, Vol. 54, pp. 472-474. The New Psychology. By E. W. Scrip- ture. Review. Ibid., Jan., 1898, Vol. 54, pp. 474-475. The Psychology of Suggestion. By Boris Sidis. Review. Ibid., April, 1898, Vol. 54, pp. 643-644. The Genesis and Dissolution of the Fac- ulty of Speech. By Joseph Collins. Review. Ibid., July, 1898, Vol. 55. p. 184. THOMAS F. NICHOLS: — A.B. , Bowdoin College, 1892 ; Scholar in Mathematics, Clark TTniversity, 1892- 93; FeUow, 1893-95; Ph.D., Clark UniverBlty, 1895; Assistant in Mathe- matics, University of Wisconsin, 1895-96; Assistant Professor of Mathematics, Ham- ilton College, 1896-. Author of : — On Some Special Jaoobians. Mathemati- eal Beview, July, 1896, Vol. 1, pp. 60-80. On the Generation of Certain Curves of the Fifth and Sixth Orders. Ibid., April, 1897,Vol. 1, pp. 141-153. ARTHUR A. NOTES: — S.B., Massachusetts Institute of Tech- nology, 1886; S.M.,i6itI., 1887; Assistant Published Papers. 533 in Chemistry, ibid., 1887-88; Ph.D., University of Leipzig, 1890 ; Instructor in Chemistry, Massachusetts Institute of Technology, 1890-93 ; Non-resident Lecturer in Physical Chemistry, Clark University, 1892-94; Assistant Pro- fessor of Chemistry, Massachusetts Insti- tute of Technology, 1893-97; Associate Professor of Organic Chemistry, ihid., 1897-99; Professor of Theoretical and Or- ganic Chemistry, ibid., 1899-. Author of : — On the Action of Heat upon Ethylene. (With L. M. Norton.) Am. Chem. Jour. Oct., 1886, Vol. 8, pp. 362- 364. The Constitution of Benzol. Technology Quarterly, 1887, Vol. 1, pp. 79-90. On the Action of Heat on Isobutylene. Ibid., pp. 278-281. Note on the Butines. (With L. M. Nor- ton.) Am. Chem. Jour., Nov., 1888, Vol. 10, pp. 430-433. An Index to the Literature of the Butines and their Halogen Addition Products. Technology Quarterly, 1888, Vol. 2, pp. 112-122. Ueher die Abweichungen von den Gasge- setzen in Losungen. Zeits. f. physik. Chemie, 1890, Vol. 5, pp. 53-67. Ueber die gegenseitige Beeinflussung der Loslichkeit von dlssociierten Korpern. Ibid., 1890, Vol. 6, pp. 241-267. Ueber vermehrte LBslichkeit. Anwen- dung der Gefrierpunktsbestimmungen 2ur Ermittelung der Vorgange in Losung. Ibid., 1890, Vol. 6, pp. 385- 402. Ueber die Bestimmung der elektrolyti- schen Dissociation von Salzen mittels LSslichkeitsversuche. Ibid., 1892, Vol. 9, pp. 603-632. Translation in Technology Quarterly, 1891, Vol. 4, pp. 259-291. Ueber die Wasserstoffionabspaltnng bei den sauren Salzen. Ibid., 1893, Vol. 11, pp. 495-500. Translation in Tech- nology Quarterly, 1892, Vol. 5, pp. 342- 349. Influence of the Introduction of a Sul- phonic Acid Group upon the Power of a Developer. (With W. K. Gaylord.) Technology Quarterly, 1893, Vol. 6, pp. 60-61. Ueber die elektrolytische Eeduction des Nitrobenzols in SchwefelsaurelSsung. (With A. A. Clement.) Ber. d. deuts. chem. Gesellschaft, 1893, Vol. 26, pp. 990-992. Translation in Technology Quarterly, 1893, Vol. 6, pp. 62-64. Ueber die Bestimmung der elektrolyti- schen Dissociation von Salzen mittels LSslichkeitsversuche. Zeits. f. phy- sik. Chemie, 1893, Vol. 12, pp. 162-166. Translation in Technology Quarterly, 1893, Vol. 6, pp. 237-240. L5slichkeit des sauren Kaliumtartrats bei Gegenwart anderer Salze. (With A. A. Clement.) Zeits. f. physik. Chemie, 1894, Vol. 13, pp. 412-416. Die WasserstofSonabspaltung bei dem sauren Kaliumtartrat. Zeits. f. physik. Chemie, 1894, Vol. 13, pp. 417-418. Kryoskopische Untersuchungen mit Alu- mlnaten und Boraten von Alkalime- tallen. (With W. R. Whitney.) Ibid. , 1894, Vol. 15, pp. 694-698. The Electrolytic Eeduction of Paranitro- benzoic Acid in Sulphuric Acid Solu- tion. (With A. A. Clement.) Am. Chem. Jour., Nov., 1894, Vol. 16, pp. 511-513. Eine Priif ung der Principe der LBslichkeits- beeinflussung und ein Vergleich der daraus und aus der elektrischen Leit- fahigkeit berechneten Dissooiations- -werte. (With C. G. Abbot.) Zeits. f. physik. Chemie, 1895, Vol. 16, pp. 125-138. Translation in Technology Quarterly, 1895, Vol. 8, pp. 47-62. Die Geschwindigkeit der Reaktion zwischen Zlnnohlorur und Eisen- ohlorid. Eine Reaktion dritter Ord- nung. Zeits. f. physik. Chemie, 1895, Vol. 16, pp. 546-561. Synthesis of Diphenylblphenyl and its Identification as Benzerythrene. (With Rolfe M. Ellis.) Am. Chem. Jour., Oct., 1895, Vol. 17, pp. 620-622. Also in Technology Quarterly, 1895, Vol. 8, pp. 178-180. 534 Titles of Die Geschwindigkeit der Hydrolyse des Salicins durch Sauren. (With "W. T. Hall.) Zeits.f. physiJc. Chemie, 1895, Vol. 18, pp. 240-244. Translation in Technology Quarterly, 1895, Vol. 8, pp. 283-293. Beitrag zur Kenntniss der Gesetze der Geschwindigkeit von polymolekularen Eeaktionen. (With W. O. Scott.) Zeits. f. physik. Ohemie, 1895, V61. 18, pp. 122-132. The Electrolytic Reduction of Paranitro Compounds in Sulphuric Acid Solu- tion. (With J. T. Dorrance.) Ber. der deuts. chem. Gesellschaft, 1896, Vol. 28, pp. 2349-2352. Translation in Jour. Am. Chem. Soc, 1895, Vol. 17, pp. 855-859. The Occurrence of Triraethylene Glycol as a By-product in the Glycerine Manu- facture. (With W. H. Watkins.) Jour. Am. Chem. Soc, 1895, Vol. 17, pp. 890-891. Also Technology Quarterly, 1895, Vol. 8, pp. 261- 262. Die katalytische Wirkung der Wasser- stoffjonen auf polymolekulare Beak- tionen. Zeits. f. physik. Chemie, 1896, Vol. 19, pp. 599-606. Bemerkung Tiber das Gesetz der Ge- schwindigkeit der Eeaktion zwischen Eisenchlorid und Zinnchloriir. Ihid., 1896, Vol. 21, p. 16. Die innere Eeibung des Queoksilher- dampfes. (With H. M. Goodwin.) lUd., 1896, Vol. 21, pp. 671-679. Translation in Physical Beview, Noy.- Dec, 1896, Vol. 4, pp. 207-216. Sind Diphenyljodonium- und Thallium- nitrat isomorph ? (With C. W. Hap- good. Zeits. f. physik. Chemie, 1896, Vol. 22, pp. 464^65. Instruction in Theoretical Chemistry. Technology Quarterly, 1896, Vol. 9, pp. 323-325. Formation of Diacetylenyl (Butadiine) from Copper Acetylene. (With C. W. Tucker.) Am. Chem. Jour., Feb. 1897, Vol. 19, pp. 123-128. Synthesis of Hexamethylene-Glycol Di- ethyl Ether and Other Ethers from Trimethylene Glycol. Ihid., Nov., 1897, Vol. 19, pp. 766-781. Die Reaktionsgeschvrindigkeit zwischen Eisenchloriir, Kaliumchlorat und Salz- saure. (With R. S. Wason.) Zeits. f. physik. Chemie, 1897, Vol. 22, pp. 210-221. Translation in Jour. Am. Chem. Soc, 1897, Vol. 19, pp. 199- 213. Bestimmung des osraotischen Druckes mit- tels Dampfdruckmessungen. (With C. G. Abbot.) Zeits. f. physik. Chemie, 1897, Vol. 23, pp. 56-77. Ueber die Auflosungsgeschwindigkeit von festen Stoffen in Uiren eigenen Lo- sungen. (With W. R. Whitney.) Ibid., pp. 689-692. Translation in Jour. Am. Chem. Soc, 1897, Vol. 19, pp. 930-934. Bemerkung uber die Kinetische Theorie derLosungen. Zeits. f. physik. Chemie, 1897, Vol. 24, p. 366. Qualitative Chemical Analysis. The Mac- millan Co., N. Y., 1897. 89 pp. Third edition. Laboratory Experiments on the Class Reactions and Identification of Organic Substances. (With S. P. Mulliken.) Chemical Publishing Co., Easton, Pa., 1897. 31 pp. Second edition. Investigation of the Theory of Solubility Effect in the case of Trionio Salts. (With E. H. Woodworth.) Jour. Am. Chem. Soc, 1898, Vol. 20, pp. 194- 201. Also Zeits. f. physik. Chemie, 1898, Vol. 26, pp. 152-158. The Reliability of the Dissociation Values Determined by Electrical Conductivity Measurements. Jour. Am. Chem. Soc, 1898, Vol. 20, pp. 517-528. Also Zeits. f. physik. Chemie, 1898, Vol. 26, pp. 699-710. The Solubility of Salts of Weak Acids in Stronger Acids. (With David Schwartz.) Jour. Am. Chem. Soc, 1898, Vol. 20, pp. 743-751. Also Zeits. f. physik. Chemie, 1898, Vol. 27, pp. 279-284. Die Theorie der Losliohkeitsbeeinflussung bei zweiioningen Electrolyten mit lauter verschiedenen Jonen. Zeits. Published Papers. 535 /. physik. Chemie, 1898, Vol. 27, pp. 267-278. The Solubility of Acids in Solutions of the Salts of Other Acids. (With E. S. Chapin.) /6id, pp. 442-446. Trans- lation in Jour. Am. Chem. Soc, 1898, Vol. 20, pp. 751-756. Die Loslichkeit von Jod in verdiimiten KaliumjodidlSsungen. (With L. J. Seidensticker.) Zeits. f. physik. Chemie, 1898, Vol. 27, pp. 857-360. Translation in Jour. Am. Chem. Soc, 1899, Vol. 21, pp. 217-220. Die Geschwindigkeit der Eeaktion zwisohen Silberacetat und Natriumformiat. Eine Reaktion dritter Ordnung. (With G.T.Cottle.) Zeits. /.physik. Chemie, 1898, Vol. 27, pp. 579-584. Die Beziehung zwischen osmotischer Ar- beit und osmotischem Druok. Ibid., 1899, Vol. 28, pp. 220-224. C. A. ORR: — A.B., University of Michigan, 1887 ; Stu- dent, Johns Hopkins University, 1887-88 ; Principal, High School, Salem, O., 1888- 89 ; Anthropologist, Solar Eclipse Iizpedition, Clark University, 1889- 90 ; Lecturer in Latin, University of Chicago, 1892- ; Instructor, Chicago High Schools, 1894-. VICTOR PAPCKB:— Ph.D., University of Gottingen, 1888; Assistant in Chemistry, Clark Univer- sity, 1889-90 ; Medical Student, Uni- versity of Leipzig, 1893. GEORGE E. PARTRIDGE: — Special Student in Philosophy, Clark University, 1895-96 ; Scholar in Psy- chology, 1896-98 ; FeUow, 1898-99. Author of: — Second Breath. Pedagogical Seminary, April, 1897, Vol. 4, pp. 372-381. Blushing. Ibid., April, 1897, Vol. 4, pp. 387-394. Some Mental Automatisms. (With E. H. Lindley.) Ibid., July, 1897, Vol. 5, pp. 41-60. Keverie. Ibid., April, 1898, Vol. 5, pp. 445-474. Child Study in Connection vrith the Va- cation Schools. (With H. S. Curtis.) Eeport on the Vacation Schools and Playgrounds, N. Y. City, Borough of Manhattan and the Bronx, 1898, pp. 51-97. Experiments upon the Control of the Keflex. Am. Jour, of Fsy. (In press.) T. RICHARD PEEDE: — Christian Biblical Institute, Kew York, 1881-84; Boston University, 1884-85; Special Student in Philosophy and Pedagogy, Clark University, 1895-96 ; Honorary Scholar in Philosophy, 1896-97 ; Pastor, South Baptist Church, Worcester, 1895-. JOSEPH DE PEROTT:— Universities of Paris and Berlin, 1877-80 ; Decent in Mathematics, Clark Uni- versity, 1890-. Author of: — Sur la sommation des nombres. SuU. des Sci. Mathematiques, 1881, 2d ser. , Vol. 5, pp. 37-40. Sur I'infinit^ de la suite des nombres pre- miers. Ibid., pp. 183-184. Sur une arithm^tique espagnole du 16™« si^cle. Bull, di bibliografla e di storia delle scienze matematiche, 1882, Vol. 15, pp. 163-170. Sur la recherche des diviseurs des fonc- tions entiferes. Bull, de la Soc. Math&- matique, 1882, Vol. 10, pp. 250-251. Sur un th^orfeme de Grau.ss. Ibid., pp. 87- 88. Sur la formation des determinants irr^gu- liers. Jour. f. Mathematik, 1883, Vol. 95, pp. 232-237. Sur le problfeme des fous. Bull, de la Soc. Mathematique, 1883, Vol. 11, pp. 173- 186. Sur la formation des determinants irr^gu- liers. Second Mtooire. Jour. f. Mathematik, 1884, Vol. 96, pp. 327- 348. 536 Titles of Demonstration du th^orfeme fondamental de I'algfebre. Ihid., 1885, Vol. 99, pp. 141-160. Demonstration de I'existenoe des raoines primitives pour les modules 6gaux k des puissances de nombre premier im- pair. Bull, des Sci. Mathematiques, 1885, 2" s6r., Vol. 9, pp. 21-24. Sur les logarithmes k un grand nombre de deoimales et en particulier sur les Ta- bles de Steinhauser. Ibid., 1887, 2» s^r.. Vol. 11, pp. 61-60. Sur requation t2 — I)u2=—l. Jour, f. Mathematik, 1888, Vol. 102, pp. 185- 223. Remarque au sujet du thdorfeme d'Euolide sur 1' infinite du nombre des nombres premiers. Am. Jour, of Mathematics, 1888, Vol. 11, pp. 99-138 ; 1891, Vol. 12, pp. 235-308. Sur une proposition empirique enoncee au Bulletin. Bull, de la Soc. Mathema- tique, 1889, Vol. 17, pp. 155-156. On a Theorem of Gauss. J. H. U. Circu- lar, 1889, No. 78, p. 30. The Gaussian Interpolation Theory, for- mulse for w = 7, 8, 9. Quar. Jour, of Mathematics, 1891, Vol. 25, pp. 200- 202. Sur les groupes de Galois. Bull, de la Soc. Mathematique, 1893, Vol. 21, pp. 61-65. Demonstration de I'existence de racines primitives pour tout module premier impair. Bull, des Sci. Mathematiques, 1893, 2» ser., Vol. 17, pp. 66-83. Demonstration de I'existence de racines primitives module premier impair. Ibid., 1894, 2« ser.. Vol. 18, pp. 64-66. Mathematical Tables. Sci. Am. Supple- ment, July 7, 1894, Vol. 38, pp. 15436- 15437. The Theory of Numbers. (Review of M. Stieltjes's "Sur la theorie des nom- bres.") Bull, of Am. Math. Soc, June, 1895, Vol. 1, pp. 217-282. DANIEL EDWARD PHILLIPS: — Graduate West Virginia State Normal School, 1890 ; Principal, Public Schools, PhiUppi, W. Va., 1890-91; A.B., Uni- versity of Nashville, 1893 ; A.M., ibid., 1894; Scholar in Psychology, Clark University, 1894- March, 1895; Pro- fessor of Pedagogy, Normal Department, University of Georgia, March, 1895-Jan., 1897 ; Honorary Scholar in Psychol- ogy, Clark University, Jan.