i! I'l CORNELL UNIVERSITY. THE THE GIFT OF ROSWELL P. FLOWER FOR THE USE OF THE N. Y. STATE VETERINARY COLLEQE. 1897 Cornell University Library QP 44.B95 ^Handbook for the Physiological laborator 3 1924 001 046 360 The original of tiiis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924001046360 HANDBOOK PHYSIOLOGICAL LABORATORY. TEXT-BOOK OF PATHOLOGICAL HISTOLOGY, WITH Two Hundred and Eight Illustrations. An Introduction to the Study of Pathological Anatomy. By Dr. Edward Rindfleisch, 0. 0. Professor of Pathological Anatomy in Bonn. Translated from the Second German Edition, by William 0, Kloman, M.D., assisted by P. T. Miles, M.D., Professor of Anat- omy, University of Maryland, etc. etc. Containing Two Hundred and Eight Elaborately Executed Microscopical Jlkistrations. Oc- tavo. Price, bound in cloth, .$6 00 ; leather, $: 00. For the first time since microseopieal anatomy has become the basis of a true pathology, American students, and indeed ^ye may say English students hare access to a suitable test-book in their own language. Heretofore, the opportu- nity of studying pathology has been limited to a comparative few who were fa. miliar with the German and French. But in the translation of Rindfleisch, we have furnished us not merely an excellent guide, but actually the best which could be made available, either to practitioner or student. It would be impos- sible, and it is indeed needless, to present a risume of its contents. The volume is a faithful exposition of the present state of pathological histology ; each sub- ject is fully and systematically treated, and may, therefore, be studied indepen- dently of any relation to others. The work of the translator has been well done, and although a few idiomatic sentences have crept into the text which are not very intelligible, they scarcely impair the value of the work. No physician or student should be without it. — Philadelphia Med. Times, Feb. ], 1S72. ^f~a^ r^z. HANDBOOK PHYSIOLOGICAL LABORATORY. ,^ LIBRARY E. KLEIN, M.D., \^ ,^ -^ HOLOGICAL LABORATORV OP THE EROWN IN^lTOTIOrT, ^'^ / ASSISTANT PROFESSOR IN THE PAT LONIiON, FORMERLY PKIV AT-DOCF^■ T IN HISTOLOGY IN THE UNITERSITY OF VIENNA; J. BURDOX-SANDERSON, M.D., F.R.S,, PROFESSOR OF PRACTICAL PHYSIOLOOY IN UNIVERSITY COLLEOE, LONDON; MICHAEL FOSTER, M.A., M.D., F.R.S., FELLOW OF, ANI> PR,"ELECTOR OF PHYSIOLOGY IN, TRINITY COLLEGE, CAMBRIDGE; AND T. LAUDER BRUNTON, M.D., D.Sc, LECTURER OX MATERIA MEDICA I.N' THE MEDIOAI. COLLEGE OF ST. BARTIIOLOMEW'y HOSPITAL, LONDON. EDITED BT J. BURDON-SANDERSON. IN TWO VOLUMES, WITH ONE HUNDRED AND THIRTY-THREE PLATES, CONTAOINa THREE Hl'.VDRED AND FIFTY -THREE ILLUSTEATIOXS. VOLUME I. TEXT. PHILADELPHIA: LliTDSAY AND BLAKISTOJST. 1813. TO WILLIAM SHARPEY, M.D. LL.D. F.R.S. F.Ii.S.E. pkofessoe of anatomy and phts:oi.ooy in dniyiirsity coli.f.oe londw, etc. etc Dear Dr. Sharpey, To you, who have been these many years the friend of physiologists throughout the world, and who, by your original work, by your teaching, by your generous aid and judicious counsel, have been the mainstay of physiology in England, we desire to dedicate this attempt to promote the study of our science. Accept it as a token of our personal regard, as well as of the high value we set on your life-long labors. Your devoted Friends, MICHAEL FOSTER, J. BURDON-SANDERgON, T. LAUDER BRUNTON, E. KLEIN. EDITOR'S PREFACE. This book is iutended for beginners in physioloo-ical work. It is a boolc of metbods, not a compendium of tbe science of pliysiology, and consequently claims a place rather in tbe laboratory tban in the study. But although designed for workers, the authors believe that it will be found not tbe less useful to those who desire to inform themselves by reading as to the extent to which the science is based on experiment, and as to the nature of the experiments which chie% deserve to be regarded as fundamental. The practical purpose of the book has been strictly kept in view, both in the arrangement and in the selection of the subjects. Many subjects are entirely omitted which form important chapters in every text-book. They have been left out either because they do not admit of experi- mental demonstration, or because the experiments required are of too difficult or complicated a character to be either shown to a class or performed by a beginner. The mode of arrangement will be found to be somewhat different in the four sections into which the work is divided. This diiierence, although in part attributable to difference of authorship, is mainly due to the peculiarities of the modes of demonstration required in the several sub- jects. As regards the physiology of nerve and muscle, it is suflicient to refer the I'eader to the author's introduction for an exposition of the method followed. lu the his- tological part will be found a jourely objective description of anatomical facts and methods. Substituting chemical for anatomical, the same thing might be said of the chap- ters relating to the chemical functions. Here, where minuteness of description is essential, great pains have been taken to give the student the most ample details as Vlll PREFACE. regards materials for work, instruments, and methods. In the chapter on the hlood, the same ohject has been kept iu view, but in those relating to the mechanical functions of circulation and respiration, where either man or the higher animals must be for the most part the subjects of observation, aud where consequently the couditions of experiment are complicated by the interference of the ner- vous system to an extent which it is often difficult to estimate, it has been found impossible to avoid entering somewhat more largely into theoretical explanations. In the chapters on digestion and secretion, and in the remainder of the chemical part, those experiments or methods which are most important and best suited for demonstration are distinguished by two asterisks (■•*), the less important by a single asterisk (*). The absence of an asterisk at the beginning of a paragraph denotes either that the experiment is unimportant or that it is difficult to perform. A dagger (f) is used to draw special atten- tion to a test or procedure. I have to record Dr. Brunton's obligation to Dr. Arthur Gamgee, F.R.S., for many important suggestions in the preparation of the chapter on secretion. Dr. Brunton farther wishes me to state that, although he has recom- mended no method as suitable for demonstration which he has not himself tried, he has freely availed himself of the well-known works of Hoppe-Seyler, Gorup-Besanez, and Ivtdme, both in the arrangement of the sections and iu the selection of exjieriments. It has been judged expedient by the Publishers to sepa- rate the illustrations from the text. In this way full justice has been done to the engravings of the Histologi- cal part, which have been executed by Mr. Collings from the original drawings of the autlior. Most of the illustrations of the Physiological part are the work of the same artist, both as regards drawing and engraving. Of the remainder, several have been borrowed (with the kind permission of the author) from Mr. Sut- ton's work on Volumetrical Analysis. CONTENTS. HISTOLOGY.— PART I. CHAPTER I. PAGE Blood Cobpuscles ' . . . .17 CHAPTER 11. Epithelium and EKDOTHELixiir 35 CHAPTER III. CONNBCTITE TISSUES 46 CHAPTER IV. Muscular Tissue 65 CHAPTER V. Tissues of the Neetous System 79 HISTOLOGY— PART IL CHAPTER VI. Peefabation op the Compound Tissues .... 100 CHAPTER VII. Vascular System 110 CHAPTER VIII. Lymphatic System 123 CHAPTER IX. Oroaks op Respieation 133 X CO^'TENTS. CHAPTER X. FAQR 135 Organs of Digestion CHAPTER XI. Skin, Cutaneous Glands, and Genito-Uiiinaet Apparatus 141 CHAPTER XII. Organs op Special Sense 150 CHAPTER XIII. Embryology 158 CHAPTER XIV. Appendix. — Study qp Inflamed Tissues .... 169 PHYSIOLOGY.— PART I. Bi.ooD, Circulation, Pv,espi ration, and Animal Heat. CHAPTER XV. The .Blood 175 CHAPTER XVI. The Circulation op the Blood 217 CHAPTER XVII. * Respiration 298 CHAPTER XVIII. Animal Heat 336 PHYSIOLOGY.— PART 11. Functions of Muscle and Nerve. CHAPTER XIX. General Directions 350 CHAPTER XX. General Properties op Muscle at Rest .... 360 CONTEXTS. Xi CHAPTER XXI. PAQE Preliminabt Observ.vtioxs on the Stimulation op Neuve a>:d Muscle 3g4 CHAPTER XXII. Phenomena and Laws op :\Iusculak Contraction . . . 365 CHAPTER XXIII. The Wave op JIuscular Contraction ..... 369 CHAPTER XXIV. Tetanus 371 ch:apter XXV. Electric Currents op Muscles 376 CHAPTER XXVI. Electric Currents op Nerves 381 CHAPTER XXVII. Electrotonus 383 CHAPTER XXVIII. Stimulation op Xerves 385 CHAPTER XXIX. Phenomena accompanying a Nervous Impulse . . . 393 CHAPTER XXX. Various Forms op Stimulation op Muscle and Nerve . . 395 CHAPTER XXXI. Urari Poisoning and Independent Muscular Irritability . 398 CHAPTER XXXII. The Functions op the Roots op Spinal Nerves . . . 402 CHAPTER XXXIII. Replex Actions 406 CHAPTER XXXIV. On some Functions op Certain Parts op the Encephalon . 413 Xll CONTESTS. PHYSIOLOGY— PART III. Digestion and Secretion. CHAPTER XXXV. Albuminous Compounds 421 CHAPTER XXXVI. Chemistry of the Tissues 442 CHAPTER XXXVII. Digestion 457 CHAPTER XXXVIII. The Secretions . . • 536 CHAPTER XXXIX. Appendix. ^Notes on Manipulation 501 HISTOLOGY. By Dr. E. KLEIF. PART I.-PREPARATION OF THE ELEMENTARY TISSUES. CHAPTER I BLOOD CORPUSCLES. In the microscopical examination of the blood, we have to do 011I3' with the study of the formed elements, namely, the colorless corpuscles and blood disks. Colorless Blood Corpuscles. — The colorless corpuscles are elementary organisms which are endowed with the power of spontaneous motion. This power belongs to them in virtue of tlie material of which their bodies are composed. This mate- rial is protoplasm. Their motion is of two kinds; it consists of change of form and change of place. The latter results from the former. As movements of this kind are seen in greatest perfection in rhizopods and amcobfe, they are called amojboid. Amcsboid Movements of Colorless Corpuscles. — Very active movements are seen in the colorless blood corpus- cles of the newt. The cells are large and easy of observation. It is of the first importance, in beginning our study of them, that they should be placed under conditions which, if not iden- tical with, are not materially different from, those under which they actually exist. The simplest method is the following: Take a clean glass slide and an absolutely clean cover-glass, which, as we must use high powers (that is, objectives of which the focal distance is short), must be thin. Take the newt out of the water, dry the tail, cut off its end. If no blood comes, squeeze the organ from the root towards the tip until a drop is obtained. One of two methods may now be used : 1st, let the blood drop upon the middle of the glass slide, and place the cover-glass on it in such a way that one edge rests on its sur- face, while the opposite edge is supported by the finger or for- ceps. Then let the glass gradually down upon the drop. Or, A 18 BLOOD COEPUSCLES. 2dly, collect the blood on the cover-glass hj bringing it into contact with the drop, then place it on the slide with its clean surface upwards. By following either of these methods, the introduction of air-bubbles will be avoided, whicli would otherwise be a source of difficulty to the beginner. The drop should be neither too small nor too large. The following in- conveniences arise from its being too large : 1. The thin cover- glass does not lie steadily in its place, but floats on the drop in such a way that, bj- the slightest movement of the table, currents are produced in the liquid whicli render observation difficult or impossible. 2. If it is desired to keep the preparation for a length of time under observation, it is necessarj^ to adopt some means to p)revent the liquid from evaporating ; for, if this is not done, it gradually dries from the edges, and soon be- comes unfit for the obsei'vation of amceboid movements, we therefore inclose the preparation in oil, as will be immediately described, and experience shows that, by so doing, the move- ments may be watched for twelve hours or more continuously ■ — a time which is sufficient for a complete study of the phe- nomena in question. This, however, cannot be done unless the drop is very small. 3. If high powers are used, the front glass of the objective comes into contact with the cover-glass, and produces currents due to pressure. If, on the other hand, the drop is too small, the elements are pressed upon by the cover-glass, and thereby subjected to unnatural conditions. No definite rule can be given as re- gards the size of the drop, which must of course vary with that of the cover-glass. The mode of surrounding a preparation of blood with oil is as follows : Take a drop with a glass rod or camel-hair pencil, and let it fall at the very edge of the cover-glass in such a way that, although most of it is on the surface of the slide, it covers a little of the cover-glass also. Tlien incline the glass slide slightly, and with the rod lead the oil from the drop along the edge of the cover-glass, taking care not to press upon the latter. If one drop of oil is insufficient, of course another must be added. Take great care to avoid smearing the cover glass too far ; for by so doing, the space available for observation may become incouveniently limited. Having thus obtained a preparation of blood entirely pro- tected from evaporation, we are readj' to begin our study of the colorless corpuscles. Varieties of Colorless Corpuscles. — As soon as we have brought a field containing Ijlood into focus, we see, in addition to a multitude of colored blood disks, to which we at present pay no attention, a greater or less number of color- less corpuscles, which themselves difl'er from one another both in size and aspect, and in their property of spontaneous BY DR. KLEIN. 19 movement. Three forms may be distiiiguislied, which wc will examine in succession : — 1. Common Large Colorless Corpuscles.— Supposing that a few moments have elapsed since tiie preparation was made, some of these pale corpuscles are sure to be seen float- ing hither and thither in the liquid with a rolling movement. They are much more numerous than the other forms. Pix the attention on one of these bodies, and observe, first, that it is so transparent that, as it rolls over and over, a single granule embedded in its substance may be kept constantly^iu view. Continuing the observation, notice that the surface of the corpuscle, at first smooth, gradually becomes uneven. The cause of the unevenness is this. The surface is beset with a greater or less number of filamentous appendages, varying in length, and distributed over the surface with variable uniformitj^ These seem to consist of the same material as the body of the corpuscle. When they are short they may be compared to prickles, when longer they are often bent at the point. Sometimes we see one of the processes lengthen itself, while another disappears; sometimes a whole group of processes push out on one side, while others are re- tracted on the opposite side. Occasionally, from the small- ness and great number of the processes, it is scarcely possible to be sure as to the changes which occur. Here is a corpuscle which appears to be gradually enlarging. Let us follow the changes it will undergo. Already it covers a space three or four times as great as before. Simultaneously with this in- crease of size, its form becomes irregular, and (as may be ascertained by the fine-adjustment screw) its vertical measure- ment is diminished, 'so that it now constitutes a thin layer limited by a distinct contour. Soon, however, the circumfer- ence thins out in certain directions, so that the edge can no longer be discerned ; the only evidence of its existence in these attenuated parts being that the field appears to be covered with a granulous film. In the layer of protoplasm we have now before us, some parts are hyaline, or contain at most a few minute granules. In others, you will notice, there are clear spots with well-de- fined contours, which differ indefinitely in size, and have no definite arrangement. Many of them are so clear that they look like perforations. It is characteristic of tiiem that they are undergoing change, both as regards their relative ])osition and relative distinctness, some coming into view while others are fading. These we call vacuoles. They are believed to be cavities filled with liquid, the origin of which is due to the constant commotion of the protoplasmic mass. If this be so, it is easy to understand why it is that the}' appear and cVis- appear so rapidly. We next observe that at some part of tlie 20 BLOOD CORPUSCLES. corpuscle (often, but not always, towards the centre) one or more bodies may be distinguished of roundish, ovoid, or irre- gular form, and tolerably distinct contour, somewhat less re- fractive than tlie surrounding protoplasm, and containing one or more granules. These bodies are commonlj' close togetlier, and are called nuclei. The nuclei are usually invisible so long as the colorless blood corpuscle is spheroidal ; when it spreads out into a layer, they can be distinguished. But they can also be observed when the lamina draws itself together into an irre- gular clump ; and it may be then seen that they are subject to continual change, both as regards form and relative position. We now leave the corpuscle we have been hitherto studying and observe another, which is roundish, and exliibits a very few delicate processes. At present we see no nuclei. After a time we notice that one of the processes suddenly becomes longer and thicker, so that the corpuscle is now club-shaped, consisting of a tapering stalk ending in a knob. The stalk incloses an oblong, compressed nucleus, and the knob two such nuclei close together, the surfaces of both being shaggy, with minute processes. AVe have not long to wait until the body loses this form. A new process, towards which the two nuclei tend, shoots out from the knob, at right angles to the stalk. The knob becomes smaller in proportion to the growtli of the process, while the two nuclei gradually approach its ex- tremity. The next change is, that each process lengthens out in the direction of its axis into a filament, the two together being of such a length as to stretch over the whole field. These filaments spring from a small clump of granular proto- plasm — the original kuob above mentioned. Each filament swells out at its end into a little mass, which, in the one case, contains a single nucleus, in the others, two nuclei. Continu- ing our observation, we notice that the clump at tlie junction of the two filaments disappears, while the other masses, which are now united bj- a straight tliread of nearljr equal thickness throughout, get larger, and send out new processes. The larger mass now creeps nearer the edge of the field ; the smaller is drawn after it, but moves more slowly, so that the hyaline thread which connects them gets tliiuner and longer. But while we are watching it, the large mass undero-oes changes which are a repetition of what we before observed in the original clump. A process shoots out from it at right angles to tlie direction of the thread : into this process one^of the nuclei finds its way; it then stretches out into a filament, which is swollen at its extremity into a protoplasmic envelope for the nucleus. Still later, we' find that the filaments become thicker and shorter ; that the clumps between which they stretch, again approach one another, until, in their confluence, the original form reappears. A similar series of changes may BY DR. KLEIN, 21 be witnessed in any corpuscle of the Idnd we liave been studying. 2. Granular Corpuscles.— Of the three kinds of pale cor- puscles which, as before stated, are to be observed in the blood of the newt, we have now to consider the granular cells. These are larger, but much less uumerous than the others, and are distinguished by the large dark granules they contain. To observe them we must make a fresh preparation, for they un- dergo changes of form much more rapidly than the others. The granular corpuscle is at first spheroidal. Very soon its surface exhibits round and entirely liyaline prominences, into which, howe\'er, granules appear sliortly to find their way. So long as the corpuscle presents this appearance, the only changes of form observable consist in heaving movements of the prominences. Eventually, one of these suddenly shoots out into a prong-like process, into which the granular mass of the original cell flows. Soon the corpuscle throws out a second similar process, into which the mass again gathers itself, and in this way advances across the field, with more or less ra- pidity. After this has gone on for a certain time the move- ments change their type : the corpuscle lengthens itself out into a thread, in which the movement of the protoplasm is rendered visible hy that of the dark granules which it contains. The thread swells out at the end into a little mass, from and towards which alternately tlie rolling motion of the granules is seen to be directed. Often a granular corpuscle may be ob- served to creep about among groups of colored blood-disks, stretching out its process with the terminal knob, as if this were a feeler. In other cases we may witness the whole series of changes described in the preceding paragraph as occurring in the ordinary form of colorless blood 'corpuscle ; the main difference being that the transformations are accomplished within shorter periods. Finally, it may be noticed that in granular cells, even when they ai'c spheroidal, the nuclei often show themselves as ovoid spaces free from granules. They are, however, much more readily distinguished after the ceil has undergone changes of form. 3. Colorless Corpuscles of the third form. — In addi- tion to the common colorless corpuscles and the granular cells we have just had under observation, we notice a considerable number of colorless elements of a different character. These are of three kinds: (a) Small, well-defined bodies, resembling nuclei, which retain only for a very short time the spheroidal form which they had at first ; (b) larger corpuscles, consisting of finely granular protoplasm, with jagged outHne, containing three or four distinct nuclei, wiiich maj^ he either roundish, or flattened against each other, exliibit a double contour, and contain a few fine nucleoli which are relatively of a large size. 22 BLOOD CORPUSCLES. SO much so, that the.y often appear to be surrounded by a narrow zone of protoplasm ; (c) large masses of finely granular protoplasm, -which commonly are of irregular form, and in- close bodies similar to the nuclei above described, varying in number from five to twenty in each mass.' Methods of Warming a Preparation.— As in our fur- ther study of the blood corpuscles it will be necessary to em- ploy artificially increased temperatures, we proceed to describe themethods employed for applj'ing heat to preparations whilst under microscopic observation. These methods are of two kinds. The first is used when we wish to subject the prepa- ration for an indefinite period to an increased temperature, to which it has been graduallj' raised ; the second when we wish to warm it suddenly, but for a very short period. To accom- plish the first of these objects, a very simple contrivance, shown in Fig. 1, may be used. Take a cover-glass, and spread all round the edge of its upper surface a thin layer of oil ; then take another cover-glass of the same size as the first, place on its centre the drop of tlie blood to be examined, and allow it to fall on the glass previously prepared, edge to edge, with the blood drop downwards. The drop will then occupy the space between the two, inclosed by the layer of oil in such a manner that it may be examined under high powers. The preparation may then be readily lifted with the aid of a lancet- shaped knife, and placed on the orifice of the copper plate (e). The copper rod (g) is then gently warmed by means of a spirit- lamp, a little cacao butter (or some other fat, the fusing point of which nearly corresponds to the desired temperature) having been previous!}- placed on the copper plate, close to the prepa- ration. As soon as tlie cacao butter begins to liquefy, the flame of the lamp is diminished, or the lamp itself is removed to a greater distance, until the heat communicated bj' it to the plate through the rod is just sufficient to keep the fat from solidifying. If it is desired to employ higher temperatures, or to measure the temperature with greater exactitude, it is necessar}' to have recourse to Strieker's warm stage. Strieker's Warm Stage. — Of this there are two forms. In one tlie mode of heating, and consequently of modifying the amount of heat communicated, is that which has been already described (see Kg. 2). From its simplicity it is well adapted for the beginner, while it enables the more practised observer to maintain any desired temperature within very inconsidera- ble limits of variation. The other, in addition to the greater exactitude which can be attained, has the advantage that, by ' Free nuclei of colored corpuscles, which may be seen if the prepa- ration has been suljjected to pressure, must not be confused with these structures. BY Dll. KLEIN. 23 its aid, it is possible to continue tlie oltservatiou for a long pe- riod. It is this which is omplo^-ed by Sanderson and Strieker for the study of the circulation in mammalia. For our present purpose we do not require the whole apparatus, so that it is only necessary to refer to those parts of it which are shown in rig. 3. In the employment of this apparatus several difRculties are encountered. For instance, the temperature of the water re- ceptacle is only in part controlled by the regulator. Then, again, the temperature of the stage is subject to variation ac- cording to the rate at which the water flows into and escapes from it; so that, if great care be not taken in tlie adjustment, constancy cannot be relied on. Another practical difficulty lies in tlie fact that the temperature of the water in the recep- tacle is different from that in tlie stage, the rate of flow being so inconsiderable that there is necessarily a great loss of heat by radiation from the metal surface. If the stage be not fitted \yith a thermometer, this difl'eronce of temperature may be de- termined, once for all, hy comparative measurements, so that the true temperature of the stage can then be known at any time by deducting the ascertained loss of lieat, i. e., the ascev- tained difference above referred to, from the temperature to which the regulator is adjusted. Method of varying the temperature rapidly. — In connection with this apparatus, it is convenient to describe the method employed for subjecting a preparation to sudden alterations of temperature. With this view the following con- trivance is used : A clip is placed on the tube leading from the water receptacle (0, Fig. 3), bj' means of which the access of warm water to the stage may be interrupted. The end of the escape-tube (D) is then allowed to dip into a vessel of cold water. This done, cold water may be readily introduced into the stage, so as to cool it suddenly, bjr suction through the tube (C), which must be provided with a branch (not shown in the figure) between the clip and the stage, for the purpose. This, of course, at once lowers the temperature. To effect a sudden rise, all that is necessary is to open the clip. For short experiments, it is not necessary to have a water receptacle spe- cially constructed for the purpose ; a large flask, supported over a lamp, and without a regulator, may be substituted for it, provided that, in addition to the discharge-tube, a thermom- eter is passed through the cork, in order that the variations of temperature may be observed, and the application of heat mod- ified according!}'. Effects of Warmth on the Colorless Corpuscles. — We now return to the study of the drop of newt's blood, in- closed between two cover-glasses, with which we were occu- pied. On subjecting the preparation to a temperature of 38° 24 BLOOD CORPUSCLES. C, the first fact that we notice is tliat tlie movements of tlie coloiiess corpuscles in general, and of the granular ones in particular, are mucii more active. We shall not, however, oc- cupy ourselves at present with these, but shall direct our atten- tion to the three kinds of corpuscles which we have included in our third division. On the warm stage we may observe in these bodies (which differ only in size) two kinds of change. One of these consists of alteration in the form of the protoplasm, from the surface of which processes shoot out in all directions. This is more particularly seen in the forms we have designated b and c. In the form a, although the nucleus at first appears bare, it is afterwards seen to be surrounded by a protoplasmic envelope ; this may throw out a pointed process, which, after stretching- out to a considerable length, is retracted, to be succeeded by others. If the preparation is kept for a length of time at 38°, the elements of the form a undergo other remarkable altera- tions. They become strongly refi'active, lose their double contour and sharply-defined aspect, and acquire a form which, at first globular, subsequently exhibits constrictions ; so that they become in succession kidney-shaped, dumb-bell shaped, and rosette-shaped, until they eventually assume a nodulated aspect. In the course of the process it is common to observe the furrows or constrictions forming, disappearing, and reap- pearing repeatedly; but, sooner or later, they become more and more distinct and complete, so that the body assumes the ap- pearance of a clurnp of highly refractive minute globules. Con- sidering the coincidence of tlie changes of form and aspect of the nucleus with those which occur simultaneously in the cell, it is scarcely possible to doubt the dependence of the former upon the latter, especially if we bear in mind the concomitant changes in optical properties. So that we must regard these appearances as indicating that the nuclei take an active part in the changes of form. In the foi-m c the cell-substance itself may be also the seat of a process of division. In one instance at least I have, of course after many hours of observation, witnessed the division of a cell whicli originally contained five nuclei. The cell in question in the first place exhibited a transverse furrow : this became deeper and deeper, so that, eventually, two masses were formed, united together by a neck, the smaller containing two nuclei, the larger three, these nuclei Iiad already under- gone the process of cleavage above described. By the length- ening, thinning out, and final rupture of the isthmus, the two corpuscles came apart. In the larger of the two, which was now exclusively observed, there appeared gradually two bos.«- like prominences, each of which contained a number of small bodies resulting from the cleavage of the nuclei. By the con- BY DR. KLEIN. 25 striction of the base of each of these prominences it gvadiially separated from the rest of the cell. One of them, after separa- tion, sent out a process ; in tlie otlier, no alteration of form could be observed. It is probable that the forms a and h are the otfspring of e. On the warm stage, division can also be observed in the first and second varietj^ of colorless corpuscles. Tlius, for example, it sometimes happens tliat the process descrilied only results in actual separation bj' rupture of the filament. In other cases a corpuscle undergoes division bj- a process of cleavage, pre- ceded by the repeated formation, disappearance, and reappear- ance of furrows. In all cases of real division it is to be observed that the j'oung cells produced exliibit \qv\ active movements, changing thereb.y in form and place. Colorless Corpuscles of Man.— The mode of examining the colorless corpuscles of otlier classes of animals is similar to that above described. It is, however, necessary to add some observations as to the characters which these bodies present in liuman blood. A drop of blood, taken from tlie finger, is placed between two cover-glasses, as above described, and examined on tlie warm stage at a temperature of 38^ C. The human colorless corpuscles are smaller than those of the newt, and exhibit much less varietj^ in their appearance. They are either quite pale, or they contain a variable number of dark granules. Tlie movements are less active than those of newt's l)lood, but sometimes are comparable with them. When they are more active than usual, the mode in which their processes are thrown out and retracted, and the characters of their pro- gressive movement correspond with the descriptions alreadj' given. On one occasion I have observed movements which were even more lively than those commonly seen in the newt, and resembled those of rhizopods in the extreme rapidity with which the successive protrusion of processes, and corresponding interstitial fluxion of the protoplasm occurred. This haiipened in the case of a patient suffering from hemorrhagic anajmia. Feeding of Colorless Corpuscles. — We have now to study the faculty possessed by the colorless corpuscles of taking, by virtue of their amojboid movement, solid particles into their substance. For this purpose we employ either finely- divided fattjr substances or coloring matters. The subject is of great interest in relation to the mode in which amoeboid cells take in nourishment. To the histologist it is further of importance, as afl:brding him a means b}^ which to niai'k indi- vidual corpuscles, so as to follow them in their wanderings through the organism. The materials used are the following: a. Vermilion. This is prepared by prolonged trituration in a half per cent, solution of common salt. h. Carmine. Car- mine is dissolved in as little liquur ammorrise as possible, in a -6 BLOOD CORPUSCLES. small beaker, and filtered. Common concentrated (commer- cial) acetic acid is then added with agitation, until a drop of the mixture, when examined under a low power, is seen to con- tain granules. If too much is added, the precipitate is not fine enough. The latter is then to be separated by careful decantation, and suspended in a half per cent, salt solution as before. It is well to dilute the liquid with its bulk of serum before using it. c. Aniline Blue is dissolved in common me- thylated spirit, and filtered. Water or salt solution must then be added gradually, so as to obtain a fine precipitate, the resulting liquid being mixed with serum as above, d. Fresh Milk. If it is intended to watch the process of feeding, a small drop of blood, to which one of the liquids above mentioned has been added, is examined, either in the ordinary way, in the case of amphibian blood, or on the warm stage if mammalian blood IS employed. If our object is merely to observe corpus- cles already fed, the liquids in question may be injected either into the jugular vein (of rabbits or guineapigs) or into the abdominal vein (of frogs), care being taken to employ a suffi- ciently large quantity. After 10-30 minutes, a drop of blood ma,y be taken for examination. (See Chapter VII., as to in- jection into the veins, and Chapter VIIL, as to the lymphatic system.) Wliichever plan is adopted, it is alike possible to satisfy ourselves that the cells not only take in foreio-n bodies but that they also have the faculty of discharging them, and tiirther, that when one cell comes into contact with another, it often gives up to it the solid bodies which it has itself before ingested. _ In general, the tendency to ingestion varies with t le activity of the ameboid movement, for the first thino- observed is an adhesion, either of the surface of the centriTl part of the corpuscle, or of a process to the foreio-n body, fol- lowed by a retraction of the adherent part into its substance. Application of Liquid Reagents.— It is, in the first place, of importance to ascertain what liquids can be added without affecting the vital phenomena of the colorless corpus- ces Such arc designated by the adjective indifferent, and aie those which are always to be used in the study of fresh living tissues. For example, we may use fresh serum or tran- suda ion liquids, as also the aqueous humour of the eye, which el™*; """^Tr""* ^f '^"t^^g« f '^""g entirely free from formed eiements. The most commonly used indifferent liquid is the halt per cent, solution of common salt already mentioned, Yiieli IS of great value; although, as may be readily under- stood. It IS not altogether without action on living tissues In the ex-am,natioii of blood, it is added as a preparatory step to the addition of other reagents. AVith this view the ^solution IS dropped from a capillary pipette (Fig. 4) upon a slide a BY DR. KLEIN. 27 drop of newt's blood being then added to it and covered. It is seen that the colorless corpuscles have undergone no mate- rial change, but that, in some instances, their movements are not quite so active. The colored corpuscles, wliich in our previous examination we have disregarded, are now seen as smooth oval elliptical disks, which, when looked at edgewise, present an outline as if they were oblong rods. Those which lie horizontally look, for the most part, like greenish-yellow bodies of oval form ; in some of which we can distinguish a central elliptical nucleus. Soon, changes occur, in consequence of which the color becomes unequally distributed, the margins are more or less curved, or the surfaces marked with what look like folds. These appearances are referable probabl}' to a pro- cess analogous to coagulation. Method of Retarding Evaporation.— If it is intended to keep a preparation of this kind long under observation, it is necessary to add saline solution from time to time from a pipette. If, however, as is often the case, it is of importance to keep an individual corpuscle in the field, this method can- not be employed without great risk of the object being carried away by the stream. To avoid this result, it is a good plan to place a drop or two of solution near each of tw^o opposite margins of the cover-glass. By these drops the liquid under the glass is preserved from evaporation, because the space in the immediate neighborhood of the margin is kept saturated with moisture. We may now proceed to studj' the action of other reagents on blood already treated with saline solution. We use the so-called method of irrigation. On one side of the cover- glass a small strip of blotting-paper is placed, while the re- agent is discharged from the pipette at the opposite edge. When the paper has become saturated with liquid it is replaced hy another, and the process repeated, so that a constant cur- rent is maintained through the preparation. If the colored corpuscles are the special subject of studj', it is best to w-ait until they have shrunk, for we are then sure that many of them will have had time to sink and adhere to the surface of tlie slide. If this precaution is neglected, they are apt to be swept away b}' the current. Action of Distilled Water. — In blood preparations irri- gated with distilled water, the movements of the colorless blood corpuscles gradually cease. The inequalities, corre- sponding to the processes, disappear, while the corpuscle en- larges, and assumes the globular form. From one to four (or even more) round vesicular nuclei come into view. Soon the nuclei coalesce to form a single mass, also having a vesicular character, which not un frequently exhibits a rotatory move- ment within the corpuscle. The substance which surrounds 28 BLOOD CORPUSCLES. the nucleus is pale. It contains numerous distinct granules, whicli show active Brownian movement. It not unfrequently happens, that a much-swollen spheroidal corpuscle, after re- maming a leugth of time in its place without change, is torn away from its attachment to the glass by the current, in which case it may either divide into two masses, one of which con- tinues adherent, while the other floats away, or it may float away en masse, leaving behind it a long filament, by which it IS still connected with its original point of adhesion. By re- newing the irrigation, the filament will probably be severed It is thus proved that the colorless corpuscle consists of a soft VISCOUS substance. The final result of the action of water on the colorless corpuscles is always disintegration; the mass suddenly disperses into the surrounding medium, all that re- mains of the previously so active entity is a collapsed, form- less clump, m which one or two motionless granules may be seen . ■' In the colored blood disks, the first change is that their surfaces become smooth, their contour becomes circular, the nucleus rounder and brighter than before, the corpuscle paler and paler, until its outline is scarcely distinguishable. Two phenomena are worth noticing before we proceed further, lie first IS, tliat, at the commencement of irrigation with dis- tilled water, it occasionally happens that, immediately their Y surfaces have become smooth, the corpuscles suddenly assume a rounder and smaller appearance, and are more intensely colored.- quickly returning, however, to the elliptical form and losing their color as before. The second will be explained later: a colored corpuscle appears to liave separated into two parts, a pale elliptical disk and a yellow mass, occupyino- a central, or more frequently, an eccentric position withiirit Irom which colored processes often stretch out like rays toward the peripheiy. ■' Strieker's Method—There is another method of studyino- the action of water on the colored corpuscles. For this nui° pose we require the warm stage (Fig. 2). A drop of water is placed on he floor ot the chamber, and on the middle of the surface of the cover-glass a drop of blood, either pure or di- luted with sal solution. The cover-glass is then inverted over the chamber, the edges of which liave been previously oiled, or surrounded with a ring of putty, so that it is aii^ tight. By warming the copper wire the water is made to evaporate from the floor of the chamber, and becomes con- densed on t lie under surface of the cover-glass. In tliis way we are enabled to study the gradual action of water on the corpuscles very advantageously. Action of Salt Solution on the Blood Corpuscles of Mammaha.