-June, 1897; PeUov7, 1897-98; Ph.D., Clark University, 1898; Professor of Philosophy and Education, University of Denver, 1898-. Author of : — The End of Education. 22 pp. Religious Education. Peabody Becord, Nov., 1893, Vol. 4, pp. 63-60. Courses of Study for Common Schools. Southern Jour, of Ed., Oct., 1896, Vol. 9, pp. 472-478. Genesis of Number Forms. Am. Jour, of Psy., July, 1897, Vol. 8, pp. 506-527. Number and its Application psychologi- cally considered. Pedagogical Sem^ inary, Oct., 1897, Vol. 5, pp. 221-282. Some Remarks on Number and its Appli- cation. Ibid., April, 1898, Vol. 5, pp. 590-599. Some Aspects of the Child Study Move- ment. Northwestern Monthly, Jan., 1899, Vol. 9, pp. 233-237. The Teaching Instinct. Pedagogical Sem- inary, March, 1899, Vol. 6, pp. 188- 246. Sunday-School Teaching. Study, March, 1899,Vol. 4, pp. 309-313. JEPPEHSON R. POTTER: — A.B., Brown University, 1877 ; A.M., ibid., 1887; Instructor, Vermont Academy, 1877-78; State Normal School, Castine, Me., 1878-85; Professor of Pedagogy, State College of Kentucky, 1885-88 ; In- structor in Natural Sciences, State Nor- mal School, Earmington, Me., 1888-90; Scholar in Psychology, Clark Uni- versity, 1890-91 ; Superintendent of Schools, Ashland and Hopkinton, Mass., 1891-92 ; Superintendent of Schools, Wal- pole, Eoxboro, and Norfolk, Mass., 1892- 95 ; Superintendent of Schools, Walpole and Foxboro, Mass., 1896-98 ; Member : Published Papers. 637 New England Conference oil Educational Workers; New England Association of School Superintendents. Author of : — History of Methods of Instruction in Geography. Pedagogical Seminary, Dec, 1891, Vol. 1, pp. 415-424. J. O. QUANTZ: — B.A., University of Toronto (Honors in Philosophy and Psychology), 1894 ; Fel- low in Psychology, University of Wiscon- sin, 1895-97 ; Ph.D., University of Wis- consin, 1897 ; Honorary Fellow in Psy- chology, Clark University, 1897-98; Honorary Eellow in Philosophy, Cornell University, 1898-99. Author of: — The Influence of the Color of Surfaces on our Estimation of their Magnitude. Am. Jour, of Psy., Oct., 1895, Vol. 7, pp. 26-41. Problems in the Psychology of Beading. Psychological Beview, Monograph Sup- plement, Dec, 1897, pp. 1-51. The Physiology of Shorthand. Phono- graphic World, March, 1898, Vol. 13, pp. 292-293. Dendro-psychoses. Am. Jour, of Psy., July, 1898, Vol. 9, pp. 449-506. An Analysis of the Muscular Sensations involved in Drawing a Line. HOLLA R. RAMSITT': — Assistant in Shop, Indiana University, 1894-95 ; A.B., Department of Physics, ibid., 1895; A.M., ibid., 1898; Science Teacher, Decatur, Ind., High School, 1895-96 ; Laboratory Assistant, Indiana University, 1896-97 ; Professor of Physics, Westminster College, 1897-98 ; Scholar in Physics, Clark University, 1898- 99 ; Assistant in Physics, Cornell Univer- sity, 1899-. Author of : — A Photographic Study of Electrolytic Cells. Physical Beview, Sept., 1899, Vol. 9, pp. 189-190, 1 pi. JOHN F. RBIGART: — A.B., Dickinson College, 1888 ; Principal of High School, Chester, Pa., 1888-90; Scholar in Psychology, Clark Univer- sity, 1890-91; Associate Professor in Education, Teachers' College, New York City, 1891-92; Professor of Psychology and History of Education, ibid. , 1892-97 ; Superintendent Workingman's School, New York City, 1897-. Author of : — The Training of Teachers in England. Pedagogical Seminary, Dec, 1891, Vol. 1, pp. 409-415. ERNEIST "W. RBTTGER: — Graduate, Indiana State Normal School; 1891; A.B., Indiana University, 1893; Principal, Rensselaer, Ind., High School, 1893-94 ; Instructor in Mathematics, Indi- ana University, 1894-95 ; Fellow in Mathematics, Clark University, 1895- 98; Ph.D., Clark University, 1898; Instructor in Mathematics, Indiana Uni- versity, 1898-. Author of : — Note on the Projective Group. Proc. Am. Acad, of Set, July, 1898, Vol. 38, pp. 491-499. On Lie's Theory of Continuous Groups. Am. Jour, of Math. (In press.) ROBERT J. RICHARDSON :- Teacher in Public Schools, Varna, Ont., 1887-90 ; Graduate, Ontario School of Pedagogy, 1891; Student at Toronto Uni- versity, 1892-93 ; Teacher in High School, Prescott, Ont., 1893-94 ; B.A., University of Toronto, 1897 ; Graduate Student, ibid., 1897-98 ; Fellow in Psychology, Clark University, 1898-99. Author of : — A case of Abnormal Color-Sense exam- ined with Special Reference to the Space-Threshold of Colors. (With J. W. Baird.) Univ. of Toronto Studies, Psychological Series, 1898, pp. 87- 100. 538 Titles of CAMILLE HIED: — Protestant School, Freiburg, Baden, 1860- 52 ; Classical Gymnasium, Lahr, Baden, 1852-60 ; Student in Paris, 1862-63 ; Resi- dent in Paris, 1862-65, and 1867-70 ; Resident in Spain, 1865-67 ; Student in Freiburg, 1870-71 ; Student in Boston, 1881-86 ; Head of School of Languages, Boston, 1887-90 ; Instructor in Modem Languages, Clark University, 1889- 91 ; Instructor, Nautical School, U. S. S. Enterp)-ise, 1891-94. STANLEY H. HOOD : — S.B., Worcester Polytechnic, in Mechan- ical Engineering, 1890 ; in Electrical En- gineering, 1891 ; Instructor in Physios, ibid., 1890-93 ; Scholar in Physics, Clark University, Sept., 1893- AprU, 1894 ; Instructor in Joinery, Mechanic Arts High School, Boston, April-June, 1894; Instructor in French, ibid., 1894- 96 ; Graduate Student, Harvard Univer- sity, 1895-96 ; Instructor in Joinery, Manual Training High School, Worcester, 1896-. ERWIN W. HUNKLE: — A.B., Western College, 1890; Graduate Student in Psychology and Philosophy, Yale University, 1890-93 ; Lecturer in the History of Philosophy, ibid., 1892-93; Ph.D., Yale University, 1893; Assistant Professor of Psychology and Ethics, Penn- sylvania State College, 1893-99 ; Honor- ary Fellow in Psychology, Clark University, Jan.-June, 1899 ; Professor of Psychology and Ethics, Pennsylvania State College, 1899-. Author of : — Education and Life. Free Lance, State College, Pennsylvania, Jan., 1894, Vol. 13, pp. 96-98. Why do we Dream? i^iU, Oct. 1895, Vol. 14, pp. 5-8. Factors in Education. Ibid., May, 1896, Vol. 15, pp. 12-18. Psychology and the Modem Novel. School Gazette, June, 1897, Vol. 8, pp. 8-12. Review of Breuer and Freud : Studien iiber Hysterie. Am. Jour, of Psy., July, 1899, Vol. 10, pp. 592-694. S. EDWARD RYERSON: — M. A., Queen's University, 1895 ; Fellow in Mathematics, Clark University, 1895-96. Died, March 25, 1896. EDMUND C. SANFORD: — A.B., University of California, 1883; Teacher in Oahu College, Hawaiian Is- lands, 1883-85 ; Student, Johns Hopkins University, 1885-88 ; University Scholar, ibid., 1887 ; Fellow, ibid., 1887-88 ; Ph.D., Johns Hopkins University; 1888 ; Instruc- tor in Psychology, ibid., 1888-89 ; Instruc- tor in Psychology, Clark University, 1889-92 ; Assistant Professor of Psy- chology, 1892- ; Joint Editor, with President Hall and Professor Titchener, of the American Journal of Psychology ; Member of the American Psychological Association. Author of : — The Writings of Laura Bridgman. (Two articles.) Overland Monthly, lS88-^7 . The Relative Legibility of the Small Letters. Am. Jour, of Psy., May, 1888, Vol. 1, pp. 402-485. Personal Equation. Tbid., Nov., 1888; Feb. and May, 1889, Vol. 2, pp. 3-38, 271-298, 403-430. A Simple and Inexpensive Chronoscope. Ibid., April, 1890, Vol. 3, pp. 174-181. Psychology at Clark University. Ibid., April, 1890, Vol. 3, pp. 284-285. A Laboratory Course in Physiological Psychology. Ibid., April and Dec, 1891 ; April, 1892, Vol. 4, pp. 141- 155, 303-322, 474-490; April, 1893, Vol. 5, pp. 390-415; Jan., 1895, Vol. 6, pp. 593-616 ; April, 1896, Vol. 7, pp. 412-424. A New Visual Illusion. (Science, Feb. 17, 1893, Vol. 21, pp. 92-93. On Reaction-Times when the Stimulus is Applied to the Reacting Hand. (With J. F. Reigart.) Am. Jour, of Psy., April, 1893, Vol. 6, pp. 351-355. Published Papers. 539 A New Pendulum Chronograph. Ibid., April, 1893, Vol. 5, pp. 385-389. Some Practical Suggestions on the Equip- ment of a Psychological Laboratory. Ibid., July, 1893, Vol. 5, pp. 429-438. Notes on New Apparatus. Ibid., Jan., 1895, Vol. 6, pp. 575-584. The Pliiladelphia Meeting of the American Psychological Association. Science, Jan. 24, 1896, Vol. 3, pp. 119-124. The Vernier Chronosoope. Am. Jour, of Psy., Jan., 1898, Vol. 9, pp. 191-197. A Course in Experimental Psychology. D. C. Heath & Co., Boston, Mass., 1898. 449 pp. CLARENCE ARTHUR SAUNDERS: B.A., King's College, "Windsor, N. S., 1885; M.A., 1888; Graduate Student, Johns Hopkins University, 1889-92 ; Assis- tant, Smithsonian Institution, Washing- ton, 1891-92 ; Fellow in Physics, Clark University, 1892-95 ; Ph.D., Clark University, 1895 ; Professor of Mathe- matics and Physics, Ursinus College, 1895-98. Died Dec. 19, 1898. Author of : — The Velocity of Electric Waves. Physical Bemew, Sept. -Oct., 1896, Vol. 4, pp. 81-105. ALBERT SCHINZ:— B.A., Neuchatel, 1888; M.A., ibid., 1889 ; Licentiate in Theology, ibid., 1892 ; Student, University of Berlin, 1892-93; Student, Tubingen, 1893 ; Ph.D., Tubin- gen, 1894 ; College de Prance et Sor- bonne, Paris, 1894 ; Second Librarian, Library of Neuchatel, and Associate Pro- fessor of Philosophy, University of Neu- chatel, 1896-97 ; Honorary FellOTw in Psychology, Clark University, 1897- 98 ; Instructor in French, University of Minnesota, 1898-99 ; Lecturer in Prench Literature, Bryn Mawr College, 1899-. Author of: — La nature du p6oh6 : 6tude psychologique. Delachaux et NiestW, NeuchStel, 1892. 134 pp. Morale et d^terminisme. Eevne Philoso- phique, Jan., 1895, Vol. 39, pp. 57-75. La philosophie de M. Ernest Naville. Se- iiue de Theologie et de Philosophie, July, 1895. Mysticisme et Magie. Centralblatt des Zofingemereins, Dec, 1895. Le recent mouvement moral en Europe et en Amferique. Bridel et Cie, Lau- sanne, Suisse. (Imprim^d'aborddans La Bevue de Th&ologie et de Philoso- phie, Sept., 1896.) Essai BUT la notion du miracle, consid^r^ du point de vue de la th^orie de la connaissance. Delachaux et NiestW, Neuchatel, 1897. 85 pp. (Reprint from La Bevue de Theologie et de Phi- losophie, March, 1897.) La morality de I'enfant. Bevue Philoso- phique, March, 1898, Vol. 45, pp. 259- 295. Die Moralitat des Kindes. Translation by Ch. Ufer. Langensalza, 1898. 42 pp. (Heft L der " Beitrage zur Kin- derforschung.")' Le positivisme est un mdthode et non un systfeme. Bevue Philosophique, Jan., 1899, Vol. 47, pp. 63-75. Les bibliothfeques publiques en Am^rique. Bibliotheque TJniverselle, Lausanne, Suisse, Aug.-Sept., 1898. Les sports dans les Universit^s Am^ri- caines. La Suisse Universitaire, Peb. , 1899. L'Universit^ de Clark k, Worcester, Mass. Bevue des Bevues, Paris, July, 1898. L'^glise aux Etats Unis d'Am^rique. (In press.) Translation of Dr. E. C. Sanford's "A Course in Experimental Psychology," Schleicher frferes, Paris, 1899. (In press.) Chronique du f^minisme aux Etats-Uniti. Bevue de Morale Sociale, Paris, June, 1898. La langue Internationale Esperanto. La Semaine Litteraire. Geneve, Suisse, 29 Juillet, 1899. La secte des Scientistes Chretiens aux Etats-Unis d'Am^rique. Bevue des Bevues, Paris. (In press.) 540 Titles of Un reprfeentant de I'Agnosticisme aux Etats-Unis, Robert G. IngersoU. (In press.) L' Education des nfegres aux Etats-Unls d'Amfirique. L'institut de Tuskegee en Alabama. La Semaine Litteraire. Genfeve. 21 Ootobre, 1899. Le culte d'Omar Khayyam. (In press.) La PMlosophie et le Sens Commun, Be- vue Philosophique, Paris. (In press.) ALVA HOY SCOTT: — A.B., De Pauw University, 1886 ; A.M., ibid., 1889; Principal, Leavenworth Schools, 1886-87 ; Student, McCormiok Theological Seminary, Chicago, 1888-91 ; Pastor, Pirst Presbyterian Church, Hanover, 111., 1891-93; Graduate Stu- dent, Harvard University, 1893-94 ; Hon- orary Scholar in Psychology, Clark University, 1894-95 ; Pastor, First Presbyterian Church, Worcester, Mass., 1894-98. COLIN ALEXANDER SCOTT: — Student, College of City of New York, 1877-78 ; Graduate, Toronto Normal School, 1879; Director of Instruction in Drawing, Kingston Schools, 1883-84 ; B.A., Queen's University, Kingston, Ont., 1885 (Gold Medalist with Honors in Chemistry, Biology, and Geology); In- structor in Chemistry, Ladies' Medical College, Kingston, 1885-86 ; Science Mas- ter, IngersoU Collegiate Institute, 1886-87 ; Science Master, Ottawa Collegiate Insti- tute, 1887-94 ; Fellow in Psychology, Clark University, 1894-96; Ph.D., Clark University, 1896 ; Head of De- partment of Physiological Psychology and Child Study, Chicago Normal School, 1896-. Author of: — Sex and Art. Am. Jour, of Psy., Jan., 1896, Vol. 7, pp. 153-226. Old Age and Death. Ibid., June, 1896, Vol. 8, pp. 67-122. Children's Fears as Material for Expres- sion and a Basis of Education in Art. Trans. III. Soc. for Child Study, April, 1898, Vol. 3, pp. 12-17. E. -W. SCHIPTUHE: — A.B., College of the City of New York, 1884; A.M., ibid., 1890; Universities of Leipzig, Berlin, and Zurich, 1888-90; Ph.D., University of Leipzig, 1891 ; Fel- loTiv in Psychology, Clark University, 1891-92 ; Instructor in Experimental Psychology, Yale University, 1892-98; Director of the Yale Psychological Labor- atory, 1898- ; Assistant Editor of Ameri- can Journal of Psychology, 1891-92 ; Edi- tor of /Studies from the Yale Psychological Laboratory, 1893- ; Member : American Psychological Association ; American So- ciety of Naturalists; Fellow, American Association for the Advancement of Science. Author of : — Vorstellung und Gefilhl. Philos. Studien, 1890, Vol. 6, pp. 536-542. Ueber den associativen Verlauf der Vor- stellungen. (Inaugural Dissertation.) Leipzig, 1891, 101 pp., and Philos. Stu- dien, 1891, Vol. 7, pp. 60-146. Arithmetical Prodigies. Am. Jour, of Psy., April, 1891, Vol. 4, pp. 1-59. The Problem of Psychology. Mind, 1891, Vol. 16, pp. 305-326. Zur Definition einer Vorstellung. Philos. Studien, 1891, Vol. 7, pp. 213-221. Einige Beobachtungen iiber Schwebungen und Differenztone. Ibid., 1892, Vol. 7, pp. 630-632. The Need of Psychological Training. Sci- ence, March 4, 1892, Vol. 19, pp. 127- 128. An Instrument for Mapping Hot and Cold Spots on the Skin. Ibid. , May 6 , 1892, Vol. 19, p. 258. Education as a Science. Pedagogical Sem- inary, June, 1892, Vol. 2, pp. 111- 114. Psychological Notes. Am. Jour, of Psy., Aug., 1892, Vol. 4, pp. 577-584. Tests on School Children. Educational Seview, Jan., 1893, Vol. 5, pp. 52- 61. 1st eine cerebrale Entstehung von Schwe- bungen mBglich ? Philos. Studien, 1893, Vol. 8, pp. 638-640. Published Papers. 541 Systematized Graduate Instruction in Psy- chology. Science, July 28, 1893j Vol. 12, pp. 43-44. A System of Color-teaching. Educational Seview, Dec, 1893, Vol. 5, pp. 464-474. Consciousness under the Influence of Can- nabis indica. Science, Oct. 27, 1893, Vol. 22, p. 233. Psychological Measurements. Philosophi- cal Beview, Nov. 1893, Vol. 2, pp. 677-689. A New Reaction-key and the Time of Voluntary Movement. (With J. M. Moore.) Studies from Tale Pay. Lab., 1892-93, Vol. 1, pp. 88-91. Drawing a Straight Line : a Study in Experimental Didactics. (With C. I. Lyman.) Ibid., pp. 92-96. Some New Psychological Apparatus. Ibid., pp. 97-100. On the Measurement of Hallucinations. Science, Dec. 29, 1893, VoL 22, p. 353. Work at the Yale Laboratory. Psycho- logical Seview, Jan., 1894, Vol. 1, pp. 66-69. Ueber die Aenderungsempfindlichkelt. Zeits. f. Psy. u. Phys. d. Sinnesorgane, 1894, Vol. 6, pp. 472-474. Observation on the Use of the Terminal Verb in Infant Speech. Science, Feb. 2, 1894, Vol. 23, p. 62. New Materials for Color- teaching. Edu- cational Beview, April, 1894, Vol. 7, pp. 382-383. The Use of Antiphones. JV. T. Med. Jour., April 7, 1894, Vol. 59, p. 43. On the Adjustment of Simple Psychologi- cal Measurements. Psychological Be- view, May, 1894, Vol. 1, pp. 281-282. The Kinesimeter. (With E. B. Titchener.) Am. Jour, of Psy., June, 1894, Vol.6, pp. 424^26. Accurate Work in Psychology. Ibid., pp. 427-430. Some Psychological Illustrations of the Theorems of Bernoulli and Polsson. Ibid., pp. 431-432. Methods of Laboratory Mind-study. Fo- rum, Aug., 1894, Vol. 17, pp. 721- 728. Aims and Status of Child Study. Educa- tional Beview, Oct., 1894, Vol. 8, pp. 236-239. On Mean Values for Direct Measurements. Studies from Tale Psy. Lab., 1894, Vol. 2, pp. 1-39. Remarks on Dr. Gilbert's Article. Ibid. , pp. 101-104. Experiments on the Highest Audible Tone. (With H. F. Smith.) Ibid., pp. 105- 113. On the Education of Muscular Control and Power. (With T. L. Smith and E. M. Brown.) Ibid., pp. 114-119. A Psychological Method of determining the Blind-spot. Ibid., pp. 120-121. Tests of Mental Ability as Exhibited in Fencing. Ibid., pp. 122-124. Reaction-time and Time-memory in Gym- nastic Work. Bep. Ninth Meet. Am. Ass^n Physical Education, 1894, pp. 44-49. On the Measurement of Imaginations, Set Am., Feb. 9, 1895, Vol. 72, p. 85. The Nature of Science and Its Relation to Philosophy. Science, March 29, 1895, N. S., Vol. 1, pp. 350-352. Scientific Child Study. Trans. III. Soc. for Child Study, May, 1895, Vol. 1, pp. 32-37. Simple but Accurate Tests for Child Study. Ibid., pp. 57-60. Practical Computation of the Median. Psychological Beview, July, 1895, Vol. 2, pp. 376-379. The Second Tear at the Yale Laboratory. Ibid., pp. 379-381. A New Method of Computation. Sci. Am. Supplement, July 6, 1895, Vol. 4, p. 16270. Thinking, Feeling, Doing. Flood & Vin- cent, Meadville, Pa., 1895. 304 pp. A New Method of Making Lantern Slides. Scientific American, Aug. 24, 1895, Vol. 73, p. 123. Some Principles of Mental Education. ScJiool Beview, Nov., 1895, Vol. 3, pp. 533-547. A Method of Stereoscopic Projection. Scientific American, Nov. 23, 1895, Vol. 73, p. 327. 542 Titles of Some New Apparatus. Studies from Tale Psy. Lai., 1895, Vol. 3, p. 98- 109. The Bad Eye Tactory. Outlook, Feb. 29, 1896, Vol. 53, pp. 398-394. Untersuchungen liber die gelstige Ent- wiekelung der Scliulkinder. Zeits. f. Psy. u. Phys. der Sinnesorgane, 1896, Vol. 10, pp. 161-182. Measuring Hallucinations. Science, May 22, 1896, N. S., Vol. 3, pp. 762-763. Child Study : Methods and Results. Se- port 65th Meeting Am. Institute of Instruction, pp. 181-188. The Third Year at the Yale Laboratory. Psychological Beview, July, 1896, Vol. 3, pp. 416-421. The Law of Ehythmio Movement, /def- ence, Oct. 9, 1896, N. S., Vol. 4, pp. 535-536. My Pedagogic Creed. School Journal, Dec. 5, 1896, Vol. 53, pp. 621-623. Nouveaux Instruments. Annee psycholo- gique, 1896, Vol. 3, pp. 658-664. The Law of Size-Weight Suggestion. Sci- ence,Veb. 6, 1897, N. S., Vol. 5, p. 227. Sources of the New Psychology. Pop. Sci. Mo., May, 1897, Vol. 51, pp. 98-106. Pleasure without Other Sensations. iV. Y. Med. Jour., July 17, 1897, Vol. 66, p. 99. Cerebral Light. Science, July 23, 1897, N. S., Vol. 6, pp. 138-139. The New Psychology. Walter Scott, Lon- don, 1897. 500 pp. Eesearches on Reaction-time. Studies from Tale Psy. Lab., 1897, Vol. 4, pp. 12-26. Researches on Voluntary Effort. Ibid., 1897, Vol. 4, pp. 69-75. New Apparatus and Methods. Ibid., 1897, Vol. 4, pp. 76-88. Elementary Course in Psychological Meas- urements. Ibid., 1897, Vol. 4, pp. 89- 139. On Binaural Space. Ibid., 1898, Vol. 5, pp. 76-80. Researches on the Memory for Arm Movements. (With W. C. Cooke and C. M. Warren.) Ibid., 1898, Vol. 5, pp. 90-92. Principles of Laboratory Economy. Ibid., 1898, Vol. 5, pp. 93-103. Reaction-time in Abnormal Conditions of the Nervous System. Medical Bec- ord, 1898, Vol. 53, p. 196. Electrical Anaesthesia. Science, June 3, 1898, N. S., Vol. 7, p. 776. The Ansesthetio Effects of a Sinusoidal Current of High Frequency. Ibid., March 10, 1899, N. S., Vol. 9, p. 377. Color Weakness and Color Blindness. Ibid., June 2, 1899, N. S., Vol. 9, pp. 771-774. Cerebral Light. Ibid., June 16, 1899, N. S., Vol. 9, pp. 850-«51. Arousal of Instinct by Taste. Ibid., Jime 23, 1899, N. S., Vol. 9, p. 878. Anaglyphs and Stereoscopic Projection. Ibid., Aug. 11, 1899, N. S., Vol. 10, pp. 185-187. CHARLES H. SEARS: — Graduate, State Normal School, Westfield, Mass. (four years' course), 1883 ; Princi- pal of Public Schools, Cheshire, Mass., 1883-85 ; Teacher, Prospect Park Insti- tute, Brooklyn, N. Y., 1885-88; Teacher of Latin, State Normal School, Edinboro, Pa., 1888-92; A.M., AUegheny College, 1893; Ph.D., AUegheny College, 1895; Principal, Normal Department, Claflin University, 1892-97 ; Honorary Fellow in Pedagogy, Clark University, 1897- 99. Author of: — Home and School Punishments. Peda- gogical Seminary, March, 1899, Vol. 6, pp. 159-187. ALBERT E. SEGSWORTH: — B.A., University of Toronto, 1890 ; Stu- dent, University of Leipzig, 1890-91 ; Uni- versity of Toronto, 1891-92 ; Student, University of Leipzig, 1892-93 ; Honor- ary Fellow in Psychology, Clark University, 1893-94. Author of: — On the Difference Sensibility for the Valuation of Space Distances with the Help of Arm Movements. Am. Jour. Published Papers. 543 of Psy., June, 1894, Vol. 6, pp. 369- 407. Ueber Innervationsempflndimgen. (Pri- vately printed.) 1894. 5 pp. BENJAMIN P. SHARPE: — A.B., Wesleyan University, 1887 ; A.M., ibid., 1890 ; Adjunct Professor of Physios and Biology, Randolph-Macon College, 1887-91 ; Graduate Student and Scholar, Johns Hopkins University, 1891-94 ; Pel- low in Physics, Clark University, 1894-96; Professor of Mathematics, State Normal School, New Paltz, N. Y., 1896-97; PeUow in Pbyslcs, Clark TTiiiversity, 1897-98. Author of : — A Double Instrument and a Double Method for the Measurement of Sound. Science, June 9, 1899, N. S., Vol. 9, pp. 808-811. An Advance in Measuring and Photo- graphing Sounds. U. S. Weather Bu- reau, No. 202, Washington, D. C, 1899. 18 pp., 7 pis. JOHN C. SHA-W: — Graduate, State Normal School, Fairmont, W. Va., 1889; Principal of Graded Schools, Paw Paw, W. Va., 1889-90; B.S., University of Nashville, 1892 ; M.S., ibid., 1894; L.I., Peabody Normal Col- lege, Nashville, 1893 ; Principal of Public School, DouglassvUle, Tex., 1893-94; Teacher of Mathematics, Marshall Col- lege, 1894r-95; Scholar in Pedagogy, Clark University, 1895-96; Pellow in Psychology, 1896-97; Teacher in State Normal School, West Liberty, W. Va., 1897-. Author ,of : — Chairs of Pedagogy in the United States. W. Va. School Journal, April, May, and June, 1895. A Test of Memory in School Children. Pedagogical Seminary, Oct., 1896,Vol. 4, pp. 61-78. What Children like to Eead. W. Va. School Journal, Charleston, W. Va., Oct., 1897, Vol. 17, pp. 5-6. HENRY DAVIDSON SHELDON: — A.B., Stanford University, 1896 ; A,M., ibid., 1897 ; Instructor in Department of Education, ibid., 1896-97; PeUow and Assistant in Pedagogy, Clark Univer- sity, 1897-99. Author of: — The Institutional Activities of American Children. Am. Jour, of Psy., July, 1898, Vol. 9, pp. 425-448. FREDERIC D. SHERMAN: — A.B., University of Michigan, 1887; Principal of Berrien Springs, Mich., School, 1887-88; Principal of Charlotte, Mich., High School, 1888-89; Principal of Bay City, Mich., High School, 1889- 94 ; Universities of Bonn and Leipzig, 1894-97; Ph.D., University of Leipzig, 1897 ; Professor of Psychology and Peda^ gogy. State Normal School, Oshkosh, Wis., 1897-98; Honorary PeUow in Psychology, Clark University, Oct.- Nov. , 1898 ; Lecturer in History of Edu- cation, Teachers College, Columbia Uni- versity, Dec, 1898-June, 1899; Assistant in Latin, Erasmus Hall High School, Brooklyn, N. Y., 1899-. Author of: — Ueber das Purkinje'sche Phanomen im Centrum derNetzhaut. Philosophische Studien, 1897, Vol. 13, pp. 434^79. TOSHIHIDE SHINODA: — Graduate, Higher Normal School, Tokio, Japan ; Graduate Student in United States and Europe, 1888-91 ; Honorary Scholar in Pedagogy, Clark University, 1889- 90 ; Professor in Higher Normal School, Tokio, Japan, 1891-. LOUIS SIFP: — S.B., Cornell University (Special Mention in Mathematics), 1897 ; Graduate Student, Johns Hopkins University, Oct., 1897- Peb., 1898; Scholar in Mathematics, Clark University, 1898-99 ; Teaching Pellow in Mathematics, University of Ne- braska, 1899-. 