-In mammalian blood which has been cmutecl BY DR. KLEIN. 29 with sfilt solution, tlie naturally bi concave colored corpuscles exhibit a remarkable alteration, which consists in their assum- ing a form very similar to that of the fruit of the horse-cliest- nut. In those corpuscles which present their surfaces, the processes -which project from the margin look like the rays of a star, while those whicli spring from the surface appear as dark points. In such a preparation it is not difllcult to float away the colored disks altogether, by irrigating it immedi- ately with salt solution. The colorless corpuscles sink very rapidly, and stick to the glass, while the colored disks remain suspended. Let us seek for a field in which one or two colorless corpus- cles onl^' are to be seen. By discontinuing the irrigation, at the same time replacing the bit of blotting-paper so a~s to with- draw the fluid, we bring the cover so near the slide that it compresses the corpuscles, which in consequence appear paler and larger. Tlie paper is now taken away, and salt solution added at the opposite edge as before. The corpuscles at once become smaller and more globulai', and seem to contract; but, immediatelj' after, dilate again, as if they were relaxing. In the resumption by the corpuscle of its original form after compression, we have to do with a phenomenon which can only be explained on the supposition that the colorless corpuscle is elastic. The nature of the contraction and the subsequent re- laxation lead us, however, to suppose that the contraction is, at least partly, a result of the excitation produced by the irri- gation with saline solution. Action of Water on Mammalian Elood. — As regards the action of water on the corpuscles of mammalian blood, there is not much to be added to what has been said with re- ference to newt's blood ; the colorless corpuscles discontinue their movements, become globular in form, exhibit vesicular nuclei and vibrating granules, and finally are disintegrated. The colored disks lose their horse-chestnut form, become smooth and pale, and eventualh^ disappear. Action of Acids. — The general action of acids is so uni- form that it is not necessary to refer separately to each. We content ourselves with describing the action of acetic acid. A special action of boracic acid will be noticed further on. The final result of the action of acetic acid on the blood corpuscles is the same, whether it is diluted or concentrated. The rapid- ity with which the changes take place is, however, dififerent. It is always better to begin with dilute acid. If a salt solution preparation of newt's blood is, after the shrinking of the colored corpuscles, irrigated with a liquid containing one per cent, of the ordinarj- commercial acid, we observe, first, that the move- ments of the colorless corpuscles cease, and that they enlarge and displa3' their nuclei as sharjjly-deflned bodies, beset with 30 BLOOD CORPUSCLES. granules. If the action of the acid has been prolonged, each corpuscle appears to consist of two parts — a distinctly gran- ular mass, which immediatel}' surrounds the nucleus, and a bright transparent circle, with sharp outline, within which that bodj' is inclosed. The nuclei are furrowed in such a way that their form is very variable, and, if the action has lasted long enough, thej' look as if actually split into smaller par- ticles. The colored corpuscles again become smooth, swell out somewhat, become cellular in their contour, just as after the addition of water, each showing an oblong granular nucleus, which is at first smooth, subsequently uneven and rough. Many of the blood disks return to their original elliptical form. All eventually lose their color, but possess, even when entirely colorless, a much more distinct contour than those which have been acted upon by water. Occasionallj^, it happens that the nucleus becomes stained with coloring matter, and assumes a yellow tint. In human blood, the colorless corpuscles exhibit, after the action of acetic acid, the appearance of globular bodies, in which two, three, or more small shrunken nuclei are visible. The colored disks lose their stellate form and their coloring matter, but their outlines are still distinct. Action of Alkalies. — If a salt solution preparation is irri- gated with an alkaline liquid, whatever be the source of the blood used, the colorless corpuscles at first swell, and then rapidl}^ disappear. The colored disks also swell out at first — those of mammalia becoming often what German authors have designated napfformig (cup-shaped) ; eventually they lose their color and disappear. Action of Boracic Acid. — We have now to describe a reaction which, especially in the blood of the newt, is of im- portance, as serving to illustrate the intimate structure of the colored blood disk. The action of a two per cent, solution of boracic acid on the colorless corpuscles in general, and on the Mood disks of mammalia, does not differ from that of other weak acids. If, however, a salt preparation of newt's blood, in which the colored corpuscles have already sunk, is irrigated with the solution in question, we observe that those bodies swell and acquire a circular contour, showing, at the same time, a pale oval nucleus. It is now seen that, as the disk grad- ually pales, the nucleus becomes more and more spheroidal and yellow, while, at the same time, it increases in size. At first it is smooth, subsequently uneven. Here and there cor- puscles are met with in which the yellow central body {zooid of Briicke) is not round, but beset with processes which stretch like rays towards the peripherj--. Occasionally, it can be made out that the processes are withdrawn, so that the yellow centre acquires a roundish form. The zooids eventually lose their central position, and if the preparation is protected from evapo- BY DR. KLEIN. 31 ration for a suflicieiit length of time, tlie observer is sure to see nianj- corpuscles in whicli tliej' lie, some i>avtly, some entirely outside of the outline of the pale disk. The latter (again fol- lowing Briicke) we designate acokJ. Briicke teaches that the zooid consists of tlie nucleus and the ha'maglobin ; that it with- draws from tlie recoid whicli it previonsly, as it were, inhab- ited, and collects itself around the nucleus, so as to form an independent individual, capable of a separate existence. In describing furlher on similar appearances observed during the action of carbonic acid gas, we shall suggest another explana- tion of the phenomenon. Action of Tannin on Human Blood — Roberts's Re- action.' — The action of tannin on tlie colored corpuscles of human blood resembles that of horacic acid on newt's blood. When two per cent, solution of tannin is added to human blood, the corpuscles, which have been already rendered star- shaped hy salt solution, acquire an even contour. Soon after, a sharpl3'-deflned, yellowish-green, roundish body is seen, either just within or at the margin of each corpuscle, or even out- side of it, while the corpuscle itself has become colorless. Action of Gases on the Blood. — For the study of the action of oxygen and carbonic acid gas on the blood corpus- cles, either of the movable stages represented in Figs. 2, 3, and 16 may be used. Around the edge of the central chamber we form an annular wall of patty. We then make on a cover- glass a preparation of newt's blood, to which about half its volume of distilled water has been added. Tlie glass is then inverted over the chamber (upon the floor of which a drop of ■water has previously been placed) with the preparation down- wards, so that its entire periphery presses evenly upon the putty ring. The chamber is thus converted into an air-tight cavity. In Fig. 3, two tubes (H, I), with India-rubber con- nectors fitted to them, are shown, both of which communicate with the chamber in such a way that when it is closed above and below, a stream of gas passing in by the one escapes by the other. By means of an apparatus in communication witli the tube PI, the construction of which will be readil}' under- stood from Fig. 5, the observer is able to fill the chamber at will with carbonic acid gas or with air. This is accomplished as follows: — If the bottle containing hydrochloric acid is raised, the clip n opened, and the India-rubber tube a shut between the teeth, the carbonic acid, whicli is developed in M, after it has passed through the wash-bottle V, flows into the chamber, and is dis- charged by the tube 5. By proceeding in this manner one hand is left free, and can be used for adjustment. To inter- rupt the current of gas, all that is necessary is to close N and 32 BLOOD CORPUSCLES. to let down the bottle. The carbonic acid gas in the chamber is easily replaced by air, by aspiration through the tube a. Action of Carbonic Acid Gas. — The preparation having been brought into focus, the gas is allowed to pass through the chamber for a short time. At first, the only observable effect is that the nuclei of the slightly smoother dislvs are more distinct. If the carbonic acid is now replaced by air, tlie nuclei again become indistinguishable. We have to do, tlierefore, with a transitory coagulation of the substance surrounding the nucleus. An excess of the gas brings the nuclei perma- nently into view. If, however, we first add to our preparation a quantity of water, sufficient not merely to swell the colored disks, but to deprive them partljr of tlieir color, the result is somewhat different. After a short action of the gas, the ap- pearances are much as they have been already described; but, if an excess is admitted, bodies similar to the zooids above described as produced by the action of boracic acid, come into view. Instead of the pale oblong nuclei, the areas of the decolor- ized disks inclose relatively large, j'ellow, roundish bodies, both the areas and the inclosed bodies being beset with fine gran- ules. In those disks which have previously lost their color, and are consequently scarcely visible, the nuclei become visi- ble after the addition of excess of carbonic acid, as pale granulous bodies, the disks themselves also containing nume- rous granules. If we now replace tlie carbonic acid by air, the corpuscles recover, in every respect, their previous aspect; tliose in which the zooids had come into view becoming smooth, and of uniform color, so tliat neither nucleus nor granules can be distinguished. Those disks which have lost their color by the action of water become, as before, uniformlj- ])ale and in- distinct. The experiment may be repeated several times. It is not difficult to explain all tliese appearances by coagulation. It is a very good plan, in order to study the action of car- bonic acid on newt's blood, in all degrees of dilution, to examine a salt solution preparation of such blood on the mov- able stage (Fig. 2), which also serves the purpose of a gas chamber. On warming the metal rod, water vapor is disen- gaged from the floor of the chamber (into which a drop of water has been previousljr introduced), and acts upon the cor- puscles. In order to study the action of carbonic acid on the colored corpuscles of man, it is best to employ a drop of blood mixed with salt-solution, taking care that the individual cells are as much as possible separate from one another. If, as soon as the corpuscles become horse-chestnut sliaped in consequence of the action of the salt-solution, the preparation is subjected to the action of the gas, we at once observe that the acuminate BY DR. KLEIN. 33 projections on the surface of the corpuscles become less marked in consequence of the levelling up of the intermediate parts ; and, although there are many which do not resume the bicon- cave form, being still saucer-shaped, they all have even surfaces. If the carbonic acid is replaced by air, the corpuscles again become horse-chestnut shaped. This reaction may also be witnessed several times in succession. The disappearance of the stellate form may be explained on the supposition that a spontaneously coagulated constituent is redissolved under the action of carbonic acid. Colorless corpuscles show their nuclei when acted on by carbonic acid, but are otherwise unaltered. Action of Electricity. — If it is intended to subject blood to the action of electrical discharges, or of the constant or in- terrupted current, we place a small drop of blood on the slide (Fig. 6) in such a position that, when it is covered, it spreads between the two poles of tinfoil, which we connect by means of either of the appliances shown in the figure with the secon- dary coil of the induction apparatus. According to Rollett, it is advisable, in using electrical dis- charges, that the tinfoil points should be six millimetres apart. The Leyden jar should have a surface of 500 square centi- metres, and give a spark one millimetre long. If, theu, the discharges succeed each other at intervals of from three to five minutes, the following changes are observed in the colored cor- puscles of man. Firstly, the circular disks become slightly crenate. This effect gradually increases, the corpuscles become rosette-shaped, then mulberry -shaped, and Anally, by the acn- mination of the projections, horse-chestnut shaped. Later, the processes are withdrawn, the blood corpuscle becomes round, and, at last, pale. In the corpuscles of the newt and frog the effects are not dissimilar. They become wrinkled and dappled, but these appearances are very transitory, and the}^ are again seen to be circular and pale, while the nucleus becomes round and sharply defined. Not nnfrequently it happens that one or more blood corpuscles coalesce before they lose their color, or that (in amphibian blood) the nucleus is discharged while the disk is still yellow. The effects produced by induction cur- rents are altogether analogous to those above described. Un- der the action of the constant current Xa single Buusen's cell) the corpuscles next the electrodes undergo changes, which at the negative pole cori-espond to the action of an acid, at tlie positive, to that of an alkali. In a salt preparation of batra- chian blood examined near the positive pole, the nucleus comes first into view, and then the corpuscles lose their coloi-. In a similar preparation of human blood in which the corpuscles are horse-chestnut shaped already-, they become smooth, lose their color, and disappear. The colorless corpuscles, when excited electricall}- dnring 3 34 BLOOD COBPUSCLES. their amceboid movements, assume the spheroidal form. Their movements, however, are resumed as soon as the excitation is discontinued. The motion is more undulating than before, but soon recovers its former character. After repeated excita- tion the corpuscles expand into laminte, but still exhibit changes of form. Under the influence of successive shocks of greater intensity, the colorless corpuscles swell out, their granules exhibiting molecular movement, and finally disappear. Blood Crystals. — In concluding this chapter, we propose to give the most simple methods of obtaining crystals of haemo- globin and hsemin for microscopic purposes, referring the reader for more detailed information to Chapter XV. Hsemoglobin. — A large drop of blood is taken directly from a living guineapig, and allowed to coagulate on a watch- glass. We now add a small quantity of water, and then, taking up tlie clot with the forceps, let fall on a glass slide several small drops. As these drops evaporate hsemoglobin crystals of varying size shoot out from the edge, separately and in bunches. Another plan is to cut out the heart and great vessels of a recently killed guineapig, placing them on a watch-glass in saturated air for twenty -four hours. Then take some blood from the heart bj' means of a capillary tube, and allow a very small drop to fall into an equally small drop of water on a slide. As it evaporates, crystals are formed as before. This method does not answer with rabbit's blood. Hsemin Crystals. — The simplest method of obtaining hsemin crystals is the following: A small quantity of dried mammalian blood (human will do) is placed on a slide. A few small crystals of common salt are then added, and a cover- glass placed over. A drop of glacial acetic acid is then allowed to enter from the side. On warming the preparation carefully until the greater part of the acid has evaporated, an immense number of the reddish-brown crystals of hsemin are seen. For a description of tlie corpuscles which occur in the lym- phatic system, see the chapter treating of that subject. The development of the blood corpuscles will be described in Chap- ter VII. BY DR. KLEIN. 35 CHAPTER II. EPITHELIUM AND ENDOTHELIUM. Under this heading are included the epithelium of the mucous membranes, of the cornea and conjunctiva, and of the integument, and the endothelium of the serous membranes. The epithelium-like structures which are in relation with the nerves of the various organs of sense will be examined in Part II. Ciliated Cylindrical Epithelium. — To investigate cili- ated epithelium in the living state, a frog should be selected, and its mouth opened with the handle of a scalpel. Then, using either a lancet-shaped needle or the blade of a sharp knife, we scrape from the projection in the roof of the oral cavity, corresponding with the floor of the orbit, a little of its epithe- lial covering. This is transferred to a small drop of an indiflfe- rent fluid (half per cent, solution of common salt) on a glass slide, slightly separated with needles, and covered in the usual manner. In such a specimen we find not only masses of epi- thelium iu connection, but also smaller groups and single cells. In the masses of epithelium we cannot distinguish quite clearly the individual cells, but on the free border — on the coast, as it were, of the epithelial island — we observe the exceedingly lively movement of the cilia. In addition we see blood disks, small round particles of protoplasm and granules driven quiek- ly along in the fluid ; and from these passing bodies we are able to recognize the direction of the movement of the cilia, an observation which could not otherwise be made, on account of the extreme rapidity of that movement. In the smaller epithelial groups we are able more easily to recognize the in- dividual shortly-conical cells. These groups are in more or less rapid rotation, the rotatory motion being due to the fact that only one portion of their surface is furnished with cilia — that, namely, which corresponds to the bases of the conical cells. Effects of Reagents on Ciliary Motion. — Dilute Alkalies. — After some time we perceive that the cilia here and there begin to strike more slowly, and, by-and-by, they come to rest. In a specimen prepared as above described, which has of course been prevented from becoming dry by the occasional addition of a drop of half per cent, solution of com- mon salt, if we choose a spot at which the ciliary movement 36 EPITHELIUM AND ENDOTHELIUM. is either exceedingly languid or has ceased altogether, and cantionsljr allow a small quantity of a very delicate solution of potash to act upon it by the irrigation process, "we soon ob- serve that the motion is renewed ; becoming equal in rapidity to that seen in the perfectly fresh preparation. The restora- tion of motion is not due to any special property of potash ; nor can it be attributed to the influence of that reagent in dis- solving coagulated material between the cilia, which might be supposed to interfere mechanicallj^ with their movements. This is proved by the fact that man}' other reagents act simi- larly as stimulants of ciliary motion — e. g., distilled water, half per cent, solution of common salt, dilute acetic acid, carbonic acid, or the induced current (applied according to the method described in Chapter I.). All these, if used with great care, accelerate the movement in the first instance. The accele- ration lasts only for a short time, and, in most cases, is quick- Ij' followed by cessation of movement, consequent upon the destructive influence of the reagent used. After the addition of dilute acetic acid (and still more rapidly witli concentrated) the bodies of the cells swell and become transparent, and their nuclei well defined, in the same manner as after the addition of water. The investigation of the respective actions of carbo- nic acid gas and oxygen upon ciliary movement is a verjr im- portant experiment. We make a preparation of the ciliated epithelium from the throat of the frog, in a half per cent, solu- tion of common salt upon a cover-glass, which is then placed on a ring of putty over the gas-chamber of the movable stage (Fig. 2). Into this chamber a drop of water has been previous- ly placed to keep it moist, and if we now allow a stream of carbonic acid to pass, we perceive, as has been already men- tioned, that for a few moments the ciliary motion becomes quicker, but, by-and-by, slower, until it finally ceases. On now substituting atmospheric air (oxygen), we find that the movement slowly recommences, and, before long, is quite as active as before the passage of the carbonic acid. The experi- ment may be repeated several times with a like result, until at last the motion can no longer be excited. Oxj-gen is there- fore as essential for the continuance of motion in the indi- vidual ciliated cell as for the maintenance of animal life in general. Study of Ciliary Motion in Situ.— To demonstrate ciliary action on a membrane in situ, the most judicious plan is to remove from a female frog or toad that portion of peri- toneum which covers the cisterna lymphalica magna, the so- called septum of the cisterna. Or, instead of this, a portion of the parietal peritoneum of the anterior abdominal wall of the newt may be employed. In either case, the part removed is to be quickly and carefully spread upon a glass slide with BY DR. KLEIN. 37 needles (avoiding eveiy kind of mechanical injury) in such a manner that the peritoneal surface looks upwards : a drop of half per cent, solution of common salt is then placed on the under surface of the cover-glass, which is cautiously applied. In such a preparation we find jilaces in which a bird's-eye view is obtained of the cilia in motion, as well as others, where, as in the preparation from the throat of the frog, we see the same in profile. The cells, which bear the cilia, are not cylindrical, but form a pavement endothelium, the elements of which are granular. We shall have occasion to return to these cells in the description of the eu,dothelium of the septum. The sto- mata are almost always guarded by the cells above described. If we are uncertain of the direction in which the cilia strike, or if we wish to demonstrate this positively, we should transmit through the preparation, by the method of irrigation described in Chapter I., coloring matter, or some similar substance, in a finely divided state, such as ground animal charcoal, cinnabar, or Indian ink, suspended in half per cent, solution of common salt. We shall then be able to recognize, from tlie direction in which the particles are driven, the direction in which the cilia strike. Forms of Ciliated Epithelium. — For the study of the various forms of ciliated cells, we remove a mucous membrane covered with these from a freshly-killed animal, and place small pieces of it in a sherry-colored solution of bichromate of potash. After they have lain in the liquid for twenty-four hours or more, we scrape with a scalpel from the free surface a little of the epithelium — place it on a slide in a small drop of bichromate of potash solution or of common water, reduce it to fragments with the handle of a needle and cover it. The most suitable objects for such a stud^' are the trachea of a mammal, the bell-shaped extremity of the Fallopian tube of the sow, and the raucous membrane of the mouth, throat, and oesophagus of the frog. By this mode of preparation the cells are preserved ver3' perfectly. In the long conical cells with ciliated bases we have to notice the granular protoplasm which composes the body, the bright basal border, the sharply- defined ovoid nucleus, with its large single or double nucle- olus ; the long filaments, simple or divided processes which ])enetrate between the cells of the deeper layers, and finally tlie cilia which pass out from the central protoplasm, perfora- ting the basal border. Besides these, we find intermediate forms of ciliated cells, which are shorter and broader, and which run out into one or two short, thick processes ; and varying forms of spindle- shaped cells, which, as we mnj convince ourselves, in large flakes of ei)ithelium, wedge themselves, by means of processes of greater or less thickness, between the processes of the ciliated elements. They possess, likewise, an ovoid nucleus. 38 EPITHELIUM AND ENDOTHELIUM. Finally, there show themselves, here and there, long, conical cells {gohlet cells), which, like the first mentioned, run into a long ijrocess ; and, in the thicker portion (Fig. la), are empty, or contain only a very few granules. The ampullate, or flask- shaped portion of these cells is bordered by a double-con- toured membrane, which, at the basal end, is open, so that we have before us only the empty shell of the cell without the basal lid. Among a number of such cells swimming about, individuals occur in which the open ends of the goblets can be seen, both obliquely and from the surface. In the deeper and thinner part of the cell the protoplasm with the nucleus is, in most cases, still present, as represented in the figure. In a few examples part of the cell (Fig. lb) is torn ofi', so that an empty funnel remains behind, in the extreme apex of which a small bit of protoplasm remains. If we look over a series of preparations we shall certainly find examples in which the complete lid, or a portion of it, remains attached at one point only of the circumference, and floats freely otherwise. The appearances show that these goblet cells are nothing more than products of changes which have occurred in the ordinary conical ciliated cells. In the description of the epithelium of the intestine we shall again have an opportunity of referring to these cells. Non-Ciliated Cylindrical Epithelium. — For the in- vestigation of this form we use the epithelium of the pap)illiB of the tongue of the frog, and that of the intestinal canal of a mammal, either in the fresh condition or with the aid of re- agents. From the dorsal surface of the frog's tongue a minute portion is snipped with curved scissors, transferred by means of a needle from the scissors on to a glass slide, and then, either covered without addition, the glass being pressed lightly down, or mounted in a drop of serum, or of half per cent, solu- tion of common salt. The specimen must be examined with high powers (as, e. g., Hartnack's No 10 immersion). We see the numerous, thin, conical papilte, both from above and in profile ; the latter especially at the borders of the preparation. A papilla seen in profile exhibits on its surface a Ijeautiful mosaic of pale cells, composed of finely granular protoplasm, marked off by sharp clear-shining lines of interstitial substance. If we fix our attention upon the borders and apices of the papilhe, we may convince ourselves that the mosaic is only the surface view of the conical or cylindrical cells, which cover and surround the papillte. Here and there we may easily perceive that these cells are coarsely granular, and that each contains a clear oval nucleus. Such coarsely-granular cells increase in number after the preparation has been mounted some time. We may mention that the cylindrical cells around the bases of tlie papillfE are generally ciliated. BY DR. KLEIN. 39 Epithelium of Villi of Intestine. — In the rabbit we proceed as follows: The animal is killed, the small intestine immediately opened, and from the borders (which then cnrl outwards) we remove a small portion with cnrved scissors as in the previous case. This is to be covered with the mucous surface upwards. The villi seen exhibit, on their surfaces, a regular mosaic of epithelium ; at their borders, where the epi- thelium is in profile, it is seen to consist of regular cj'lindrical cells. If the observation of the mosaic is continued for some time, granular spherical bodies come into view; at first singly, but afterwards in numbers, which are raised above the general surface of the cells, as may be learnt by using the fine adjust- ment. These spherical bodies have escaped from the cylindri- cal cells. We shall see that it is by this means that the goblet cells alreadjr mentioned are i)roduced. The epithelial cells on the borders of the villi display distinctly the broad, finely- striated border, which spreads over their ends like a cuticle. Equally instructive specimens may be obtained from the intes- tine of the cat, dog, guineapig, rat or hedgehog. Tlie epithe- lium of the villi may be as successfully studied, while still attached, in a preparation, mounted in serum, or half per cent, solution of common salt. For more prolonged examination, especially if we wish to studj^ isolated cells, we put a piece of intestine, cut from the rabbit, dog, or cat, into a sherry-yellow solution of bichromate of potash, allow it to remain there for one or more days, and make our preparation in the manner al- ready described with regard to the trachea. In such speci- mens we find not only numerous isolated cells, but also com- plete villi, and parts of the same, on which the epithelium, when its surface is viewed, resembles, as in the fresh prepara- tion, a pavement of granular cells, each of which contains a relatively large, sharply-bordered, and apparently round nu- cleus. The lines of interstitial substance are sharp and dark. At the edges of each villus the epithelial cells are cylindrical, with finely-striated border. Each cell consists of granular protoplasm, and contains a sharply-defined nucleus, in which a distinct nucleolus is to be seen. If we examine attentively the surface of a villus, or of a por- tion of villus (especially in a preparation from the intestine of the dog or cat, which has been allowed to remain in a solution of bichromate of potash), we shall find, between the mosaic of granular cells, roundish structures, either single or in small groups, and with a diameter greater than that of the cells of the mosaic ; these are quite clear in the centre, have a doubly-con- toured membrane, and give the impression of vesicular bodies. If we search on the borders of the villi for a structure in profile corresponding to this surface appearance, we find between the cylindrical cells, which are full of protoplasm, bodies of a bell- 40 EPITHELIUM AND ENDOTHELIUM. or goblet-shape, containing in the part which is next tlie tissue of the villus, a bit of protoplasm of variable size, refracting light strongly; within tliis is included a compressed, nuclear body. Amongst the isolated cells, also, we meet with nume- rous goblet-sliaped ones, which maj' be examined in various positions. These cells are most numerous in the intestines of the dog and cat, in which it often occurs in preparations which have been kept in dilute chromic acid, or bichromate, that the epithelium is almost entirely transformed into goblet cells. Tlie facts show that thej' are transformations of cjdindrioal epithe- lial cells, and that they maj' either be produced spontaneouslj', or, as more commonly happens, may be the product of certain reagents. Pavement Epithelium. — This vai-iety is well known to occur, chieily as laminated epithelium, in the conjunctiva cornea;, mucosa of mouth and pharynx of mammals, and in the skin. In the urinary bladder of mammalia the epithelium is not purely pavement, but is mixed with, and shades off into, the c.ylindrical variety. We accordingly call it "transitional." The epithelium of the frog's urinary bladder is a single layer of pavement epithelium. That of tlie serous membranes, of the mernbrana Descemeti, and of the iris, consists mostly of a single layer of flat cells. Fresh specimens of the epilhelium of the mouth may be pre- pared either with indifferent reagents or with very dilute solu- tion of bichromate of potash ; but, if we wish to study the relation of the various layers of the laminated epithelium to each other, it is needful to make vertical sections through the superficial layers of the mucous membrane. To study the forms of the various cells of the separate layers, we may ob- tain a thin shred from the surface of the tongue or gums of a mammal by energetically scraping it with a scalpel. What is removed is broken up with needles, and covered either in half per cent, solution of common salt, or, what is quite as good, a very weak solution of bichromate of potash. In the surface layers of the epithelium, we find flat tablet-shaped cells, with small, oblong, strongly refracting nuclei; the borders of these cells are sharp and doubly-contoured. Their substance is mostly clear, containing only a few granules, generally situated in the immediate neighborhood of the nucleus. Their surface is generally beset with irregular folds and furrows. If one of these cells is seen edgewise it appears spindle-shaped, because the thickness of the nucleus is greater than that of the cell. Besides these we find smaller polyhedrio pavement cells, which consist of a nearly uniformly granular protoplasm, and possess one, or very rarely two, roundish, clear, and sharply-defined nuclei, with one or two large granules— «. e., nucleoli— within them. Finally, if we have scraped very energetically with the BY DR. KLEIN. 41 scalpel, we meet with cells corresponding to the deepest la^-ers, wliich possess more of a c^'liudrical form, and contain an oblong nncleus. Similar results may he obtained if we mace- rate a portion of the mucous membrane in bichromate of pot- ash solution. To study the epithelium of the cornea in the fresh condition we proceed in a somewhat similar viay. A frog is licld by an assistant, its nictitating membrane drawn down, and from the anterior corneal surface a thin layer is scraped with a lancet- shaped, or a cataract knife; the fragment removed is then broken up and covered in aqueous humor, or in half ^er cent, solution of common salt. Here we find not onlj- isolated cells, but connected masses of epithelium arranged in layers. By means of the fine adjustment the individual cells of these laj'ers may be studied ; but we shall not at present occupy ourselves further either with the epithelium of the anterior corneal sur- face, or with the membrana Beseemed, since they will be fully described when we treat of the cornea. The epithelium of the skin (epidermis), and especially of the elements of the stratum corneum, may be readily brought under investigation as follows : A small shred is raised from either the back, or palm of the hand, and covered in water ; reagents- which act upon horny structures, as, p. " lies in such a position that the white pole is directed downwards, a crater-like dimple may be seen on the surface. This dimple extends itself over the margin of the hemisphere, diminishing at the same time gradually in depth. It is called the plaited band (Fallenlcranz), because a number of smaller creases proceed from it at right angles. This appearance owes its name to the erroneous impression that it is due to a folding of the vitelline membrane, but in reality it merely depends on the amoiboid movement of the germ. In fact, it is possible, by close observation, to convince one's self that the furrows of the plaited band are subject to active changes, for succes- sive groups of them disappear, again crop up, become more extensive and deeper, and then again retire. After a longer or shorter time— commonly one hour from the appearance of the first dimple— one of the folds of the jjlaited circle becomes deeper, and spreads itself more and more towards the periphery of the hemisphere, whilst the others gradually disappear. Eventually a deep cruciform furrow is apparent in the hemi- sphere we have hitherto had under observation, and which, as previously stated, is on the opposite side to the white pole. We will call this the upper hemisphere. At this tirne, only a single shallow furrow is seen in the lov)er hemisphere. Subsequently the furrowing proceeds somewhat more rapidly; for the third, or eqvMorial furrow, occurs half an hour after; other furrows then appear at right angles to the three first formed, generally in the same succession in which the principal farrows h'.ve originated; from these secondary furrows of the first order proceed others of the second, and from these, others of the third, and so on. The upper hemisphere divides much more quickly than the lower. The ova of the trout are prepared as follows : The egg is placed upon an object-glass betwef;n the points of a broad pair of forceps, so that the blastoderm is uppermost; the forceps are held with their blades at a fixed distance from each other, while the egg is pierced near its equator with a lance-shaped knife. On rapidly withdrawing the knife it generally happens that the blastoderm in tola, with a large part of the tenacious semi-fluid yolk, spirts out. The object must now be surrounded with a ring of putty and covered. Tlie attention of the ob- server should be directed to the appearance of the elements, their arnoiboid movement, and to the various forms of cleavage. The preparation of the ova of Batrachia is far simpler. The e:fg is pjlaced upon an object-glass, and as much as possible of the gelatinous investment is removed with the aid of forceps BY DR. KLEIN. jgj^ and scissors. The vitelline membrane is ruptured by means of our; ?' \'r'] ''"''"'V' '''' '''■^'^'^^'S content's " sp ad d-^ ts old \TJ T '■^■"':- " '^"^ 'Sg is not more than Uiree ^ nr%? '-H 1' ^° '"vestigated under low powers (Hartnack's ci.Tlv^obse rved ' 'T^'''''' ■ '^'^ ^'°"^ ^^'^^ ^'-"'^1 ^e es^e- c ally obseved and the active movements of the pio-ment tt i. ftirther directed to tlie hyaline prominences which the latter send out and retract, particularly after the addition of a very small drop of distilled water. The Cleavage Cavity.- The second important point to Tvhich the embryologist should direct his itten t^r s the tt'InlYfTh?; 1 J" ''" '™^*' ^^^^ '''^'' ''^'^ e^istenc^to^ai ; tne end o the cleavage process. The blastoderm appears to ?cX wt r" "f -T,'"^ '' '''' saucer-shaped deprEn b,^ hulV.I g'-'-i'liially increases in width and depth. The Was oderm zs not however, entirely detached from the yo^ but ren ams connected with it here and there by chains of cells P "ed "ITZ"' ''"r " «"b-g«-'--l P^-ocesses^-may b '0^ aied to columns by means of which the blastoderm rests npon the yolk (see fig. 16^). The cells of the sub-^rmina' {a™:r::^'Sole°" "' ','" ''''''': '^'-''' °f ^'- bl-tocferm ";; Jaigei and more coarsely granular than those of the more sperficial layers. By degrees the cells of the sub-germ"ual processes become separated from the blastoderm, andl'e u Jn in th^s^L ■ ' ''""'r '""'"''y- ''''' '''^'^^'^ -l^'^h are fo lid n his position are characterized by their greater size, and by Sn ta •[•^f'"""''"!" appearance; they "are produc s of the vil n, furT\^l "'" '^''^"- "^f t'^e blastoderm from the ' tor ,i I , 'A^"r °^ '^'' '""''''^^ ''' ^' '"greases in size, ioi the study of the formation of the cavity, that is of the whisht "rl; "" '' ^^ '''""^^ °° ^'^ ««-■ («- ''esiiSt on of winch we shall again have occasion to mention) and of the simultaneous expansion of the blastoderm over the cavity sec ions are alone available. Eggs of the requisite stage (10- tin, T/^ r"'" ^''''''\''' "^ ^'"-y dilute (one-tenth per cent!) soln- Afe, f 'T'° T^^ '^'^ ^•'1"^'^ ^*^i"g frequently changed. After a few days the eggs will have become almost black and quite friable. An egg is now pierced with a lance-shaped needle and the vitelline membrane carefully torn open at one place by means of sharp forceps, the rent being extended in a hod! zontal direction until it describes a complete circle ; the mem- uZ^ H ]? rernoved from the upper hemisphere, which con- tains the blastoderm. Thereupon the blastoderm, to<.ether sJ, aiaJ^n °'' f '''' ''1''?' '''' Baucei-shaped depl-esslon, i sepaiated by a sharp scalpel and placed in dilute alcohol, where It may^i^main for any length of time. It is, however, ready IQ2 EMBRYOLOGY. for further treatment in one or two hours. It may be stained hy steeping it for twenty-four hours in very dilute carmine (see Chapter VIL), and it is then washed in weakly acidulated water The object is now placed in absolute alcohol lor trom half an hour to an hour. After this, it is embedded m the followins? manner: A layer of the mass used for embedding (wax and oil) is poured upon aflat piece of glass, wood, or cork, or into a little box, and is allowed to harden ; the object, after its surface has been carefully dried, is placed m the desired position upon this mass, and a further lajer is poured around and over it, which must be warm, but not too hot. When the mass is thoroughly solidified, sections are made as follows: The razor is moistened, by means of a small brush, with oil ot cloves or with turpentine, and a section made, which is floated off from the razor to an object-glass with oil of cloves. When the section is thoroughly transparent, a process which occupies a few seconds, or at most minutes, if the object has been long enouo-h in absolute alcohol before embedding, the excess ot oil of clo^ves is to be carefully soaked up with strips of filter-paper. A window is cut out of fine tissue paper, and apphed to the preparation in such a wav as to afford protection from the pressure of the cover-glass. A drop of Dammar varnish is allowed to fall upon the preparation thus inclosed by the paper, and the whole is covered. The eggs having been placed m one-tenth per cent, solution of chromic acid until the gelatinous investment is entirely dissolved, they are transferred to common alcohol for two or three days and then preserved m glycerin. They may be used even after an interval of months. For the study of the cleavage-cavity of Batrachia, sections should be made of the eggs of Bufo, beginning with the stage at which the first furrows are already formed. The egg is taken, by means of a spoon, out of the glycerin, dried with filter-paper, and embedded according to the method above described. The razor in this case is to be moistened with absolute alcohol, and the sections floated on to the object- glass, with the same liquid. The alcohol is removed by filter- paper, and the section moistened with a drop of oil of cloves, after which the process is the same as above. Batrachian eggs require great care apd attention, both in making and handling the sections; first, because the ovum is less easily fixed than is the case with the disk-like germ of the trout or chick, and, further, because it is extremely friable, so that sometimes, out often sections, only one will be brought entire under the cover-glass. The first indication of a cavity may be traced shortly after the appearance of the first two furrows. In sections made at this stage, it is seen that the upper two quarters of the germ, that is to say, those furthest removed from the white pole, and which are always smaller than the BY DR. KLEIN. -[g3 two lower, are rounded off at their inner angles, i.e., those fZ'VTr't *''' '!""'" "' '''' ^"■"^' ^^« "■ t'"^y h;d retracted tiom It ; the lower two, also, are somewhat rounded at their inner angles, but not so markedly as those above- by this whZ th 'T '"'''^^ *' ^°™''^' ^^''""^ ^'^' J"«t "^ the place wheie the four segments meet. In sections of proo-ressivelv later stages, it will be observed, in the first pirce,"that thi uppei segments have undergone cleavage much more rapidly -m other words, that their elements are considerably smaller • and secondly, that the cavity becomes enlarged at the expense' of the upper half of the germ. In a still laterstage of cleavage forms will be met with in which the cavity takes 1,p the greatei^ pait of the space occupied by the upper segments. The cavity IS spanned by a thin dome, consisting of only two or three ayers of small elements; whilst its floor is flat and lined by larger elements belonging to the lower segments. Undei neath these elements, which still contain pigment, elements occur which become larger as the white pile is appioTched! At this time It may be observed, that these large elements- from H?