544 Titles of ERNEST B. SKINNER: — A.B., Ohio Uniyersity, 1888; Professor of Mathematics, Amity College, College Springs, la., 1889-91 ; Scholar in Mathe- matics, Clark TTniversity, 1891-92 ; Instructor in Mathematics, University of Wisconsin, 1892-95 ; Assistant Professor, ibid., 1895- ; Member American Mathe- matical Society. STEPHEN E. SLOCtTM : — B. E. , Union University (Honors in Mathe- matics and Physics), 1897 ; Scholar in Mathematics, Clark University, 1897-98; Fellow, 1898-99. Author oi : — Note on the Chief Theorem of Lie's Theory of Continuous Groups. Proc. Am. Acad. (In press.) JAMES R. SLONAEER : — Graduate, Indiana State Normal School, 1889 ; Supervising Principal of Schools, Elroy, Wis., 1889-91 ; University of Wis- consin, 1891-93; B.S., ibid., 1893; Fel- lov7 in Biology, Clark University, 1893-96; Ph.D., Clark University, 1896 ; Instructor in Zoology, Indiana University, 1896- ; Member Indiana Academy of Science. Author of: — A Comparative Study of the Point of Acute Vision in the Vertebrates. American Naturalist, Jan., 1896, Vol. 30, pp. 24-32. A Comparative Study of the Area of Acute Vision in Vertebrates. Jour. of Morph., May, 1897, Vol. 13, pp. 445-502. The Fovea. Proc. Ind. Acad, of Science, 1896, pp. 304-310. A Method of Preserving the Eye for Sectioning, or for Demonstrating the Area of Acute Vision. Jour, of Applied Microscopy, 'Feb., 1896, Vol. 1, p. 18. The Eye of the Mammoth Cave Eat. Proc. Ind. Acad, of Science, 1898. MAURICE H. SMALIi: — A.B., Colby University, 1887 ; Principal, High School, Norway, Me., 1887-92; ibid., Westbrook, Me., 1892-95 ; Scholar in Psychology, Clark University, 1895-96; Fellow, 1896-98; Prin- cipal High School, Passaic, N. J., 1898-. Author of : — The Suggestibility of Children. Peda- gogical Seminary, Dec, 1896, Vol. 4, pp. 176-220. Methods of manifesting the Instinct for Certainty. Ibid., Jan., 1898, Vol. 5, pp. 313-380. An Experiment borrov?ed from the School- room. Northwestern Monthly, Nov., 1898, Vol. 9, pp. 184-135. WILLARD STANTON SMALL: — A.B., Tufts College, 1894 ; A.M., ibid., 1897; Tufts Divinity School, 1894-96; Professor of English Language and Lit- erature, Lombard University, 1896-97 ; Scholar in Psychology, Clark Uni- versity, 1897-98; FeUow, 1898-99. Author of : — Friedrich Nietzsche (Review). Pedagogi- cal Seminary, April, 1898, Vol. 5, pp. 606-610. Note on the Psychic Development of the Yoimg White Eat. Am. Jour, of Psy. , Oct., 1899, Vol. 11, pp. 80-100. WARREN R. SMITH: — A.B., Bowdoin College, 1890 ; Instructor Leicester Academy, Leicester, Mass., 1890-91 ; Scholar in Chemistry, Clark University, 1891-92 ; Fellow in Chem- istry, University of Chicago, 1892-94 ; Ph.D., ibid., 1894 ; Assistant in Chemistry, Bowdoin College, 1894-95 ; Instructor in Science, New Bedford High School, 1895- 96 ; Instructor in charge Department of Chemistry, Lewis Institute, Chicago, HI., 1896-. Author of : — On the Addition Products of the Aro- matic Isocyanides. Am. Chem. Jour., May, 1894, Vol. 16, pp. 372-393. Published Papers. 545 HUGH A. SNEPP: — A.B., Heidelberg College, 1893 ; Princi- pal, High Soliool, Germantown, 0., 1893- 94; Tutor in Mathematics, Heidelberg College, 1894-95; Scholar in Mathe- matics, Clark Umversity, 1895-96; Instructor in Mathematics and Science, High School, Tiffin, O., 1896-98; Student in Mathematics, University of Chicago, Summer Quarter, 1897. PRANK B. SPAULDING: — A.B., Amherst College, 1889; Instructor, Military Academy, Louisville, Ky., 1889- 90 ; Instructor and Associate Principal, ibid., 1890-91 ; Student in Universities of Leipzig, Paris, and Berlin, 1891-94; Ph.D., University of Leipzig, 1894; Honorary Fellow in Psychology, Clark University, Oct., 1894-May, 189S ; Superintendent of Schools, Ware, Mass., May, 1895- June, 1897; Superin- tendent of Schools, Passaic, N. J., Sep- tember, 1897- ; President, New Jersey Association for the Study of Children and Youth, 1899. Author of: — Richard Cumberland als Begriinder der Englischen Ethik. Leipzig, 1894. xii. + 101 pp. The Province of the Elementary School. Jour, of Pedagogy, Sept., 1896, Vol. 9, pp. 129-137. Mental Images. Educational Founda- tions, Sept., 1897, Vol. 9, pp. 15-21. The Dynamics of Mental Images. Ibid., Oct., 1897, Vol. 9, pp. 65-70. Some Psychic Processes involved in Read- ing. Ibid., Nov., 1897, Vol. 9, pp. 130- 137. The Psychology of Defective Reading. Ibid., Dec, 1897, pp. 194-201. Mental Economy in Reading. Ibid. , Jan., 1898, Vol. 9, pp. 257-262. Psychic Aspects of Learning to Read. Ibid., Eeb., 1898, Vol, 9, pp. 347- 353. Preventing and Correcting Defective Reading. Ibid., March, 1898, Vol. 9, pp. 389-395. 2n What can One Read ? Ibid., April, 1898, Vol. 9, pp. 614-520. Psychology in Geography. Ibid., May and June, 1898, Vol. 9, pp. 572-577, 619-625. The Elementary Character of Secondary Education. Jour, of Pedagogy, Jan., 1899, Vol. 12, pp. 11-24. Immediate Educational Work. Annual Beport, Supt. of Schools, Ware, Mass., Feb. 1, 1896, pp. 17-22. . Educational Policy and Aims. Ibid., Feb. 1, 1897, pp. 14-32. The Course of Study ; Grading and Pro- motion, etc. Annual Beport, Supt. of Schools, Passaic, N. J., 1897-98, pp. 9-64. EDWIN D. STAHBUCK: — A.B., Indiana University, 1890 ; Teacher of Mathematics and Latin, Spioeland, Ind. Academy, 1890-91 ; Teacher of Mathematics, Vincennes College, 1891-93 ; Student in Psychology, Harvard Univer- sity, 1893-95 ; A.B., ibid. ; 1894 ; A.M., ibid., 1895; Fellow in Psychology, Clark University, 1895-97 ; Ph.D., Clark University, 1897 ; Assistant Pro- fessor of Education, Stanford University, 1897-. Author of: — A Study of Conversion. Am. Jour, of Psy., Jan., 1897, Vol. 8, pp. 268-308. Some Aspects of Religious Grovfth. Ibid. , Oct., 1897, Vol. 9, pp. 70-124. Child Study and its Possibility as a Sci- ence. Northwestern Monthly, March- April, 1899, Vol. 9, pp. 358-362. Psychology of Religion. With an intro- duction by Professor William James. Contemporary Science Series. (In press.) ORLANDO S. STETSON: — Worcester Polytechnic Institute, 1896-98 ; Scholar in Mathematics, Clark Uni- versity, 1898-99. COLIN C. STEWART : — B.A., University of Toronto, 1894 ; Scholar in Physiology, Clark Uni- 546 Titles of versity, 1894-95 ; FeUow, 1895-97 ; Ph.D., Clark TJniverBity, 1897; As- sistant in Physiology, Harvard Medical Sohool, 1897-98; Tutor in Physiology, Columbia University, 1898- ; Member American Physiological Society. Author of: — The Influence of Acute Alcohol Poisoning on Nerve Cells. Jour, of Exp. Medi- cine, Nov., 1896, Vol. 1, pp. 623-629. Variations in Daily Activity produced by Alcohol and by Changes in Barometric Pressure and Diet, with a Description of Eeoording Methods. Am. Jour, of Physiology, Jan., 1898, Vol. 1, pp. 40- 56. On the Course of Impulses to and from the Cat's Bladder. Ibid., Jan., 1899, Vol. 2, pp. 182-202. A Simple Etherizing Bottle. Ibid. (Proc. Am. Physiol. Soc, Dec, 1898), Vol. 2, p. X. The Relaxation of the Cat's Bladder. Ibid., Aug., 1899, Vol. 3, pp. 1-8. JULIUS STIBGLITZ: — University of Berlin, 1886-89 ; University of Gottingen, 1888; Ph.D., University of Berlin, 1889; Scholar in Chemistry, Clark University, Jan.-June, 1890 ; Chemist, Parke, Davis & Co., Detroit, Mich., 1890-92 ; Decent in Chemistry, University of Chicago, 1892-93 ; Assistant in Chemistry, ibid., 1893-94; Instructor in Chemistry, ibid., 1894-97 ; Assistant Professor in Chemistry, ibid., 1897- ; Pel- low of the American Association Advance- ment of Science; Member, Deutsche Chemisohe Gesellschaft. Author of : — Ueber das Verhalten der Amidoxime gegen Diazobenzolverbindungen. Ber. d. deuts. chem. Cfesellschaft, 1889, Vol. 22, pp. 3148-3160. On Benzoquinone Carboxylic Acids. Am. Chem. Jour., 1891, Vol. 13, pp. 38-42. Alkaloidwertbestimmung von Extrakten. Fharmaceutische Bundschau, 1892 and 1893, 3 papers. Ferric Phosphate, U. S. P., and Terric Pyrophosphate, U. S. P. Journal of Pharmacy, 1891. Notes on Pyrophosphoric and Phosphoric Acid. Ibid., 1891. Derivatives of Nitrogen Halogen Com- pounds. (With F. Lengfeld.) Am. Chem. Jour., 1893, Vol. 15, pp. 215- 222, 504-518 ; Vol. 16, pp. 370-372. The Action of Phosphorus Pentachloride on Urethanes. (With F. Lengfeld.) Ibid., 1894, Vol. 16, pp. 70-78. Ueber Alkylisoharnstoffe. (WithF. Leng- feld.) Ber. d. deuts. chem. Gesell- schaft, 1894, Vol. 27, pp. 926-927. Ueber die Einwirkung von Natrium- athylat auf Carbodiphenylimid. Ibid., 1895, Vol. 28, pp. 573-574. Ueber Thiamine. (With F. Lengfeld.) Ibid., 1895, Vol. 28, pp. 575-576, 2742- 2744. On Imidoethers of Carbonic Acid. (With F. Lengfeld.) Am. Chem. Jour., 1895, Vol. 17, pp. 98-113. On the "Beokmann Rearrangement." Ibid., 1896, Vol. 18, pp. 751-761. On the Constitution of the Salts of Imido- ethers and other Carbimide Deriva- tives. Ibid., 1899, Vol. 21, pp. 101- 111. P. E. STINSON: — Iowa Agricultural College, 1884r-86 ; Prin- cipal, Poplar Grove Institute, Ark., 1889- 90; Instructor in Physics and Mathematics, Paris Academy, Ark., 1890-92; Scholar in Mathematics, Clark University, 1892-93 ; Fellow, 1893-95. WILLIAM E. STORY: — A.B., Harvard University, 1871 ; Parker Fellow, ibid., 1874-75; Universities of Berlin and Leipzig, 1871-75; Ph.D., University of Leipzig, 1875 ; Tutor of Mathematics, Harvard University, 1875- 76 ; Associate, Assistant Professor, and Associate Professor of Mathematics, Johns Hopkins University, 1876-89 ; As- sociate Editor in Charge, American Jour- nal of Mathematics, 1878-82 ; Professor of Mathematics, Clark University, Published Papers. 547 1889- ; Editor, Mathematical Beview, 1896-. Author of : — On the Algebraic Relations e3dsting be- tween the Polars of a Binary Quantic. Dissertation approved for the degree of Ph.D., Leipzig, 1875. 58 pp. On the Elastic Potential of Crystals. Am. Jour, of Math., 1878, Vol. 1, pp. 177- 183. Note on Mr. Kempe's Paper on the Geo- graphical Problem of the your Colors. Ibid., 1879, Vol. 2, pp. 201-204. Note on the "15" Puzzle. Ibid., 1879, Vol. 2, pp. 399-404. On the Theory of Rational Derivation on a Cubic Curve (followed by a Note on Totients). Ibid., 1880, Vol. 3, pp. 856-387. On the Non-Euclidean Trigonometry. Ibid., 1881, Vol. 4, pp. 332-335. On the Non-Euclidean Geometry. Ibid., 1882, Vol. 5, pp. 180-211. On Non-Euclidean Properties of Conies. Ibid., 1882, Vol. 5, pp. 358-381. On the Absolute Classiiication of Quadratic Loci, and on their Intersections with each other and with Linear Loci. Ibid., 1885, Vol. 7, pp. 222-245. The Addition-Theorem for Elliptic Func- tions. Ibid., 1886, Vol. 8, pp. 364- 375. A New Method in Analytic Geometry. Ibid., 1887, Vol. 9, pp. 38-44. On the Covariants of a System of Quan- tics. Math. Annalen, 1893, Vol. 41, pp. 469-490. On an Operator that produces aU the Co- variants and Invariants of any System of Quantics. Proc. London Math. Soc, 1892, Vol. 23, pp. 265-272. Hyperspace and Non-Euclidean Geometry. I. Mathematical Beview, April, 1897, Vol. 1, pp. 169-184. J. RICHARD STREET: — A.B., Victoria University, 1884; A.M., ibid., 1888 (with Eirst Honors in English, French, German, and Italian) ; Modem Language Master, Smithville High School, 1885-86 ; "Walkerton High School, 1886- 87 ; Principal Caledonia High School, Ontario, 1887-95 ; Associate Member of the Board of Government Examiners, 1891-95 ; Member and Secretary of the County Board of Examiners for Profes- sional Teachers' Certificates, 1889-95 ; Sometime Examiner in English, French, and German for Albert, Alma, and Brant, ford Colleges ; Instructor in the Mechanics Institute, Caledonia, 1898-95; Scholar in Pedagogy, Clark University, 1895- 96 ; Fellow in Psychology, 1896-98; Ph.D., Clark tJmversity, 1898; Pro- fessor of Pedagogy, Bible Normal College, Springfield, Mass., 1898- ; also Professor of Theory and Practice of Teaching, Mount Holyoke College, 1899-. Author of: — A Study in Language Teaching. Peda- gogical Seminary, April, 1897, Vol. 4, pp. 269-293. A Study in Moral Education. Ibid. , July, 1897, Vol. 5, pp. 5-40. A Genetic Study of Immortality. Ibid., Sept., 1899, Vol. 6, pp. 267-313. Linguistic Interpretation. (In press.) CHARLES A. STRONG: — A.B., University of Rochester, 1884 ; A.B., Harvard University, 1885 ; Rochester Theological Seminary, 1885-86; Fellow, Harvard University, 1886-87 ; University of Berlin, 1886-87 ; Instructor in Philoso- phy, Cornell University, 1887-89; Uni- versities of Paris, Berlin, and Freiburg, 1889-90 ; Docent in Philosophy, Clark TTniversity, 1890-91 ; Associate Pro- fessor of Psychology, University of Chi- cago, 1892-95 ; Lecturer in Psychology, Columbia University, 1895-. Author of : — A Sketch of the History of Psychology among the Greeks. Am. Jour, of Psy. , Dec, 1891, Vol. 4, pp. 177-197. Dr. Miinsterberg's Doctrine of Mind and Body and its Consequences. Philo- sophical Mevi&w, March, 1892, Vol. 1, pp. 179-195. 548 TitUs of Mr. James Ward on Modern Psychology. _ Psychological Beview, Jan., 1894, Vol. I, pp. 73-81. The Psychology of Pain. Ibid., July, 1895, Vol. 2, pp. 329-347. Physical Pain and Pain Nerves. Ibid., Jan., 1896, Vol. 3, pp. 64-68. Consciousness and Time. Ibid., March, 1896, Vol. 3, pp. 149-157. CHARLES K. SV^-ARTZ: — A.B., Johns Hopkins University, 1888; University of Heidelberg, 1888-89; Fel- low in Chemistry, Clark University, 1889-90 ; Gettysburg Theological Semi- nary, 1890-91 ; Oberlin Theological Semi- nary, 1891-92; B.D., ibid., 1892 ; Pastor, Congregational Church, Bellevue, 0., 1892-. HENR7 TABER: — Ph.B., Yale University (Sheffield Scien- tific School), 1882 ; Johns Hopkins Univer- sity, 1882-85 and 1886-88 ; Ph.D., Johns Hopkins University, 1888 ; Assistant in Mathematics, ibid. , 1888-89 ; Docent in Mathematics, Clark TTniversity, 1889- 92; Assistant Professor of Mathe- matics, 1892- ; Resident Fellow Ameri- can Academy of Arts and Sciences ; Member : London Mathematical Society ; American Mathematical Society. Author of: On the Theory of Matrices. Am., Jour. of Math., July, 1890, Vol. 12, pp. 337- 396. On the Application to Matrices of any order of the Quaternion Symbols 8 and V. Proc. London Math. Soc, Deo. II, 1890, Vol. 22, pp. 67-79. On Certain Identities in the Theory of Matrices. Am. Jour, of Math., Jan., 1891, Vol. 13, pp. 159-172. On Certain Properties of Symmetric, Skew Symmetric, and Orthogonal Matrices. Proc. London Math. Soc, June 11, 1891, Vol. 22, pp. 449-469. On the Matrical Equation ^0 = Qep. Pub. Instr., State of New York. Numerous signed biographical and edu- cational articles in Johnson's "Univer- sal Cyclopaedia" (new edition), 1892- 94 ; 1898-99. Editor of "Twentieth Century" Text- Books. FREDERICK TRACY: — Pickering College, 1883-85; B.A., Uni- versity of Toronto, 1889 ; Fellow in Phi- losophy, ibid., 1889-92 ; Fellow in Psy- chology, Clark University, 1892-93 ; Ph.D., Clark University, 1893 ; Lec- turer in Philosophy, University of Toronto, 1893- ; Member Illinois Society for Child Study; President Ontario Child Study Association. Author of : — The Testimony of Consciousness. Wood- stock Col. Mon., March, 1891. The Language of Children. Proc. Int. Ed. Congress, 1893. The Psychology of Childhood. D. C. Heath & Co., Boston, 1893. 2d ed., 1894. The New Psychology. Can. Meth. Mag., Nov., 1894. The Scottish Philosophy. Univ. of To- ronto Quar., Nov., 1895. Hypnotism. Can. Meth. Mag., Nov., 1895. Results of Child Study applied to Educa- tion. Trans. III. Soc. for Child Study, 1895, Vol. 1, No. 4, p. 12. Child Study and Pedagogy. Froc. Ont. Ed. Ass'n, 1895. Character as a Product of Education in Schools . Overland Monthly Publishing Co., 1896. Published Papers. 551 A Syllabus of Psychology. Toronto, 1896. The Culture of the Spiritual Life. Ma- Master Univ. Mon., Jan., 1897. Die Kinderpsychologie in England und Nord- America. Die Kinderfehler, April and July, 1897, Vol. 2, pp. 33-42, 72-87. Results of Child Study. N. T. School Jour., July 10, 17, and 24, 1897. Left-handedness. Trans. HI. Soc. for Child Study, 1897, Vol. 2, pp. 68- 76. Child Study, its Practical Value. iVoc. Ont. Ed. Ass''n, 1897. Sully's "Studies of Childhood." Ibid., 1898. Psyohologie der Kindheit. Translated by J. Stimpfl. E. Wunderlich, Leipzig, 1899. 158 pp. NORMAN TRIPLETT : — A.B., Illinois College, 1889 ; Principal New Berlin, 111., School, 1889-91 ; Prac- tised Law, ibid., 1891-94; Instructor in Physios, Chemistry, and Psychology, Quincy, 111., High School, 1894-97 ; A.M., Indiana University, 1898 ; Fellow in Psy- chology, Clark Umversity, 1898-99. Author of : — The Dynamogenic Factors in Pacemaking and Competition. Am. Jour, of Psy., July, 1898. Vol. 9, pp. 507-533. FREDERICK TUCKERMAN : — B.S., Boston University, 1878; M.D., Harvard Medical School, 1882; Student, London and Berlin, 1882-83 ; Lecturer in Anatomy and Physiology, Massachusetts Agricultural College, 1883-86 ; Fellow in Vertebrate Anatomy, Clark Univer- sity, 1889-90; Student. Universities of Berlin, London, and Heicfelberg, 1892-94; A.M. and Ph.D., University of Heidel- berg,1894; Private Laboratory at Amherst, Mass., 1894- ; Fellow of the Massachusetts Medical Society, 1888-95; Member of: American Society of Naturalists, Boston Society of Natural History, Anatonucal Society of Germany, etc. Author of : — Some Observations in Reference to Bilat- eral Asymmetry of Form and Function. Jour. Anat. and Fhys., 1885, Vol. 19, pp. 307-308. Supernumerary Leg in a Male Frog (Rana palustris). Ibid., 1886, Vol. 20, pp. 516-519, PI. xvi. The Tongue and Gustatory Organs of Me- phitis mephitica, Quar. Jour. Micr. Sd., 1887, Vol. 28, pp. 149-167, PI. xi. The Tongue and Gustatory Organs of Fiber zibethicus. Jour. Anat. and Phys., 1888, Vol. 22, pp. 135-141, PI. vii. Note on the Papilla f oliata and other Taste Areas of the Pig. Anat. Anzeiger, 1888, Vol. 3, pp. 69-73. An Interesting Specimen of Taenia sagi- nata. Zool. Anzeiger, 1888, Vol. 11, pp. 94-95. The Anatomy of the Papilla f oliata of the Human Infant. Jour. Anat.and Phys., 1888, Vol. 22, pp. 499-501, PI. xviii. Antipyrine in Cephalalgia. N. Y. Med. Beeord, 1888, p. 180. Observations on the Structure of the Gus- tatory Organs of the Bat (Vespertilio subulatus) . Jour. ofMorph., 1888, Vol. 2, pp. 1-6, PI. i. Supplementary Note on Taenia saginata. Zool. Anzeiger, 1888, Vol. 11, pp. 473- 475, figures. Anthropometric Data Relating to Students of the Massachusetts Agricultural Col- lege. Amherst, 1888. On the Gustatory Organs of Putorius vi- son. Anat. Anzeiger, 1888, Vol. 3, pp. 941-942. On the Gustatory Organs of Vulpes vul- garis. Jour. Anat. and Phys., 1889, Vol. 23, pp. 201-205. On the Gustatory Organs of Arctomys mo- nax. Anat. Anzeiger, 1889, Vol. 4, pp. 334-335. On the Development of the Taste-Organs of Man. Jour. Anat. and Phys., 1889, Vol. 23, pp. 559-582. On the Gustatory Organs of Sciurus caro- linensis. Microscope, 1889, Vol. 9, pp. 193-196, PI. vii. 552 Titles of On the Gustatory Organs of EretMzon dor- satus. Am. Mo. Micr. Jour., ISSOjVol. 10, p. 181. An Hitherto Undescribed Taste Area in Perameles nasuta. Anat. Anzeiger, 1889, Vol. 4, pp. 411-412, figure. On the Gustatory Organs of the American ' Hare (Lepus americanus) . Am. Jour. of Sd., 1889, Vol. 38, pp. 277-280. Note on the Tongue of Chrysotis aestiva. Microscope, 1889, Vol. 9, pp. 289-290. The Gustatory Organs of Belideus ariel. Jour. Anat. and Phys., 1889, Vol.24, pp. 85-88, PI. v. Further Observations on the Development of the Taste-Organs of Man. Ihid., pp. 130-131. The Gustatory Organs of, Procyon lotor. Ibid., pp. 156-159, PI. x. On the Gustatory Organs of the Mammalia. Proc. Boston So. Nat. Sist., 1890, Vol. 24, pp. 470-482. On the Gustatory Organs of some Eden- tata. Internat. Monats. f. Anat. u. Phys., 1890, Vol. 7, pp. 335-339. On the Gustatory Organs of some of the Mammalia. Jour. ofMorph., 1890,Vol. 4, pp. 151-193. The Development of the Gustatory Organs in Man. Am. Jour, of Psy., April, 1890, Vol. 3, pp. 195-197. On the Gustatory Organs of Sciurus hud- sonius. Internat. Monats. f. Anat. u. Phys., 1891, Vol. 8, pp. 137-139, PI. xi. Observations on some Mammalian Taste- Organs. Jour. Anat. and Phys., 1891, Vol. 25, pp. 505-508. On the Terminations of the Nerves in the Lingual Papillse of the Chelonia. In- ternat. Monats. f. Anat. u. Phys., 1892, Vol. 9, pp. 1-5, PI. i. The Gustatory Organs of Ateles ater. Jour. Anat. and Phys., 1892, Vol. 26, pp. 391-393. Further Observations on the Gustatory Organs of the Mammalia. Jour, of Morph., 1892, Vol. 7, pp. 69-94. Note on the Structure of the Mammalian Taste-Bulb. Anat. Anzeiger, 1898,Vol. 8, pp. 366-367. The Development of the Organs of Taste. Jieference Sand-book of the Medical Sciences, 1893, Vol. 9, pp. 857-859, fig- ures, 600-607. JOHN N. VAN DER VRIES: — A.B., Hope College, 1896; Principal of School, East Saugatuck, Mich., 1896-97; Scholar in Mathematics, Clark ITni- versity, 1897-98 ; PeUow, 1898-99. FRANK L. O. "WADS'WORTH: — E.M., Ohio State University, 1888; M.E., ibid., 1889; B.S., ibid., 1889; Assistant in Physics, ibid., 1888-89; Fellow in Physics, Clark University, 1889-90; Fellow and Assistant, 1890-92 ; Special Assistant and Delegate from the Smithsonian Institution to the Bu- reau Internationale des Poids et Mesures, Paris, 1892 ; Senior Assistant in Charge, Astrophyslcal Observatory, Smithson- ian Institution, 1892-94; Assistant Pro- fessor In Physios, University of Chicago, 1894-96; Assistant Professor of Astro- physios, Yerkes Observatory, 1896-97 ; As- sociate Professor of Astrophysics, ibid., 1897-98 ; Special Engineering and Expert Work, Pittsburg and Washington, 1898- 99; Director of the Allegheny Observa- tory, May, 1899- ; Assistant Editor, As- trophy steal Journal; Associate Editor, Harper's Scientific Memoirs ; Member As- tronomical and Astrophyslcal Society of America. Author of: — Some New Forms of Dynamos. Mectrical World, Sept. 13, 1890, Vol. 16, pp. 183- 184. On the Eelation between Else of Temper- ature and Current in Electric Conduc- tors. Ibid., Feb. 27, 1892, and March 12, 1892, Vol. 19, pp. 145-146, 180- 181. Application of Interference Methods to Base Line Measurement. Philosophi- cal Society, Washington, Nov., 1892. Beport of the Smithsonian Astrophyslcal Observatory. Smithsonian Ann. Sep., Appendix V., 1893, pp. 60-67. Published Papers. 553 Electric Controls and Governors for Astro- nomical Instruments. Astronomy and Astrophysics, April, 1894, Vol. 13, pp. 265-272. A Simple Method of determining the Ec- centricity of a Graduated Circle with One Vernier. Am. Jour, of Sci. , May, 1894, 3d ser.. Vol. 47, pp. 873-376. The Manufacture of Very Accurate Straight Edges. Jour, of the Franklin Institute, July, 1894, Vol. 20, pp. 138. Re- printed in American Machinist, Aug. 2, 1894. An Improved Eorm of Littrow Spectro- scope. Philosophical Magazine, July, 1894, 5th ser.. Vol. 38, pp. 137-142. A New Design for Large Spectroscope Slits. Am. Jour, of Sci., July, 1894, 3d ser.. Vol. 48, pp. 19-20. Some New Double Motion Mechanisms. Astronomy and Astrophysics, Aug., 1894, Vol. 13, pp. 527-528. Reprinted in Zeits. f. Instrumentenkunde, Jan., 1895, Vol. 15, pp. 32-35. Fixed Arm Spectroscopes. Philosophical Magazine, Oct., 1894, 5th ser.. Vol. 38, pp. 337-351. Reprinted in Astronomy and Astrophysics as No. 9 of the series. The Modem Spectroscope, Dec, 1894, Vol. 13, pp. 835-849. Ein neuer Spektroskopspalt mit Doppel- bewegung. Zeits. f. Instrumenten- kunde, Oct., 1894, Vol. 14, pp. 364-366. A Simple Method of mounting an Equa- torial Axes on Ball Bearings. As- tronomy and Astrophysics, Nov., 1894, Vol. 13, pp. 723-728. A New Method of magnetizing and asta- tizing Galvanometer Needles. Philo- sophical Magazine, Nov., 1894, 5th ser.. Vol. 38, pp. 482-488. An Improved Form of Interrupter for Large Induction Coils. Am. Jour, of Sci., Dec, 1894, 3d ser.. Vol. 48, pp. 496-501. Description of a Very Sensitive Form of Thomson Galvanometer and Some Methods of Galvanometer Construc- tion. Philosophical Magazine, Dec, 1894, 5th ser.. Vol. 38, pp. 553-558. General Considerations respecting the Design of Astronomical Spectroscopes. Forming No. 10 of the series. The Modern Spectroscope. Astrophysical Journal, Jan., 1895, Vol. 1, pp. 52-79. Bemerkungen uber Versilberungsfliissig- keiten und Versilberung. Zeits. f. Instrumentenkunde, Jan., 1895, Vol. 15, pp. 22-27. Reprinted in the Astro- physical Journal, March, 1895, Vol. 1, pp. 252-260. The Design of Electric Motors for Con- stant Speed. Astrophysical Journal, Feb., 1896, Vol. 1, pp. 169-177. Some New Designs of Combined Grating and Prismatic Spectroscopes of the Fixed Arm Type and a New Form of Objective Prism. Forming No. 11 of the series. The Modern Spectroscope. Ibid., March, 1895, Vol. 1, pp. 232- 247. Einfacher Unterkreoher fur grosse Induk- tionsapparate. Zeits. f. Instrumenten- kunde, July, 1895, Vol. 15, pp. 248- 250. A New Multiple Transmission Prism of Great Resolving Power. No. 13 of the series. The Modern Spectroscope. As- trophysical Journal, Nov., 1895, Vol. 2, pp. 264-282. Fixed Arm Concave Grating Spectro- scopes. No. 14, The Modern Spectro- scope. Ibid., Dec, 1895, Vol. 2, pp. 370-382. A Very Simple and Accurate Cathe- tometer. Am. Jour, of Sci, Jan., 1896, Vol. 1, pp. 41-49. Reprinted in Phil- osophical Magazine, Feb., 1896, Vol. 41, 123-133. The Use and Mounting of the Concave Grating as an Analyzing or Direct Comparison Spectroscope. No. 15, The Modem Spectroscope. Astro- physical Journal, Jan., 1896, Vol. 3, pp. 47-62. A Simple Optical Device for completely isolating or cutting out any Desired Portion of the Diffraction Spectrum and Some Further Notes on Astro- nomical Spectroscope. No. 16, The Modern Spectroscope. Ibid., Marohj 1896, Vol. 3, pp. 149-192. 