^Y ^V'T"^ "formative elements"_spread upwards from the floor of the cavity over the under surface of tlie dome until at last a stage is reached at which the whole of that sur- ace IS covered with them. In the middle part of the dome these formative elements are disposed in a single layer- on the parts which are in closer proximity to the flooi of'the cavity, the number of layers is greater. The dome consists, theiefore, at this stage, in the first place, of two or, at most three layers of small elements which originally belonged to it (and which are also continuous with the cortex of the rest of the germ) ; and secondly, below these, in its central part, of a layer of larger elements, which before formed part of the floor 01 the cavity. Simultaneously with the changes just mentioned, another important change occurs at the white pole, as may be ascer- tained by the study of sections at different stages. This nole has been getting gradually smaller, and now presents the appearance of a sharply bounded white patch of the size of a pm s head— the so-called yolk-plug {Botterpfrovf). A fissure occurs, which constantly extends further and further upwards increasing at the same time in width, until it gradually ex- pands to a cavity, which is eventually only separated from the cleavage-cavity by a single layer of the larger elements. As this cavity (called the visceral cavity, Rusconi's cavity, Leibe.hohle) increases, the cleavage-cavity diminishes. In consequence of these changes, the position of the eo-g is altered ; that which before was the upper half now becomino- the lo\yer. (As regards the formation of the cleavage and visceral-cavities, compare figs. 169-1Y3.) -[g4 EMBRYOLOGY. Formation of the Lamellae of the Blastoderm. - From a comparative study of sections of the egg of the trout at successive' stages, from that at which the ^^^-''^^'^J''S!r^ to form a cover over the saucer-shaped depression, consisting of ^ middle thinner, and a peripheral thicker part (margmal s^ye\Ymr. Gamgee has shown that the blood of animals poisoned with nitrites, as e.g., nitrite of amyl, assumes a chocolate color. This color may be observed strikingly if a fevv drops 194 THE BLOOD. of nitrite of amj'l are added to a solution of haemoglobin. The color of the latter almost instanth' becomes brown. On adding reducing agents to solutions so altered, reduced haemoglobin (see § 18) appears — a fact which seems to square best with the assumption that the action of the nitrites on hsemoglobin is to peroxidize it, and that on reduction, oxj'hfemoglobin is iirst formed, then reduced. The precise nature of the reaction is still matter for investigation. 18. Optical Properties of Hsemoglobin. — G?-ystals. — The crystals are doubly refractive, i. e., they look luminous ■when examined with the aid of the polarization microscope (.see Part I., Chap. IV.), between ci'ossed Nicols. They shine in sunlight with a lustre compared by Preyer to that of silk. When formed in liquids freely exposed to air or oxygen, they are of the color of arterial blood, but have the wonderful pro- perty of becoming dark without altering their form when placed in vacuo at a low temperature. The}' then exhibit two colors, looking green along the orc^fs, purplish-red elsewhere. On the admission of air or oxygen, the color is restored. If a glass plate to which cr3'stals of haemoglobin adhere is placed in front of the slit of the spectroscope, two characteristic absorption bands (Hoppe-Seyler) are seen in the j'ellow between the Frau- enhofer's lines D and E (see Fig. 19.5, 1). Solution. — The bands just mentioned are also seen when solution of haemoglobin or of blood corpuscles is placed in the same position : they can be distinguished even when the solution contains on]}' one ten- thousandth of its weight of coloring matter. The bands differ, however, in their characters according to the degree of dilu- tion. According to the experiments of Prej-er, solutions vary- ing in strength from one to five per 10,000, show both bands faintlj' ; in solutions of six per 10,000, it can be distinguished that the band next the line T> is the darker of the two, the other being broad^er and fainter (see Fig. 195, 5) ; in solutions of thirty per 10,000, the violet end of the spectrum is completely absorbed, and the blue partiall}-. As the concentration is in- creased the two bands approach each other, until finally (when the solution contains seventy per 10,000) they form a single band, while the whole of the more refrangible rays are absorbed, so that the spectrum does not extend beyond the limits of the green (see Fig. 19.5, 6). In 1862 it was discovered by Stokes that hiemoglobin exists in the blood in two states of oxidation, which are distinguished alike b}' color and bj' the spectroscope ; that the oxygenized haemoglobin, or (as it has since been called) oxyhremoglobin, is deprived by reducing agents of its oxygen, and that when it has been so reduced, it can be restored to its original state by agitation witli air. The nature of the change of color is ex- pressed in two facts, which can be observed with the aid of the BY DR. BURDON-SANDERSON. 1P5 spectroscope. The first is, that when solutions of iuxMiiocrlohiii, or of blood, are deprived of oxygen, either by placing tiiera in vacuo or by the addition of redncing agents, the more refran- gible rays (blue and violet) are much 'less absorbed, and the green more absorbed than they were before. The second fact is, that in solutions so concentrated that most of the spectrum is extinguished, the last color which is transmitted is orange- red if the blood is arterial, red if it is venous. These two facts may be shortly expressed by saying that the color of arterial- ized blood consists of orange-red plu» green, of venous blood- red plus blue. These differences, however, are not the most remarkable which are observed when oxydized and reduced solutions of blood or its coloring matter are compared spectroscopically. The most striking change produced by reduction relates to the two bands of absorption in the yellow part of the spectrum which have been already mentioned. This change is most readily demonstrated by following the directions given by Stokes in his original paper. A solution of protosulphate of iron, to which a sufficient quantity of tartaric acid has been added to prevent its being precipitated by alkalies, is rendered decidedly alkaline by the addition of ammonia, and is intro- duced into the solution of blood. " The color is almost in- stantly changed to a much more purple red, as seen in small thicknesses, and a much darker red than before, as seen in greater thickness. The change of color, which recalls the dif- ference between arterial and venous blood, is striking enough, but the change in the absorption spectrum is far more decisive. The two highly characteristic dark bands seen before, are now replaced by a single band, somewhat broader and less sharply defined at its edges than either of the former, and occupying nearly the position of the bright band separating the dark bands of the original solution (see Fig. 195, 2). The fluid is more transparent for the blue, and less so for the green than it was before. If the thickness be increased till the whole of the spec- trum more refrangible than the red be on, the point of disap- pearing, the last part to remain is green, a little beyond the fixed line 6, in the case of the original solution ; and blue, some way beyond P, in the case of the modified fluid. If the purple solution be exposed to the air in a shallow vessel, it quickly returns to its original condition, showing the same two char- acteristic bands as before ; and this change takes place imme- diately, provided a small quantity only of the reducing agent were employed, when the solution is shaken up with air. If an additional quantity of the reagent be now added, the same effect is produced as at first, and the solution may thus be made to go through its changes any number of times." [Stokes, •On the Reduction and Oxydation of the Coloring Matter of 196 THE BLOOD. the Bloorl. Proceedings of the Roy. See, vol. xiii. p. 355.] The same facts can be demonstrated quite as advantageously, and pei'iiaps witli greater ease, if the solution of the siilplihy- drate of ammonium is substituted for the solution of sulphate of iron used by Stokes. The change is, liowever, not so rapid: it is accelerated by subjecting the liquid to a temperature of 40° C. 19. Methaemoglobin.— If a pure solution of hsemaglobin is left to itself at tlie ordinary temperature, it gi'adually loses its brightness, and if it is then examined spectroscopicall.y, it is seen that a new band has appeared in the orange at a ]joint where in ordinary blood there is least absorption. This band is due to tlie presence of a new coloring matter, called by Hoppe-Seyler methannoglobin. The same change occurs under otlier circumstances, e. c/., wlien' carbonic .ncid gas is passed through dilute solutions of hijemaglobin, or when glacial acetic acid is added to dilute solution of defibrinated ox-blood, in ex- tremely small quantity. [In larger proportions, acetic acid determines tlie formation of hsematon. — See § 22.] Haemoglo- bin undergoes tlie same transformation when acted on b}' per- manganate of potash. If a crystal of pure permanganate is dissolved in distilled water, and the solution added to very dilute solution of blood, before the slit of tlie spectroscope, at a temperature of about 25° C, the hiemoglobin bands gradu- ally disappear. In their place we have a spectrum, in wliich there are not only the band mentioned above, but two otliers, of which one nearly corres])onds in position to the second haa- nioglobin band, while the other lies half way between the lines B and F. Methsemoglobin is a substance of which the chemi- cal constitution and i-eiations are imperfectly ascertained. Its presence is indicated spectroscopically in all collections of blood which have been for some time exli'avasated witiiin the body, e. g., in thrombi, sanguinolent transudation liquids, etc. 20. Preparation of the Crystalline Coloring Matters 'Which result from the Decomposition of Haemoglo- bin, and Demonstration of their Absorption Spectra.— Hsemin.— When dried blood is ti'eated with glacial acetic acid and warmed to tlie temperature of the body^a solution is ob- tained which yields crystals of a new coloring matter, of re- markable properties, wliich has been designated hajmin. Tlie crystals vary extremely in shape, sometimes occurring as rhombic plates, sometimes as rods crossing each other at vari- ous angles. They are not soluble'wilhout decomposition in any liquie. Hse- min differs from hasmatin (§ 21) in contaTning an additional equivalent of hydrochloric acid, on which account it is also BY DR. BURDON-SANDERSON. ] 97 called hydro-ciilorate of hrematin. Its carbon, nitroocn, and iron are in the same relative proportions as in hannatin, but necessarily it contains a little less iron per cent, than 'that U,ody. Tlie mode of preparing the so-called Teiehraann's crystals— in other words, the mode of obtaining hosrain for the "purpose of demonstrating its crystalline form mieroseopicaljy— has been fully described in the histological part (Chap. I., p. 34J. Haemin may be obtained from blood in quantity, as follows, but the process is one which appears to present great difficulty, as it frequently fails. Deribrinated blood is diluted with a vol- ume and a half of distilled water. The transparent liquid is then precipitated with neutral acetate of lead, for the purpose of separating the albumin. The excess of lead (with respect to which it is' desirable to be careful not to add more than is necessary) having been got rid of by the addition of a con- centrated solution of carbonate of soda, the liquid is filtered, and the filtrate evaporated to dryness either in the air or in vacuo. The dry residue is then finely powdered and rubbed up with fifteen times its own weight of glacial acetic acid, to which a trace of chloride of sodium has been added. The brown liquid thus obtained is introduced into a flask and warmed in the water bath until it is entirely dissolved, and the solution is mixed with five times as much distilled water, and allowed to stand for many days, protected from eva]joration. The crystals collect on the bottom of the beaker and may be readily purified by repeatedly treating them with distilled water, allowing them to subside and then decanting. As hse- min contains chlorin, it cannot be prepared from hajmatin unless chlorides be present. Wlien it is [jrepared from blood, the quantity of chloride of sodium present is sufficient, so that the addition of that salt is not essential. The solution of hte- min in liydrocliloric acid gives no characteristic spoetrura. 21. Haematin. — HsEmatin can only be obtained in a state of perfect purity from the crystals of iisemin, the mode of pre- paration of which has just been given. The process is simple : the hpemin crystals are dissolved, i. e., decomposed in ammonia. The solution of haematin thus obtained is evaporated to dry- ness, the i-esidue is then extracted with water, which removes the chloride of ammonium, and dried. The product is pure hsematin. It is insoluble in water, alcohol, and ether, soluble in alkalies and alkaline carbonates, but not soluble in acids without decomposition. In the impure state, haematin may be obtained in various ways. The change occurs more gradually at ordinary tem- peratures in solutions of blood, or hairaoglobin, which are de- cidedly alkaline, wliether the alkalinity is derived from potash, soda, ammonia, or their carbonates. Solutions of liasmoglobin 198 THE BLOOD. which have imclergone this last change exhibit, when placed before the slit of the spectroscope, in place of the hfemoglobin bands, a less distinct and paler band on the opposite side of the D line, i. e., in the orange. This change is characteristic of the presence of hajmatin. It is attended witli an obvious darkening of the color of the liquid. When an alkaline solution of hasmatin is subjected to the action of reducing agents, such as sulphuret of ammonium or protosulphate of iron, it exhibits, when examined spectroscopi- cally, two much more distinct bands (Fig. 195, 4), one of which is exactljr opposite the bright space wliicli separates the two haemoglobin bands ; the other, which is less intense, is close to Prauenhofer's line, E, i. e., nearer to tlie blue end of the spec- trum tlian the broader of the two htemoglobin bands. If the solution is fresh and dilute, and- the quantitj- of the reducing agent small, these bands can be made to vanish bj^ agitation with air, giving way to the so-called oxj'htematin band above described. All these facts may be as readily demonstrated in solutions of blood corpuscles ; i. e., of cruor, as in solutions of ha-moglobin. Blood rendered distinctly alkaline cither by soda, potash, ammonia, or their cai'bonates, shows the absorption band of oxyhajmatin. After addition of sulphuret of ammo- nium, this is replaced by the more distinct spectrum of reduced hsematin. 22. Hsematoin. — When acetic acid is added to blood, the iron of the hemoglobin is separated and takes the form of a protosalt, and a new coloring matter remains in solution, the spectrum of which was iirst described by Professor Stokes, and has been subsequently known as acid hasmatin. More recently, Preyer has shown that it is not identical with ha;matin, biit with the body to which Hoppe-Seyler gave the name of iron-free haem.atin. It is produced whenever concentrated sulphuric acid acts on htematin. According to Hoppe-Seyler, it is pre- pared by rubbing up finely powdered hiiematin in concentrated sulphuric acid. A liquid is obtained which is green in thin layers, reddish-brown in thicker layers, and gives a brown pre- cipitate when diluted with water. This precipitate is easily dissolved in ammonia. On evaporating the ammoniaeal solu- tion, a bluish-black residue with metallic lustre is left, which is free from iron. It may be obtained in like manner by acting on methojmoglohin by sulphuric acid. The solution of hsm;^ toin in ammonia exhibits four absoi-ption bands. It is ad- mirably shown by the method recommended by Professor Stokes, i. e., by extracting with ether blood which has been mixed with acetic acid. The ethereal liquid thus obtained ex- hibits a four-banded spectrum. Of these bands, three only are easy to recognize— one in the orange, nearer to the red than the reduced haematin band ; a rather broad band in the green; BY DR. BURDON-SANDERSON. 199 and a narrow but "well-defiiied one in the blue. (See fig. 195, 3.) 23. Quantitative Analysis of the Blood, w^ith refer- ence to its Corpuscles, Serum, Fibrin, Haemoglobin, Albumin, and Salts. — The following summary of tiie order of proceeding in the anal3-sis of the blood, will be found sufficient for the guidance of those who liave been previously trained in quantitative methods. The student who has not learnt accuracy by practice, in the anal3'sis of bodies of known composition in the chemical laboratorj-, should not attempt the quantitative determinations relating to the blood or other animal liquids, partl3r because the operations are complicated, but principally because the operator has no means of detecting his mistakes. The blood to be analyzed is received in four vessels, the contents of which are as follow : 1. Ten or twelve centimetres of blood are allowed to flow into a weighed porcelain capsule and covered with a weighed watch-glass. After weighing, the blood is evaporated in a water-bath, dried in the air-bath at 120° C, and the residue used for the deter- mination of the total albuminous constituents, fat and salts, as follows: After standing till it is cool in a receiver over sul- phuric acid, it is weighed. The weight, deducted from that of the capsule and watch-glass, gives the total solids. The dry residue is then pulverized in a glass or porcelain mortar with common alcohol (Sp. G. 890) and transferred to a small beaker, the mortar being subsequeutl}- carefully washed with alcohol, and the washings added to the quantity in the beaker. This done, the contents of the beaker are boiled, and the alcoholic solution thus obtained is poured into a small previously weighed filter. What remains in the beaker is similarly treated with a second quantity of alcohol, which is thereupon poured into the same filter. After carefully washing the filter with boiling alcohol, the filtrate together with the washings is evaporated on the water-bath, dried at 110° C, allowed to cool over sulphuric acid, and weighed. The weight gives the solids soluble in alcohol a. Distilled water is added to the residue in the beaker, which is warmed in the water-bath. The water-extract is then poured on to the filter last used, and the filtrate collected in a weighed covered capsule, evaporated on the water-bath, dried at 110°, cooled over sulphuric acid, and weighed. The weight, minus that of the capsule, is that of the solids soluble in loater . b. The remainder on the filter is dried at 110°, and then over sulphuric acid, and weighed repeatedly, till it is found no longer to lose weight. For this purpose it must be inclosed between two watch-glasses, held together bj' a clamp. The weight, minus that of the watcli-giasses, filter, etc., is that of the insoluble solids c. 200 THE BLOOD. The fats of the blood are contained in a. from wliich the_y are extracted liy repeatedlj^ treating it with etlier and evapo- rating the ethereal extract. The residue is washed into a small platinum capsule for incineration. h is incinerated in the capsule in which it was weighed ; e, with the filter in which it is contained, is incinerated in another capsule. Tlie ash of a and b represents the soluble salts of the blood, viz., the chloride of sodium (five-sixths of the whole), phosphate, sulphate, and carbonate of soda ; chloride and sulphate of potash. The ash of c consists of phosphates of lime and magnesia.' 2. A second quantity of twenty-flve centimetres is used for the determination of the fibrin. For this purpose a small beaker is used, over the top of which a vulcanized India-rubber cap with a single neck [see Fig. 196) can be drawn without difficulty. Through the neck or tubulature, a rod of whale- bone, which, at its lower end, widens out into a blade, is grasped by the tubulature. The blood is received into the beaker, covered at once with-the cap, and immediately agitated very briskly with the blade of the whalebone, the purpose of the whole arrangement being to prevent loss of weight by evaporation during the process. As soon as coagulation is complete, the beaker and its contents are weighed. The weiglil, minus that of the beaker, its co\'er and the oar, is that of the quantity of blood used. The cover is then removed and the beaker filled with water, to which a trace of chloride of sodium has been added. After agitation and subsidence the clear liquid is poured off, and the fibrin again treated with as much more water with a trace of salt. The fibrin is then collected on a weighed filter, and washed with distilled water ' In incinerating, it is of importance that the capsule or crucible should be large enough to hold four or five tunes as mucli material as is used. Platinum vessels are preferable. If the substance contains much organic matter, and at the same time much soluble salts, e. g., chlorides, it is necessary to perform the operation in two stages, i. e., first to car- bonize the substance, then extract the ash with boiling water, collect the insoluble part on a filter free from ash or containing a known weight of ash. The filter, after careful washing, must be dried at llOO C, and gradually heated to whiteness until the carbon is entirely destroyed. Almost the whole of the soluble salts are contained in the extracts. Thus the decomposition of tlie alkaline carbonates and chlorides, which occu rs at a higher temperature, is avoided. In incine- ration of the total solids of the blood this interruption of the process is desirable, if for no other reason, on account of the extreme difficulty of getting rid of the carbon in presence of so great a quantity of alkaline salts. If, however, the method described in the text is followed, these difficulties are got rid of in .another way. For, on the one hand, the watery and alcoholic exti-acts contain very little organic matter ; on the other, tlie insoluble residue (c) is free from alkaline salts. In both cases, therefore, the incineration can be proceeded with continuously. BY DR. BURUON-SANDERSON. 201 until the filtrate is colorless. The pink fihriii thus obtained is then finally washed on the filter witii boiling alcohol, dried first in the air-bath, then over sulphuric acid, and finally "vveigiied. 3. A third portion of blood is received in a similar apparatus, defibrinated, and the defibrinated blood strained through a calico filter and weighed. The filtrate is then mixed in a tall jar, with ten volumes of a solution of salt, prepared by adding nine volumes of water to one of saturated solution. After a day, the corpuscles having subsided, the liquid is decanted off, and replaced by a second similar quantity of saline solu- tion. Again the corpuscles are allowed to subside, and the liquor removed by decantation. The deposit is then washed with water into a porcelain capsule, evaporated on the water- bath, dried, pulverized with alcohol, and then proceeded with for the separation of the albuminous compounds from the soluble constituents, as in the first quantity. The weight of the insoluble residue (o), minus the weight of its salts, corre- sponds to that of the albumin and htemogiobin of the whole blood. 4. The fourth quantity is allowed to coagulate in a capsule. The serum is then poured off, and tlie albumin contained in a weighed quantity determined by the method already de- scribed. The results stand as follows : From 3, we learn the propor- tion in a known weight of blood, of albumin and hreraoglobin contained in the corpuscles; from 1, the corresponding pro- portion of albumin and hiemoglol)in contained in the corpus- cles and plasma together; and lience, b.y deducting the former from the latter, the proportion of albumin in the plasma. From 4, the proportion of albumin contained in the serum is known, and thereby that of the serum in tlie blood. The weiglit of the plasma is equal to the weight of the fibrin (2), plua that of the serum. Finally, by deducting the weight of the plasma from that of the blood, we have that of the corpus- cles in the moist. 24. Quantitative Determination of the Haemoglobin contained, in Blood. — It is often of great importance to be able to determine the proportion of hsemoglobin in a small quantity of blood ; such, for example, as may be obtained by cupping. This is accomplished by making a solution of a measured or weighed quantity of blood in water, and then ascertaining, with the aid of the spectroscope, what degree of dilution is necessarj' in order to bring it to such a strength that only tlie red rays are transmitted (see § 18). The point of dilution at wliich tlie green is entirelj' extinguished, has been found by Pi'eyer to be so constant, tliat it may be used as a basis for quantitative determinations. 202 THE BLOOD. The determination of the percentage of hfemoglobin which is required to 3'ieid the spectroscopic result above described, is accomplished bjr introducing a concentrated solution of a known weight of pure haemoglobin cr3'stals into a glass cham- ber (so-called haeraatinometer), of which the parallel sides are one centimetre from each other. The chamber is then placed in fi'ont of the slit of the spectroscope, the source of light being a paraffin lamp. Distilled water is then carefully added from a finely divided burette, so long as all of the spectrum is extinguished excepting the red. The moment that the green begins to appear, the operation is ended. The volume of the diluted solution is determined ; and the exact conditions, viz., the distance of the lamp and chamber, and the width of the slit, are carefully noted. The percentage of lisemoglobin con- tained in the solution is that at which, uncle?- the. given condi- tions, complete absorption of the green takes place. It may be designated k. In order to ascertain the percentage of hseraoglobin con- tained in any given specimen of blood, all that is required is to repeat the process just described. A small quantity of fresh blood, which has been well agitated with air and deflbri- nated, is introduced into a finely graduated small pipette, from whicli exactly one centimetre is delivered into the glass chamber above mentioned, and diluted before the slit of the spectroscope (the liquid being cai-efully stirred after each addition) until the green begins to appear. At this moment the liquid contains a percentage of hemoglobin equal to k. If the volume of distilled water including the centimetre originally added, be designated c, and the original volume of blood 6, the percentage of hiemoglobin which the blood con- tains is readily calculated according to the formula -jr=—r~- Whence, if the quantity of blood used, as above supposed, be one centimetre, we have x=k (1 + c). 25. Determination of the Quantity of Hemoglobin in Blood, by the Estimation of its Iron. — Assuming that haemoglobin contains 0.42 per cent, of iron, and that the whole of the iron of the blood is contained in its coloring matter, it is evident that if the percentage of iron existing in any quantity of blood is known, the perccntao;e of hsemowlobin can be readily calculated.. Although the process has disad- vantages as compared with that last described, both as regards the time required for carrying it out, and the accuracy of the results, it cannot be omitted, as, under many circumstances (o.y., when the blood to be investigated is not perfectly fresh), the spectroscopic method is inapplicable. To ascertain the proportion of iron in blood, a weighed or measured quantity of the liquid must be incinerated. The asii must then be dis- BY DR. BURDON-SANDERSON. 203 solved in pure dilute hj-drochloric acid, and tlie iron deter- mined volumetrically with permanganate of potash. This is accomplished as follows : — The volumetrical solution of permanganate which is usual- ly employed, is prepared by dissolving the pure crystals in distilled water, in the proportion of 3.1C grammes to the litre. It is of such strength that 1*7.85 centimetres correspond ap- proximativelj' to one-tenth of a gramme of metallic iron. It is, however, necessary, before using it, to determine its exact strength, by means of a weighed quantity of solution of the double sulphate of iron and ammonia. The mode of preparing this salt will be found in Sutton's " Volumetrical Analysis." It contains exactly one-seventh of its weight of iron, so that 0.7 gramme represents 0.1 gramme of iron. The mode of ap- plying it is as follows: — 0.7 gramme of the salt having been dissolved in a beaker in distilled water, and five or six c. c. of dilute (1 : 5) sulphuric acid added, the permanganate solution is delivered from a bu- rette, having a glass stopcock, until a point is reached at which the rose color no longer disappears on shaking. As the per- manganate must be slightly in excess to produce a percepti- ble color, a correction should be made by ascertaining experi- mentally how much of the salt is required to produce the observed intensity of color in the quantity of liquid used. This quantity should then be deducted from the result. The number of cubic centimetres used for 0.7 gramme of the double sulphate, (i. e., 0.1 gramme of metallic iron) must be marked on the bottle. As the method depends on the con- version of the iron from the lower to the higher stage of oxi- dation at the expense of the permanganate, it is obviouslj' ilecessarjr that the whole of the iron in the liquid to be ope- rated upon should be in the condition (to use modern lan- guage) of a fei'rous salt. For this reason, the first step in dealing with the hj^drochloric acid solution of blood ash, is to reduce it. With this view, the solution of ash is first intro- duced into the flask already mentioned, in which it is gently boiled with a few pieces of zinc until the latter is dissolved and the liquid is colorless. It is then allowed to cool and diluted to fifty centimetres, after which the solution of per- manganate is added to it from the burette, as before, until the rose color becomes permanent after agitation. Tor each centimetre of the red liquid emploj'ed in attaining this result, the quantity of solution in the flask contains 0.0056 gramme of iron. 204 THE BLOOD. Section IV. — Gases op the Blood. 1. The gases of the blood are ox^ygen, carbonic acid and nitrogen. The Itnowledge we possess of the conditions under which they are contained in the blood, and of tiie relative quantities of eacli, is founded entireh* on the researches of Luduig and his pupils, published during the first yeav of the last decade. As I'egards oxjrgen,a correct method (that of displacement hy carbonic oxide) had already been employed by Claude Bernard ; but, as regards carbonic acid, the methods previous- ly used were imperfect and the results erroneous. 2. In round numbers, one hundred volumes of arterial blood deliver to the Torricellian vacuum about twenty volumes of oxygen (estimated at 760 millimetres pressure and 0° temper- ature) — venous blood about twelve volumes. Of the quantity of oxygen so extracted, by fai; the greatest part is in combina- tion with hwmoglobin — in other words, in the concrete state. The propoi'tion of free oxygen in blood is so smnll that ox^'gen is absorbed from any atmosi)here containing it in which its tension is greater than from twenty to twenty-five millimetres — in other words, from any space in which it exists in a pro- portion gi-eater than about one-eighth of the proportion in which it exists in the atmosphere. Consequently, in subject- ing blood to the air-pump, no oxygen is given off till the press- ure sinks to about 125 millimetres (i. e., about a sixth of an atmosphere) ; whereas, in the case of other liquids (e. g., water), oxygen, with the other contained gases, begins to be disengaged, ijari passu, vflth the reduction of pressure, in a quantity determinable according to Dalton's law. These facts are expressed by saying (1) that the absorption of oxygen by the blood is independent of Dalton's law, and (2) thatVhe ten- sion of oxygen in tlio blood is from twenty to twenty-five millimetres of mercury. ^ 3. When blood is subjected to the Torricellian vacuum, the disengagement of oxygen is complete. The blood is converted into frotli, and rapidly assumes a dai'k color. This appear- ance is due partly to the discharge of the coloring matter from the corpuscles, partly to the complete reduction of the htemo- globin which accompanies the extraction from the liquor san- guinis, of its free oxygen. 4. When blood is sulijected to an atmosphere wdiich con- tains no oxygen, the result, so far as relates to the extraction of oxygen, is the same as if it were exposed to the vacuum. This is particularly the case if the gas employed be one which has the power of combining with hemoglobin. The gas which pre-eminently enjoys this faculty is carbonic oxide. When blood is subjected to an atmosphere of this gas, the oxygen it BY DR. BURDON-SANDERSON. 205 contains, whether free or combined, escapes from it, its place being talven by carbonic oxide. The blood-coloring matter in combination -with this gas acquires optical and othei'characters which remarkably' resemble those of oxyhemoglobin. 5. Carbonic acid gas may be extracted from arterial blood by the Torricellian vacnum in the proportion of about 35 vol- umes (as estimated at 7(30 millimetres pressure and 0° tempe- rature) to 100 volumes of blood. Venous blood may yield 43 volumes, aspiiyxial blood 50 volumes. Of this quantity a cer- tain but very varying proportion is merely absorbed, the rest is in loose combination, principally with the sodic carbonates of the plasma. It is probable tliat some of it is held by the bibasic sodic phosphate of the blood, and perhaps some other- wise. Hence it may be readily understood that serum con- tains as much carbonic acid gas as a corresponding volume of blood. 6. When a fixed acid, <». ty., tartaric acid, is added in vacuo to blood which has been already deprived of its absorbed and loosely combined carbonic acid (which together constitute what may be called its inexhaustible carbonic acid), an addi- tional quantity of carbonic acid may be obtained from it, which previously existed in the blood in the condition of neutral car- bonate, principally if not entirely sodic. Every apparatus for extracting the gases of the blood must consist of two parts, a mercurial i)ump and a recipient. The form and character of the latter necessarily depend ui)on those of the former. The most important foi'ms of pump in use are those of Dr. Geissler, and others simihir, employed in Ger- many, and of M. Alvergniat, in Paris. Jn this country, under the dii-ection of Professor Fi-anldand, Mr. Cetti has constructed a Sprengel's pump for the purposes of extracting the gases of water. Dr. Gamgee, of Edinburgh, has a|)plied this foi'm of pump to the extraction of the gases of the blood with complete success. 26. Alvergniat's Pump. — A long barometer tulie, the scale of which is divided into millimetres, is fixed to a vertical board on a suitable stand. This tube is dilated at the top into a large bulb (a. Fig. 191), and is then continued upwards untilit ends in a three-way stojjcock ((/), surmounted by a funnel. To the right, the stopcock is in communication with a glass tube, ending in a bulb {g), and possessing a flexible joint at/. To the lower end of the barometer tube is fitted a long tube of thick-walled vulcanized caoutchouc, which ends in a globular mercury-holder (u). The vertical board is fitted at regular in- tervals with perforated shelves, on one of whicli the mercury- holder is resting. Tiie pump is worketl as follows: v having been filled with mercury, the metal enters the vulcanite tube, and rises to the same height in the tube a c as in v. If v is 206 THE BLOOB. raised from its present level to that of the highest of the shelves, the stopcock being :it the same time turned so that the vertical tube communicates with the external air, but not with the bulb, the mercury will rise till the whole of the verti- cal tube is occupied. The stopcock is now turned so as to make communication only lietween a c and the bulb, and the mercury-holder is replaced in its original position. As the re- sult of this manipulation, the air previously contained in the bulb and the tube leading from it occupies the whole cavitj', and (according to Marriotte's law) is expanded, i. e., dimin- ished in density in the same ratio that the volume occupied bj' it is increased. In other words, the density of tlie air in the bulb, before the depression of i), is to its density after as the capacity of the barometer plus the bulb is to that of the bulb alone. To repeat the operation, the stopcock must first be placed in such a position that all channels are closed, v is then raised and the stopcock again turned as at first — viz., the horizontal waj^- closed, the vertical way open. The air contained in a c having been discharged, the stopcock is again opened horizontally and closed vertically, and i) depressed. The air remaining in the bulb is again expanded in the same proportion as before. If the capacity of the tube, together with its dilatation, be equal to that of the bulb and its tube, it is obvious that the effect of each stroke of the pump will be to halve the density of the air in the bulb ; consequently, if the operation is repeated ten times, the density of the air con- tained in the bulb (supposing it to be dry, and to have an ori- ginal density of *?60 millimetres) becomes T60x(|^)'"^0.14 mil- limetre. "Qy filling the bulb and the tube leading to it, before attaching it, with water deprived of its gases by boiling, the process of exhaustion can be veiy much shortened. No sooner does the mercury sink in the vertical tube {a c) than the water follows it, and can be discharged by raising the mercury- holder with the stopcock o])en vertically and closed horizon- tall j', as before. A vacuum which is almost perfect is thus obtained at a single working of the pump. In the pumps recentl}' made by M. Alvergniat, he has substituted a movable sup|)oi't which works up and down the vertical board \)y a winch. 27. Geissler's Pump. — The instrument {see fig. 198) con- sists, like that just described, of a fixed vertical tube (a), wdiich is dilated into a large bulb near the top and communicates near its lower end by means of a flexible tube of thick walled caout- chouc with another vessel (6) which can be moved up and down by turning a winch. Above the bulb, the vertical tube, which is nearly a metre in length, ends in a stopcock ((7), so con- structed that the bulb can be completely shut off, or may be brought into communication eithei with the external air or with BY DR. BUKDON-SAKDERSON. 207 the cavity to l)e exhausted. The pump is worked in the same manner as that just described. In order, if necessary, to dry the vacuum, a Pfliiger's drying apparatus is interposed between the pump and the recipient. Tliis may be described as a U tube, the bend of which is dilated into a bulb (c). It is so constructed that the fragments of pumice or the glass balls moistened with sulphuric acid which are used for drying can be readily introduced into either limb. The tubeleading°from the dessicator to the pump communicates with a vacuum"gauo-e (m). The advantage which this instrument possesses consists in the relatively large size of the bulb, the perfection of the workmanship (particularly of the stopcocks) and the arrange- ment whereby the vacuum obtained is dry. 28. Frankland-Sprengel Pump.