554 Titles of A Note on Mr. Burch's Method of Draw- ing Hyperbolas and on a New Hyper- iDolagraph. Philosophical Magazine, April, 1896, Vol. 41, pp. 372-378. Review of Boy's Work on the Newtonian Constant of Gravitation. Astrophysical Journal, April, 1896, Vol. 3, pp. SOS- SI 1. The Conditions of Maximum Efficiency in the Use of the Spectrograph. No. 18, The Modern Spectroscope. Ibid., May, 1896, Vol. 3, pp. 321-347. Review of Langley's Report on the Smith- sonian Astrophysical Observatory for 1895. Ibid., May, 1896, Vol. 3, pp. 398-401. The Objective Spectroscope. No. 19, The Modern Spectroscope. Ibid., June, 1896, Vol. 4, pp. 54-78. Review of Professor Stoney's paper on the Equipment of the Astrophysical Ob- servatory of the Future. Ibid., Oct., 1896, Vol. 4, pp. 238-243. A Note on the Preparation of Phosphores- cent Barium Sulphide. Ibid., Nov., 1896, Vol. 4, pp. 308-309. A Note on a Combined Equatorial Tele- scope and Polar Heliostat. Ibid. , Nov., 1896, Vol. 4, p. 310. On a New Form of Mounting for Reflect- ing Telescopes, devised by the late Arthur Cowper Eanyard. Ibid., Feb., 1897, Vol. 5, pp. 132-142. A Note on a New Form of Fluid Prism. Ibid., Feb., 1897, Vol. 5, p. 149. On the Resolving Power of Telescopes and Spectroscopes for Lines of Finite Width. Memorie delta Societa degli Spettroscopisti Italiani, Jan., 1897, Vol. 26, pp. 2-22. Philosophical Maga- zine, May, 1897, Vol. 43, pp. 317-343. Thermal Measurements with the Bolo- meter by the Zero Method. Astro- physical Journal, April, 1897, Vol. 5, pp. 268-276. The Application of the Interferometer to the Measurement of Small Angular Deflections of a Suspended System. Physical Review, May-June, 1897, Vol. 4, pp. 480-497. Tables of the Practical Resolving Power of Spectroscopes. Astrophysical Jour- nal, June, 1897, Vol. 6, pp. 27-36. Ueber das AuflSsungsvermogen von Fern- rohren und Spectroskopen ftir Linien von endlicher Breite. Ann. der Physik u. Chemie, June, 1897, Vol. 61, pp. 604-630. On the Conditions which determine the Limiting Time of Exposure of Photo- graphic Plates in Astronomical Pho- tography. Astronomische Nachrichten, Vol. 144, pp. 97-110. The Effect of the General Illumination of the Sky on the Brightness of the Field at the Focus of a Telescope. Monthly Notices of Hoy al Astronomical Soc, June, 1897, Vol. 57, pp. 686-589. A Note on Spider Lines. Ibid., pp. 589- 591. On the Conditions which determine the Ultimate Optical Efficiency of Methods for observing Small Rotations, and on a Simple Method of doubling the Ac- curacy of the Mirror and Scale Method. Philosophical Magazine, July, 1897, Vol. 44, pp. 83-97. On the Conditions of Maximum Efficiency in Astrophilographio Work. Part I. General Theory of Telescopic Images of Different Forms of Radiating Sources. Astrophysical Journal, Aug., 1897, Vol. 6, pp. 119-135. A Comparison of the Photographic and of the Hand and Eye Methods of de- lineating the Surface Markings of Celestial Objects. Popular Astron- omy, Aug., 1897, Vol. 5, pp. 200-206. Astronomical Photography. Knowledge, Aug. and Sept., 1897, Vol. 20, pp. 193- 195, 218-221. A Note on the Effect of Heat on Phos- phorescence. Astrophysical Journal, Aug., 1897, Vol. 6, pp. 153-155. Adam Hilger. Ibid., pp. 139-141. Review of Dr. Braun's Die Gravitations Constante die Masse und mittlere Dichte der Erde. Ibid., pp. 157-163. Sur le Pouvoir S6parateur des Lunettes et de Spectroscopes pour les Raies de Largeur Finie. Jour, de Physique, Aug., 1897, Vol. 6, pp. 409. Published Papers. 555 A Determination of the Specific Kesist- ance and Temperature Coefficient of Oil in Thin Films and the Application of these Results to the Measurement of the Thickness of Oil Films in Jour- nal Bearings. Physical Beview, A\i.g., 1897, Vol. 5, pp. 75-97. On the Photography of Planetary Sur- faces. Observatory, Sept., Oct., Nov., 1897, Vol. 20, pp. 333-341, 365-370, 404^410. On the Conditions required for attaining Maximum Accuracy in the Determina- tion of Specific Heat hy the Method of Mixtures. Am. Jour, of Set, Sept., 1897, Vol. 4, pp. 265-282. On the EfEect of the Size of an Objective on the Visibility of Linear Markings on the Planets. Astronomical Jour- nal, Oct. 6, 1897, Vol. 18, pp. 41- 45. On the Reduction of Observations. 06- servatory, Oct. 1897, Vol. 20, pp. 390- 392. Note on the General Theory of Telescopic Images. Astrophysical Journal, Dec, 1897, Vol. 6, p. 463. On the Theory of Lubrication and the Determination of the Thickness of the Film of Oil in Journal Bearings. Jour, of Franklin Institute, Dec, 1897, Jan., 1898, Vols. 144-145. On the Conditions of Maximum Efficiency in Astrophilographic Work. Part II. Effect of Atmospheric Aberration on the Intensity of Telescopic Images. Astrophysical Journal, Jan., 1898, Vol. 7, pp. 70-76. A Note on the Discovery of an Error in the Papers of Struve and Lord Ray- leigh dealing with the Application of the Principles of the Wave Theory to the Determination of the Intensity of the Images of Fine Lines and Ex- tended Areas at the Focus of a Tele- scope. Astrophysical Journal, Jan., 1898, Vol. 7, pp. 77-85. A Note on an Error in the Expression for the Intensity of Illumination at the Focal Plane of a Telescope due to an Infinitely Extended Luminous Area. Astronomical Journal, Jan., 1898, Vol. 18, pp. 124^126. A Note on a New Form of Mirror for Re- flecting Telescopes. Popular Astron- omy, Feb., 1898, Vol. 5, pp. 518-524. On the " Worthlessness " of Methods of Geometrical Optics in dealing with the Problems relating to the Definitive and the Delineating and Eesolving Power of Telescopes. Ibid., pp. 528- 536. A Note on the Figuring and Use of Eccentric and Unsymmetrical Forms of Parabolic Mirrors. Astrophysical Journal, Feb., 1898, Vol. 7, pp. 146- 149. A Note on the Result concerning Dif- fraction Phenomena recently criticised by Mr. Newall. Monthly Notices of Boyal Astronomical Soc, March, 1898, Vol. 58, pp. 286-291. Notes on the Use of the Grating in Stellar Spectroscopic Work. Astrophysical Journal, March, 1898, Vol. 7, pp. 198- 208. CHARLES WALKER: — B.C.B., University of Tennessee, 1885; M.A., ibid., 1886 ; Assistant Professor of Chemistry and Physics, ibid., 1886- 88 ; Assistant in Chemistry, U. S. Naval Academy, Annapolis, 1889-90 ; Fellow in Chemistry, Clark University, 1890- 93 ; Professor of Chemistry and Physics, Wisconsin State Normal School, 1893-94 ; Professor of Natural Science, Carson- Newman College, Mossy Creek, Tenn., 1898-. Author of : — Oxidation of Meta-Brom Toluene and Ni- trotoluene Sulphamide. (With Dr. W. A. Noyes.) Am. Chem. Jour., June, 1886, Vol. 8, pp. 185-190. Oxidation of Parar-xylene Sulphamide. (With Dr. W. A. Noyes.) Ibid., April, 1887, Vol. 9, pp. 93-99. The Condensation-Products of Acetacetic- ether Hydrazide and Oxalciticether Hydrazide. Ibid., Dec, 1892, Vol. 14, pp. 576-586. 556 Titles of The Condensation-Products of Aromatic Hydrazydes of Acetaciticether. Indol and Pyrazol Derivations. Ibid., June, 1894, Vol. 16, pp. 430-442. On the Action of Potassium Hydroxide on Orthomethoxysulphaminebenzoic Acid. Ihid., 1897, Vol. 19, pp. 578- 580. ARTHUR J. WARNER: — A.B., Marietta College O., 1889; A. M., ibid., 1897; Scholar in Physics, Clark University, 1889-90 ; Engaged in Electrical Work, Johns Hopkins Univer- sity, 1890-92 ; Certificate in Electrical Engineering, ibid., 1892 ; With the Cher- okee Mining Co., Chute, 6a., 1898-. SHO WATASE: — B.S., Sapporo, Japan, 1884; Student of Zoology, University of Tokio, 1884-86; Fellow in Biology, Johns Hopkins Univer- sity, 1888-89 ; Bruce Eellow, ibid., 1889- 90 ; Ph.D., Johns Hopkins University, 1890 ; Lecturer and Assistant in Mor- phology, Clark University, 1890-92 ; Reader in Cellular Biology, University of Chicago, 1892-93 ; Instructor in Anat- omy and Physiology of the Cell, ibid., 1898-95 ; Assistant Professor in Cellular Biology, ibid., 1895-99 ; Professor of Cellular Biology, Imperial University, Tokio, Japan, 1899-. Author of : — Caryokinesis and the Cleavage of the Ovum. J. H. U. Circulars, April, 1890, Vol. 9, pp. 53-56. On the Morphology of the Compound Eyes of Arthropods. Quar. Jour, of Micr. Sci., June, 1890, N. S., Vol. 31, pp. 143-158, 1 pi. On Caryokinesis. Woods Soil Biological Lectures, 1890. Ginn & Co., Boston, 1891, pp. 168-187. Studies on Cephalopods. I. Cleavage of the Ovum. Journal of Morphology, Jan., 1891, Vol. 4, pp. 247-302, 4 pis. The Origin of the Sertoli's Cell. Ameri- can jffaturalist, May, 1892, Vol. 26, pp. 442-444. On the Significance of Spermatogenesis. Ibid., July, 1892, Vol. 26, pp. 624-626. On the Phenomena of Sex Differentiation. Jour. ofMorph.,J-a\j, 1892, Vol. 6, pp. 481^93. Homology of the Centrosome. Ibid., May, 1893, Vol. 8, pp. 433-444. On the Nature of Cell Organization. Woods Soil Biological Lectures, 1893. Ginn & Co., Boston, 1894, pp. 83-103. Origin of the Centrosome. Ibid., 1894. Ginn & Co., Boston, 1895, pp. 273-287. On the Physical Basis of Animal Phos- phorescence. Ibid., 1895. Ginn & Co., Boston, 1896, pp. 101-118. Microsomes and their Eelation to the Centrosome. Science, Eeb. 5, 1897, N. S., Vol. 5, pp. 230-231. Protoplasmic Contractibility and Phos- phorescence. Ibid., 1898. (In press.) OLIVER P. ■WATTS: — A.B., Bowdoin College, 1889 ; A.M., ibid., 1892; Scholar in Chemistry, Clark University, 1889-90 ; Instructor in Physics, Chemistry, and Mathematics, Eranklin Academy, Malone, N. Y., 1892- 98 ; Instructor in Physics, High School, Waltham, Mass., 1898-. ARTHUR GORDON 'WEBSTER: — A.B., Harvard University, 1885; In- structor in Mathematics, ibid., 1885-86; Parker Fellow, ibid., 1886-89; Student, Universities of Berlin, Paris, and Stock- holm, 1886-90 ; Ph.D., University of Ber- lin, 1890 ; Decent in Physics, Clark University, 1890-92 ; Assistant Pro- fessor of Physics, 1892- ; Resident Fellow, American Academy of Arts and Sciences; Fellow, American Association for the Advancement of Science ; Mem- ber: American Mathematical Society, American Physical Society. Author of : — Versuche uber eine Methods zur Bestim- mung des Verhaltnisses der elektro- magnetischen zur elektrostatischen Einheit der Elektricitat. (Inaugural- dissertation.) Berlin, 1890. Published Papers. 557 A National Physical Laboratory. Peda- gogical Seminafy, June, 1892, Vol. 2, pp. 90-101. Unipolar Induction and Current without Difference of Potential. Electrical World, April 14-21, 1894, Vol. 23, pp. 491-492, 523-524. On a Means of producing a Constant An- gular Velocity. Am. Jour, of Set, May, 1897, Vol. 3, pp. 379-382. A Rapid Break for Large Currents. Tbid. , pp. 383-386. A New Instrument for measuring the In- tensity of Sound. ("WithB.P. Sharpe.) Beport British A. A. S., Toronto, 1897, p. 584. Also Proc. A. A. A. 8., Bos- ton, 1898, p. 136. The Theory of Electricity and Magnetism, being Lectures on Mathematical Phys- ics. Macmillan & Co., London, 1897. 