— Sprengel's pump as modified by Frankland, consists essentially of a vertical glass tube (0 Fig. 199) about four feet long, with thick walls and nar- row bore, the lower end of which is bent up in such a way that, if filled with mercury, and closed at the top, it would constitute a barometer. At its upper end, however, it is not closed, but is continuous by a bend with the second vertical tube (g) or ascending limb of the Sprengel (the supply tube), which is of wider bore, and runs parallel to the first. At the top, or con- vexity of the bend, a third tube, about four inches in length (the exhaustion tube), is sealed on, by which the barometer tube or descending limb communicates with the cavity to be exhausted. The ascending limb communicates by a flexible tube, strengthened by a covering of strong canvass and guarded by. a screw clip, with the descending limb of another bent tube (c) of similar construction to the first ; the only dif- ference between it and the one just described being that it com- municates at the bend, not witii any cavity, but merely with a bulb (d) closed at E by mercury. Its other limb finally com- municates by a second flexible tube with a reservoir of mer- cury (b), the arrangement of which will be best understood from the figure. It consists of two glass funnels, each having long stems, the relative sizes of which are such that the one can be contained within the other. To work the pump, the exhaust- ing tube of the first bent tube must be connected with the cavity to be exhausted by means of a junction of vulcanized caout- chouc, guarded by a chamber filled with glycerin. Mercury is then poured into the inner funnel (the tube leading to the first bend having been previously closed) until it rises in the space between it and the outer to the same level. This done, the clip is opened, and a stream of mercury is allowed to flow over the two bends in succession, great care being taken that the stream is not so abundant as to cause the mercury to ascend in the exhausting tube above the level of the bend. The flow must then be gradually diminished with the aid of the clip, 208 THE BLOOD. until tlie column of mercury in the descending limb of the Sprengel tube is broken into fragments by intervening spaces containing air. This liappens whenever the quantity of mer- cury which reaches the bend by tlie ascending limb in any given time, is less than that which leaves it b3r the descending limb. In a time wliich varies according to the capacity of the cavitj^ to be exhausted, vacuum is attained. No more bubbles are discharged at the lower end of the Sprengel. Each drop of mercnrj' as it falls produces a peculiar click, and if the current is stopped, it is seen that the height of the column in the de- scending limb is less than that of the barometer at the time, by a number of millimetres wliich is equal to the tension of aqueous vapor at the temperature. The apparatus is so arranged that the bend of tlie first tube is supported at a level several inches liigher than that of the second. Consequently, as the process of exhaustion approaches, the bulb with which it communicates becomes emptied of mercury, the vacuous space thus formed gradually extending till the level of the mer- cury in the descending limb coincides with that of the bend of the second tube. We next pass to the description of tlie method of obtaining blood from an artery or vein, and of transferring it to tlie vacuum. Although it is not possible to produce a vacuum with tlie Si^rengel pump above described, as rapidljr as with the ordinary mercurial pum]),' its action in other respects is very satisfactory. It completely fulfils the conditions enume- rated by Ludwig as essential to an efficient blood-pump. The vacuum produced is perfect ; it is bounded by mercury which, having previously passed through a vacuum (in the first tube^, is completely deprived of air; and it can be renewed any num- ber of times after the blood is introduced. 29. Method of Transferring the Blood to be Ex- hausted from the Artery or Vein to the Vacuum. — It is essential that the transference should be effected without contact with air ; the blood must therefore either flow as directly as possible from the artery or vein into the vacuum tube: or, if it is intended to defibrinate it, it must be received in a space previously occupied by mercury. Eefore describing the mode of transferring, an account must be given of the chamber or re- cipient in which the blood is exhausted, and of the mode in which it communicates with the pump. The exhaustion tube (see Fig. 199, n) is connected by a vulcanite union, inclosed in an external tube containing glycerin, with a long nearly capil- lai'y tube, of such form and length as to reach the table by the side of which the pump stands. Near its lower end it is bent I The instrument probably admits of coDsiderable improvement in this respect. BY DR. BURDON-SANDERSON. 2l.9 at an obtuse angle, so tbiit the last few inches are horizontal. A little above the bend there is a bulb : the horizontal jjart is firnilj supported on a block. With this tube the recipient is united either by a mercurial joint (i) or by a connector of vul- canized India-rubber, inclosed iu a glyceriu chamber. The recipient is a large glass tube (j), of about an inch and a quarter diameter, and forty inches long. At its lower end it terminates in a capillary tube, which is guarded by a stopcock (l). Its capacity is about 250 centimetres, consequently six- teen times that of the blood it is intended to receive. In selecting a method of transference, preference ought to be given to those plans which are least complicated and most rapid in execution. The method I have found to answer is as fol- lows: The animal having been secured, a canula fitted with an India-rubber connector is inserted in the vessel, which is closed by a clip lege artis. For receiving the blood as it flows from the artery or vein, a straight-glass tube (Pig. 199, m) of known capacity is used ; one end of this tube is guarded bv a stop- cock, while the other is drawn out, and so formed tliat it can be accurately stopped by the finger. A trough having been filled with mercury, completely freed from air by passing through the pump, the narrow end of the tube is dipped into it. The tube is then easily filled up to the stopcock by aspira- tion and the stopcock closed. It having been ascertained that the tube is perfectly full, it is placed iii an inclined position, with the stopcock end downwards, and the open end at such a distance from the canula that the India-rubber tube can be easily slipped over it at the required moment. Tliis having been accomplished, and the other end of the tube having been fitted with a bit of India-rubber tubing of sufficient length to convey away the mercury to a convenient receptacle, "all is ready. The clip on the canula is opened, and blood allowed to flow freely from the tube for a few moments while tlie mercury tube is grasped by the operator. The warmth of the hand causes the mercury to expand and project from the open end of the tube: at that moment the India-rubber connector from which blood is flowing is slipped over it, and the connection is completed without the slightest risk of the introduction of air. Without a moment's loss of time the stopcock is opened, and the blood allowed to replace the mercury. The stopcock having been closed, the India-rubber connector is slipped ofl', and the open end of the tube closed with the finger. The tube is now placed with its open end downwards in the mercurial trouo-h (u), the finger being still kept on the orifice, while an assistant fills the bit of capillary tube beyond the stopcock with boiled distilled water, and connects it with the corresponding end of the recipient by means of an India-rubber connector. The mo- ment that this is accomplished, the finger is removed from the 14 210 THE BLOOD. orifice of the tube, and both stopcocks are opened. The blood passes rapidly into the recipient, followed by a column of mer- cnry, and is at once converted into froth. A few drops of mer- cury liaving been allowed to enter, the stopcocks are finally closed. It will be understood from the figure that the joint between the measuring lube and the recipient, as well as the stopcocks, are under water, the purpose of which arrangement is, it need scarcely be said, to obviate the risk of the entrance of air. At first the water in the wooden trough (n, which is not in- troduced until M has been joined to l) is kept cool with frag- ments of ice, in order to prevent the blood from coagulating during the preliminary operations. As soon as all is complete, hot water is gradiiallj' added until the temperature rises to about 40° C, care being taken not to expose the stopcocks to the air during the process. The only moment in the process at which air can be admitted, is that of joining the measuring tube to the I'ecipient. For this reason it is desirable, before opening the second stopcock of the measuring tube, to keep the pump in action for a few minutes so as to be certain that the vacuum is unimpaired before admitting the blood. This is not attended with inconvenience, if the blood is kept at a tempera- ture approaching that of freezing. When it is desired to defibrinate the blood before exhausting it, it must be collected over mercury. This is best effected in Ludwig's recipient. This recipient is a tube closed at one end and furnished with a Geissler's stopcock having a remarkably large way. The tube is inverted over merenrj-, with the stop- cock open, and the blood allowed to flow directly from the ves- sel into it until it is nearlj' filled. It is then closed by the hand, deflbrinated bj* vigorous shaking with mercury, and replaced in the trough. The stopcock is now closed, and the tube, from which the blood contained outside of the stopcock has been washed, is united with the recipient of the pump by an India- rubber joint. To carry out this method, Sprengel's pump is scarcely applicable ; for, inasmuch as the process of exhaustion cannot be begun until the connection is made, a long time must elapse before the tap can be opened. Blood alters so rapidly after removal from the bod}- — the oxygen diminishing, the car- bonic acid increasing — that if much time is lost the results are of little value. 30. Method of Analysis. — In France most of the analy- ses which have been published by Bernard and his pujiils have l>e«n made by a method which, although rapid, is inexact. In Germanj' the analyses of Ludwig and his pupils, as well as those of Pfliiger, have been made according to the accurate methods first introduced by Bunsen, and commonly known by hie name. Bernard's method is practised in the physiological BY DR. BURDON-S ANDERSON. 211 laboratory of the Jardin des Plantes, in Paris. The analysis is made in a circular merciuial trough, in the centre of which is a well sixteen inches deep, and large enough to contain about 12 lbs. of mercury. The gas having been transferred from the tube in which it is collected from the pump, to a eudiometer, the latter is plunged into the mercury, in order that its contained air may acquire the temperature of the metal. It is then raised with the aid of a wooden tube-holder until the level of the mercury inside is the same as that out- side. The quantity of gas having been measured, a fragment of caustic potash is introduced, which rapidly dissolves in the few drops of water which always float on the surface'-of the mercury. The column of mercury is then gently agitated by alternately raising and lowering the eudiometer, which, afteV the completion of absorption, is again plunged into the mercury. The gas having been again measured, about a centimetre of strong solution of pyrogallic acid is introduced with tlie aid of a pipette with a bent beak. The agitation is repeated and continued for some time. As soon as the absorption of the oxygen appears to be complete, the tube is transferred to a basin containing water, into which the mercury with the pyro- gallate of potash is allowed to fall. The residue, consisting of nitrogen, is read over water. The results obtained by thisroiTgh- and-ready method must necessarily be erroneous, not only be- cause the measurements are inaccurate, but because the absorp- tions must always be incomplete. If, however (as in certain pathological inquiries), it is more important that the anal^r- ses should be numerous than that they should be exact, it may be available. For class illustrations of the general nature of the blood gases, it is completely adapted. For more exact purposes the process of gas analysis has been during the last few years much shortened by Frankland, Russell, and others. With a view to the analysis of the gases of drinking water, Frankland has introduced an apparatus of great simplicity (see Fig. 200), the working of which will be readily understood by the diagram. It consists of two parts, viz., a laboratory tube (k), in which the gas to be analyzed is first received, and a measuring apparatus to which it can be transferred from the laboratory, in order that its volume may be determined before and after each absorption. The measur- ing apparatus consists of two tubes (a, b), fixed vertically side by side in a stand, surrounded by a chamber containing water (n). They communicate below both with each other and (by the long flexible tube) with a mercury-holder (t), like that of Alvergniat's pump. One of them can be brought into communication by the arm (g) with the laboratory tube ; the other (6) is open at the top. A scale of millimetres is en- graved on it, the zero of which is opposite o. A corresponding 212 THE BLOOD. scale, starting from a zero at the same level, is engraved on the measuring tube. The apparatus is filled with mercury by raising the mercury-holder (t) to a sufficient height, the stop- cock (/) remaining open ; in doing which the surface of the mercury in t must not be more than a few millimetres higher than the tap. As soon as the mercury appears at g, the stop- cock is closed. The next step is to fill the laboratory tube. Having inverted it in the trough, which has been previously raised to the proper height, the operator draws out most of the air b.y means of a bent tube, the point of which rises to the top of the laboratory tube, and shuts the stopcock as soon as the mercury rises. The removal of the air is completed by joining g and g' so as to connect the laboratory tube with the measuring apparatus, and then causing the air contained in the former to pass over into the latter, by depressing t. The stopcock h must now be closed and g and g' disconnected to allow of the expulsion of the air from a. This having been accomplished, g and g' are again brought together and care- fully secured. The whole apparatus is now full of mercury ; as soon as it has been ascertained that the joint is air-tight at all pressures, it is ready for use. Before proceeding further, however, the measuring tube, which, as already stated, is graduated in millimetres measured from an arbitrary zero line near the bottom, must be calibrated. In other words, it must be ascertained as regards each principal mark of the gradu- ation, what volume of air or water (as the case may be) the tube contains, when the upper convex surface of the mercury stands exactly level with it. For this purpose the orifice a is connected by means of an India-rubber tube with a reservoir (a funnel) containing distilled water. The mercurial column is then allowed to descend until it stands exactly at zero. A weighed beaker having been then placed under a, water is ex- pelled till the column stands at a height of fifty millimetres, and the beaker again weighed. In a similar manner the out- flow of water corresponding to a rise of the mercurial column from fifty to one hundred millimetres is determined, until the capacitjf which corresponds to each fifty millimetres of the scale is ascertained. To insure accurac3r, the process must be repeated several times. If the results, after correction for difference of temperature, are in close accordance, the means may then be taken as expressing the capacities required. In the upper part of the tube, calibration must be made at short- er intervals. In calibrating, as in all subsequent measure- ments, the height of the column must be read horizontally through a telescope, so adjusted that its axis is at the same height as the surface of the mercury. The temperature is read by a thermometer suspended in "the cylinder of water by which the barometer and measuring tube are surrounded. BY DR. BURDON-SANDERSON. 213 31. Introduction of the Gas to be Analyzed.— The measuring and laboratoiy tubes having been brouglit into con- nection in the manner described above, and both filled with merciny, the gas to be anal^-zed is introduced into the labo- ratory tube from the test tube to which it has been discharged by the Sprengel. It is then at once transferred to the mea- suring tube by depressing t until tlie mercury rises in the laboratory tube as far as the stop-cock g' . this done, the stop-cock g is closed, and t raised or depressed till the column stands at one of the marks of the graduation, in reference to which the capacity of the tube has been determined. The temperature is then observed, and the pressure determined by addmg the difference between the height of the cokimn in the measuring tube and that in the pressure tube, to the reading of a barometer which stands by. A few drops of solution of caustic potash having been introduced into the laboratory tube, the gas is returned from the measuring tube. Absorption takes place rapidly. It is accelerated by slightly agitating the trough, and by allowing the mercury to stream into the labo- ratory tube after the gas has passed. The measurement of the gas after absorption is performed in the same manner as before. About half a centimetre of strong solution of pyro- gallic acid is then introduced in the same way as the potash, and the gas again returned. After absorption" of the oxyo-enj what remains is nitrogen. In analysis of blood gases, "the proportion of nitrogen is nearly constant, viz., about 2. .5 vol- umes in 100 volumes of blood. If a larger quantity is obtained, the fact indicates that air has entered. Whatever method of analysis is employed, the results must be reduced to 0° tem- perature and 760° millimetres pressure— i. e., they must be expressed as if the measurements had been made under those conditions. A further deduction must be made from each measurement in respect of the aqueous vapor which the o-as contains (the measuring tube being always moist). This'' is accomplished by the following well-known formula : 1 + t o-ooser 76o V denotes the corrected volume ; V the volume read ; t the temperature; H' the observed pressure ; and / the tension of aqueous vapor at the temperature t. The values ofl+t 0.003CT and /are always obtained from tables. For these, and many other important practical details relating to the performance of gas analysis, the reader is referred to Mr. Sutton's " Volu- metrical Analysis," whom I iiave to thank for two of the woodcuts with which this section is illustrated. To illustrate the application of the method to the analysis of the gases of the blood, I give the following example: — 214 THE BLOOD. Analysis of Gases of Arterial Blood of Dog. IstMeasureraent. Total quantity of gasextracfed. 2d sreasurement. After absorption of cai'bouic acid gas. 3d Measureraenl:. After absoi-ptioa of oxygen. Height of column in measur- iug-tnbe Height of column in pres- sure-tube 230.0 312.8 270.0 369.0 450.0 320.0 Difference Reading of barometer 83.8 764.0 99.0 764.0 —130.0 764.0 H'= Temperature=19.8''C.=t. Tension of aqueous vapors from table=f= 846.8 17.2 863.0 17.2 634.0 17.2 H'-f= Volume of gas as measured in cubic centimetres=V'= 839.6 11.833 845.8 3.865 626.8 0.563 1 + t 0.003G7 (from table) = 1.0725. Hence from the first mefisurement we have — V = 11.822 829.6 1.0725 From second measurement — y .3.865 760 845.8 = 12.030. 1.0725 From third measurement — 0.562 760 = 4.010. 626.8 1.0725 760 = 0.432. Thus the total volume of gases obtained as measured at 0° 0. and 760 m. m. was 12.030 cubic centimetres ; of carbonic acid gas was 12.030 _ 4.010 = 8.02 c. c. ; of oxygen 4.010 — 0.432 = 3.578 c. c, and of nitrogen 0.432 c. c. As the volume of blood emploj'ed was 20.266 cubic centime- tres, we have the following final result : — In 100 volumes of blood — Carbonic acid gas 39.585 volumes 8.020 Oxygen Nitrogen Total 17.652 2.138 59.375 0.20266 3.578 "0'20l66 0.432 "0T20266 _ 12.030 "0.20266 vols ■) vols. vols. vols. BY DR. BURDON-SANDERSON. 215 In the pi-eceding example such vtiriatious of temperature and barometric pressure as ma_v occur daring the analj^sis are disregarded. The readings are taken immediately after the absorption of the carbonic acid gas ; as the time occupied in the aaalj'sis up to this point is very short, the error arising from the variations in question is inconsiderable. As regards the absorption of oxygen, the error might be of more conse- quence, were it not that tlie residue of nitrogen is so small. As it is, it can be easily shown that it would require a differ- ence of pressure amounting to three millimetres, and a dif- ference of a degree of temperature, to make an error of one- hundredth of a percentage in the result as regards nitrogen or oxygen. Witliin these limits, therefore, the errors arising from this source may be regarded as trivial. Although determinations of oxygen made by absorption witli hydrate of potash and pyrogallic acid are' not entirely free from objection on the score of accuracy, the results ob- tained by the method above described are quite accurate enough for most of the purposes of physiological research, for the small errors are practically inappreciable, as compared with the varia- tions in the proportion of oxj^gen contained in tlie blood to be analyzed, produced by what might be regarded as very trifling diflerenees in tlie mode of collecting it. If it is desired to have recourse to explosion with hydrogen, the best methods for the purpose are those of Dr. W. Russell, and of Prankland, and Ward. The following short description of the latter will be readily understood from what has preceded. The apparatus (Fig. 201) consists of two parts, corresponding to the labora- tory-tube and measuring-tube of the instrument previously de- scribed. The measuring-tube communicates, as in that instru- ment, with a second tube (the one most to the right in the figure) containing a column of mercury, by the height of which the pressure to which the gas to be measured is subjected, can be estimated, The chief difference is that, whereas in the for- mer more simple instrument the pressure-tube is open at tlie top, so that if air is contained in the measuring-tube, and the stopcock by which it communicates with the laboratory-tube is closed, the difference between the heiglits of the two columns indicates the difference between the tension of the gas in the measuring-tube and that of the atmosphere; in the instrument now before us tlie tube is closed, and constitutes a barometer, so that the difference expresses the actual tension of the gas in inches of mercury. In the horizontal channel, by which the measuring-tube and barometer communicate at the bottom, is a three-way stopcock (not shown in tlie figure), by which they may be brought into communication cither with a vertical escape-tube, the end of which dips into a receptacle containing mercury several feet below, or with a tube open at the top (the 216 THE BLOOD. middle and longest in the flgiire), called the filling-tube. In this way the gas can be expanded or compressed at the will of the operator, and consequently can (in most analyses) be readily brought to the same volume after each successive ope- ration. The convenience of this is very great, for obviously the tensions of difierent quantities of gas when expanded to the same volume are proportional to the volumes they would assume if they were all under the same pressure, so that the original volume of gas to be analyzed being known, the rela- tion between that volume and tlie volume of the other quanti- ties to be measured can be readily calculated, the several vol- umes being proportional to the corresponding readings of the barometer. The original volume of gas to be analyzed is mea- sured as before described, with this difference, that the absolute pressure to which it is exposed is known without reference to the barometric pressure outside at the time. The explosion is effected in the eudiometer, into the upper end of which two platinum wires are fixed for the purpose ; the arrangement of these wires is the same as in Bunsen's eudiometer. As to the mode of preparing and introducing pure hydrogen, and of ex- ploding tlie mixture, the reader will find sufficient information in Roscoe's translation of Bunsen's Gasometry. 32. Bernard's Method of Determining the Propor- tion of Oxygen combined -with the Coloring Matter of the Blood by Displacement -with Carbonic Oxide. — As was before stated, the property whicli carbonic oxide pos- sesses of displacing the oxj'geu combined with the coloring matter of the blood, has been used by Bernard, as a substitute for the vacuum, for the determination of the quantity of free and combined oxj'gen contained in the blood. Bernard's method consists in agitating the blood to be analyzed in a tube half filled with carbonic oxide. The carbonic oxide to be used must be perfectly pure. Tiie tubulated retort into which the oxalic and sulphuric acid are introduced must be cleared of atmospheric air, by passing a stream of carbonic acid through it, before heat is applied. The gas is best collected in flasks, over water containing potash in solution. Two I'c- sults are produced. In the first place, the oxygen of the he- moglobin is replaced by carbonic oxide; and, secondly, the atmosphere of carbonic oxide acts on the blood as if it were a vacuum, the displaced oxygen and other gases passing ont into it until equilibrium is established. Inasmuch as tlie pro- portion in which oxygen is absorbed is very small, as com- pared with the quantity held in combination by haemoglobin, nearly the whole is discharged, so that if the proportion of that gas contained in the gaseous mixture which fills the place originally occui)ied by tlie carbonic oxide be detei-mined, it is found to fall very little short of the proportion obtained from BY DR. BURDON-S ANDERSON. 217 the same blood by exhaustion. The remainder of tlie mixture contains, in addition to the excess of carbonic oxide, nitrogen and carbonic acid gas, derived from tlie blood, but the propor- tions of these gases discharged are very variable. As regards oxygen, the method has yielded, in the hands of Bernard, re- sults of the greatest value. It has the immense advantage that it can be carried out without a mercurial pump, and for pathological purposes is sufinciently accurate. CHAPTER XVI. THE CIRCULATION OF THE BLOOD. In commencing the stud3r of the circulation of the blood, it is desirable to direct our attention first to that part of tlie circulatory apparatus in which the phenomenon presents itself in its simplest form. In systematic physiological treatises the heart is usually described first; but for our present purpose, considering that the heart is an organ of verj^ complicated structure, that it is constantly influenced by ever-varying conditions of the vessels on the one hand, and of tlie nervous centres on the other, it is much better to begin with the arterial sj'stem. Part I. — The Arteries. At the commencement of the period of relaxation of the heart — i. e., of the jieriod which intervenes between one con- traction and its successor — the progressive movement of the lilood in the aorta all but ceases. At that moment, and during the remainder of the time which precedes the bursting open of the aortic valve, the pressure exercised by the wall of the vessel on its contents is the only cause of the continuance of the blood-stream. During each ventricular systole the aortic pressure is reinforced by the motion communicated to the blood by the contracting ventricle. Consequently, if, for the sake of facilitating our understanding of the matter, we assume the heart to be .a mere pump, acting regularlj-, and discharging at each stroke an invariable quantitj' of liquid, we have the force by which the circulation is carried on at any moment expressed by the tension of the arteries, and varying with that tension; or if, on the other hand, we assume the tension of the arterial system to remain constant, then the quantity of work done varies with the mean velocity of the 218 CIRCULATION OF THE BLOOD. stream at tlie commencement of the aorta — in other words, with the quantity of blood delivered by the heart per minute. The work done by the heart in maintaining the circulation, manifests itself in the aorta in two modes, those of pressure and progressive motion of the blood. These two phenomena are not, however, collateral results, i. e., they do not stand in the same relation to the agent which produces them. The former is rather the efficient cause of the latter; for so long as the arterial pressure continues, i. e., so long as the pressure in tlie aorta is greater than that in the vense cava, progressive movement also continues. As soon as equilibrium is estab- lished, circulation stops. Systemic death consists in decline of aortic pressure. This decline may occur rapidly, as in syncope; but usually, even in deaths by violence, it is very gradual. In deaths from disease it may last for days, weeks, or even months. Section I.— Aktebial Pressure. 33. The arterial pressure, althougli in the mean remarkably constant, almost as constant as the temperature of the body, is subject to recurring variations— ):. e., alternate augmenta- tions and diminutions, which are of tliree orders. Of tiiese, the first is dependent on the rhythmical injection of blood into the arteries by the contraction of the heart ; the second, on the influence which the respiratory movements, or rather the alter- nate acts of breathing, exercise on the circulation; the third, on augmentations or diminutions of what is called the tonus oi the arteries, by virtue of which they are constantlj' undergoing cl)anges of diameter, consequent on varying conditions of the nervous system. In the measurement of the arterial pressure we have, there- fore, two distinct problems. The first is the determination of the mean or average pressure, which, as I have said before, is almost as constant as the temperature in the same animal so long as it remains in a natural state ; the second is the investi'- gatiou of the variations due to the heart's action, to respira- tion, or to arterial contractility', respectively. For the determination of the mean arterial pressure, and of those variations which belong to the second and third class, preference is to be given to the ordinary mercurial manometer, one branch of which is connected witli the artery to be investi- gated, while the other is open. This instrument, as so applied, constitutes what Poiseuille designated by the term hasmadyna- mometer. It was employed in this simple form until Ludwig, in 1848, by his invention of the kymograph, laid the foundation of the more exact methods of investigating blood-pressure which are now in use. Just as the first "method of Poiseuille originated in the ruder experiments of our countryman Hales, BY DR. BURDON-S ANDERSON. 219 SO the notion of the kymograph is said to have been suggested by a contrivance of Watt's for registering the pressure of the steam-engine. The principle of the kymograph consists in causing a pen, fixed horizontally at the upper end of a vertical rod, tiie lower end of which rests by a floating piston on the surface of the mercurial column in the distal open limb of the manometer, to write the up and down movements of the column on a surface of paper progressing horizontally at a uniform rate by clock- work. Since the time that Ludwig first employed it, the con- trivance has developed into a method now commonly known as the graphic method. Description of the Kymograph and Accessory Ap- paratus now used in the Laboratory of University College.' — 1. The arterial canula is a T-shaped tube of glass, of the size and form shown in fig. 193, c. B3' its stem it is con- nected with the manometer; one branch is drawn out and bevelled, the other is of the same size as the stem, and when in use is fitted with a short bit of caoutchouc tubing, guarded by a steel clip. The cannlated end is made as follows : The tube which it is intended to use for the purpose is first softened in the flame of the gas blow-pipe, and drawn out gently at the softened part. It is then allowed to cool, and again heated in a pointed flame at X, and drawn out so as to make it assume the form 193, b. It is then scratched with a sharp three-cornered file opposite x, and sundered by drawing the one end of the tube from the other in the direction of its axis. The last step in the process consists in filing off the cut end in the direction of the dotted line, and smoothing the edges by touching them with the border of an ordinarj' gas flame. A tube of this kind can be inserted with great ease into an artery of considerably less diameter than itself. Canulae of glass are always to be pre- ferred to those of silver, not merelj- on the ground of facility of introduction, but because a glass surface is much less apt than one of metal to determine coagulation of the blood wiiich comes into contact with it. 2. The stem of the arterial canula communicates with the proximal arm of the manometer (see fig. 202) by a tube (c), of which the part next tlie canula only is of India-rubber. The rest is of lead; the purpose of the arrangement being to avoid a certain modification of efiect due to the yielding of the wall of the tube, which becomes appreciable if the whole connector is elastic. ' This instrument was made for me by Mr. Hawksley, of Blenheim Street, and has advantages over any other form with which I am acquainted. 220 CIRCULATION OF THE BLOOD. 3. The proximal arm of the manometer communicates at its end, by means of along flexible tube (b) guarded by a clip, with a " pressure bottle" coutainiug solution of bicarbonate of soda . A horizontal arm, which springs from it near the top, is con- tinuous with the lead tube already mentioned. 4. The manometer is fixed to the edge of the small mahogany table on whicli the recording apparatus stands by means of a brass clamp, which admits of its being raised or lowered at will. The floating piston and rod (a) are made of black vul- canite. The piston is in the form of an inverted cup, which embraces the convex surface of the mercurial column. The rod is quadrangular, and works in a guide, fixed at a height of six inches above tlie upper end of the tube, b}^ which it is kept vertical. The writer, a fine sable miniature pencil, is supported on the rod bj' a horizontal arm of thin wire, one-third of an inch in length. One end of the wire is coiled round the rod, the other round the stem of the pencil. From the guide just men- tioned springs a horizontal arm, from which a silk plummet-line is allowed to fall in such a wa.y tliat it rests against the hori- zontal part of the wire. By this means the point of tlie writer is kept in constant contact witli the paper, without exercising too much pressure. 6. The recording apparatus consists of a single cylinder, wliich revolves at a constant rate of one revolution per minute. The clock-work by wliich it is moved is constructed by Mr. Hawksley on the model of the so-called "Foucault's Regula- tor." To the right of the cylinder, as seen in the drawing, is shown a large brass bobbin, of the same width as the cylinder, on which a riband of paper is tightly rolled by machinery, of sufficient length to serve for many hundred observations. From the bobbin the paper riband is drawn off' by the cylinder as it revolves, against the surface of which it is accurately applied, furnished with ivory friction wheels. 34. Rules and Precautions to be observed in mak- ing a Kymographic Observation. — Before commencing, it is necessary to see that the manometer is in proper order. The mercury in the distal column must be clean and dry, and the writing pencil moist and free from the remains of the ink. To insure this, it should always be steeped in water after each observation. To dry mercury, tlie best Swedish filtering paper is used. It is cleaned by straining it through calico, or still better through chamois leather. If the latter is used, it must be strained under a considerable pressure. The system of tubes communicating with the proximal Timb of the manometer must now be filled with solution of bicarbonate of soda. To accomplish this, the arterial tube is first closed by a clip, and the solution introduced with the aid of a pipette into the open BY DR. BURDON-SANDERSON. 221 end of the proximal limb. Some of the solution is then allowed to flow from the bottle hy the long communicating tube (b) so as to fill it completely, after which its end is brought into communication witli the manometer. If any air bubbles are introduced, they are readily got rid of through the artery tube. According to the height to whicli the pres's- ure bottle is raised above the level of the manometer, the mercurial column in the distal limb rises above that in the proximal. It must be adjusted so that the difference between the two is a little less than the probable arterial pressure of the animal to be used. This having been accomplished, and the communication between the manometer and the j^ressure bottle closed, all is ready. The only arteries which are used for observations of arterial pressure are the carotid and the crural. On the whole, the latter is preferable ; for the carotid cannot be exposed without some risk of disturbing the vagus nerve. In the rabbit, the carotid is prepared as follows : The animal having been secured on Czermak's 7-abbit-board, and the fur clipped, the skin is pinched up between the finger and thumb on either side of the upper end of the trachea, so as to form a horizontal fold, which an assistant divides vertically. As soon as any slight bleeding has ceased, the wound is dabbed with a sponge moistened with saline solution, and the fascia, which stretches from the edge of the sterno-mastoid to the middle line, is seized with blimt forceps and opened with knife or scissors. The opening having been enlarged with the aid of a second pair of blunt forceps, the sterno-mastoid is slightly drawn aside, so as to bring the arterj', with its three accompanying nerves, the vagus, the depressor, and the sympathetic, "into view. The sheath having been opened, the artery is raised on a blunt hook, and easily cleared from its attachments to a distance of three-quarters of an incli in either direction. The distal end of the prepared part is tied, and the proximal end closed b^' a clip. A splinter of wood, or a bit of card of similar shape, is slipped under the artery close to the ligature, and a second ligature looped round it. Finally a V-shaped snip is made in its wall with scissors which cut well at the point; the canula is inserted, and the ligature tightened round the constriction. The whole operation ought to be accom- plished in three minutes ; it is desirable to have an assistant. The instruments requirecl are indicated by the italics. {See fig. 203.) They must be placed in readiness on the table of the kymograph. Czermak's rabbit supporter is shown in fig. 204. It consists of a strong wooden board, about 8 inches ■wide and 30 inches long. At one end it is strengthened with an iron plate, into which a strong vertical stem is screwed. This stem bears a sliding block of brass, in which an iron rod 222 CIRCULATION OF THE BLOOD. also slides horizontally. Near its base it is bent twice at right angles, so that the upper part on -which the block slides is not in tlie same line with the lower part. Consequently the rod, while still remaining horizontal, can be moved in four different ways. It can be shortened or lengthened, heightened or lowered, rotated round its own axis, rotated round the axis of the stem, or moved from side to side witliout change of direction. It ends in a kind of forceps the blades of which, when kept closed by the adjusting screw, seize upon the head of a cat or rabbit in such a manner as to hold it firmlj' without inflicting the slightest injurjr. The neck of the animal rests on a cylindrical cushion, covered with water-proof cloth, and the rest of the bodj' on a mattress of similar material. Along the edges of the board there are convenient attachments for the extremities. The preparation of the crural artery is even more simple than that of the carotid. The skin having been divided in a line leading from the middle of Poupart's ligament towards the inner side of the knee by first pinching up a fold of skin as above directed, the pulsation of .the artery is felt by the finger in the hollow between the adductor muscles and those which cover tiie femur. The sheath of the vessels having been exposed from Poupart's ligament downwards, the vein and crural nerve are seen, the artery lying behind and to the outer side of the former. On drawing the vein inwards it is easily got at, and must lie prepared from the origin ot the arle7-ia profunda close to Pou- part's ligament, nearly to the point at which it enters the ad- ductor ; first giving off the arleria saphena, which accompanies the saphenous nerve and veins. Tlie lower of the two circum- flex arteries which are given off within a short distance from the profunda must be tied doubly and divided between the liga- tures, as it is desirable to place the clip as high as possible. In the dog or cat, the operation is equally simple, but requires more time on account of the greater abundance of fat in these animals. The canula having been inserted, the next step is to bring the artery into communication with the manometer. The clip on the artery remaining closed, that on the stem of the canula is opened for a couple of seconds. At once the soda solution fills the canula and passes out bj^ its open branch. In doing this, great care must be taken not to allow the solution to flow into the wound. Air bubbles, if they exist, are got rid of by passing a thin rod of whalebone into the canula, which must then be closed bj' means of the terminal clip. All being now ready, the stem of the canula is finally opened, and the clip re- moved from the arter^r. The mercurial column at once begins to oscillate ; but no record should be taken until a minute or two have elapsed, for it often happens that a small quantity of BY DR. BURDON-SANDERSON. 223 soda solution enters the artery and produces a sliglit and transi- tory disturbance of tlie circulation. If, indeed, the previously existing pressure in the artery tube is somewhat less than that of the artery, no such effect occurs; but inasmuch as we have no means of knowing the arterial pressure of any particular animal beforehand, it is usually unavoidable. A kymographic observation may last a few minutes or several hours, according to the question to be investigated. In the latter case, tracings are taken at intervals. Two persons are ' required, one of whom performs the experiment, while the other undertakes the charge of the writing apparatus, and notes on the paper-roll, with a soft pencil, tlie events as tiiey occur and the times of beginning eacli tracing. In tiiis way the roll stands in the place of a protocol, and is less liable to errors of time and order than any other kind of record. 35. Measurement of absolute Arterial Pressure at any given moment during the period of observation, —lor this purpose it is necessary to draw tlie abscissa of the pressure curve, i. e., the horizontal line which the writer would have drawn had the arterial pressure been equal to that of the atmosphere. Tliis is accom|)lislied immediately after the ter- mination of the experiment, by closing the stem of the canula and then removing it from the artery, and immersing it in a capsule containing soda solution, standing at a level equal to that of the_ artery. The clip having been opened, the clock- work is set in motion for a moment, and a horizontal line draAvu which coincides with the abscissa required. In this line the paper is then pierced with a pointed instrument in such a way as to perforate the several layers of paper at the same level. By removing the roll from the cylinder and connecting the holes, a horizontal straight line is obtained which runs from end to end of the record. By drawing an ordinate from any point in the tracing to this line, measuring its length in milli- metres and doubling the result, the absolute arterial pressure at the corresponding moment is obtained in millimetres of mercuiy. The mean arterial pressu?-e is obtained by drawino- ordi- nates at regular intervals and measuring the' length of each. The mean of the lengths corresponding to the period investi- gated, multiplied by two, is the mean pressure required. [I never use paper divided into squares— in other words, with the ordinates ready measured— finding by experience that they do not tend to accuracy. Moreover, such paper is expensive, and thereby furnishes an inducement for an undesirEible economy m its use.] In all normal kymographic records it is seen that the arterial expansions due to the contractions of the left ven- tricle are indicated by oscillations which differ very materially in form, and that these differences are dependent on their fre- 224 CIRCULATION OF THE BLOOD. qnency. (See Fig. 206.) When extremely frequent, they are mere iiudulations'; but when the intervals are longer, they ex- hil)it forms which, as we shall afterwards see, have a definite relation to the changes of tension which actually occur in the arteries during each cardiac period. It is farther seen that there are larger waves which correspond, not to the beats of the heart, but to the respiration— the valley and ascending limb of each of these greater undulations corresponding to inspira- tion, the summit and descending limb to expiration and to the pause. These and other details will be referred to in future' sections. Section II. — Observation op the successive Changes of Artb- niAL Tension which occub dueino each Cardiac Period. In studying tracings obtained by the mercurial kymograph, it is to be borne in' mind that what is inscribed on the cylinder is not the record of the actual movement of the arterj', but of the oscillations of the mercurial column. It is true that the latter are the immediate results of the former, and that the elevation of the distal column produced by each arterial ex- pansion has some relation to the increase of lateral pressure, of which the expansion is the expression ; but the curve drawn is not that of the artery, but of the manometer. The artery expands suddenlj^, the mercury rises comparatively slowly, so that at tlie moment it attains its acme the artery has already collapsed. Consequently, if tlie interval between each pulsa- tion and its successor is very short, the extent of oscillation (or, as it is usualljr called, the excursion) of the manometer is relatively too small ; and conversely', if the interval is much prolonged, the excursion is relatively too great. The descent of the column is almost entirely independent of the collapse of the artery. It falls back to equilibrium, and describes a curve, which (as ma3' be learnt b}- comparison) has the same characters as that made bj' the lever in returning to its origi- nal position, by whatever way — as, e. g., hy squeezing the con- necting-tube — the equilibrium of the manometer may have been momentarily disturbed. This being the case, it is easy to understand tliat no conclu- sion can be derived from observations with the mercurial mano- meter, either as to the duration of the effect produced by each contraction of the heart, or as to the relative duration of the periods of expansion and collapse. The use of the instru- ment is limited to the investigation of the mean pressure, and of those varieties of pressure of which the periods of recur- rence are long enough to prevent their being interfered with by the proper oscillations of tlie instrument. BY DR. BURDON-S ANDERSON. 225 36. The Spring Kymdgraph.— If we desire to obtain a record of tlie complicated succession of variations of arterial pressure which constitute an act of pulsation, precisely as they occur as regards order, duration, ami degree, or of the exact interval of time between the close of one arterial expan- sion and the commencement of the next, tlie instrument with which we write must be of such a nature that it shall transmit the movements communicated to it without mixing with them any movements of its own. The most perfect of snch instru- ments is the so-called Federkymographion of Professor Fick. The construction of the instrument will be readily understood with the aid of Fig. 205. It consists essentially of a C-shaped hollow spring of thin metal. The cavity of the spring is filled witli spirits of wine, and communicates with the artery by means of a connecting-tube containing bicarbonate of soda. "As the pressure increases, the crescentio spring tends to straigliten, and vice versa. Hence, if the proximal end is fixed, the^distal end performs movements which follow exactly the variations of arterial tension. These movements are of very small ex- tent, but they are so exact that the slightest and most transi- tory variations are expressed by them. Before they are writ- ten on the cylinder they must be enlarged by a lever. It is not necessary to make any remarks as to the mode of connecting the spring kymograph with an artery, tlie modus operandi being the same as that described in § 34. It is, how- ever, to be noted, that if it is intended to use the tracing ob- tained by it for the purpose of determining the absolute "arte- rial pressure, the instrument must be first graduated by com- parison with a mercurial manometer. Tiiis is effected as follows : The kymograph being placed so as to write on the recording cylinder, its artery tube, which communicates by a side opening with a pressure bottle, is united with tlie proxi- mal arm of the manometer. The pressure bottle is first lowered until the liquid it contains stands at the same level as the mercury in the proximal arm. A tracing is made on the cylinder, which is the abscissa. The bottle is then raised till the distal mercurial column is ten millimetres higher than the proximal, and a second tracing taken, and so on at suc- cessive increments of 10 mill, pressure, up to 150 mill, or more. By measuring vertically the distances in millimetres between the horizontal lines so traced and the abscissa, a series of results are obtained which express the values of the ordinates of the tracing in millimetres of mercurial pressure. In tracings obtained by the spring kymograph it is seen that the ascent of the lever, which corresponds to the period during which the artery is acted on by the contracting ven- tricle, is abrupt — indeed, nearly vertical ; that towards the vertex the tracing changes direction, gradually approaohinc 15 J II ^ 22'5 CIRCULATION OF THE BLOOD. a horizontal line touching it at the highest point; that the line of descent — much more oblique than that of ascent — ter- minates in the same vi&y hy gradually approaching a horizon- tal line touching the curve at its loioest point, (^ee fig. 207.) 37. Observation of the Expansive Movements ■virhioh accompany the successive Changes of Arte- rial Pressure above described.— When an artery is ex- posed in a living animal, as, e. (/., wlien it is prepared in the manner described in § 34, two kinds of motion are seen. The bit of artery which is separated from the surrounding parts lengthens, and its diameter visibly increases eacli time it is acted on i)y the contracting heart. Of these two phenomena, the first is commonly called locomotion, because in certain superficial arteries of the human body (especially wlien they are enlarged in advanced life), the artery, as it lengthens, is compelled to bend to one side or the other, and thereby visibly clianges its place each time that it is distended. The other, viz., the expansive movement, is called pulsation, and is practically of great importance, seeing that it is the only phenomenon of the arterial circulation "which admits of being investigated without exposing the artery, and consequently affords the only direct means by wliich we can judge of its ever-varying conditions in man. Arteries being elastic, their changes of diameter express all changes of the pressure exercised hj their liquid inelastic con- tents on their internal surfaces. If, therefore, the expansive movements of an exposed artery wei-e to be measured and re- corded graphically, the record would correspond closely with that of the pressure obtained bj^ Tick's kymograph. For just as in that instrument tlie variations of pressure are converted by the C-shaped spring into nearlj' rectilinear movements, the artery expands with every increase of pressure on its internal surface, and contracts with every diminution of it, so that any point taken on its surface is constantl}' performing, in relation to its axis, orderly successions of rectilinear movements in opposite directions. In both cases — that of the spring and that of the artery — the expansion, and the pressure which produces it, vary in the same directions during the same times, but not in the same degree. As regards the spring, we can readily determine the relation of expansion to pressure by the method of graduation described in the preceding paragraph, and so use the former as an expression for the latter. In the case of the arterj', no such empirical graduation is possible. The expansion of an artery, or any other elastic tube, due to any given increase of pressure against its internal surface, depends upon the degree in which the tube is alreadjr distended at the commencement of the act of expansion. The greater the original distension, BY DR. BURDON-SANDERSON. 227 the less will be the effect ; so that the condition of an artery in which the expansive movement is reLitivel3- greatest, is that in which its walls, when the expanding agency is suspended, are in the state of elastic equilibrium, *. e.,"when tlie minimum pressure is least. A moment's consideration teaches us that there are two circumstances which must diminish the minimum pressure in the arteries, viz., diminution of the mean arterial pressure, and prolongation of the period which intervenes be- tween one expansive act and its successor. In other words, the less frequent the contractions of the heart and the lower the arterial pressure, the greater the expansion in pjroportion to the expanding force lohich produces it. 38. The Sphygmograph. — In man, no artery can be di- rectly measured either as regards pressure or expansion. In feeling the pulse, we attempt to measure both by the sense of touch, and obtain results, which, although incapable of nu- merical expression, are sufHciently exact to be of great value. In the sphygmograph, an attempt has been made to obtain tlie same kind of information by a mechanical contrivance, whicli the physician obtains by the tactiis eruditus ; the supposed advantage of the instrumental results over the others being, that they can be estimated by measurement and weighing, md that tliey are unaffected by variation in the skill and tactile sensibility of the observer. The purpose of the sphygmograph is to measure the com- plicated succession of alternate enlargements and diminutions which an artery undergoes whenever blood is forced into it by the contracting heart, to magnify those movements, and to write them on a surface, progressing at a uniform rate by watch-work. The construction of the instrument is so well known, that it is scarcely necessary to give a detailed description of it. It consists essentially of th)-ee parts : a frame of brass which is applied along the outer edge of the volar aspect of the fore- arm, in such a way that it is maintained in a fixed position with reference to the bones of the wrist and radius— a steel spring which, when the instrument is in use, presses upon the radial artery and receives its movements — and lastly, mechani- cal arrangements for magnifying these movements and record- ing them. Both of these ends are accomplished by means of a light wooden lever (a a', fig. 208) of the third order, which is supported by steel points (c). There is a second lever of the same order (b e) which has its centre of movement near the attachment of the spring (at e). It terminates in a vertical knife-edge (d), and is traversed by a vertical screw (t). When the extremity of the screw (n) rests upon the spring above the ivory plate, every movement of the plate is transmitted to this lever (b e), and, by means of the knife edge, to the wooden 228 CIRCULATION OF THE BLOOD. lever (a a'). The purpose of the screw (t) is to var}' at will the distance between the wooden lever and tlie upper surface of the spring, without interfering with the meclianism by which the movement is transmitted. As the distance between tlic steel points (o) and the knife-edge (d) is much less than tlie length of the lever, the oscillations of the extremity of the lever (a') are much more extensive than the vertical move- ments of the spring. The lever ends in a metal point, which writes on a glass plate blackened by passing it rapidly back- ward and forward through the flame of a spirit-lamp trimmed with paraffin. When this instrument is applied in the proper manner to the wrist, the radial artery is compressed between the sui'face of the radius and a spring, the bearing of which is in a fixed position in relation to that surface. This being the case, the spring performs movements which are more or less conform- able with the variations of the diameter of the artery. These movements are transferred in a magnified, but otherwise little altered, form to the lever. As regards the relative and actual duration of the movements, the correspondence is exact; but as regards their extent, this is true only in so far as the lever follows the movements of the spring with precision,' and as the strength of the spring, i. e., the pressure exercised b3' it on the arter_y, is adapted to the antagonistic pressure exerted by the blood stream on the internal surface, and to the extent of the movements it is intended to measure. The relation between the pressure of the spring and its effect on the artery is a complex one, and need onlj' be considered here in so far as is necessary for the interpretation of sphyg- mographic results. To facilitate our understanding of it, let us call the position which the spring takes when left to itself its equilibrium position ; and as regards the arter3', let us de- signate a plane parallel to the surface of the skin, and touch- ing the surface of the artery, when most dilated, the plane of expansion ; and a plane in similar relation to it, when least expanded, the plane of collapse ; and to simplify the problem, let us suppose that the artery is not covered by skin. It is evident that, if the sphygmograph accomplished its professed end completely, the under surface of its spring would coincide with one of these planes at the moment of the pulse, and with the other during the interval. The question is. How ought the spring to be set, in order to obtain a movement which shall approach this standard of perfection as nearly as possible ? We may proceed one step towards answering this question without difficulty. It should be set so that if the spring were in the equilihrium position its under surface would lie within ' See note on p. 235. BY DR. BURDON-SANDERSON. 229 the plane of collapse — i.e., nearer the axis of the artery. For if it were further from the arter_y it would be affected by the arterial movement only during its period of expansion, remain- ing the rest of the time motionless. If, on the otlier hand, it were ranch nearer, tlie vessel would be flattened against the bone during the period of collapse, so that in tins case, as in the other, there would be no motion (of the spring) during diastole. Hence it is easy to understand how it happens that the tracings obtained with excessive and defective pressure are very similar to cash other in tlieir general characters. Stating the same tiling in other words, we arrive at the general rule that the spring must be so set that the ivory plate on its under surface is at such a distance from the opposed surface of bone that the artery is i)ressed upon at all degrees of expansion, yet not so strongly pressed upon as to bring its walls into contact even when it is relaxed. Witliin these limits, the variations of form of the tracing — in other words, its departure from truth — are very inconsiderable; so that observations made on the same individual at dilTerent times yield closely correspond- ing forms. As, however, the results obtained b}' strong [jress- ure are less subject to accidental error than those obtained witli weaker ones, it is better always to begin with a pressure sufficient to flatten the artery, and then to weaken the spring until tlie effects of over-compression disappear — ;. e., until it is found that the lever continues to descend until the very end of diastole. 39. Use of the Sphygmograph as a Means of Appre- ciating those Changes of Mean Arterial Pressure ■which occur in Disease. — We have alreadj' seen tliat the spli^-gmograph is of no use as a gauge of arterial pressure. It is possible, however, by the comparison of observations made at successive periods on tlie same individual, to determine whether the arterial tension has clianged, and in what direc- tion the change has taken place. We have seen that if the spring is so strong tliat the artery is either partially or en- tirely flattened against the radius, the fact is indicated by tlie cessation of the motion of the lever. Tlie strength of spring which is required to bring about this result varies with the pressure by which the artery is distended ; so that if in any in- dividual the arterial pressure is increased, a greater tension of the spring is required to compress it than was required before. With Marey's spbygmograph, as imported, it is not possible for the observer to avail himself of this principle, because the instrument is not graduated — i.e., there is no means l)y which the pressure exerted by the spring at any moment can be ascer- tained. I have therefore modified that instrument as follows (t'fle Fig. 209, a) : The brass frame, instead of being bound on to the arm by bandages, rests firmly on the bones of the wrist 230 CIRCULATION OF THE BLOOD. (particularly tlie scaphoid) bj- a plate of brass, the under sur- face of which is covered VTitii ebonite. In the middle of the upper surface of this plate is a socket for the reception of the point of a finely-cut screw, which revolves in it freely. Above, the screw ends in a milled head (y), between which and its point it passes, first loosely through a guide, wdiich is of the same piece with tlie brass plate ; and, secondly, through a hole in the end of the brass frame of the sph3'gmograph (f), in winch it fits closely. This being the construction, it is scarcely necessary to explain that, by turning the milled head, the dis- tance between the ebonite surface and the frame is varied according to tlie direction of revolution, and that in this way the pressure on the artery may be readily modified when the instrument is in use. The extent of tlie modifications thus produced, however, still remains undetermined, for they vary according to the form of the limb and the relative position of the arm and forearm at the time of observation. To measure them, we must have recourse to another method which is at once simple and accurate. It is obvious that, provided that the spring is firmly and immovably fixed in its place, the press- ure which it makes against any object pushed against it from below is determinable hj the force which is exerted in pushing it. If, for example, I turn the instrument upside down, and place a weight of 200 grammes on what was before the under surface, now the upper surface, of the spring, I push it back some fraction of an inch from its position of equilibrium ; I learn that, whenever it is pushed back to this extent, the press- ure it exerts on the surface opposed to it is that of 200 grammes' weight. Repeating the experiment with a series of other weights, I can in a similar wa}- obtain other measure- ments of distance corresponding to them, and thus, by com- bining the results, accomplish the graduation of the spring in such a way that the pressure made b}' it can be alwaj^s known ■from the extent of its deflexion. The most convenient wa}' of determining this deflexion is either to measure the distance between the head of the steel screw, the point of which rests on the upper surface of the spring, and the surface of the brass lever, with a scale (as shown in Fig. 210); or, better still, to have the screw itself graduated. In either case, care must be taken to fix the writing lever in the proper position — i. e., in a direction which coincides with the direction of movement of the writing surface — -before making the measurements. 40. The Artificial Artery or Arterial Schema. — The phenomena of arterial pulsation cq,n be best studied in a well- constructed schema or artificial artery, consisting iu an elastic tube through which water is propelled by an artificial heart, i. e., bj' a pump of such construction that it discharges its contents into the tube in a manner which mechanically BY DR. BURDON-SANDERSON. 231 resembles that in which tlie heart discharges its blood into the arteries. Several instruments of this kind have been con- trived, from the simple schema of B. II. Weber, to the com- plicated "artificial heart" of Marey. It may be stated generally that those forms of schema are most instructive which are of the simplest construction; and inasmuch as the object in view is not to illustrate but to explain, it is of no importance whatever that tlie schema should have any outward rese\nlilance to the organs of circu- lation for which it stands. What is essential in a schema is, that as regards the quantity of liquid discharged at each stroke of the pump, the period occupied in the discharge, the distribution in time of the pressure exorcised on the mass of liquid expelled, and the resistance opposed to the terminal outflow of liquid from the elastic tube, the representation should resemble, as closely as possible, the thing represented. To the student, it is far from an advantage that the resem- blance should extend be3-ond this to tlie details of external form and arrangement ; for his attention is thereby apt to be drawn off from the essential conditions of the act, to the accessory peculiarities of the niacliine which produces it. Two kinds of schema may be usefully emploj-ed for the study of the phenomena of the pulse, which differ from each other in the construction of the pump which does the work of the heart. The first is represented in fig. 211. Here the pump consists of a glass tube (a), closed at the upper end, and connected below by two branches — on one side with a cistern, at a level of some eight or ten feet above the table ; on the other, with the experimental tube which represents tlie artery. These communications are controlled by valves, placed at the opposite ends of a horizontal lever (e, d) of such construction that the same act which closes the one must necessarily open the other ; so that, as regards their actions, one represents the semilunar, the other the auriculo-ventricular valves of the heart. By means of a spring (shown in the figure to the right of d), when the apparatus is not working, i. e., during the period corresponding to diastole, the former is kept closed, the latter open. Under these circumstances, the water rises in the tube, compressing the column of air which it contains in a proportion which is determined by Marriotte's law. If, as in the present instance, the pressure is about one-third of an atmosphere, tlie volume of the inclosed air is diminished in the proportion of 2 ; 3, and so on. When, by depressing the opposite end of the lever, the aortic valve is opened, and the mitral closed, the compressed air suddenl}' expands, and forces the water which the tube contains into the aorta. We shall see, when we come to consider the modes of contraction of the heart, that the above is as close an imitation as could be ■ 232 CIRCULATION OF THE BLOOD. made by any artificial means. Just as, wlien the heart con- tracts, it compresses its contents most energetically at the outset, while its force rapidly diminishes towards the end of the systole, so here the most rapid movement of the column is at the first moment after the depression of the lever. The arterial tube where it passes under the valve d is about four lines in thickness. Soon it divides into two branches of smaller diameter, each of which is several yards long. One of these tubes passes under the spring of the sphj'gmograph, which is fixed at h in such a manner that tracings may be conveniently taken. Both open finally into a waste basin ; but each is provided with screw clamps, by which it can be compressed or constricted at any desired distance from the pump. The purpose of the bifurcation is, that the observer may be enabled, without interfering in any way with the con- dition of the tube, of which the expansive movements are re- corded sphygmographically, to vary the quantity of liquid which is discharged through it per minute. To experiment with the schema satisfactorily, it is desirable to leave the working of the lever to an assistant, or, still better, to arrange the apparatus so that the work can be done by an electro- magnet. The observer is then at liberty to watch the eflfect of modifications of resistance, etc., on the form of the tracings while they are in progress. The most important facts to be demonstrated with the aid of the schema, as above described, are the following: — 1. It is shown that the artificial and the natural pulse resemble each other closely, each consisting in a succession of expansive and contractile movements which always occur in the same order (see Fig. 212, a). In describing these movements, it is convenient to speak of the experimental tube as the artery, and to assume that elevation of the lever of the sphygmoo-raph is equivalent to expa7ision of the tube, and depression to^conlrac- Hon. This granted, the tracing shows that when the valve d is opened, a sudden expansion of the artery takes place; that so long as the heart continues to act the vessel remains full and that the cessation of the injection of liquid from behind de- termines a contraction of the artery which is as rapid as the previous expansion. No sooner has the artery accomplished its contraction than it begins a second expansion inferior to the first both in extent and rapidity ; and then finally contracts, continuing to get smaller until the aortic valve again opens. 2. It can next be shown that just as the expansion of the lever is consequent on the opening of the aortic valve, so its descent is consequent (not on the closing of the valve, but) on the cessation of the injection of liquid by the pump, i. e., the cessation of the systolic contraction of the ventricle. To prove this, I use a contrivance which will be readily understood from BY DR. BURDON-SANDERSON". 233 the figure. Its purpose is to write on tlie plate of the spliyg- mogrnph the duration of the injection of liquid. It consists of a cylinder of box-ivood (Pig. 211, ii), the steel axis of whicii rests horizontally on bearings so placed that the cylinder revolves in a direction at right angles to that of the movement of the plate at a short distance from it. From one side of the cylinder a steel needle projects, which, when the c.ylinder turns, makes a mark on the smoked surface. Round one side of the cjdinder runs a cord of spun silk, the two ends of which stretch, one from either side of it, to the point of a vertical arm (l) ; this arm springs from the wooden lever already described, by which the valves are opened and shut. Of the two cords, the upper one is rendered partly elastic by the interposition of a short length of caoutchouc. So long as the aortic valve is closed, the needle remains in contact, but the moment the valve is opened, it is withdrawn, and we obtain, first, an upper horizontal line, broken at regular intervals — which are, of course, limited in time by the opening and closing of the aortic valve — and, secondly, a pulse-tracing (Fig. 212, b), which maybe compared with it. This exact correspondence between the length of time the heart is acting and the time which elapses between the begin- ning of the expansion and the commencement of the contrac- tion, affords evidence that the latter is dependent on the former. 3. Lastly, it can be shown that the second expansion is not, as might be supposed, connected with the closure of the com- munication between the pump and the elastic tube (the shut- ting of the aortic valve), but is a consequence of the disturb- ance of equilibrium produced in the tube itself by the act of distension. To demonstrate this, the second expansion must be studied under various conditions and by various methods; among the best is the follow^ing: A narrow tube, closed at one end, and containing air, is connected by means of a T-piece with the experimental tube or artery. The volume of air con- tained in the tube varies with the pressure, indicating its varia- tions with great sensitiveness. If the surface of the liquid in the tube is watched during the action of the pump, it is very easy to see that the volume of air is diminished as the valve d opens, enlarges for a moment, and again contracts after the injection has ceased. If no^vthe action of the pump is so modi- fled that, after opening the valve d, the discharge of liquid is continued for some seconds (both valves remaining open), we learn that the first expansion is followed by a second just as before. If the same experiment is made with the sphygmo- graph, a tracing is obtained in which the ascent due to the open- ing of the A-alve is succeeded by a momentary descent, then a second ascent, the lever finally assuming a position correspond- 234 CIRCULATION OF THE BLOOD. ing to the- increased pressure producecl b}' the continuous cur- rent "wliicli is now passing tlirough tlie tube. From this experiment we leani, as regards the artificial arterj', first, that the second beat of the pulse is not, as has been sometimes imagined, a mere product of the instrumental method we employ to demonstrate it, for it can be shown quite as distinctly in other ways ; and secondly', that it is a result of the disturbance produced in the tube by the sudden disten- sion of its proximal end, independently of anj^ subsequent move- ment or action of the pump. 41. Experiments with the Schema relating to the Form of the Arterial Pulse. — In the schema, the injection of liquid bj' tlic artificial heart into the proximal end of the elastic tube produces two effects, which can not onlj- be dis- tinguished in the tracing, but can be proved experimentall_y to be independent of each other. One of these consists in the transmission of a series of vibratorj' movements of the liquid (i. e., movements in alternately opposite directions) from the proximal to the distal end; the other, in the communication of the pressure existing in the artificial heart at the moment that the valve d is opened to tlie contents of the arterial tube. The first of these effects can be readilj' demonstrated on the schema. If 3'ou take an elastic tube, distended with water, and closed at both ends, and give it a smart rap with a hammer at one end, an efl'ect is transmitted along the tube which, although of an entirely different nature to that which constitutes the pulse, yet mixes itself up with it under certain conditions. This effect is called, from its mode of origin, a percussion-wave. To produce it, close the communication between the schematic heart and artery, and arrange the lever (Fig. 211) in such a manner that, by striking on it with a hammer (at d), the required percus- sion may be produced. The tube being placed under the spring of the sphygmograph (at o), in such a position that the length of tubing between the point of percussion (b) and the spring (g) is equal to two metres, a succession of percussion-waves is produced, and a tracing olitaiued similar to those shown in Fig. 213, in which the interruptions in the upper line indicate the moment of percussion, the vertical ascents in the lower line the effects. In the figure, the interval of time between cause and effect corresponds to the portion of the horizontal line (in the lower tracing) which lies between the short vertical scratch and the commencement of the ascent. The rate of movement of the clock-work during the experiment being 8 centimetres per minute, this distance corresponds to about a fifteenth of a second. The other effect, the communication of pressure from the artificial heart to the elastic tube, may be readily illustrated BY DR. BURBON-SANDERSON. 235 with the aid of a schema in which the heart is represented by an elastic bag of such size that it can be squeezed with the hand. This bag communicates at one end with a long elastic tube representing the arterial S3-stem, at the other with a vessel con- taining water, the apertures being furnished with valves which open in directions corresponding to those of the heart. If three levers, like those we have just been using, are so arranged as to receive the successive expansion-waves — produced by repeatedly squeezing the bag — at different distances from their origin, the three tracings are obtained which are represented in Fig. 214. It is instructive to observe that these tracings have no resemblance to those of the arterial pulse. The reason is, that the contracting hand is entirely unlike the contracting heart. The real heart, like the schematic heart used in the pre- vious experiments, contracts suddeidy, exerting its greatest vigor at the commencement. The hand contracts gradually, and is, moreover, incomparably weaker, as compared with the resistance to be overcome, than the heart. Hence the expan- sion of the tube is slow, lasts a long time, and is followed by no rebound. This very slowness of the process enables one to see tiie steps of it better. In the distal part of the tube, to which the upper tracing corresponds, the expansion culminates later than in the proximal part, because the motion commu- nicated to its contents by the grip of the hand at the outset does not begin to tell on the former (distal) until the latter is fully expanded. In the pulse tracings obtained with the schema arranged as in Fig. 211, so as to imitate the natural pulse, the two effects produced in the preceding experiments separately, are combined with eacli other. Thus in Fig. 212 a, tlie abrupt initial ascent of the lever is the first of a series of vibratory movements of the same kind as those shown in Fig. 213, and is instantly fol- lowed by a recoil. In the same tracing, the more gradual ac- cumulation of arterial pressure manifests itself in the fact that the lever jerked up' by the vibration does not (as in Fig. 213) descend to its previous position, but remains elevated for a period, whicb, as already seen, depends on the duration of the injection of liquid. This combination of effects is seen with equal distinctness in the natural radial pulse. The abrupt line of ascent with which ' In the spliygmographs, lately made by Bregrfet, the movement of the spring is communicated to the writing lever by a mechanism shown in Fig. 209 S, more simple and effectual than that described on p. 337. The screw is hinged to the upper surface of the spring in such a way that it presses gently against the axis of the lever, and acts upon it as a rack ou its pinion. In this way the lever follows the movements of the screw muck more exactly, and the jerk is diminished. {See Garrod ou Spbygmography, Journ. of Anat. and Phys., May, 1873, p. 399.) 236 CIRCULATION OF THE BLOOD. every normal tracing begins, expresses not the more or less gradually increasing arterial distension, but the antecedent transmission of a vibration. 42. Postponement of the Pulse. — Tliere is a sensible dif- ference in time between the beat of tlie carotid arterj^ and that of tlie radial. Any one can satisfy' himself of the fact by feel- ing his own carotid with the left thumb and forefinger, while he feels the left radial with the other hand. The reason why time is lost in the transmission of the expansion from the centre to the periphery, is that the arteries are elastic. Let us sup- pose a tube, A, B, c, to represent the arterial system — a the proximal end, c the distal. At the instant that blood bursts suddenly out of tlic contracting lieart into A, it yields to the pressure against its internal surface and expands. In this expansion great part of the sensible motion of the blood momentarily disappears, and consequentljr, so long as the expansion lasts, produces comparatively very little effect in distending b ; but immediately that A becomes tense, the lost, or rather converted, motion again becomes sensible, and adds itself to the motion which the contracting heart is still communicating. And, inasmuch as b deals with the accumu- lated effect wliicli it receives from a in exactly the same way as A dealt with that which it received from the heart, c is as far behind b in attaining its maximum of distension as b was behind a. This being tlie case, it is easy to see that the loss of time between a and c, or between aorta and radial, depends on tlie yieldingness (extensibilit_y) of the tube by which the two points arc connected. If the tube is absolutely rigid, there is no postponement ; if, though elastic, it is tense at the moment that it receives the discharge, there is scarcel}^ any ; whereas that condition of the tube is most favorable to postponement, in which it is longest in attaining its maximum of distension, or in wliich the time taken by any part of it to expand to the uttermost is longest. The preceding explanation relates exclusively to so much of the pulsation as is due to the communication of pressure. As regards the antecedent vibration-effect, we have also time occu- pied in transmission, but the rate of propagation is so rapid that in the case of an artery, or of an elastic tube of similar length, it is inappreciable. This fact enables us to explain how it is that in some persons the pulse seems to be much more postponed than in others. The reason of this is, not that there is more time lost in the former case than in the latter, for even if this were so the difference would be certainly too inconsiderable to be judged of by the finger, but that in some BY DR. BURDON-SANDERSON. 237 individuals, and under certain conditions of liealth, the instan- taneously transmitted vibration-effect is more felt by the fin- ger ; in others, the moment at which the artery attains its greatest extension. Thus a pulse of the form shown in Fig. 21.5 a seems to the finger delayed, because the vibration-effect is in abeyance on account of the existence of an obstruction between tiie heart and the wrist; whereas, in the pulse re- presented in b, the initial shock is so intense that it masks the other. 43. Cause of the Second Beat.— The facts relating to the postponement of arterial expansion are also the key to the understanding of the phenomenon of dicrotism. In applyino- them in explanation of the production of the second expansion in arteries which, like the radial, are not far from the periphery, there are two facts to be borne in mind: first, that these arte- ries, ns they become smaller, become more distensible; and secondly, that in the capillaries themselves the resistance to the passage of blood is much greater than any which is en- countered in the arteries. Just as the expansion of the aorta determines that of the radial, the radial expansion determines and is followed by that of the peripheral arterioles. Hence at a certain moment the radial is subsiding, while the arterioles are still swelling; so that, when they are at their acme of dis- tension, tlie pressure is greater at the periphery than in the radial itself. From the other fact — the resistance to the flow of blood in the capillaries — it results that, immediately behind this resistance, pressure accumulates so long as blood enters the arterioles from behind more rapidlj' than it is discharged in fi'ont. The state of the arterial circulation during the period of cardiac diastole may therefore be described as follows: The arterial system is closed by the aortic valve behind, and vir- tuall^f closed in front by the capillary resistance. In the largest arteries the expansion is ebbing, in the smallest it is culminating; so that, for an instant, the pressure is greater in the latter than in the former. There is but one effect possible. The restoration of equilibrium must take place by increase of pressure towards the heart and diminution towards the peri- pherj'. This restoration of equilibrium constitutes the second beat. It may manifest itself in very different degrees, accord- ing to the yieldingness of the arteries. When, as in health, the arteries are tense, it is seen merely in a slight arrest or in- terruption of the arterial collapse — a break in the descending limb of the tracing. In fever, when the arteries are relatively much more distensible, the second expansion is separated by so distinct an interval of relaxation from the first that the pulse feels double to the finger. To facilitate the comprehension of the subject, the S3'nchronous conditions of central, peripheral, and intermediate arteries may be stated in parallel columns. 