563 pp. An Experimental Determination of the Period of Electrical Oscillations. (Elihu Thomson Prize, Paris, 1895.) Physical Beview, May-June, 1898, Vol. 6, pp. 297-314. Note on Stokes's Theorem in Curvilinear Coordinates. Bull. Am. Math. Soc, June, 1898, 2d ser., Vol. 4, pp. 438- 441. A New Chronograph and a Means of Eating Tuning-forks. Proc. A. A. A. S., Boston, 1898, p. 136. A Geometrical Method for Investigating Diffraction by a Circular Aperture. Hid., p. 136. Report on the State of the Mathematical Theory of Electricity and Magnetism. Ibid., pp. 103-112. Also Science, Dec. 9, 1898, Vol. 8, pp. 803-810. Ten Lowell Institute Lectures on Elec- tricity and Magnetism, Light, and the Ether, 1897. Six Lectures for the Colloquium of the American Mathematical Society, 1898. JULIUS B. •WEEMS: — B.S., Maryland Agricultural College, 1888 ; Instructor in Chemistry and Mathe- matics, ibid., 1888-89; Student, Johns Hopkins University, 1889-91 ; Chemist at Phosphate Mines, Florida, 1891-92 ; Fel- low in Chemistry, Clark University, 1892-94 ; Ph.D., Clark University, 1894 ; On Special Research at New York Experiment Station, Geneva, N. Y., Oct., 1894-March, 1895 ; Professor of Agricul- tural Chemistry, Iowa State College of Agriculture and Mechanic Arts, and Chemist, Iowa Experiment Station, Ames, la., March, [1895- ; Chemist, Iowa Geo- logical Survey, Jan., 1899- ; Member: German Chemical Society, American Chemical Society, Society of Chemical Industry of London, Society for Promo- tion of Agricultural Science, American Academy of Political and Social Science ; Fellow, Iowa Academy of Science. Author of : — On Electrosyntheses by the Direct Union of Anions of Weak Organic Acids. Am. Chem. Jour., Dec, 1894, Vol. 16, pp. 569-588. The Chemical Composition of Squirrel-tail Grass. Iowa Mxperiment Station Bull, No. 30, pp. 320-321. Studies on Milk Preservatives. Ibid. , No. 32, pp. 499-504. Soil Moisture. Ibid., No. 32, pp. 505-515. The Adulteration of Pood. Bep. of State Dairy Com. of Iowa, 1895, pp. 212-216. Soil Moisture. Iowa Experiment Station Bull, No. 36, pp. 825-848. Milk Preservatives. III. State Dairyman' s Ass'n, 1898, pp. 103-110. Chemistry and some of its Relations to Agriculture. Bep. of the Iowa State Agric. Soc, 1898, pp. 42-48. GERALD M. 'WEST: — A.B., Columbia College, 1888; A.M., ibid., 1889; Ph.D., Columbia College, 1890 ; Fellow in Anthropology, Clark University, 1890-91 ; Assistant in Anthropology, 1891-92 ; First Assist- ant in Anthropology, Bureau of Ethnology, World's Columbian Exposition, 1892-93 ; Dooent in Ethnology, University of Chicago, 1893-95 ; Curator of Physical Anthropology, Field Columbian Museum, Chicago, 1894. 558 Titles of Author of: — The Status of the Negro in Virginia during the Colonial Period. (Thesis for the Doctorate.) New York, 1890. 76 pp. The Growth of the Breadth of the Face. Science, July 3, 1891, Vol. 18, pp. 10- 11. Eye-Tests on School Children. Am. Jour, of Psy., Aug., 1892, Vol. 4, pp. 595- 596. The Growth of the Body, Head, and Face. Science, Jan. 6, 1893, Vol. 21, pp. 2-4. The Anthropometry of American School Children. Mem. Internal. Congress of Anthropology, 1893 (Chicago, 1894), pp. 50-58. Anthropometrische XJntersuchungen tiher die Schulkinder in "Worcester, Mass., Amerika. Arch. f. Anthropologic, Braunschweig, 1893, Vol. 22, pp. 13-48. The Growth of the Human Body. Hdu- cational Meview, Oct., 1896, Vol. 12, pp. 284-289. Ohservations on the Relation of Physical Development to Intellectual Ability, made on the School Children of To- ronto, Canada. Science, Aug. 7, 1896, N. S., Vol. 4, pp. 156-159. A. HARRT "W-HKEiLER: — S.B., Worcester Polytechnic Institute, 1894 ; Instructor in Mathematics, English High School, Worcester, 1894-Deo., 1896; and 1899- ; Scholar in Mathematics, Clark TJmversity Dec, 1896-June, 1899. WILLIAM MORTON "WHEELER: — Graduate, German and English Academy, Milwaukee, Wis., 1880 ; Graduate German- American Normal College, Milwaukee, Wis., 1883; Ward's Natural Science Es- tablishment, Eochester, N. Y., 1883-85; Teacher of German and Assistant in Biol- ogy, Milwaukee Public High School, 1885- 88; Curator, Milwaukee Public Museum, 1887-90; PeUow and Assistant in Morphology, Clark University, 1890- 92; Ph.D., Clark University, 1892; Student at the University of Wtirzburg and University of Li^ge ; Occupant of the Smithsonian Table at the Zoological Sta- tion, Naples, 1893-94; Instructor in Em- bryology, University of Chicago, 1892-95 ; Assistant Professor of Embryology, ibid., 1895-99; Professor of Zoology, University of Texas, 1899. Author of : — Spiders of the Sub-family Lyssomanss. (With G. W. and E. G. Peckham.) Trans. Wis. Acad. Science, Arts and Letters, Vol. 7, 1888, pp. 222-256, Pis. zi. and xii. On Two New Species of Cecidomyid Plies producing Galls on Antennaria planta^ giuifolia. Froc. Wis. Nat. Hist. Soc, April, 1889, pp. 209-216. Two Cases of Insect Mimicry. Ibid., 'pp. 217-221. Ueber driisenartige Gebilde im ersten Ab- dominal-segment der Hemipterenem- bryonen. Zool. Ameiger, 1889, 12 Jahrg., pp. 500-504, 2 fig. Homologues in Embryo Hemiptera of the Appendages to the First Abdominal Segment of other Insects. American Naturalist, 1889, pp. 644-645. The Embryology of Blatta germanica and Doryphora decem-lineata. Jour, of Morph., Sept., 1889, Vol. 3, pp. 291- 386, 7 pi. On the Appendages of the First Abdomi- nal Segment of Embryo Insects. Wis. Acad. Science, Arts and Letters, Sept. 20, 1890, Vol. 8, pp. 87-140, Pis. i.- iii. Ueber ein eigenthumliches Organ im Lo- oustidenembryo. Zool. Anzeiger, 13 Jahrg., 1890. Note on the Oviposition and Embryonic Development of Xlphidium ensiferum Scud. Insect Life, 1890, Vol. 2, pp. 222-225. Descriptions of Some New North American DolichopodidsB. Psyche, 1890, Vol. 1, pp. 337-343, 356-362, 373-379. The Supposed Bot-fly Parasite of the Box- Turtle. Ibid., 1890, Vol. 1, p. 403. Hydrocyanic Acid secreted by Polydesmus virginiensis Drury. Ibid., 1890, Vol. 1, p. 442. Published Papers. 559 The Embryology of a Common Fly. Ibid., 1891, Vol. 2, pp. 97-99. The Germ-band of Insects. Ibid., 1891, Vol. 2, pp. 112-115. Neuroblasts in the Arthropod Embryo. Jour, of Morph., Jan., 1891, Vol. i, pp. 337-343, 1 fig. Concerning the " Blood-tissue " of the In- secta. Ibid., 1892, Vol. 2, pp. 216-220, 233-236, 253-258, PI. vii. A Contribution to Insect Embryology. (Inaugural Dissertation.) Jour, of Morph., April, 1893, Vol. 8, pp. 1-160, 6 pis. The Primitive Number of Malpighian Ves- sels in Insects. Psyche, 1893, Vol. 2, pp. 457-460, 485-486, 497-498, 509-510, 639-541, 545-547, 561-564, 2 figs. Synccelidium pellucidum, a New Marine Triclad. Jour, of Morph., April, 1894, Vol. 9, pp. 167-194, 1 pi. Planocera inquilina, a Polyclad inhabiting the Branchial Chamber of Sycotypus canalioulatus Gill. Ibid., April, 1894, Vol. 9, pp. 195-201, 2 figs. Protandric Hermaphroditism in Myzo- stoma. Zool. Anzeiger, 17 Jahrg., 1894. The Behavior of the Centrosomes in the Fertilized Egg of Myzostoma glabrum Leuckart. Jour, of Morph., Jan., 1895, Vol. 10, pp. 305-311. The Problems, Methods, and Scope of Developmental Mechanics. (Trans- lated from the German of Wilhelm Eoux.) Biological Lectures, Marine Biological Laboratory, Woods HoU, 1895, pp. 149-190. The Sexual Phases of Myzostoma. Mitth. a. d. Zool. Station zu Neapel, 1896, Vol. 12, pp. 227-302. Pis. x.-xii. The Genus Ochthera. Entomological News, April, 1896, Vol. 7, pp. 121- 123, 1 fig. Two Dolichopodid Genera New to Amer- ica. Ibid., May, 1896, Vol. 7, pp. 152- 156. A New Genus and Species of Dolicho- podidse. Ibid., June, 1896, Vol. 7, pp. 185-189, 1 fig. A New Empid with Remarkable Middle Tarsi. lUd., June, 1896, Vol. 7, pp. 189-192, 3 figs. An Antenniform Extra Appendage in Dilophus tibialis Loew. Arch. f. Ent- wick. Mech. d. Organismen, 1896, Vol. 3, pp. 261-268, PI. xvi. The Maturation, Fecundation, and Early Cleavage of Myzostoma glabrum Leuckart. Arch, de Biologie, 1897, Vol. 15, pp. 1-77, Pis. i.-iii. A Genus of Maritime Dolichopodidse New to America. Proc. Cal. Acad. Sci., Zool, July, 1897, 3d ser., Vol. 1, pp. 145-152. PI. iv. A New Genus of DoUchopodidse from Florida. Zo'ological Bulletin, Feb., 1898, Vol. 1, pp. 217-220, 1 fig. A New Peripatus from Mexico. Jour, of Morph., Oct., 1898, Vol. 15, pp. 1-8, 1 pi. George Baur's Lite and Writings. Amer- ican Naturalist, Jan., 1899, Vol. 33, pp. 15-30. Anemotropism and Other Tropisms in Insects. Arch. f. Entwick. Mech. d. Organismen, 1899, Vol. 8, pp. 373-381. New Species of Dolichopodidse from the United States. Proc. Cal. Acad. iSci., Zool., 3d ser, Sept., 1899, Vol. 2, pp. 1-77, Pis. i.-iv. The Development of the Urinogenital Or- gans of the Lamprey. Zool. Jahr- bucher, Abth. f. Morph., 1899, Bd. 13, pp. 1-88, Pis. i.-vii. The Life-History of Dicyema. Zool. An- zeig., April, 1899, Vol. 22, pp. 169-176. J. Beard on the Sexual Phases of Myzos- toma. Ibid., July, 1899, Vol. 22, pp. 281-288. Caspar Friedrich Wolfi and the Theoria Generationis. Biological Lectures, Marine Biological Laboratory, Woods HoU, 1899. GUY MONTROSE "WHIPPLE: — A.B. , Brown University, 1897 ; Scholar and Assistant in Psychology, Clark XJmversity, 1897-98 ; Assistant in Psy- chology, Cornell University, 1898-. Author of : — The Influence of Forced Respiration on Psychical and Physical Activity. Am. 560 Titles of Jour, of Pay., July, 1898, Vol. 9, pp. 560-571. On Nearly Simultaneous Clicks and Flashes. Ibid., Jan., 1899, Vol. 10, pp. 280-286. HENR7 S. ■WHITE : — A.B., Wesleyan Uniyersity, 1882 ; Assistant in Astronomy and Physios, ibid., 1882-83 ; Instructor in Mathematics, Hackettstown, N. J., 1883-84 ; Tutor in Mathematics, Wesleyan University, 1884-87 ; Ph.D., University of Gbttingen, 1890 ; Aasiatant in Mathematics, Clark University, 1890-92 ; Associate Professor of Mathe- matics, Northwestern University, 1892-94 ; Noyes Professor of Pure Mathematics, ibid., 1894- ; Member American Mathe- matical Society. Author of: — Ueber zwei covariante Formen aus der Theorie der Abel'schen Integrate auf vollst^ndigen, singularitStenfreien Sohnittcurven zweier Flacheu. Math. Annalen, 1890, Vol. 36, pp. 597-601. Abel'sche Integrale auf singularitaten- freien, einfach uberdeckten, voUstan- digen Schnittcurven eines beliebig ausgedehnten Baumes. Nova Acta Leop.-Carol. Akad., 1891, Vol. 57, pp. 41-128. On generating Systems of Ternary and Quaternary Linear Transformations. Am. Jour, of Math., July, 1892, Vol. 14, pp. 274-282. A Symbolic Demonstration of Hilbert's Method for deriving Invariants and Covariants of Given Ternary Forms. Ibid., pp. 283-290. Review of Klein's Evanston Lectures. Bull. N. Y. Math. Soe., Feb. 1894, Vol. 3, pp. 119-122. Beduction of the Resultant of a Binary Quadric and n-ic by Virtue of its Semi- combinant Property. Ibid. , Oct., 1894, Vol. 1, pp. 11-15. Semi-combinants as Concomitants of Af- filiants. Am. Jour, of Math., July, 1895, Vol. 17, pp. 235-265. Kronecker'sLinear Relation among Minors of a Symmetric Determinant. Bull. Am. Math. Soc, Feb., 1896, Vol. 2, pp. 136-138. Numerically Regular Beticulations upon Surfaces of Deficiency higher than 1. Ibid., Dec, 1896, Vol. 3, pp. 116- 121. The Cubic Resolvent of a Binary Quartic Derived by Invariant Definition and Process. Ibid., April, 1897, Vol. 3, pp. 250-253. CoUineations in a Plane with Invariant Quadric or Cubic Curves. Ibid., Oct., 1897, Vol. 4, pp. 17-23. Inflexional Lines, Triplets, and Triangles associated with the Plane Cubic Curve. Ibid., March, 1898, Vol. 4, pp. 258- 260. The Construction of Special Regular Re- ticulations on a Closed Surface. Ibid. , May, 1898, Vol. 4, pp. 376-382. Elliott's Algebra of Quantics. Review. Ibid., July, 1898, Vol. 4, pp. 545-549. The Cambridge Colloquium. Ibid., Oct., 1898, Vol. 5, pp. 57-58. Report on the Theory of Projective Inva- riants ; the Chief Contributions of a Decade. Ibid., Jan., 1899, Vol. 5, pp. 161-175. CHARLES O. 'WHITMAN: — A.B., Bowdoin College, 1868; Principal Westford Academy and Master in the English High School, Boston, 1869-76; Ph.D., University of Leipzig, 1878 ; Fel- low, Johns Hopkins University, 1878-79 ; Professor of ZoSlogy, Imperial University of Japan, 1880-81 ; Naples Zo51ogical Station, 1881-82 ; Director, Allls Lake Laboratory, 1886-89 ; Director, Marine Biological Laboratory, Woods HoU, Mass., 1888- ; FrofesBor of Animal Morphol- ogy, Clark TTniversity, 1889-92 ; Head Professor of Zoology, University of Chicago, 1892- ; Editor of : Journal of Morphology, 1887- ; Biological Lectures from the Marine Biological Laboratory, Woods HoU, Mass., 1890- ; American Naturalist, Department of Microscopy, 1883-96 ; ZoSlogical Bulletin, 1897-99 (continued in Biological Bulletin, 1899-). Published Papers. 