238 CIRCULATION OP THE BLOOD. Carotid. Radial. Periplieral Arterioles. Fully expanded . Expanding . . Collapsed. Contracting . Expanded . . Expanding. Again expanding . Contracting . . Expanding. Stationarj^ . Again expanding . Slowly contracting. Contracting . Contracting . Contracting. Hence, as sphygmograpUic tracings show to lie the case, the second expansion in the great arteries lasts longer than in the smaller ones ; for, although it commences the sooner the nearer the lieart, the subsidence is simultaneons throughout the whole arterial system. Rules for Sphygmographic Observation. — 1. The forearm should be supported on a table or other similar sur- face, with the back of the wrist reposing on a firm, well-padded cushion, of such a height that the dorsal surface of the hand makes an angle of from 20° to 30° with that of the forearm. 2. The sphygmograph must be placed on the wrist in a di- rection parallel with that of the radius, in such a position that the block rests upon the trapezium and scaphoid, and the extremity of the spring is opposite the stj-loid process of the radius. 3. In beginning an observation, adjust the instrument so that the pressure exerted by the spring is sufficient to flatten the artery against the radius ; then weaken the spring until the effects of over-compression disappear — i.e., until j'ou find that the lever continues to descend until the end of diastole. Note the pressure at which this result is attained, as well as that which is required to fiatten the artery, and take tracings at each of the two pressures. Section III. — Phenomena op the Cieculation in the smallest Akteeies. The smallest arteries may be studied during life with the aid of the microscope, in fish, batrachians, and mammalia. 44. For the microscopical study of the circulation in fish, a contrivance devised by Dr. Caton, of Liverpool, is used (fig. 216). It consists of an oblong box of gutta percha, open at one end, closed at the other, and just large enough to hold the body of a minnow or stickleback very loosely. This box forms part of a plate of gutta percha, which is fixed on to the stage of the microscope in such a position that tlie tail of the fish contained in it covers a perforation in the plate prepared for its reception. The tail is held securely in its place by a ligature, and the caudal fin which rests on a square of glass is further secured by a couple of fine springs. The box itgelf, which incloses the head and gills of the fish, contains water, which is constantly renewed by means of the two tubes, of BY DR. BURDON-SANDERSON. 2S9 which the upper, guarded by a screw-clamp, communicates TTith a vessel at a higher level, the lower conveys the water away as fast as it is supplied. The excellency of this method lies in the fact that the animal can be kept under observation, -without the use of any narcotizing drug, for a long time in a perfectly natural condition. The frog is used both in the larval and adult state. To observe the circulation in the tail of the tadpole, the animal is placed in a moderately strong solution of curare, care being taken to remove it before it is completely paralyzed— the moment, in short, that its motions become sluggish. It is also possible to secure it, without the aid of curare, in a holder of construction similar to that of the in- strument I have just described— a method which has this great advantage, that the animal is in a more normal condition; for even when curare is given with the greatest care, the action of the heart is weakened by it. For most purposes the adult frog is more useful than tl'ie tadpole, particularly -when it is desired to observe not merely the circulation as it is, but to witness the modifications which the phenomena undergo under the influence of conditions acting on the bloodvessels^'through the nervous sj-stem. There are three transparent parts of the frog— the mesen- tery, the -u'eb, and the tongue— each of -which has its special advantages for the purposes of study. For a first view of the relation bet-ween arteries, capillaries, veins, and lymphatics, the mesentery is superior to either of the other two. The frog must be placed under the influence of curare, the dose of which, for the ordinary specimens of rana tem2:>oraria, is about ^oVo^^li of a grain. The solution of curare is prepared by weighing out five milligrammes of the substance, and rubbing it up in a glass mortar witli a little alcohol. The proper quantity of water— that is, sufficient to make up ten cubic centimetres — is then added, and a straw-colored, nearly limpid liquid is obtained, a single drop of which is a sufficient dose. It is injected under the skin of the back with an ordinary subcutaneous syringe, and ans-wers best when the efl'ect does not manifest_ itself for some time after the injection. The most convenient apparatus for the purpose of exposing the n-iesentery is that shown in fig. 211. The manipulation is fully described in Chapter VII. It is always desirable to commence the examination -with a low power. It is then seen that the arteries are smaller than the veins, the latter exceed- ing the foi'mer in diameter by about a sixth ; that the arterial stream is quicker than the venous; that it is accelerated appreciably at each beat of the heart; and that in every artery a space can be distinguished within the outline of the vessel, which is entirely free from corpuscles. The arterial stream, indeed, is so quick that the forms of the corpuscles 240 CIRCULATION OP THE BLOOD. cannot be discerned, but in the veins both colored and color- less corpuscles can be distinguished ; and it is soon noticeable that, \yhile tlie former are confined to the axial current, the latter show a tendency to loiter along the inner surface of the vessel, like round pebbles in a shallow but rapid stream. The observation may be continued without material change for manj' hours ; but if anj' artery is measured from time to time micrometrically, it will be found that after a while it becomes wider. On this dilatation of the arteries follows a correspond- ing though less marked enlargement of the veins, and, if tiie attention of the observer is fixed upon these last, it is seen that the circulation, which v^as before so active, undergoes a marked and almost sudden slowing. This slowing indicates that the memljrane, in consequence of its exposure to the air, is becoming inflamed; simultaneously with it, the colorless corpuscles, instead of loitering here and tliere at the edge of the axial current, crowd in numbers against the venous walls. In this way the vessel becomes lined with a continuous pave- ment of these bodies, which remain almost motionless, not- withstanding that the axial current still sweeps by them, though with abated velocitj-. If, at tliis moment the atten- tion is directed to the outer contour of the vessel, it is seen that minute, colorless, button-shaped elevations spring from it, each of which first assumes the form of a hemispherical pro- jection, and is eventually converted into a pear-shaped body, attached by a stalk to the outer surface of the vein. This bod}', which has thus made its wa}' tlirougli the vascular mem- brane, is, I need scarcely say, an amoeboid colorless corpuscle. It soon shows itself to be so by throwing out delicate prongs of transparent protoplasm from its surface, especially in the direction from which it has come. The methods to be employed for the study of the circulation in the tongue and in the wel) are fully described in Chapter VII. For investigations relating to the innervation and con- tractile movements of the smallest arteries, the tongue is of little value, though superior to the mesentery and web for the study of inflammation. The web, on the other hand, is pre- ferable, for the purposes first mentioned, to either the tongue or mesentery. 45. Capillary Circulation in Mammalia.— The study of the capillary circulation of mammalia under tlie micro- scope IS attended with great diflBculty— in the first place be- cause (if we except the wing of the bat) there is no external part sufficiently transparent for observation under hio-h power- and, secondly, because if internal parts are used, the'injurious eflects of exposure are much greater than those which occur m batrachiaus. To overcome these difficulties it is necessary BY DR. BURDON-SANDERSON. 241 to have recourse to more complicated appliances and apna- ratus. ' ' The mesenteries of small rodents have been repeatedly nsed for the demonstration of the mammalian capillary circulation These, however, are not to be compared, as subiects of obser- vation, with the omentum, and 'particularly with that of the guineapig. This structure forms a delicate membranous ex- pansion of from twelve to fifteen cubic centimetres in extent which IS attached by its upper margin to the greater curvature ot the stomach. It differs from the organ of the same name in man in consisting, for the most part, of only two layers of peritonffium, m being much more delicate in its structure, and containing very little fat. Hence, from the simplicity of the anatomical relations, and particularly from its being attached by one side only to the stomach, from its perfect transparency from Its abundant vascularity, and, lastly, from its containing not only vessels but living cells, it is obvious that this mem- brane offers a good field for research. The observations hitherto made on the mammalian mesen- tery have been without practical result, the reason being that so vulnerable a tissue as that of the peritoneum cannot be exposed, even for a few minutes, without injury; so that, although the greatest care is taken in demonstration, only a momentary glimpse can be obtained. To obviate this difHculty the arrangements for placing the membrane under the micro-' scope must be of such a nature, that the structure is bathed during the whole period of observation in a liquid at the tem- perature of the body. It need scarcely be said that water, from Its destructive influence on living tissues, would not answer the purpose. Serum would probablv be best, if it were always at hand ; but, practically, solution of common salt of the strength ordinarily used (| per cent.) answers the piirpose perfectly. The temperature is maintained by keepino- the glass trough, in which the membrane is spread out, ovel- the warm stage, the construction of which has been already de- scribed. The mode of procedure is as follows: The guineapig is first placed under the influence of chloral by injecting that sub- stance in solution under the skin, three grains beino- required for an animal about lib. in weight. It is then laic! on a sup- port, the upper surface of which is on the same horizontal plane as that of the microscope-stage. An incision not more than an inch in length is next made, extending outwards from theedge of the left rectus muscle a little below the end of the ensiform cartilage. The muscles having been divided, and the pentonffiura cautiously opened for about half an inch, or even less, the free edge of the omentum is carefully drawn out. It must tlien be floated in the warm bath prepared for it, and is 16 242 CIRCULATION OF THE BLOOD. ready for examination. It is, however, found very advanta- geous to cover those parts of it which do not lie under the microscope with sheets of blotting-paper, for by this means the rislv of exposure is diminished, and the undulating move- ments of the water are prevented ; so that the object is rendered much steadier than it would otherwise be. So long as low powers are employed, this arrangement is sufficient; but if it is desired to use objectives of short focal distance, it is necessary to warm the objective by allowing a stream of water from the same source as that which supplies the stage to pass round it. The objects which present themselves to the observer are manifold. Veins and arteries maybe studied of various di- ameters, some of which are free, while others are surrounded by sheaths of tissue in which there are labyrinths of capillaries of surpassing beauty. Several new observations have already been made by this method. One of the most important, phy- siologically, is the fact that the maintenance of the capillary circulation is wonderfully dependent on temperature ; and, in particular, that any rise of temperature above the normal is in the highest degree injurious, partly, perhaps, from its direct influence on the blood corpuscles, but mainly because it pro- duces changes similiar to those we have already noticed as occurring in batrachians after long exposure — viz., arrest of the capillary blood-stream and escape of the liquor sanguinis and corpuscles into the surrounding tissue. 46. Artificial Circulation.— For many purposes of re- search, it is desirable to observe the circulation independently of the action of the heart. This is accomplished either in the whole body or in an organ, by injecting blood, or a liquid which may be substituted for it, in a constant stream into the arterial system, at the same temperature and under the same pressure as that which naturally exists in the arteries. In the case of batrachians, this is accomplished without difficulty, for the temperature of the bodj' differs little from that of the atmosphere, and the nutritive processes can be maintained for long periods, not only without respiration, but without the agent by which ox^'gen is convej'ed to the tissues — haemoglo- bin. Consequently the conditions to be observed are very simple. The requirements for the purpose are as follows : — 1. The liquid to be injected maj' be either serum, deflbri- nated blood, or J per cent, solution of chloride of sodium. When serum is used, it must be absolutely fresh. For this reason, the serum obtained from the slaughter-house is usuallj' not to be depended upon. It is therefore necessary to use a small rabbit for the purpose. In order to obtain a sufficient quantity of blood from this aniu:al, a canula must be care- fully secured in the carotid, and a clip placed on the artery. BY DR. BURDON-SANDERSON. 243 The connector adapted to the caniila must be of sufficient length to reach an absolutely clean flask or capsule destined for the reception of the blood. If serum is required, the cap- sule must be allowed to stand in a cool place until it is coaou- lated. If dcfibrinated blood, the flask must be agitated britk- ly immediately after it is collected. The blood sliould be taken in successive portions, for in this way a much larger quantity is obtained than would be yielded if the animal were allowed to bleed to death at ouce. 2. The apparatus for injection consists of a funnel, supported on a holder at a height of about two feet from the table, to the stem of which a flexible tube, guarded by a clip, is adapt- ed. In addition to this, two canuliE must be prepared, one for the bulbus M-teriosus, the other for tlie vena cava inferior. Both should be made of thin fusible glass, and of the size and form shown in figure 218. The arterial canula must be con- nected by an India-rubber tube of the same width as itself with a glass joiner, and its end must be supported by a holder which can be best made of a strip of sheet lead bent to the proper form. The funnel having been filled with the liquid to be injected, and connected with the canula by the joiner, a sufficient quantity is allowed to flow into the tube to occupy it completely, and the clip closed. All being now ready, a frog, previously slightly curarized, is fixed on the table in the supine position. The integument is divided over the sternum in the middle line, and the anterior wall of the upper part of the visceral cavity removed, so as to expose the pericardium, great care being taken not to injure the abdominal vein, or any other large vessel. The ventricle is then opened, and the canula passed through the opening into the bulb, and secured by a ligature. This done, the heart is drawn upwards, and to the right (after severance of the small vein which stretches from the back of the ventricle to the pericardium), so as to expose the sinus venosus, which is then opened in the line of junction between it and the auricles. By this opening, the canula for the vena cava is easily introduced into the funnel- shaped dilatation (see fig. 228 b), and pushed into the vein. If the canula is of proper size, a ligature is unnecessary. On opening the clip on the tube leading from the funnel, the cir- culation is restored. The blood contained in the vascular system of the animal is soon replaced by the liquid injected. The most instructive observations, relating to frogs in which the circulation is maintained artificially (sometimes called salt or serum frogs, according to the liquid used), are made with the aid of the microscope. The examination of the web shows us that even when saline solution is used, the ves- sels and the circulation through them remain unaltered for some time. If serum is used, this period is longer, provided 244 CIRCULATION OF THE BLOOD. tliat it is perfectljf fresh. A very slight admixture, however, of kept sernm is fatal to the experiment. After a time, de- cline of tissue life manifests itself by a change in the appear- ance of the preparation, the elements losing their plumpness and distinctness of outline. Along with tliis change, the ves- sels, and particularly the arteries, become relaxed, and the normal exchange between the liquid inside and that outside of the vessels is perverted, the latter increasing in such a way as to render the wliole animal oedematous. If, while tlie circulation is still normal, an injurj^ is inflicted on a part of the web— as, for example, by applying mustard to a spot on its surface — it is seen that in the' injured part changes occur suddenly which are analogous to those which, as tissue death approaches, affect the whole bodj'. These changes are known by the term istasis, and form part of the process of inflammation — a w^ord which is used as a general expression for the local effects of injuring living parts to such a degree as not to destroy their vitality at once. They are best studied wi)en serum which contains a few corpuscles, or defibrinated blood diluted with saline solution, is employed. It is then seen that in any part of the web to which a so-called irritant is applied, as, e. g., mustard— the blood stream is re- tarded, and the corpuscles crowd together in the dilated ves- sels. This is not due to any property of mutual attraction peculiar to tlie corpuscles, for tlie same thing happens if milk, diluted with saline solution, is substituted for blood ; so that, whatever be tlie nature of the change, its seat is not in the circulating liquid itself, but in the vessels or surrounding tis- sues. Section IV. — Functions op Vasomotob Nebves. In the proceeding section the artei-ies have been regarded merely as passive elastic tubes, dilating or contracting accord- ing to the pressure exercised upon tliem by the circulating blood. They must now be studied as not only elastic but contractile. The arteries owe their contractility to the unstriped muscu- lar fibres which they contain. These fibres shorten under the influence of impressions conveyed to them by the vascular nerves, which nerves, together with the automatic centre from winch they radiate, constitute tlie vasomotor nervous system. Of the centre which governs arterial contraction, notliino- is known anatomically ; for there is no point or tract in the brain or spinal cord to which vascular nerves can be traced back. All^ that is known has been learnt exclusively by experiment. That there is a vasamotor centre, and that it is intivacranial we learn by observing, first, that if the medulla is divided ini- BY DR. BURDON-SANDERSON. 245 mediately below tlie cerebellum, all the arteries are relaxed and that a similar effect is produced if certain afferent nerve hbres, which lead to the intracranial part of the cord, are ex- cited. Its position has lieen lately determined with great pre- cision in the rabl)it by Ludwig and Owsjannikow, who have found by experiments, to which further reference will be made that it IS limited towards the spinal cord by a line four or five millimetres above the calamus scriplorius, and extends towards the brain to within a millimetre of the corpo7'a quadrigemuia. _ That the vasomotor centre is in constant automatic action, is shown by the paralyzing effect of section, whether of the spinal cord, or of any nerve known to contain vascular fibres. If the action of the centre were not constant, division could not produce arterial relaxation. In relation to this constancy of action, the word tonus is used. Arterial tonus means that degree of contraction of an artery which is constant and nor- mal. It is maintained only so long as the artery is in com- munication witli the vaso-motor centre. 47. Experiments relating to the Influence of the Cerebro-Spinal Nervous Centres of the Vascular Sys- tem.— (1.) Destruction of the Nervous Centres.— Two frogs are sliglitly curarized, and placed side by side on the same board, in the supine position. In botli, the heart and great vessels are exposed, as in the preceding section. It having been ascertained that the circulation is normal in each animal, and the frequency of the contractions having been noted, the brain and spinal cord are destroyed in oue°of the frogs, by inserting a strong needle into the spinal canal imme- diately below the occipital bone, and then passing it upwards and downwards. This may usually be accomplished without much loss of blood. If now the frog which has been deprived of its nervous centres is compared with the other, it is seen that in the former, although tlie heart is beating with perfect regularity and unaltered frequency, it is empty, and in conse- quence, instead of projecting from the opening in the anterior wall of the chest, it is withdrawn upwards and backwards towards the OBSophagus. The emptiness of tlie heart is not limited to the ventricle and bulb. The auricles are alike deprived of blood ; and if the heart is drawn forwards liy tlie apex, it is seen that the sinus venosus and vena cava inferior are in the same condition. The state of the heart is therefore not dependent on any cause inherent in itself, but on the fact that no blood is conveyed to it by the veins. To make this still more evident, the rest of the visceral cavity may be 0[)ened, when it is seen that, although the vena cava is collapsed, the intestinal veins are distended. The second frog, which is no longer required for comparison, 246 CIRCULATION OF THE BLOOD. should now be pithed in the same manner as the first. A can Ilia is then introduced into the abdominal vein, with its orifice towards the heart, and connected, by an India-rubber tube guarded by a clip, with a funnel containing three-fourths per cent, solution of chloride of sodium. The heart having been exposed, and its empty condition noted, the clip is opened. Its cavities at once distend, and it acts as vigorously and efl'ectually as before the destruction of the nervous cen- tres. The experiment may be varied thus: Two frogs are suspended side bj' side, one of which has been pithed in the manner above described. In both, tlie lieart is exposed and the ventricle cut across. In the pithed frog, a small quantity of blood escapes, the quantity contained in the heart itself and the commencement of the arterial s^'stem. In the other, blood continues to flow for some minutes, in consequence of the con- tinued contraction of the arterial sj'Stem. To what extent the veins may participate in it is uncertain. These simple experiments show, first, that in the frog the arteries, unaided by the heart, continue tlie circulation for a certain time after equilibrium of pressure has been established, by virtue of their contractility ; and second!}', that in this ani- mal the influence of arterial contractility in aid of the circula- tion is so considerable that, when it is abolished, circulation is no longer possible. It maj' be well to point out that this fact affords no ground for supposing that the arteries take any active part in main- taining the circulation. All that is proved is, that in the re- laxed state the vascular system of the frog is relatively so capacious that it is more than large enough to contain the whole mass of the blood, which consequently comes to rest in it out of reach of the influence of the iieart. During life, the arterial tonus is usually constant ; so long as, and in so far as this is the case, the function of tlie arteries is a passive one, the motion they give to the blood-stream during diastole being a mere restitution of that received b}' them irom the heart during systole. On the other hand, whenever they contract, they originate motion of tliemselves ; but in this ease the dura- tion of the effect is limited by that of the contraction, and can never be continuous. 48. (2.) Direct Excitation of the Spinal Cord in the Frog. — The requirements are as follows : a. A thin board of soft wood about 8 inches long and 2 inches broad, one end of which has a V-shaped notch cut out of it, corresponding in form and size to one of the interdigital membranes of the web of the frog's foot. b. A pair of common strong sewing-needles ; around the blunt end of each of these needles, the end of a length of thin copper wire is closely coiled ; they are then cov- ered nearly to their points with a protective and insulating BY DR. BURDON-SANDERSON. 247 coating of soft sealing-wax, foi- which purpose it is necessary to warm them in the flame of a lamp. In doing this, care must be taken not to heat the point, c. A battery and Du Bois's induction apparatus and key. Tlie key must be interposed in the secondary circuit. A frog having been curarized just sufflcientlv to paralyze its voluntary muscles, a straight line is drawn from the notch along the upper surface of the board in a direction parallel to Its edges. Two small perforations are made in this line, a couple of millimetres from each other, at a distance from the notch equal to that from the web of the frog to its occiput. Through these perforations the needles are thrust, so as to pro- ject about 5 millimetres, after which the board is arranged in such a way on the microscope, that the V-shaped notcir rests over the stage aperture, and the opposite end on a support at the same level. All being now ready, the integument is opened along the middle line of tlie back of the neck, and the occipital bone perforated in the middle line with a fine awl, close to its posterior margin. The frog is then laid, back downwards on the board, in such a position that one of the needles enters tlie cranium through the hole in the occipital bone, the other the spinal canal. The web is then laid on a plate of glass which covers the notch, and secured if necessary by fine pin's. Finally, the heart is exposed as before. On opening the key for a moment, so as to allow the induced current to pass through the needles, it is seen that all the arte- ries of the web at once contract, the contraction increasing for four or five seconds and then gradually subsiding. If the ex- citation is continued for several seconds, the circulation stops. To judge of the effect accuratelj^, it is desirable, first, to fix upon an artery for observation beforehand, and bring it well into view ; and secondly, to measure its diameter before^during, and after excitation. For this purpose, a sheet of paper Is placed on a board in such a position that its surface is at right angles to the direction in which the image is thrown by the prism (isee fig. 219), and at a distance of about 10 inches from it. The outlines of the vessel are then traced on tiie paper with a fine hard pencil. During and after excitation, other tracings are made in the same way; by comparison of which the changes of the diameter of the vessel can be accuratelj'- estimated. The microscope must of course be so placed that light is received from the side, and that the surface of the paper is sufficiently illuminated to enable the observer to distinguish the point of the pencil. To insure success in this fundamental experiment, the following precautious must be attended to. The dose of curare must be very small, and should therefore be given an hour or two before the observation is made. One at least of the electrodes must be inserted within the cranium; for if butli 248 CIRCULATION OF THE BLOOD. are below the occipital bone, the effect is uncertain. Lastlf, great care must be taken to use feeble currents, and not to pro- long the excitations, for the vasomotor nervous s^-stem of the frog is very readily exhausted. 49. (3.) Excitation and Section of the Spinal Cord in the Rabbit. — The requirements and preliminary preparation for this experiment are the following: A canula and subcuta- neous syringe for injecting 20 per cent, solution of curare into the jugular vein ; apparatus for a kymographic observation of arterial pressure ; apparatus for artificial respiration ; a needle for ligaturing the muscles, in addition to tiie ordinary instru- ments. The canula for the jugular is shown in fig. 220 An India-rubber tube is fitted to it, the end of which is closed by a ligature. It is inserted as follows: The rabbit having been placed in the usual way on Czermak's rabbit supporter, with the cushion under its neck, the integument is divided in the middle line from the pomurn ^(faoit'downwards, as directed in Section I. On drawing the edge of the incision to either side, the jugular vein is readily seen as it crosses the sterno-mastoid. It is then carefully cleared of the platysma fibres and fascia which cover it, and of its slieatli to the extent of an inch or more, with the aid of two pairs of blunt forceps. A clip having been placed on the proximal end of the cleared part, a ligature is looped round the distal end, which is tightened as soon as it is seen that the vein is distended. This being accomplished, a second ligature is placed round the vessel between the first ligature and the clip, and then a V-shaped incision is made in the vein immediately beyond it. Finally, the canula, which lias been previously filled with saline solution, is slipped into the vein and secured in its place by the ligature prepai'ed for it. When it is intended to inject, the point of the subcutaneous syringe is shrust through the closed tube of India-rubber. On withdrawing it no liquid escapes. The plan has the advantage that successive quantities may be' injected with the greatest facility. The mode of preparing the carotid artery, and of con- necting it with tlie kymographic canula, has been described in § 34. For the i)resent purpose it is necessary to free the artery from its connections to a greater extent than usual. The canula having been secured in the artery,and the latter divided beyond the point of insertion, the canula is turned back and fixed to the animal's thorax (by tying it to the fur) in such a position that the artery forms a loop, witli its convexity towards the head. The purpose of this arrangement is to prevent the artery from being strained when the animal is turned. The apparatus for artificial respiration has not yet been described. It is re- quired because the animal being under the influence of curare, its voluntary muscles are paralyzed. As a substitute for natu- ral breathing, air must be injected in the proper quantity at BY DR. BURDON-SANDERSON. 249 regular intervals, wliicli correspond with tlie previous frequency of the respiratory acts. In the absence of self-acting apparatus, the best instrument to use is the caoutchouc blower and ex- panding regulator sold by Messrs. Griflin for working the gas blow-pipe (see fig. 221). The blower is worivcd by means of a squeezer. It consists of an oblong board or lever, 10 inches long, S inches wide, and | inch thick. This board is hinged in the middle to a fulcrum, in such a way as to admit of a see-saw movement. The fulcrum is firmly screwed to the table. When It IS in use, the blower is placed under one end, i. e., between it and the table, the degree of compression being limited by a strong cord attached at the opposite end to the table. By varying the length of the cord, the quantity of air injected at each stroke is regulated. The blower communicates with the respiratory cavity by a tracheal canula. No valve is required, the expired air passing out freely during the intervals between each injection and its successor, by a hole in the tube. The quantity of air discharged by the blower at each stroke must, therefore, considerably exceed the quantity which is required for respiration. This contrivance can be worked with much less fatigue than bellows. The time must be regulated by a metronome. The self-acting apparatus consists of two parts — a constantly acting blower or expirator, and an arrange- ment for interrupting the current of air at regular intervals. The best constant blower is that known as Sprengcl's blowpipe,' the structure of which will be understood at onc^ from fig. 222. The essential part of it is the vertical tube d, with its branch e, the lower end of which opens into a bottle having two other openings. Of these, one, which communicates with the top of the bottlfe, is for the efflux of air; the other, near the bottom, for the escape of water. If a continuous ftirrent of water is caused to pass through d, e remaining open, it carries with it a quantity of air which passes down into the bottle; and if the screw clamp c is so adjusted as to allow the water to flow out of the bottle at the same rate that it flows in from a, the water in the bottle remains at the same level, and a constant stream of air escapes from b. The interruption of the stream of air so produced is effected by means of an electro-magnet, which is so arranged that each time the voltaic current is closed, a weight by which the tube is compressed is lifted, and thus air is°in- jected so long as the magnet is in action. The voltaic current may be closed aud opened either liy a metronome or by the mercurial breaker, show-n in flg. 223. Two copper wires, one of which is connected with the battery, the other with the mag- net, run along the top of the wooden bridge, nearly meeting at ' A somewhat more complicated apparatus ( Wasserluflpumpe zur JSi-zeugungcomprimirtei- Luft) is sold by Desaga of Heidelberg. 250 CIRCULATION OP THE BLOOD. the crown of the arch ; here they descend parallel to each other, hut not in contact. Below the arch is a flat vulcanite bag, on the upper surface of wiiich a U tube is supported vertically', with its concavity upwards. Tiie ends of the two wires are received into the two limbs of tlie U. As the bend contains mercury, it is obvious that whenever the bag expands the cir- cuit is closed, and broken when it contracts. The rest of the mechanism is so arranged that the tube is closed beyond the breaker whenever the magnet is not acting, and open so long as the current passes. This condition can, however, never be permanent ; for after an interval of time, which can be very readily regulated by altering the quantity of mercury in the U tube, the bag becomes sufficiently distended to close the cir- cuit. When this happens, the magnet acts and opens the tube, allowing the distended bag to discharge itself. This contriv- ance^ answers particularly well for the artificial respiration of rabbits. The needles for exciting the cord are constructed in the same manner as those described in the preceding paragraph ; they should, however, be thicker and stronger. The Canute having been placed in the tiTichea and external jugular vein, and the apparatus for artificial respiration being in order, three-tenths of a centimetre of a one per cent, solution of curare is injected. As soon as respiration ceases, air is in- jected at regular intervals by the metronome, the beats of which express the previous frequency of breathing. The carotid artery is now connected with tiie kymograph, and the animal placed in the supine position, the head-holder being so arranged that the head is very much flexed on the cervical part of Ihe spinal column, so as to make the space between the occipital bone and the atlas as wide as possible. In doing this, great care must be taken not to strain or twist the arterj" or kink the air tube. This done, an observation must be made of the arte- rial pressure, and the atlanto-occipital membrane exposed with as much despatch and as little bleeding as practicable. This IS best eff'ected with the aid of the notched needle, fig. 203/. With the help of this needle, three ligatures are passed under- neath the muscles which stretch vertically on either side of the spnie of the atlas, its point being directed towards the occipital spme as close to the bone as possible. It is usually necessary to pass two such ligatures in line on either side, the upper entering where the lower passes out. The ligatures havino- been tightened and tlie muscles divided in the middle line, ft IS easy to expose the posterior tubercle of the atlas, the mem- brane, and the edge of the occipital bone, without hemorrhao-e The next step is to expose the cord by dividing the atlanto- occipital membrane; this is best done with scissors and for- ceps. While a tracing of the arterial pressure is taken by an assistant, the cord is divided: at once the mercurial column BY DR. BURDOX-SANDERSON. 251 sinks from, sa}^, 100 millimetres to 20 or 30. One needle is tlien inserted in the middle line above the posterior tubercle of the atlas, the other below it, the key being closed. On opening the latter so as to direct the induced current through the needles, the arterial pressure rises to a height which at first equals, if not exceeds, that at which it stood before sec- tion. The effects of exciting the cord in increasing the arterial pressure are seen with equal distinctness when the cord is not previously divided. In both cases the ascent is accompanied with an increase of the frequency of the contractions of the heart, the cause of which will be investigated in a future sec- tion. Direct Observation of the Ar-terien during Excitation of the Cord — That the increase and diminution of arterial pressure observed is in great part, if not entirely, dependent on con- traction of the arterial systems, can be shown in several ways. The most direct consists in the observation of the arteries themselves. In the rabbit, the arteria sajjhena, which, after leaving the femoral, just as that vessel enters the adductor sheath, takes a superficial course towards the inner side of the knee, may be observed with great facility. All that is neces- sary is to divide carefully, first the skin, and then the fascia which covers it : the two saphena veins which lie on either side of it serve to determine its exact position. In this artery it can be readily seen that as the pressure rises the vessel contracts. To observe the eflect of vascular contrac- tion on the heart, that organ must be exposed. In a curarized animal, this can be efl'ected without interfering materially witli the vital functions. Ligatures of fine copper wire having been passed, with the aid of a curved needle (fig. 203, e), around the 3d, 4th, 5th, and 6th cartilages, close to the left edge of the sternum, and a second vertical series of ligatures around the corresponding ribs at a sufficient distance outwards, the portion of the thoracic wall which lies between the two series can be removed without hemorrhage. It is then seen that after section of the cord, the heart is flaccid and empty, and that its cavities fill and its action becomes vigorous when the vascular contraction caused by excitation of the peripheral end forces the blood forwards so as to fill the right auricle. [For the experimental proof that the efl'ects of excitation of the cord above described are not dependent on the increased vigor of the contractions of the heart, see §§ 80, 81.] 50. (I.) Section of the Medulla Oblongata in the Rabbit, -within the Cranium. — The recent experiments of Ludwig and Owsjannikow have showni that the medulla may be divided within the cranium with the same results as regards arterial pressure as are obtained when it is severed immediately ■^0-^ CIRCULATION OF THE BLOOD. below the occipital foramen. For tliis purpose, tlie occipital bone must be perforated with a small trephine (fig. 203, d) in the midflle line between the occipital protiiberan°ce and the occipital spine (see fig. 224). By this opening, a thin-bladed knife is introduced in the middle plane, with its edge outwards, by which the medulla is divided, first on one side, then on the other. If the division is made as much as five millimetres above the calamus scriptorius, the diminution of arterial press- ure prodnced is as great as after section outside of the cranium. In experiments in which the division was made higher, the eff'ect was found to be lessened, disappearing when a point was reached about a millimetre below the corpora quadrigemina. Experiments belating to the Reflex Excitation oe the Vaso- MOTOE CeNTEE. The vasomotor centre, although constantly in activity, mav be stimulated, by impressions received by it through afferent nerves. This can be shown both in the frog and in mammalia. 51. Reflex Excitation of the Medulla Oblongata in the Frog.— For this purpose, the nerves in question may be excited either with the aid of the ordinary excitor (fig. 22.5), or by the application of a metallic brush to the skin. °In the latter ease, one of the wires which form the secondary circuit ends in a point which is inserted into the muscles; the other, in the brush which is kept in contact with the skin in the im- mediate neighborhood. The etfect should be observed in the web, in the mesentery, and in the great vessels leading to the heart. The currents employed must be feeble when the nerves are excited by the direct application of the electrodes to the sensory nerves, but strong when it is intended to excite their cutaneous or mucous endings. The periods of excitation should always be very short. The experiment may be varied as follows: a. A frog having been carefully curarized, with the same precautions as were recommended for studyino- the effect of direct excitation of the medulla, and arranged fol- the microscopical observation of the circulation in tlie web, the points of the excitor are placed upon the tongue, the mouth being kept open for the pui'pose. On opening the key, the same changes exactly are observed in the vessels as are pro- duced by direct excitation. At the first moment the blood- stream in the arteries is accelerated, but immediately after the arteries begin to contract sensibly. The contraction increases gradually but rapidly for one or two seconds, and is attended with slowing, and finally with arrest, of the circula- tion. A maximum of narrowing having been attained, the effect passes off as it came on. Even if the excitation is BY DR. BURDON-SANDERSON. 253 continiied, the arteries do not remain contracted, but often exhibit alternations of contraction and relaxation at irregular intervals. For observing the changes of rate of movemel'it in the velocity of the blood-stream, the \'eiiis should be preferred; tor in them the initial acceleration is not quite so transitory as in the arteries, while the subsequent slowing is as distinct. If It is desired to make a more exact observation, the method devised by Dr. Riegel must be used. It consists in comparino- the movements of the blood corpuscles in a selected artery or vein, with that of a current of water containing solid particles in suspension, which passes through a horizontal glass tube hxed in the eye-piece of the microscope at such a distance from the eye-glass as to be distinctly seen by the observer. One end of the tube communicates with a large bottle placed on a shelf at a higher level than the table, containing the liquid ; the other, with the discharge tube of the movable warm staoe represented in fig. 3. By varying the height of the dropper, the rate of flow through the eye-piece can be readily regulated. The rate of flow is learnt by measuring the quantity of liquid discharged per second, and dividing it by the product of the lumen of the glass tube and the magnifying power of the microscope. Thus, if the rate of discharge were a cubic centi- metre in 15 seconds, i. e.] 6.6' cubic millimetres per second, the lumen of the tube 0.8 square mill., and the magnifying power 300, the velocity of the current would be ,^^^-5— = 0.02*775 mill. Ihe determination of the absolute velocity is of little import- ance, the object being rather to appreciate, with exactitude and certainty, the changes of rate which occur during the period of observation, b. If, instead of the tongue, the surface of the skin is excited with the brush, the appearances observed are very similar. The initial acceleration of the blood-stream is more easily observed by this method than by the otiier. c. Direct Excitation of a Sensorij Nerve. — A frog having been curarized, the integument is divided along the outer and posterior aspect of the thigh in a line which corresponds in direction with the slender biceps muscle, or rather with the groove between the muscular mass which covers the front of the femur (tricepn femoria) and the bulky semi-membranosus. The sciatic nerve, accompanied by the sciatic artery and vein, lies immediately underneath the biceps, between it and the semi-membranosus. In order to separate it from the vessels, it is best to bring it into view by raising the biceps on a blunt hook. Both webs having been arranged for observation under the microscope, the nerve is divided a little above the knee, and the central end laid on the copper points. The secondary coil having been placed at a considerable distance from the primary, and the eye fixed on an artery of the web of the un- 254 CIRCULATION OF THE BLOOD. injured limb, the key is opened. The same series of phe- nomena present themselves as before — contraction and slowing of the circulation, preceded by a much less obvious accelera- tion. If now the other web is brought under the microscope, it is seen that the contraction of the arteries is very inconsider- able, the acceleration is more distinct. The explanation of this is easy. The sciatic nerve being the channel by which most of the vasomotor fibres find their way to the arteries of the web, those vessels are in great measure (but not entirely) paralyzed by its division. Consequently, of the three effects produced by excitation of the vasomotor centre— viz., increased vigor of the contractions of the heart, increase of arterial press- ure, and contraction of the arteries — tlie first two only mani- fest themselves in acceleration of the blood-stream. In the other limb, the vasomotor nerves being intact, the phenomena present themselves in their completeness. The eflect of direct and indirect excitation of the medulla on the vessels of the mesentery has as yet been imperfectly investigated. It is certain that in general the contraction of the mesenteric arteries is much less marked than of those of the web. It is often entirely absent, the only change observed during excita- tion being that the stream is accelerated. These facts do not indicate that these arteries are out of the control of the cerebro-spinal centres, but merely that the uerves excited are not in reflex relation with them. 52. Reflex Excitation of the Medulla Oblongata in Mammalia. ^ — The vasomotor centre may be stimulated iu the dog, rabbit, or cat, by the electrical excitation of any sen- sory nerve. The most convenient for the purpose is the sciatic. The requirements are the same as for an ordinary kymographic observation. If it is intended to excite the trunk of the sciatic nerve, the animal must rest on its side. It must first be ren- dered insensible by opium or chloral, and subsequently curar- ized. In order to expose the sciatic nerve, an incision must be made from a point lialf way between the trochanter and the promontory of the ischium towards the tendon of the biceps. Such an incision runs nearly parallel to the inner and posterior edge of the long head of the muscle just named, which edge must be found and drawn outwards. In the upper third of the thigh, the nerve lies between the biceps and the adductor magnus, further down, between the biceps and the semi-membranosus. If it is desired to stimulate the nerve near its distribution, the peroneal nerve may be found very readily in front of the ankle, on the fibular side of the com- mon extensor of the toes. It is often called the n. dormlis pedis. Excitation of the central end of the divided sciatic or of the peronaeal nerve produces effects which are indistinguishable in BY DR. BURDON-SANDERSON. 255 kind from those of direct excitation of tlie medulla, althoiio-h the augmentation of arterial pressure and other coucomita'nt phenomena are less considerable. In the case of the do?-saUs pedts, however, and other nerves to be immediate^ referred to, there is a marked difference between the condition of the arteries in the region to which the excited afferent nerve is distributed, and those of the rest of the body. EXPEKIMENTS SHOWING THAT THE SAME DbGBEE OP EXCITATION OP A Sensory Nerve which produces General Contraction OP the Arteries in other Parts op the Body, diminishes the loNus op the Arteries op the Part to which the Ex- cited Nerve is Distributed. 53. (1.) Excitation of the Nerves of the External Ear of the Rabbit— The ear of the rabbit derives its sensi- bilit_y from two nerves, both of considerable size. One of these, the posterior auricular, approaches the surface at the back of the neck, very near the middle line, and runs forwards and outwards, under a thin covering of muscle, to the root of the ear, where it penetrates a process of cartilage, easily felt in passing the finger from the occiput outwards. By making an incision between this process and the occipital spine, the nerve can be very easily found. The other nerve (?i. auricu- laris magnua, see fig. 226) springs from the anterior branches of the second and third cervical nerves ; it becomes superficial at the posterior edge of the stcrno-mastoid, and then runs np- ■wards, covered only by integument, towards the thin edge of the external ear, where it soon divides into two branches? It is most easily found at the root of the ear, just before it di- vides. The animal having been curarized, the apparatus for artificial respiration is connected with the trachea, and the manometer of the kymograph with the carotid artery. The great auricu- lar nerve is then carefully exposed, separated from the sur- rounding parts with the aid of two pairs of blunt forceps, and divided. The next step is to arrange the lobe of the ear in such a way that the central artery can be well seen. With this view, if sunlight is not at command, a paraffin lamp should be so placed that its light may be thrown on the ear from behind by a condensing lens, while the lobe itself is sup- ported vertically by a suitable holder. Before beginning the experiment, the central artery should be carefully observed, attention being particularly directed to the rhythmical changes of diameter which it undergoes. Its condition havino- been carefully noted, and a preliminary kymographic tracing having been taken, for the purpose of preserving a record of the pre- vious arterial pressure, the central end of the nerve is laid upon the points of the excitor, and the key opened for a couple 256 CIRCULATION OF THE BLOOD. of seconds. If no increase of arterial pressure takes place, the secondary coil, which in beginning the experiment must be distant from the primary one, is cautiously brought nearer to It until this effect is produced. As soon as this is the case, it is usually observed that the artery of the ear, instead of contracting, dilates, and tliat the whole lobe obviously con- tains more blood tiian it did before. Frequently, however, it happens tliat, notwithstanding the increase of arterial press- ure, no increased vascular injection is observable. In this case, recourse must be had to the posterior auricular nerve, the excitation of the central end of which is almost certain to be followed by the effect in question. The augmentation of arterial pressure and the dilatation of the auricular artery appear to be collateral phenomena, both increasing gradually during the few seconds which succeed the commencement of electrical excitation. If care is taken neitlier to prolong the excitation unduly nor to use too strong currents, the reaction may be witnessed a great number of times in the same animal. 54. (2.) Excitation of the Dorsalis Pedis.— When the central end of the divided dorsal nerve of the foot is excited phenomena occur of a similar nature. To enable the observer to judge of the effect, the saphenous artery must be exposed in Its course down the inner side of the lower half of the thio:h as recommended in § 49. It is then seen that durino- and alter excitation of the central end of the divided nerve the artery gradually dilates, subsequently regaining its former dimensions. The general result of the preceding experiments may be expressed by saying that the afferent nerves to which they relate (m common probably with other sensory nerves) con- tain fibres so endowed that, when they are excited, the action of the vasomotor centre is inhibited or suspended, as regards certain regions with which the nerves in question are in close anatomical relation. In its relations to the vasomotor ner- vous s3-stem, the words « inhibitory" and "depressor," both of which are used by physiologists to denote the case in which arterial tonus is diminished by excitation of an afferent nerve may be regarded as equivalent. ' Experiments relating to the effects of direct Excitation AND Division of the Vasomotor Neetes. When a vasomotor nerve is excited directly, tlie arteries of tlie region to which it is distributed contract. When it is divided, they become permanentlv larger, and remain unaffect- ed by changes m the condition of the vasomotor centre whether these are determined by direct or reflex excitation ' BY DR. BURDON-SANDERSON. ' 257 55. (1.) Demonstration of the Vasomotor Functions of the Cervical Portion of the Sympathetic Nervous System in the Rabbit.— In 1852, Biown-Seqiiard showed that Miien the sympathetic nerve is divided in the neck, tlio central artery of the ear dihUes, and the organ becomes vascu- lar ; and that when the peripheral end is excited, the same ar- teries contract; and in the same year he demonstrated that the iormer effect was dependent on paralysis, the latter on spasm of the muscidar walls of the vessels. A rabbit having been placed on tlie support in the prone position, about four cnbic centimetres of a five per cent, solu- tion of cliloral (obtained by diluting a stronger solution with the required proportion of the ordinary solution of chloride of sodium) IS gradually injected into the crural vein. [For the method of exposing the crural vein and of inserting the canula, see § 49]. As soon as the animal is insensible, an incision is made about two inches in length parallel with the trachea, so as to expose the edge of the sterno-mastoid muscle on one side. The carotid artery is then brought into view, separated from the vagus, and drawn forward from beneath the edo-es of the muscle with the (fig. 203, c) hook, when it is seen tha^t two small nerves, both mucli smaller than the vagus, are drawn forward with it, embedded in the membranous sheath (fig. 221). ^ Of these two nerves, one, which is the smaller of tl?e two, is the depressor — an important cardiac branch of the vagus ; the other is the sympathetic. To discriminate between them, all that is necessary is to trace them both upwards. It is then seen that the depressor arises by one root from the vagus trunk, by another from the superior laryngeal ; whereas the sympathetic continues its course upwards alongside of the arteiy. The sympathetic is also distinguishable by its gray color. A loose ligature having been placed round the nerve, the condition of the posterior auricular artery should be care- fully observed, and noted in the manner recommended in the previous paragraph. On dividing the nerve, it is seen that the artery dilates, the rhythmical movements cease, and the whole vascular network of the ear rapidly becomes injected with blood. The change in the condition of the organ is very similar, both in degree and in kind, to that observed after ex- citati(jn of the central end of the auricular nerve, but differs from it ill being more permanent. If after a few minutes the ears are held, one in each hand, it is felt that that of the in- jured side is warmer than the other. If now the peripheral end of the divided nerve is placed between the copi)er points and the key opened, the artery contracts and the congestion of the ear disappears. This experiment shows conclusively that most of the spinal Tasomotor nerves which are distributed to the arteries of the 17 258 CIRCULATION OF THE BLOOD. integument of the head, must reach their destination b3- pass- ing through the superior cervical ganglion. As, however, the superior ganglion is also in direct communication with the spinal cord, the vascular paralysis is incomplete unless this communication is broken by the extirpation of the ganglion. To accomplish this, the incision must be continued upwards in the angle of the jaw (see fig. 227). The carotid artery and the vagus which accompanies it, liaving been brought into view as far upwards as the stylohyoid muscle, are drawn for- wards and towards the middle line with the blunt hook by an assistant, while the sympathetic trunk is followed upwards behind the artery with the aid of two pairs of blunt forceps. The space in which the ganglion lies is crossed by the trunk of the hypoglossal nerve, and by the stylohyoid muscle. The latter should be divided. The extirpation of the ganglion is best effected with blunt-pointed scissors. After sectioifof the sympathetic trunk in the neck, the normal condition of the ear is gradually restored; but if the ganglion is destroyed, the effect is permanent. 56. (2.) Demonstration of the Vasomotor Functions of the Splanchnic Nerves.— The splanchnic nerves con- tain (in addition to those fibres which govern the peristaltic movements of the intestine, with which we have at present no concern) sensory and vasomotor fibres. The vasomotor fibres are distributed to the arteries of the abdominal viscera. Their importance depends on the fact that these arteries receive so large a share of the systemic blood-stream (especially in the I'abbit), that the resistance offered by the arterial system to the discharge of blood from the heart is largely affected by any alteration of their calibre. The sensory part of the nerve in common with other sensory nerves, contains fibres by which the vasomotor centre is influenced. It is also, as will be seen in a future section, in reflex relation with the heart throuoh the vagus. The^splanchnic nerve in the rabbit leaves tlie sympa- thetic trunk at the 8th or 9th ganglion, passes downwards in tront of the psoas major muscle, receiving branches from the other thoracic ganglia. At the level of the tenth thoracic vertebra, the two nerves lie on either side of the descendin<^ aorta, and accompany it downwards until it reaches the dia- phragm, at which point the right splanchnic is further away trom the vessel than the left. After entering the belly the left splanchnic retains the same relation to the aorta as before ending m the lower of the two cseliac ganglia, which is easily found above the left supra-renal capsule on the front of the aorta. The right nerve is more difficult to find from its lyiuo- further from the aorta, separated from it by the breadth of the vena cava. It ends at the level of the right supra-renal cap- sule, m the superior cteliac ganglion which lies in front of the BY DE. BURDON-S ANDERSON. 259 vein. The splauchiiic nerve may be reached eitlier in the ab- domen or in the tliorax. In ver^' exact experiments, and es- pecially in those that rehite to tlie functions of the afferent fibres, It is obviously desirable that these organs should not be exposed b.y opening the p^-itoni«al cavity; but for the pur- pose of demonstrating the vasomotor functions of the nerve, tins precaution is unnecessary. Wlien one of the splanclinic nerves is divided in the rabbit, the arterial pressure sinlcs; on electrical excitation of tlie divided nerve, it rises to a height which far exceeds the normal limits. Section of the other nerve is followed by further reduction, which, however, is not so considerable as that produced by division of the first. Tlie reduction of pressure after section is attended with iHcrea.se, the elevation of pressure after excitation with decrease of the frequency of the pulse. These facts are demonstrated as fol- lows : — A chloralized rabbit having been secured in the prone position, and one carotid connected with the kymograph, tlie abdominal cavity is freely opened in tlie linea alba. The in- tegument is then carefully divided by a transverse incision, which extends outwards from the first incision a little below the edge of the ribs. A curved needle, of the form shown in fig. 20.8 e, guarded by the left forefinger, is then passed under the abdominal wall in the direction of the incision. Its point having been brought out about two and a half inches from the linea alba, the ligatures are tightened in such a way that the muscles are constricted at different levels. The part between the ligatures is then divided by a horizontal incision, wliich may be continued in the same direction without hemorrhage. This done, the left splanchnic nerve is plainly seen running down parallel to the aorta on its left side, towards the supra- renal capsule. The space in which it lies is occupied by very loose cellular tissue covered by peritoneum, which must be broken through to get at the nerve. Imraediatelj' after the abdominal cavity is opened — that is, before the nerves are touclied — there is a very considerable rise of arterial pressure, which is accompanied with slowing of the pulse. These efliects are, however, only transitory, tlie mercurial column sometimes sinking immediately afterwards below its original level. After division of the left splanchnic it sinks very considerabl}'-, often as much as forty millimetres (1 e., more than an inch and a half). On placing the peri- pheral cut end between the copper points of the excitor and opening the key, the column suddenljr rises. The sinking pro- duced by section of tlie right nerve is comparatively incon- siderable. As it is very difficult to get at, its division may be omitted, all that is essential in the experiment being observ- able after section of the left. 260 CIRCULATION OF THE BLOOD. The following numerical results are derived from one of Ludwig and Cj'on's experiments: Previous arterial pressure, 90 millimetres; after division of left splanchnic, 41 mill.; during excitation of peripheral end of divided nerve, 115 mill.; after division of right splanchni'c, 31 mill. After section of both nerves, the vessels of all the abdominal viscera are seen to be dilated. The portal system is filled with blood ; the small vessels of the mesenterj^, and those which ramify on the surface of the intestine are beautifully injected, the vessels of the kidneys are dilated, and the parenchyma is hypersemic ; all of which facts indicate, not merely that by the relaxation of the abdominal bloodvessels a large proportion of the resist- ance to the heart is annulled, but that a quantity of blood is, so to speak, transferred into the portal system, and thereby as completely discharged from the systemic circulation as if a great internal hemorrhage had taken place. Part II. — The Heart. Section V.— The Movements op the Hbakt. The method of demonstrating the movements of the heart, stated in the order of their importance, are the following: 1. Exposure of the contracting heart in situ. 2. Application of instruments to the prajcordia, for the purpose of measuring the cardiac movements of the wall of the chest. 3. Listening to the sounds of the heart. 4. Imitating the movements of^the living heart by the production of similar passive movements in the dead heart c 57. Study of the Movements of the Heart in the Frog.— Before beginning the study of its movements, an ade- quate knowledge of the form and anatomical relations of the organ must be gained by dissection. For this purpose, the heart and great vessels should be filled with some solid sub- stance which can be rendered fluid by warming it ; such, for example, as cacao butter or the ordinary gelatin 'mass '(see Chap. VI.). This must be injected by the vena cava inferior in sufficient quantity to fill the heart and great vessels (see fig. 228). It is then seen that the organ, as a whole is eo-g- shaped ; but is more or less flattened from side to side by a furrow which crosses the heart nearly at right angles to its axis, but inclines downwards towards the left; it is divided into an upper globular (formed of the two auricles) and a lower conical part (tiie ventricle). On its anterior aspect the ventricle is continuous with a cylindrical prominence (the bulb), which projects from the anterior aspect of the right auricle, and terminates above by dividing into two arteries the BY DR. BURDON-SANDERSON. 261 right and left aorta. Of these aortre, which part from each other at the middle Hue, the left is the larger. The posterior wall of the rigiit auricle extemls backwards iato a club-shaped appendage, the sinus venosus. This body may be described as the dilated end of tlie large vena cava inferior. It first extends vertically upwards in the middle line, in continuity with that vein, applying itself against the esophagus behind, and opening towards the front into the right auricle, from which it is separated by a slight furrow. At the top it re- ceives on either side the two vense cavee superiores^ which, however, are relatively small. The two auricles are separated from each other by a septum, which stretches as a curtain from before backwards, between them. This curtain ends below in a crescentic margin, beneath which the two caAities communi- cate freely. The orifice leading from the sinus venosus into the right auricle is guarded by a well-marked Eustachian valve, whicli hangs downwards and towards the right. The auriculo- ventricular valve consists of an anterior and a posterior cur- tain, both of which are continuous at their edges with the auricular septum. The mode of exposing the heart has already been described. The facts to be observed when tlie pericardium is opened are the following: The series of muscular movements which are performed by the heart each time it contracts is seen to begin at the upper end of the vena cava inferior and sinus venosus. From the sinus the peristaltic wave extends to the auricles; but it is not until the auricular contraction is complete that the ventricle suddenly draws itself together. Before this last act is accomplished, it is usually seen that the sinus venosus is full, and the auricles are already filling. In a moment they become distended and contract, transferring the blood they contain to the now empty and flaccid ventricle, which in its turn forwards it onwards to the hulbus aortee and arterial system. In consequence of the fact that during the contrac- tion of the ventricle the auricles are already filling with blood, and that the ventricle does not fill until the auricle contracts, the successive appearances presented by the heart during each cardiac period are very much as if there were a constant ex- change of blood between the two great chambers into which the organ is divided, and at once suggest the notion that the auricles and ventricle dilate and contract alternatelj^, the one seeming to contract while the other dilates, and vice versa. It is easy, however, for any one who possesses the faculty of observation to satisfy himself that this is not the case, and that, while the ventricular contraction is determined hy the auricular, and the auricular by that of the sinus, the last originates of itself — i. e., independently of any previous movement. 262 CIRCULATION OF THE BLOOD. The precise time between the successive acts above described may be measured by arranging a lever of the second order in such a way that, while it rests near its bearings on the con- tracting heart, and follows its movements, its distal end in- scribes those movements on the cylinder of the recording ap- paratus. In this way a tracing is obtained (Fig. 229), in ■which the relaxation of the heart is marked by a rapid descent of the lever, the auricular contraction bj^ a first ascent, the commencement of that of the ventricle by a second, and its continuance b}' a slow subsidence, suddenly ending in the rapid diastolic descent already mentioned. Thus, in the ex- ample given, the interval between the vertical lines a and h cor- responds to the auricular systole ; that between h and c to the contraction of the ventricle — so that the auricles are in dia- stole from h to a, the ventricles from e to h. 58. Study of the Movements of the Heart in Mam- malia.— For this purpose a rabbit must be completely chlo- ralized. The trachea having been connected with the appa- ratus for artificial respiration, and the frequency and quantity of the inflations carefully regulated, the chest is opened in the manner already indicated in § 49. The facts to be studied are the following : a. At the beginning of the period of relaxation, the heart is so flaccid that it obeys the law of gravitation, and is consequently flattened from side to side, jus't as we usually see it in the dead body. It does not follow, from this observa- tion, that the relaxed heart has the same form when inclosed in the thorax, but on other grounds it probably is so, for its form within the chest when in the flaccid condition is mani- festly determined partly by gravity, partly by the shape of the space in which it is contained; and inasmuch as the space is a wedge-shaped one, bounded anteriorly by the sternum and ribs, posteriorly by the diaphragm, but virtually unlimited towards either side, we may be quite sure that the organ is at least as much flattened antero-posteriorly in the natural state, as it is seen to be when the chest is open. h. During the re- mainder of the diastole the ventricles are still flaccid'and per- fectly passive, but the conditions are changed. While gradu- ally filling with blood, they go through those changes of form which are exhibited by a bladder contained in a basin when it is gradually filled with water, e. At the end of diastole fol- lows a very short period, during which, although the ventricles are still soft, active muscular movements can be observed. This is known as the prce-systolic period. Systole has in re- ality begun; but the auriculo-ventricular valves not having yet had time to close, tlie ventricular contraction is unresiste(r. The heart, like any other muscle, so long as it contracts with- out opposition, is soft. d. The moment that the valves close, the heart hardens and becomes globular, slightly twistino- BY DR. BURDON-SANDERSON. 263 round its axis, while the apex is thrown forward, and at the same time approaches the base. If at the moment of ventri- cular hardening the attention is fixed on the aorta, that great arteiy is seen to undergo the same changes of form which we have already studied in the ai'terial pulse — changes due partly to lateral expansion, i. e., increase of diameter ; partly to axial expansion, i.e., increase of length. The "locomotive" move- ment, whicli results from the axial expansion of the aorta, has its influence on the heart, for it compensates for the axial shortening which occurs when tlie heai-l gathers itself up into a globe to overcome the arterial resistance which is opposed to it at the moment that it begins to force its contents into tlie alreadjr distended arteries. In the preceding paragraphs the attention of the student has been directed entirely to the arterial side of the heart, i. e., to tlie movements of the ventricles and great arterial trunks. These having been mastered, he must next observe those of the auricles, with special reference to the order of time in wliich they occur. At the commencement of the period of ventricular relaxa- tion the whole heart is flaccid. The duration of this period varies inverselj^ as the frequency' of the pulse, so that no general statement can be made with respect to it. As long as it lasts, blood enters the auricles from the systemic and pulmonary veins. At a moment which anticipates the harden- ing of the ventricles (in the rabbit) by something like a fifth of a second, the auricles harden, while the ventricles, which have alreadjr received a certain quantity of blood through the open auriculo-ventricular orifices, fill much more rapidly. This liardening of the auricles is not, however, to be compared either in vigor or suddenness to that of the ventricles ; It does not affect the whole auricle at once, but rather seems to spread from the venae cavse towards the ventricles as a wave of contraction. While the auricle is still contracting, the pre- paratorj' " priE-systolic" movements begin in the ventricles, culminating, as already described, in the ventricular shock, or heart pulse. To complete the study of the movements of the heart in situ, they should be observed under various abnormal condi- tions, e. g., under the influence of section and excitation of the vagi, in dyspncea, and after hemorrhage. The appear- ances then seen will be referred to under the proper heads. 59. The Cardiac Impulse. — It has been already stated that the ventricular part of the heart is contained, both in man and in the lower mammalia, in a somewhat wedge-shaped space, the posterior wall of which formed by the diaphragm is more or less resistant. Consequently, wlien the ventricles suddenly harden and become globular, they knock against the 264 CIRCULATION OF THE BLOOD. wall of the chest with more or less violence. This knock is called the cardiac impulse. It is precisely coincident with the complete closure of the auriculo-ventricnlar valves, and deter- mines the bnrstiug open of the sigmoid valves. If the base of the heart, i. e., the roots of the great arteries, were fixed, the shortening of the ventricular axis, which, as we have seen, occurs at the moment of hardening, would determine a with- drawal or retraction of the apex from the position occupied by it in diastole. As, however, this shortening is attended with lengthening of the aorta, its retractive effect is more or less neutralized, so that the seat of impulse— in other words, the centre towards which the muscular mass of the ventricles draws itself together— is not far from the position occupied by the apex of the heart when in a state of relaxation. This can be demonstrated both in man and in the lower animals. In a rabbit or dog rendered insensible by opium or chloral, a number of long slender needles are introduced into the heart in the following positions: JSTo. 1 is inserted vertically into the ventricle at the point at which its knock can be felt by the finger most distinctly. From this point a line is drawn npwards and inwards towards the root of the aorta, along which Nos. 2, 3, and 4 are inserted in a similar manner in the intercostal spaces. In like manner, Nos. 5 and 6 are inserted at equal distances on either side of the impulse in the same intei-costal space. The movements executed by these several needles differ according to their relation to tlie central one, No. 1, whicli, although it is affected by the ascent and descent of tlie diaphragm, is indiflferent as regards the heart. Of tlie series, Nos. 2, 3, and 4, the free end of each performs an in- stantaneous upward movement, the extent of which is in pro- portion to its distance from No. 1 ; and finally, Nos. 5 and 6 oscillate more or less horizontally, their free ends receding from each other, as well as from No. 1, at the moment of the impulse. From these facts we learn that, whereas tiiat part of the ventricular mass which knocks against the chest is nearly stationary, the base of the heart moves downwards, and to the left at the moment of the ventricular hardenino-' I. e., of the aortic pulse; and that the other parts of the ven- tricles are drawn towards the impulse in a degree proportional to tlieir distance from it. In man, the same facts are demonstrated with the aid of the cardiograph. The word cardiograph has been applied by various writers to a variety of instruments, which differ from each other both in their form and in the principles on which they are constructed, but agree in the purpose which they are intended to fulfil. This purpose is the recording of the cardiac movements of the wall of the chest by the graphic method BY DR. BURDON-SANDBRSON. 265 60. The Cardiograph.— The cardiograph I use is shown m fig. 230. Its most important part is a hollow disk, the rim and back of which are of brass; tlie front is of thin India- rubber membrane. This disk is called a tympanum. To the brass back a flat steel spring is screwed, which is bent twice at right angles in the same direction, in such a way that it over- hangs the India-rubber membrane. The extremity of this spring, which is exactly opposite the centre of the face of the tympanum, is perforated by a steel screw, the point of which rests on the membrane, while its head is surmounted by an ivory knob. The tympanum is further provided with three adjusting screws, by which, when in use, it rests on the wall of the chest, with its face parallel to the surfoce, and can be approximated or withdrawn at will. It is evident that when the screws are so adjusted that the spring presses on the chest whatever movements of expansion or retraction are made by the_ surface to which it is applied are communicated to it, and by It to the India-rubber membrane with which its point is in contact. The cavity of the disk communicates by a vulcanized India-rubber tube with a second tympanum, represented in fig. 231, in such a way that the two tympana and the tube inclose an air-tight cavity. The result of this arrangement is, that whatever movement is performed by the first is simultaneously reproduced, but in the reverse direction, by the second. If the tympana are of equal area, the extents of the primary and secondary movements are equal. Wiien, as is usually the case, the areas are unequal, the extent of movement is approxi- mately inversely proportional to the areas. The movement of the second tympanum is magnified and inscribed on the regis- tering cylinder by a lever in the manner explained in a pre- vious paragraph. By this apparatus a tracing is obtained, which IS an exact representation of the movements of the sur- face against which the spring is applied, so that, if the instru- ment is graduated, it may be used not only for the purpose of estimating the relative duration of those movements, but for measuring their extent. For the purpose of studying the cardiac impulse in the hu- man chest, the subject should be allowed to rest supine on a flat surface, with his head on a pillow. The impulse is sought for in the normal position, i.e., in the space between tlie fil'th and sixth ribs, about half an inch nearer the sternum than the mammary line (the line which passes vertically tlirough the nipple). On applying the cardiograph in this position, with the ivory knob pressing against the seat of impulse, a tracing is always obtained which has the general characters exhibited in Fig. 232a, in which tlie moment of hardening is indicated by a sudden ascent of the lever, and the end of the ventricular systole by an equally marked, but not so sudden, descent. If 266 CIRCULATION OF THE BLOOD. now the cardiograph is shifted towards the sternum, the character of the tracing is entirely' altered. (See Fig. 2326). The ventricular hardening is still, indeed, indicated b}' a jerk upwards of the lever; bcit this is immediately succeeded hy a descent of such a cliaracter as to afford evidence that at the point investigated the thoracic w.all, instead of bidging, is re- tracted during the S3'Stolic effort. This phenomenon, which is well known to pathologists, being so marked in some con- ditions of disease that it is easily appreciated by the unaided hand or eye, has been called the " negative impulse." It means that the heart, which, when gradually filling with blood applies itself to the whole prtecordia, gathers itself from all directions towards the centre of impulse — in bedside language, commonly miscalled the apex. If the cardiographic tracing of tlie im- pulse is compared with that obtained manometrically by a method to be immediatelj' described, it is obvious that the two correspond with each other very closely; so that we. are per- fectly safe in assuming, as has been done above, that the ascent denotes the beginning, the descent the end, of the ventricular effort. We can thus determine with the greatest precision the moment at which tlie mitral and triciipsid valves close. The moment of the closure of the arterial valves is not so certain, for it does not coincide with the end of the systole. It is sometimes marked by an up-and-down movement of the lever, due to the vibration into which the chest wall is thrown at the moment tiiat the curtains of the aortic valve come together. The auricular contraction is often indicated by a slight eleva- tion, which precedes the impulse by a distinct interval. 61. Investigation of the Sounds of the Heart. — The sounds of the heart can be studied both in man and in the lower animals. The first or dull sound coincides with the hardening of the ventricles, the complete closure of the auriculo-ventricular valves, and the bursting open of the arte- rial orifices. It is caused principally by the sudden distension of the ven- tricles, but can be proved experimentally to be also in part of the same nature with the noise made by all muscles in the act of contracting against a resistance. The second or sharp sound is coincident with and caused by the closure of the sigmoid valves. This is proved by the observation that if the valve is injured, or prevented from closing by mechanical means, the sound is no longer heard. In studying the sounds of the heart in the lower animals, particularly in the dog, the student of medicine should direct his attention specially to the modifica- tions of the sounds under known conditions — e.g., in dysp- noea, when the heart is distended with blood ; after hemorrhage, when the ventricles are, insufficiently filled in diastole; after section of the vagi, when the frequency of the contractions is BY DR. BUEDON-SANDERSON. 267 SO great that the aortic valves have not even time to close or under the various conditions in which tliese nerves are directly 01- indirectly excited. From all these modifications, the effi- cient causes of which are known and understood, lessons may be learnt which may be applied directly at the bedside as aids in the interpretation of analogous phenomena when they pre- sent themselves in man. 62. Study of the Action of the Valves in the Dead Heart.