561 Author of : — The Embryology of Clepsine. Quar. Jour. Mior. Sci., 1878, Vol. 18, pp. 215-315. Ueber die Embryologle von Clepsine. Zool. Anzeiger, 1878, Vol. 1, pp. 5-6. Changes Preliminary to Cleavage. Proc. A. A. A. S., 1878, Vol. 27, pp. 263- 270. Do Flying Fish Fly ? American Natural- ist, Sept., 1880, Vol. 14, pp. 641-653. Zo81ogy in the University of Tokio, Yoko- hama, 1881, pp. 1-44. Methods of Microscopical Research in the Zoblogioal Station of Naples. Ameri- can Naturalist, Sept., 1882, Vol. 16, pp. 697-785. A New Species of Branchiobdella. Zool. Anzeiger, Sept. 10, 1882, Vol. 5, pp. 1-2. The Advantages of Study at the Naples Zoological Station. Science, July 27, 1883, Vol. 2, pp. 93-97. A Bare Form of the Blastoderm of the Chick, anfl its Bearing on the Question of the Formation of the Vertebrate Embryo. Quar. Jour. Micr. Sci., 1883, Vol. 23, pp. 375-397. A Contribution to the Embryology, Life- History, and Classification of the Di- cyemids. Mitth. aus d. Zool. Station von Neapel, Jan. 23, 1883, Vol. 4, pp. 1-89, 5 pis. On the Development of some Pelagic Fish Eggs. (With Alexander Agassiz.) Proc. Am. Acad. Arts and Sciences, 1884, N. S., Vol. 12, pp. 23-75. The External Morphology of the Leech. (With Alexander Agassiz.) Ibid., 1884, N. S., Vol. 12, pp. 76-87. The Connective Substance in the Hiru- dinea. American Naturalist, Oct., 1884, Vol. 18, pp. 1070-1071. The Segmental Sense-Organs of the Leech. Ibid., Nov., 1884, Vol. 18, pp. 1104-1109. The Pelagic Stages of Young Fishes. (With Alexander Agassiz.) Mem. Mus. Comp. Zoology, 1885, Vol. 14, pp. 1-56. Methods in Microscopical Anatomy and Embryology. Boston, 1885. 255 pp. 2o The Germ-Layers of Clepsine. Zool. Anzeiger, 1886, Vol. 1, pp. 1-6. The Leeches of Japan. Quar. Jour. Micr. Sci., April, 1886, Vol. 26, pp. 317^16. 5 pis. Biological Instruction in Universities. American Naturalist, June, 1887, Vol. 21, pp. 507-519. A Contribution to the History of the Germ-Layers in Clepsine. Jour, of Morph., Sept., 1887, Vol. 1, pp. 105- 182, 3 pis. The Kinetic Phenomena of the Egg during Maturation and Fecundation. Ibid., Dec, 1887, Vol. 1, pp. 227- 252. The Seat of Formative and Kegenerative Energy. Ibid., July, 1888, Vol. 2, pp. 27-49. Address at the opening of the Marine Biological Laboratory, July 17, 1888. First Annual Beport for the Tear 1888, pp. 24-31. The Development of Osseous Fishes. (With Alexander Agassiz.) IL The Pregmbryonio Stages of Development. Part I. The History of the Egg from Fertilization to Cleavage. Mem. Mus. Comp. Zo'ology, 1889, Vol. 14, pp. 1-40. Some New Facts about the Hirudinea. Jour, of Morph., April, 1889, Vol. 2, pp. 686-599. Specialization and Organization, Compan- ion Principles of all Progress. The Most Important need of American Bi- ology. Woods Soil Biological Lec- tures, 1890. Ginn & Co., Boston, 1891, pp. 1-26. The Naturalist's Occupation. Ibid., 1890. Ginn & Co., Boston, 1891, pp. 27-52. Spermatophores as a Means of Hypoder- mic Impregnation. Jour, of Morph., Jan., 1891, Vol. 4, pp. 361-406, 1 pi. Description of Clepsine Plana. Ibid., pp. 407-418, 1 pi. Metamerism of Clepsine. LeuckarVs Festschrift, 1892, pp. 385-395. The Marine Biological Laboratory, Fri- day Chapel Address. University News, Chicago, Deo. 17, 1892. 562 Titles of General Physiology and its Relations to Morphology. Fifth Annual Jteport Marine Biological Laboratory, 1892. Keprlnted in American Naturalist, Sept., 1893, Vol. 27, pp. 802-807. A Marine Biological Observatory. Pop. 8d. Mo., Feb., 1893, Vol. 42, pp. 459- 471. A Marine Observatory the Prime Need of American Biology. Atlantic Monthly, June, 1893, Vol. 71, pp. 808-818. A Sketch of the Structure and Develop- ment of the Eye of Clepsine. Spen- geVs Zool. Jahrbucher, 1893, Vol. 6, pp. 616-625. The Inadequacy of the Cell-Theory of De- velopment. Jour, of Morph., August, 1893, Vol. 8, pp. 639-658 ; also Woods Soil Biological Lectures, 1893. Ginn & Co., Boston, 1894, pp. 105-124. The Work and the Aims of the Marine Biological Laboratory. Woods Moll Biological Lectures, 1893. Ginn & Co., Boston, 1894, pp. 235-242. Evolution and Epigenesis. Ibid., 1894. Ginn & Co., 1895, pp. 205-224. Bonnet's Theory of Evolution. Ibid., 1894, Ginn & Co., 1895, pp. 225-240. The Palingenesia and the Germ Doctrine of Bonnet. Ibid., W9i, Ginn & Co., 1895, pp. 241-272. The Egg of Amia and its Cleavage. (With A. C. Eycleshymer.) Jour, of Morph., Feb., 1897, Vol. 12, pp. 309-354. 2 pis. Some of the Functions and Features of a Biological Station. Presidential Ad- dress to the Society of American Nat- uralists, Ithaca meeting, 1897. Woods Soil Biological Lectures, 1896-97. Ginn & Co., Boston, 1898, pp. 231- 242; also in Science, Jan. 14, 1898, Vol. 7, pp. 37-44. The Centrosome Problem and an Experi- mental Test. Science, Feb. 5, 1897, N. S., Vol. 5, p. 67. Lamarck and "A Perfecting Tendency." Ibid., Jan. 21, 1898, Vol. 7, p. 99. Apathy's Grief and Consolation. Zool. Ameiger, May 1, 1899, Vol. 22, pp. 196-197. Myths in Animal Psychology. Monist, July, 1899, Vol. 9, pp. 524-537. Animal Behavior. Woods Soil Biologi- cal Lectures, 1898, pp. 285-338. FRANK B. 'WILLIAMS: — C.E., Missouri State University, 1890; M.S., ibid., 1893; Teaching Fellow in Mathematics, ibid., 1892-93 ; United States Assistant Engineer, Tennessee Eiver Improvement, 1895-97 ; Scholar in Mathematics, Clark TTniversity, 1897-98 ; FeUow, 1898-99. Author of: — Note on the Finite Continuous Groups of the Plane. Proc. Am. Acad, of Arts and Sci., Nov., 1899, Vol. 35, pp. 97-107. J. FRANCIS •WILLIAMS: — C.E., Eensselaer Polytechnic Institute, 1883 ; B.S., ibid., 1884 ; Ph.D., Univer- sity of Gottingen, 1886 ; University of Berlin, 1887 ; Director, Technical Museum of Pratt Institute, Brooklyn, N. Y., 1887- 89 ; Dooeut in Mineralogy, Clark Uni- versity, 1889-90 ; Assistant Professor of Geology, Cornell University, 1890-91. Died Nov. 9, 1891. Author of: — Tests of Rutland and Washington County Slates. Van Nostrand's Eng. Mag., 1884, No. 188. Ueber den Monte Amiata in Toscana und seine Gesteine. Stuttgart, 1887. Igneous Rocks of Arkansas. Annual Be- port of the Geological Survey, Arkan- sas, 1890, Vol. 2. 457 pp. Illustrated. ALBERT P. "WILLS: — B.E.E., Tufts College (with Honors in Electricity), 1894; Scholar In Physics, Clark University, 1894-95 ; Fellow, 1895-Jan., 1897; Ph.D., Clark Uni- versity, 1897 ; Professor of Physical Sciences, Colorado State Normal School, Jan., 1897-June, 1898 ; Student in Phy- sics, Universities of Gottingen and Ber- lin, 1898-99 ; Associate in Applied Published Papers. 563 Mathematics and Physios, Biyn Mawr College, 1899-. Author of: — On the Susceptibility of Diamagnetic and weakly Magnetic Substances. Philo- sophical Magazine, May, 1898, 5th ser., Vol. 45, pp. 432-447 ; also Physi- cal Beview, AprU, 1898, Vol. 6, pp. 223-238. Moleculare Susceptibilitat paramagneti- scher Salze. (With O. Liebknecht.) Vei-handl. der deuts. physik. Gesell- schaft, Sitz. vom 30 Juni, 1899 (to be published later in extenso). Zur thermometrischen und kryogenen Ver- wendung des Kohlensaureschnees. (With H. du Bois.) Verhandl. der deuts. physik. Gesellschaft. Sitz. vom 30 Juni, 1899. (To be published later in extenso.) On the Magnetic Shielding Effect of Tri- lamellar Spherical and Cylindrical Shells. Physical Beview, Oct., 1899. Vol. 9, pp. 193-213. MINOSUKE YAMAGUCHI: — LL.B., Tokio Law School, 1892 ; Student in Philosophy, Be Pauw University, 1894- 97 ; A.B. , Lombard University, 1897 ; Scholar in Psychology, Clark Univer- sity, 1897-98 ; Graduate Student, Yale University, 1898-99. ALBERT H. YODER: — Teacher in Public Schools, Dakota, 1882- 87 ; Graduate, State Normal School, Madison, So. Dak., 1888; Superintendent of Schools, ibid., 1888-91 ; A.B., Univer- sity of Indiana, 1893 ; Scholar in Peda- gogy, Clark University, 1893-94; Principal, San Francisco Normal School, 1894-95 ; Scholar in Psychology, Univer- sity of Chicago, 1895-96 ; Specialist in Pediatrics, Northwestern University Medi- cal School, 1896 ; President of the Faculty and Professor of Philosophy and Peda- gogy, Vincennes University, 1896- ; Edi- tor of the Bulletin of the Preparatory Teachers' Department, Vincennes Univer- sity, Nov. 1896-. Author of: — The Study of the Boyhood of Great Men. Pedagogical Seminary, Oct., 1894, Vol. 3, pp. 134-156. A Syllabus for the Study of Pubescence. Child Study Monthly, Feb., 1896, Vol. 1, pp. 280-282. Investigations in Pubescence. Trans. Ml. Soc. for Child Study, 1897, Vol. 2, No. 2, pp. 81-84. Pubescence. Northwestern Monthly, May, 1898, Vol. 8, pp. 597-600. LE'WIS EDWIN YORK: — Tutor in Mathematics, Mt. Union College, 1891-93 ; B.S., Mt. Union College, 1894 ; Superintendent of Public Schools, Newton Falls, C, 1894-96; Graduate, King's School of Oratory, 1896; President Du- quesne College, 1896-97; Ph.D. (pro merito), Duquesne College, 1897 ; Scholar in Pedagogy, Clark University, 1897- 98; Superintendent Public Schools, Kingsville, 0., 1898-. Author of : — America's Need — Men. Plutocrat, Oct., 1893. Thoughts on Oratory. Dynamo, Jan., 1895. J. -W. A. YOUNG: — A.B., Bucknell University, 1887; A.M., ibid., 1890 ; Instructor in Mathematics, Bucknell Academy, 1887-88 ; University of Berlin, 1888-89; Fellow in Mathe- matics, Clark University, 1889-92 ; Ph.D., Clark University, 1892 ; Asso- ciate in Mathematics, University of Chi- cago, 1892-94; Instructor in Mathematics, ibid., 1894-97 ; Assistant Professor of Mathematical Pedagogy, ibid., 1897- ; In- vestigating Methods of Teaching Mathe- matics in Prussia, 1897-98 ; Member American Mathematical Society. Author of: — On the Determination of Groups whose Order is a Power of a Prime. Am. Jour, of Math., April, 1893, Vol. 15, pp. 124-178. 564 Titles of Published Papers. Baohmann's Theory of Numbers. Bull. N. T. Math. Soc, June, 1894, Vol. 3, pp. 215-222. Theory of Numbers and of Equations. Bull. Am. Math. Soc, 1896, 2d ser.. Vol. 3, pp. 97-105. Zur mathematisohen Lehrbiioherfrage : Eine schulstatistische Untersuchung. Soffmanri's Zeits. f. math. u. natur- wiss. Unterricht, Sept., 1898, Vol. 29, pp. 410-414. The Elements of the Differential and Integral Calculus. (With C. E. Line- barger.) D. Appleton & Co., New York. (In press.) SPECIAL STUDENTS AND MEMBERS OF THE SATURDAY TEACHERS' CLASS. [The positions here specified are those held while the incumbents were connected with the University.] Allen, Nellie B., Instructor, State Normal School, Fitchburg, Mass. Andrews, Calvin H., Instructor in Physios and Mathematics, English High School, Worcester, Mass. Andrews, Walter E., Instructor in Mathematics, English High School, Worcester, Mass. Benneyan, H. G., Pastor, Armenian Congregational Church, Worcester, Mass. Boyden, Arthur C. , Vice-Principal, State Normal School, Bridgewater, Mass. Brown, Anna L., Instructor, Northfield Training School, East Northfield, Mass. Buck, Jonathan I., Principal, High School, Webster, Mass. Calkins, Mary Whiton, Assistant Professor of Philosophy, Wellesley College, Wellesley, Mass. Carroll, Clarence E., Superintendent of Schools, Worcester, Mass. Casey, Daniel H., Principal, Grafton Street School, Worcester, Mass. Childs, Anne Gertrude, Instructor, State Normal School, Oneonta, N. Y. Clinton, Mrs. C. W. (Candidate for A.B., University of Minnesota), Worcester, Mass. Cole, George P., Instructor in Modern Languages, English High School, Worcester, Mass. Colvin, Stephen S., Instructor in English, English High School, Worcester, Mass. Dean, Harold M., Sub-master, High School, Webster, Mass. Defendorf, Allen E., Interne at Worcester Insane Hospital, Worcester, Mass. Delano, Charles W., Instructor, Classical High School, Worcester, Mass. Drake, Mary A., Principal, Washington Street School, Worcester, Mass. Edmund, Gertrude, Principal, Training School, Lowell, Mass. Fish, Rachel C, Instructor, The Dalzell School, Worcester, Mass. Flagg, Edward W., Instructor in English, State Normal School, Potsdam, N. Y. Goodwin, Edward R., Principal, Classical High School, Worcester, Mass. Gray, Albert, Instructor in Greek History, English High School, Worcester, Mass. Grout, Edgar H., Principal, High School, North Brookfield, Mass. tHale, Abby C, Teacher, Downing Street School, Worcester, Mass. Died, May 1, 1899. Hale, Edward B., Principal, High School, Brookfield, Mass. Halsey, Lila S., Principal, Northfield Training School, East Northfield, Mass. Hamlin, Alice J.