— Although tliis method forms no exception to the general rule that little can be learnt in physiolooy by teleo- logieal inferences from the properties of dead organs or tis- sues, It IS yet of great value to the student for the purpose of Illustrating the purely mechanical part of the action of the heart. J he heart of any mammalian animal may be used, that 01 the pig being most suitable. The simplest method of imi- tating the conditions which actually exist in the circulation, consists 111 bringing one or other of the ventricles into commu- nication with a reservoir placed at a sufficient heioht above it by means of two flexible tubes. The most convenfent form to be given to the reservoir is tliat of a glass funnel, the stem of w ucii communicates by one of the flexible tubes with the aorta llie other tube ends in a large glass canula, whicli is securely tied into the ventricle near its apex ; its opposite end is fitted to a glass syphon, the short leg of which dips into a fuunel • the tube IS guarded by a clip. The funnel and syphon havincr' been filled with water, and the clip closed, the apparatus il ready. On opening the clip, water flows into the right ven- tricle and distends it; on closing it and compressing the ven- tricle with the hand, its contents are forced upwards throuo-h the aorta into the funnel, while the tricuspid valve is distende^d. To observe the action of that valve, all that is necessary is to cut away part of the wall of the right auricle. It is then seen that, when the ventricle is squeezed, the liquid contained in it tends^ to rush outwards by the auriculo-ventricular opening, carrying the valve with it. In a moment the curtains beconie distended, meeting by their borders so as to form a tense mem- branous dome, which projects into the auricle. The time which intervenes between the commencement of the compression and the tightening of the valve varies according to the vieor of the contractions, the quantity of blood contained in the^-entricle, and the previous position of the valve, but must always be ap- preciable. It corresponds to the prEe-systolic period previously referred to. All these facts are learnt much more impressively by introducing the index finger into the right auricle of a large animal. In the horse this can be done easily by an opening of such size that the finger is tightly grasped by it. The valve bulges out as a tense membranous dome into the auricle at the moment of auricular contraction. In observing the action of 268 CIRCULATION OF THE BLOOD. the tricuspid valve in tlie dead lieart, it is important to notice wliat are the conditions which render the valve incompetent, i. e., prevent it from closing completely. The most important of these conditions is over-distension of the ventricle, by which the ostium becomes too large to be covered by the valve. When this occurs during life, the phenomenon known as the venous pulse presents itself The right ventricle being still in communication with the venous system at the moment that it hardens, blood is injected by it backwards. When, in the human subject, this condition is permanent, it leads first to dilatation of the great veins, and, secondly, to similar incom- petence of the vein-valves nearest the heart. In such persons two large swellings are seen on either side of the neck — the distended jugular veins — which pulsate nearly synchronously with the heart. Section VI. — Endocardial Pbessttbe. By this term is understood the pressure exercised by the blood contained in the heart, against its internal surface. It can be measured in the frog and in mammalia. 63. Investigation of the Endocardial Pressure in the Heart of the Frog under various Conditions. — In the frog the action of the heart is maintained unimpaired after the separation of the organ from the cerebro-spinal nervous centres. It is not even necessary that it should be supplied with blood. Serum (if perfectly fresh) of another animal may be substituted for it, without apparently affecting either the vigor or regularity of the cardiac contractions. These two facts render it possible to use the heart of the frog for the solu- tion of a number of problems, in reference to which it is desira- ble to investigate the mechanical functions of the heart inde- pendentljr of the influence of the nervous system. The method of preparing the heart for such experiments is that first employed by Dr. Coats, of Glasgow, in an investiga- tion relating to the mechanical work done by the heart in a given time, in Ludwig's laboratory. It has been since used with various modifications by Bowditch, Brunton, Blasius, and others. The brain and spinal cord having been destroyed by the introduction of a needle, the body of the frog is cut across below the liver. The sternum with the anterior extremities are removed, great care being taken to reserve on one side a large flap of skin which may be used as a cover for the nerves and the heart. The heart is then freed of its pericardium, and tlie little serous ligament by which it is connected with the posterior surface of that membrane is ligatured and divided. The next step is to tie one branch of the aorta, and then to pass a canula through the other and the bulb into the ventricle. The BY DR. B0RDON-SANDEESON. 269 suspensory ligaments of the liver are then severed so as to ex- ™ ;-.ena cava inferior. A ligature is passed round tliat Aes^el, which IS then slit open so as to allow a large caiiula to pass into the right auricle. The cannla having been secured, the liver and lungs are removed, the stomach is severed tlirouo-h the middle, and a stont glass rod, tapering at either end, is passed Irom the mouth down the oesophagus. This rod should be as large as possible, as the stretching of the parts between the heart and the spinal column which is thus produced mate- 1 ally facib ates their satisfactory exposure. The end of the glass rod which projects from the month must then be fixed in L^fifrf'-^l''^ i''" •V',''" "''"^''^ '' ^"^^^'-t*^'! i" tl^e right auricle befit ed with a flexible tube and connected with a |lass reser- ^npl n"'fin i^'"'T''.*'r ""^^^^ P'^^-^""^ sypl^on inkstands does best) filled with reddish rabbit serum. The aorta is in like manner connected with a manometer of the form indicated m tig. iSo, from which the general arrangement of the heart reservoir, and manometer will also be best understood. Ihe heart is charged with serum and brought into action bv filling the reservoir. From thence the liquid fills the rio-ht auncle, passes therefrom to the ventricle, and is discharffecfby It into the manometer. As soon as it is seen that no more air bubbles pass through the proximal limb of the manometer (the upper end of which is connected with a flexible tube for the purpose of conveying the liquid pumped by the heart to a suitable receptacle), the apparatus is ready. The mode of ex- periment may be varied according as it is intended merely to measure the variations of endocardial pressure which occur during a cardiac period, or to observe the modifications which that pressure undergoes under different mechanical conditions 64. a. Variations of Endocardial Pressure which occur during each Cardiac Period — To observe these, the heart must communicate exclusively with the manometer, the prox- imal limb of which with the tube leading to it from the ven- tricle, and the ventricle itself, must form one cavity filled with serum and closed towards the auricles by the valve, and in the opposite direction by the mercurial column and a clip, by which the tube connected witii the upper end of the proximal limb is guarded. The manometer should be at such a heitrht that when the pressure is greatest the top of the proximal column is at the same level as the heart ; and the quantity of mercury it contains must be adjusted, by addition or subtrac- tion, with the aid of a capillary pipette, so that when the heart is m diastole the distal column is still about a millimetre higher than the other. The reservoir for the supply of serum must now be placed at such a height above the heart that the auricle is equal to that existing during diastole in the ven- tricle; and inasmuch as this has been already arranged at a 270 CIRCULATION OF THE BLOOD. millimetre of mercuiy, the height of the renous column of serum must he about hfilf an inch = 12 millimetres, the spe- cific gravitj' of mercur}- being about twelve times that of serum. In the distal column of the manometer is a glass piston, the upper end of which bears a horizontal arm arranged in the same way as that which bears the writing pencil in the ordi- nary k3'mograph — the main differences lieing that in this case the manometer is much smaller, and tliat, in order to avoid friction, the tracing is recorded, as in the sphygmograph, on glazed paper, blackened by passing it over the flame of a paraffin lamp. The record so obtained is shown in fig. 234. On account of the relative slowness of the movements and the inconsiderable lumen of the manometer, the curve is very little modified by the oscillation proper to the mercurial column, and is therefore a true representation of the succession of changes of pressure which take place in the ventricle. TTe learn from it that in the frog the pressure exercised bj' the ventricle on the blood it contains arrives at its acme somewhat gradually, and persists for an appreciable period ; and that when the lieart relaxes, the sirbsidence of pressure is at first estremelj* rapid, but subsequenth" somewhat more gradual. The rate of move- ment of the paper being 40 centimetres per minute, the dura- tion of each systole can be easily measured. 65. b. Modifications of the. Endocardial Pressure Curve under various Conditions. — For the purpose of investigating the influence of various mechanical conditions on the action of the heart, and particular!}' of changes in the relation of the pressure in the veins and that in the arteries, the apparatus must be so modified tliat the ventricle, instead of communi- cating exclusivel}' with the manometer, pumps the liquid, con- stantlj' supplied to it from the venous reservoir, along a tube or system of tubes representing the arterial system. To fulfil these conditions, all that is necessary is, (1) to insert the arte- rial canula, not in the bulb, but in the left aorta (the right being tied), so as not to interfere with the play of the aortic valve ; and (2) to join to the proximal limb of the gauge an India-rubber tube, dilated near the junction into an elastic bulb, and ending in a nearlj- capillar}- beak of glass, the pur- pose of the latter being to furnish the required resistance, that of the former to render tlie discharge as nearly equable as pos- sible — in short, to replace the elasticity of the arteries. The advantage of this arrangement does not lie in the cir- cumstance that the mode of action of the heart is more natural, for it makes little difference to that organ whether the liquid it discharges at one contraction returns to it during the next relaxation or is pumped forwards, provided that the pressures to which it is subjected are the same in systole as in diastole. It is rather that when the heart is so arranged that liquid is BY DR. BURDON-SANDERSON. 271 pumped through it continuously, the observer has it in hi, power to modify the arterial pre's^ure.Cby dte inrtl ,■ si ance) ^^Mthout modifying the venous presiure, and" vSe ve^ and so to reproduce conditions which\actuali; exist 4d ex "' cise a most important influence in the livino- body heSt'ist^vT,"''* ''' '•''' ^"''''''' "" t'"' ^-^"""^ «i'l<^ «f the ea> t IS ;n/ no progressive movement will occur, whatever may If t le'nnf^ '"'' "\V" "'"■''^^' ^^"^'' ''' the other hand, t^ia't mn n o 1 "''' °" '''' '^'^ ''^^'^ «f t''^ ''*^^'-t ^'-e equal, 'there must also be no movement, for, the auriculo-ventricular valve remaining open, the heart would act as in the previous expei! ment, receiving back again in diastole .yhateverliqu 1 u'di - ™ nf ' T^ '^'■'"'■'='1 pressures and that of total V n!nJ ^'T'T '" ''^' ''"'■^^■^^'' '-^ '"^''^" ^-^l^tion exists ^vhich IS most advantageous to efficient action, and cannot be de- tT. i-fcT '" fl\'^' ^"'■'='=t'°n without impairment of effect. Jemo^^strn'rH '^" ''''''° f ^''"''''' efficiency has been lately demo istrated experimentally byBlasius;' and it hasbeenfound, hist, that for every value of arterial resistance, it is possible by uccessive trials to ascertain what venous pressure enables the foTevPvvT'f ,'"'"'*''" »"^''"'* ^'f^^t; ''^"'^' secondly, that foie^eij heart there is a certain value of arterial resistance which is most advantageous. The mean result of numerous obsei vations IS, that the frog's heart (rana esculenta) does most woik when it^ 18 opposed by an arterial pressure of about .35 mdlimetres of mercury. If the resistance is greater than this, the heart becomes ovei-disteuded, and its valves incompetent! 66. Application of the preceding Methods to the Investigation of the Problem of the Mechanical Work done by the Heart in a given Time-In the pieceding paragraph, the expressions, mechanical "effect" of the heart s contractions, and "work" done by the heart, have been used without explanation. Before proceedin-^ further it is necessary to define them. The work done by the heart' in any given time is equal to the product of the aortic pressure and the quantity of blood which passes through the aortic orifice m the same time. To illustrate this, it is necessary to revert to the experiment described in § 46, in which the ci'rcu- ation IS maintained artificially in the frog by substitutino- for the heart a column of serum of sufficient height. In this case so long as the height of the column remains unaltered 'the' work done m carrying on the circulation truly represents that of the heart. If it is allowed to diminish, the rate of flow diminishes with it. To maintain constancy in the circulation, ', ^'»- froscJi-Eerzen angesUlUe Yersuche iiber die Herz-Arbeit, etc Fick s Arbeiten, Wurzburg, 1873, p. 1. 272 CIRCULATION OF THE BLOOD. the liquid discharged by the sinus venosiis must be constantly replaced in the funnel as it flows out. The worli which is ex- pended in doing this per minute is the work by which the cir- culation is carried on. Thus, supposing the height of the column of serum to be 400 millimetres, and that it is found that the level of the liquid in the funnel begins to subside ■when not supplied at such a rate that the weight of serum flowing through the aorta during one second is equal to one- flfth of a gramme, tlien the force expended per second would be that required to raise one-fifth of a gramme 400 millimetres, I.e., one gramme to the height of a metre in 12.5 seconds, or 0.08 grammes to the same height in one second ; and tliis re- sult has been arrived at in accordance witli the proposition with which we started, by multiplying the aortic pressure (expressed in tlie heiglit of a column of blood corresponding to it) bj' the quantity discharged in the given time. If exact information were attainable as to the quantity which the heart actually discharges at a stroke, it would be possible to measure the quantity of work done b}- the heart in the maintenance of the circulation in a mammalian animal, and inferentially in man ; but inasmuch as no such method at present exists, no estimate can be given which possesses even approximate value. In the frog, however, a reliable estimate can be made by the methods described in § 63, whichever form of experiment is employed. Thus, when the heart communi- cates exclusively with the manometer, the work which the heart is made to do is to raise whatever quantity of mercury is contained in the manometer between the level at which it stands during diastole and that to which it rises in sj'stole, to the mean heiglit height |, where h denotes the difference in millimetres of the two levels. For evidently', of the wliole number of particles of mercury in the distal column, the sur- face of which is caused to rise h millimetres above the surface in the proximal column, it is onlj' the top particles which are raised h millimetres above the level of the proximal column ; those in the exact middle are raised only lialf h ; those above and below, less or more in proportion to their distance from the middle ; so that the mean elevation is half /i. The weight is easily known if we know the aera, i. e., lumen, of the lube, and the specific gravity of tlie mercury. If we designate the former as a and the latter as s, we have the weight lifted by the heart in each contraction to tlie height -^, expressed bjr a s A, and the work done (that is, the product of the weight lifted and the height to which it is lifted) '-^ '. If it is desired to obtain perfectly accurate results, a manometer must be used of whicli the area of the surface of the mercurjr in the proximal limb is relativelj' very large. In tiie other form of experiment, § 64, i.e., when a continuous current of serum is pumped by BY DR. BURDON-SANDERSON. 273 the heart along a tube representing au arterial system, the problem assumes a somewhat different form. The rate of flow through the tube must be first ascertained by measuring the discharge from its terminal orifice. This being known" the answer to the question is arrived at by considerino- what height of column of serum would, if substituted for the heart, be sufficient to determine the same rate of eflSux. This can be learnt most accurately by a comparative experiment; it can be deduced approximately from the measurement of 'the mean pressure actually existing in the aorta. Here, as before the mechanical work done by the heart is the work which -would be required to raise the quantity of serum discharo-ed per second to the height corresponding to the pressure, i'e to a height something like twelve times that indicated by the mercurial manometer. 67. Investigation of the Endocardial Pressure in Mammalia.— As this mode of investigation can only be prac- tised on animals of large size, and has already perhaps yielded all the results which can be expected from it, it will be suffi- cient to give a cursory account of it here, referring the reader to the papers of its author. Professor Chauveau, for detailed information. The method consists in lodging in one or otlier of the cavities of the heart of an animal, an ludia-rubber bao-, or ampulla, which communicates by a long narrow tube with^a manometer. The introduction of the instrument in question (which has received the name of cardiac sound) into the right cavities through the external jugular vein is perfectly easy, and can be effected in the horse, as 1 can testify from my own ob- servation, without occasioning the animal the slightest suffer- ing or even inconvenience— a fact easily enough understood when we reflect that the internal surface of the vascular system is not supplied with sensory nerves. The ampulla does not come in contact witli the surface of the heart. Tlie left ven- tricle is reached through the carotid artery with somewhat greater difficulty. The left auricle is of course inaccessible. The most important results have been obtained by a cardiac sound so constructed that the variations of pressure can be recorded in the right auricle and ventricle simultaneously. By means of this instrument, M. Chauveau has been able to demon- strate the order of succession of the movements of the heart, and the intervals of time which separate them from each other' with au exactitude which would have been otherwise unattaina- ble. Thus he has shown that in the horse the interval between the hardening of the auricle and that of the ventricle is just about a tenth of a second, and that the duration of the ven- tricular systole is about three-tenths, whatever be the number of contractions per minute ; so that frequency of the pulse de- pends not on the time taken by the heart to accomplish each 18 274 CIRCULATION OF THE BLOOD. contraction, but on the interval of relaxation which separates one s3'stole from its successor. (See fig. 235.) Chauveau found the systolic pressure in the horse to be about 128 millimetres in the left ventricle, and 25 millimetres in tlic right. These numbers express the relative values of the me- chanical woik done by the two ventricles. The absolute values, as has been already stated, are unknown, from the impossibility of determining the quantity of blood which flows through the heart in a given time. Section VII.— Intbixsic NERVors Ststem op the Hbaet. _ Nothing is as yet known either as to the anatomical distribu- tion of nervous elements in the hearts of mammalia, or as to the functions which they perform. In the frog, both have been the subject of minute and repeated investigation. We have already had frequent occasion to observe tliat the frog's heart continues to beat after its removal from the body, and that this rhythmical movement often goes on for liours or even for days, under fa^•orable circumstances. Prom this it is evi- dent that its maintenance is dependent on conditions which are contained within the heart itself. 68. Proof that the Ganglion Cells contained in the Heart are the Springs of its Automatic Movement- It IS objected by some physiologists that the rhythmical con- tractions go on not merely in the whole heart when deprived of blood and severed from the cercbro-spinal nervous system, but also in mere fragments of the muscular substance which cannot be admitted to contain ganglion cells. The answer lies in the results of the following experiments: The heart of a frog just removed from the body is placed in a watch-glass containing serum, or three-fourths per cent, saline solution, in which it will continue to pulsate for many hours, bmall portions of muscularsubstance are then taken either from the sinus venosus, the auricles, or tiie ventricle, and observed m a drop or two of the indifferent liquid, under a low power. It is then seen that portions taken from the sinus, the auricles, or that part of the ventricle which is in the immediate neighbor- hood of the auriculo-ventricular constriction, pulsate rhythmi- cally, but that similar portions taken from the ventricle near the apex do not pulsate. The pulsating bits may be further divided with sharp scissors under the dissecting microscope until preparations are obtained which consist of only a few muscular fibres. Many of these still contract rhythmicallv eacli fibre becoming shorter and thicker at eacli contraction but not losmg Its rectilinear contour. If now the pulsatino-'and non-pulsating shreds are submitted to microscopical examina- tion, It will be found that, wliereas ganglion cells cannot be BY DR. BURDON-SANDERSON. 275 seen in the latter, they exist as a rule in the former. In the recent state, indeed, it is quite impossible to demonstrate tiicir presence m either case, but they can be detected after prepa.a- tion with cidonde of gold in the manner directed in Chap IV *!, rr ^^^"iPy*^" °^*^® Intrinsic Nervous System of the Heart of the Frog.-The heart of the frog is not known to receive nerves from any source exceitting the vao-us Tlie cardiac branches of this nerve, as thev enter the he!art (see S 73), apply tliemselves to the superior vena cava close to its origin, and then, after giving numerous branches beset with ganglionic cells to the sinm venoms, the two nerves combine to torm a plexus at the upper part of the septum, between tlie auricles. From this plexus two filaments descend, the smaller along the anterior edge of the septum, the larger alono- the posterior. On approaching the auriculo-ventricular orifice each of them exhibits a distinct bulging (Bidder's ganglia) from winch radiating streaks maybe seen to spread towards the ventricle. So long as the nerves are still outside of the heart they do not contain any ganglion cells, nor give off any branches ; but as they approach the plexus they become beset with cells, and give off numerous filaments to the sinus venosus. The two branches (anterior and posterior) have no special relation to the two rami carchaci from which they in common orio-jnate although Bidder finds that the anterior contains raore^flbres from the right side, the posterior from the left. In their course, both filaments give off branches, wiiich ramify in the septum or pass into the wall of the auricles. In order to see these nerves, the heart must be exposed by openint^ the peri- cardium. Its point must then be drawn upward's, the two aortis divided, and the ligamentous shred which connects it with the posterior surface of the pericardium cut throuo-h The two vense. cavae must then be divided as far from the heart as possible, and the heart removed. If the organ is now stretched on a wax plate by means of fine pins stifck into the vena; cava;, one into the vena cava inferior, and one into each vena cava superior, and examined under water, the two vao-i {rami cardiaci) can be seen where they are in relation wit\ the vena cava superior. If now the apex is drawn to the rioht and fixed by a fourth pin, the side of the left auricle is "ex- posed, and may be slit open with fine scissors, so as to brino- into view tlie septum, which must then be cleared of the outer wall of the auricle by careful dissection. Fig. 236 shows the appearance of the septum prepared in tliis way. 70. Demonstration of the Special Functions of the Ganglia. 1. Stannins's Experiment The lieart of a frog having been exposed in the usual way, a short glass rod is introduced into the 03sophagus. All the other organs may 276 CIRCULATION OP THE BLOOD. now be removed in the manner directed in § 63, care being taken to avoid interfering witli the venas cavae. Tiie glass rod having now been fixed horizontal!}' on the table, and the oesophagus secured bj' pins stuck through it into the table so as to prevent it from slipping on the rod, the apex of the heart is seized with blunt forceps and drawn forwards and to the right. A silk ligature is then passed, with the aid of the needle shown in fig. 2036, between the vena cava inferior and the ventricle, and between the vense cavse superiores and the right auricle, in such a position that when it is tightened it will grasp the line of junction between the sinus venosus and the right auricle. The ligature having been looped by an assistant and carefully adjusted in the proper position, the heart is left to itself As soon as it is seen that it is con- tracting regularly, the ligature is tightened. After one or two beats, the heart stops in a state of relaxation. The pulsations of the sinus, however, continue at the same rate as before. After a time the ventricle also begins to beat ; but on com- paring its rhythm with that of the'sinus, it is seen that they do not agree. 2. In another heart, prepared in the same manner, the sinus is cut off from the right auricle, the line of amputation corre- sponding with tliat of the ligature in 1. In doing this, the heart must be drawn forwards with the forceps by its apex as above directed. The result is more striking when the scissors used are not very sharp. 3. If in either of the above experiments the ventricle is cut off from the auricles immediately after the ligature or amputa- tion, as the case may be, it begins to beat again at once. 4. In a third heart, the line of ligature, i. e., the junction between the sinus venosus and the right auricle, is excited by the induced current. For this purpose Du Bois P^eymond's induction apparatus is used. The points of the excitor must be very close to each other. The effect resembles that of the ligature. If the electrodes, instead of being i^laced so as to include the sinus, are applied to the auricles, no effect is produced. 5. In another animal, jjjV^ of a grain of atropin (or less) is injected underneath the skin. After a few minutes the heart is removed, and experiment 4 is repeated. The electrical exci- tation produces no effect, the ganglion of the septa being para- lyzed. Experiment 1 is then repeated. The heart stops as before. All the preceding results can be obtained in the separated heart. The method recommended facilitates the manipulation without in the slightest degree impairing the value of the re- sults. Stannius's experiment admits of two different explana- tions, which are not, however, inconsistent with each other: BY DR. EURDON-SANDERSON. 277 1. The arrest of the heart maj^ be regarded as a result of the excitation of the ganglion of the septum, i. e., the mechani- cal irritation of that part produced by the scissors or ligature ; in other words, as an effect of the same nature as that pro- duced in experiment 4, where that centre is subjected directly to electrical stimulation ; or, 2. It is dependent on the severance of the sinus venosus from the rest of the heart. In this case it must be regarded as of a different nature from the arrest produced by electrical excitation. If it were not for experiment 5, we should be inclined to adopt the former of these views : for it is very easy to imagine that it is not likely to make nmch difference whether" we squeeze the ganglion with a ligature, nip it between the blades of a pair of scissors, or excite it by Faradaic electricity. In- deed, any one who compares the two results— the arrest of the heart by electrical excitation of the sinus on the one hand. and that produced by ligature across the upper part of the auricles on the other— would probably at once decide on their identity. By previously subjecting the heart to the influence of atropin, we are enabled to demonstrate that such a conclu- sion would be erroneous ; for if the effect of ligature were of the same nature, it would be counteracted by the same agency. In order to explain the phenomena, it is necessary to assume, what has not yet been proved anatomically, namely, that the venous sinus contains an automatic motor centre. By this term we understand (in accordance with the general notions entertained as to rytlimical action) a ganglionic centre, in which energy tends to accumulate and discharge itself in the form of motion at regular intervals, the length of which varies (a) with the resistance to the discharge, and (b) with the rapidity of accumulation. The physiological ground for this assumption of the exist- ence of a motor centre in the sinus venosus is, first, that the succession of acts which make up a cardiac contraction com- mences distinctly in the sinus, and that it is the only part of the heart which contracts independently, i, e., without being affected by the action of any other part of the organ; and, secondly, that electrical stimulation of the sinus induces in- creased frequency of the contractions of the whole organ. Ad- mitting the existence of such a centre, and assuming also that the ganglion of the vagus, situated, as we have see^ii it to be, close to the line of ligature or amputation on the auricular side of it, has the power of inhibiting, i. e., increasing the re- sistance to the discharges from that centre, and further that it exercises a similar inhibitory influence on the motor ganglia at the base of the ventricle, we are enabled to harmonize the experimental results completely thus : In the ligature and am- 278 CIRCULATION OF THE BLOOD. putation experiments, the heart stops for two reasons: first, liecause the ventricle is separated from tlie motor centre; and, secondly, because, by the pressure or naechanical irritation of tlie ligature or blunt scissors, the vagus ganglion is excited. In electrical excitation, on the other hand, the second of these effects is produced without the first ; consequently, when under the influence of atropin, the vagus ganglion is paralyzed— the influence of ligature and amputation, in so far as they are de- pendent on severance of the sinus from the rest of the heart, are nnaltererl, Ijut electrical excitation is without result. On this subject the student will do well to consult the ori- ginal papers, the references to which are as follows : As regards the anatomy of the ganglia, the most important paper is that of Bidder, m Miiller's Archiv, 1852, p. 163; as regards their functions, Stannius (Miiller's Archiv, 1852, p. 85), Nawrocki (Dcr Stanniusche Herzversucli, Heidenhain's Studien, 1861, p. 110), and Schmiedebei-g (Untersuch. iiber einige Giftwirkuno-en am Froschherzen. Ludwig's Arbeiten, 1871, p. 41). ° 71. Study of the Influence of Changes of Tempe- rature on the Heart.— (a) In the Frog. Inasmuch as the influence of temperature is obviously dependent on the in- trinsic nervous system, the present is the proper time for con- sidering It. Tlie modes of investigation are the same as those already described in the section on endocardiac pressure. Ex- act and extended researches have been made by both of the methods there given, the first having been employed by Cyon tiie second by Blasius. Of the two, the latter is preferable on account of the greater ease with which the work done can be measured. The general result is, firstly, that the quantity of mechanical work which can be done by the heart in a o-iVea tune '"creases with the temperature up to a certain point (about 20^ C, but it differs in different animals, .and no doubt also at different seasons), so that it may be doubled or trebled by a gradual rise from ordinary winter temperature to that of summer; and, secondly, that under the same circumstances the frequency of the contractions increases in much greater proportion than the mechanical effect. Hence it results that although the total qu.antity of work done in a given time is tes« at lower temperatures than at higher, the effect of each in- dividual contraction is much greater. If it is desired merely to observe the effect of chano-es of temperature on the frequency of tlie pulse, much simpler an- joaratus will answer the purpose. Either the whole heart may be used or a pa.-t of it. In the former case, the organ having been removed from the body is suspended by a thre.°d attached to the aorta m the interior of a tolerably wide test-tube fur- nished with a cork, through the centre of which the thread is drawn. At the bottom of the tube there is a bit of blottincr- BY DR. BURDON-SANDEUSON. 279 paper, soaked with water. The " moist chamber" so prepared is immersed vertically in a test tube filled with cold water, which also contains a thermometer. The water in the beaker is then very gradually warmed, while its temperature and the frequency of the contractions of the heart are noted from time to time. It is then seen that the frequency gradually increases up to about 34° C, above which the contractions become ir- regular, and are difficult to count with exactitude, until at last the condition known as " heat rigor" (with reference to which see Chapter XX.) supervenes. Similar observations may be made with respect to portions of the heart, as, e. g., the base of the ventricle or the sinus venosus. For this purpose it is convenient to place the fragment on a cover glass in a drop of serum, and invert it over the chamber of Strieker's warm stage. 72. (6) In Mammalia. — Prom the observation of the very remarkalile effects which diminution and increase of the in- ternal temperature of the body respectively produce, the one in diminishing, the other in increasing, the frequency of the pulse in rabbits and dogs, it seems probable that the mammalian heart is more sensitive to temperature changes than that of tlie amphibia. As, however, it is not possible to eliminate the in- fluence of the central nervous system, this cannot be proved experimentally. Section VIII. — The Inhibitory Nerves op the Heart. 73. 1. Demonstration of the Influence of the Vagus Nerve on the Heart in the Frog. — Description of the Vagus Nerve. — The vagus nerve originates in the frog from the posterior aspect of the medulla ol)longata by tiiree or four roots, the lowest (analogous to the spinal accessor}') being more to the front than the rest. The nerve passes out of the cranial cavity through the condyloid foramen of the occipital bone, outside of which it forms a ganglion, and is in close relation with the sympathetic trunk. After leaving the sym- pathetic {see fig. 2.37), it divides into two branches, of which the anterior contains the glossopharyngeal, the posterior the nerves which are distributed to the heart, lungs, and other viscera. The vagus itself and its cardiac branch run along- side of and in the same direction with the lower of the three petrohyoid muscles, as far as the exti'emity of the posterior horn of the hyoid bone, into which the muscle is inserted. During this part of its course it is accompanied by the laryn- geal nerve, which leaves it just before it reaches the insertion of the muscle. At about the same point it crosses the apex of tiie lung, passing behind the pulmonarjr arter}', and gives off pulmonary branches which accompany that vessel. Having 280 CIRCULATION OF THE BLOOD. crossed the lung, the nerve finds its way directly to tlie sinus venosus, but is so surrounded witli gray-looking connective tissue, that in small frogs it is difficult to trace it. As it enters the heart it is closely applied to the superior vena cava and to the wall of the sinus. 74. Method — A frog, having been slightly curarized or rendered motionless by section of the medulla, is fixed in the prone position. The sternum is then divided in the middle line, and tlie two halves of the wall of the chest drawn to either side, so as to expose the pericardium and lungs, while a stout glass rod is passed down the oesophagus. The followino- objects (see fig. 231} are then seen : 1. Tbe two aorta, parting from each otlier in the middle line, ascend outwards and up- wards close to the cartilaginous tips of the posterior horns of the hyoid bone. 2. From each of these horns muscular fibres are seen to stretch backwards and upwards, towards the occipital region; these are the petrohyoid muscles already mentioned, which originate from the petrous bone, and are inserted into the cartilaginous processes just referred to. The lower of these nearly parallel bundles of fibres, is the guide to the vagus nerve, which always lies along its lower edo-e. 3. Pollowmg the muscles backwards, they are seen to be crossed by a white nervous cord (the hypoglossal nerve), which ascends upwards and inwards towards the muscles of the tono-ue Nearer the middle line, lying somewhat further from ''the surface, but following the same general direction, another nerve is seen, the glosso-pharyngeal. 4. Crossing upwards to the larynx, over the tip of the inferior horn of the hyoid, the laryngeal nerve is seen. This is the only nerve which is likely to be mistaken for the vagus ; it must therefore be traced back for a short distance from the cartilage and divided. It is convenient also to get rid of the hypoglossus. The vagus, with the muscular slip which accompanies it, can now be readily placed on or between the electrodes. On opening the key, the heart usually stops in diastole, with its cavities full of blood, the arrest not being preceded by any previous slowing. If, however, Ilelmholtz's arrano-ement of the induction apparatus is used, and the secondary coil is placed at a suflSeient distance, a degree of excitation may be attained which, while it falls short of stopping the heart, is enough to diminisli its frequency. With reference to this effect It IS to be noticed that, although it is mainly due to mere lengthening of the diastolic intervals, it is also accompa- nied with an impairment of the vigor of the ventricular systole; so that if the heart is connected with a manometer (see § 63), the manometer rises less during the period of slow- ing than It did before. Another interesting and important BY DR. BURDON-SANDERSON. 281 fact is, that the effect does not attain its maximum till several seconds after the commencement of the excitation. [In this and all other experiments in which it is desired to note the time which elapses between the application of a stimulus and its effect, we use the electrical indicator. It is an arrangement exactly similar to an electrical bell, with the exception that the hammer, instead of striking a bell, writes on the recording cylinder of the kymograph. By a simple mechanical arrangement, the same act which opens the Du bois key closes another circuit, of which the electro-mao-net ot the indicator forms part, and vice versa. This beino- the case, the instrument makes vertical strokes on the cylinrfcr at the moment that the excitation of the nerve begins and ends.] 75. 2. Demonstration of the Influence of the Vagus Nerve on the Heart in Mammalia.— In mammalia, the inhibitory nerves contained in the vagi are in constant action, consequently division of both vagi produces acceleration of the contractions of the heart. In the dog, this effect is much more considerable than in the rabbit, and is attended with an increase of the arterial pressure, whicli in the latter is absent (see fig. 238). On the other hand, electrical excitation of the vagus, whether previously divided or not, retards the contrac- tions of the heart in all animals, and, if the induced current is strong enough, arrests the organ in diastole. (See flg. 239 a & ) To show these facts in the rabbit, all that is necessarv is to narcotize the animal, to insert a needle in the heart at the upper part of the prajcordia (i. e., about an inch to the left of the middle line, at the level of the third cartilage), and to ex- pose the vagi on both sides of tiie neck. If, now either nerve is placed between the electrodes, and the key opened the movement of the needle either stops, becomes irreo-ular' or IS merely retarded and diminished in extent, accordino- to the strength of the current. To observe the effect of section loose ligatures must be placed round both nerves, and the animal tiien left to itself, while tlie number of pulsations per fifteen seconds is carefully counted. The two nerves are then divided at once, and the countings repeated. The increase of frequency usually amounts to about twenty per cent. Finally the peripheral end of one nerve is excited, and the same effects' produced as by excitation of the undivided trunk. In demonstrating the influence of the vagus on tlie heart in the dog, it is desirable to connect the carotid or crural artery with the kymograph ; for the most important effects are those which relate to the changes in the arterial pressure. The pre- liminary steps of the experiment are those described in § 34. Loose ligatures having been placed round botii vagi, and a kyraographic observation made, to determine the normal arte- rial pressure and frequency of the pulse, both nerves are 282 CIRCULATION OF THE BLOOD. divided simultaneously^ Tlie mercurial column at once rises, and the contractions of the heart become so frequent, that the oscillations can no longer be followed by the eye, all that can be distinguished being a vibratile movement of the column. On exciting the peripheral end of eitlier vagus, the same effects are produced as in the rabbit. If the current is sufficiently strong to stop the heart, the mercurial column sinks rapidl}^, inscribing a parabolic curve on the paper (fig. 2396), the exact form of which depends on the condition of the arterial system; the rate of descent varing iuversel}' as the arterial resistance encountered b.y the blood in its progress towards the veins. On discontinuing tlie excitation, the lieart begins to beat again, at first at long intervals, subsequently more frequentlj', the pressure rapidly increasing until (for a few moments) it exceeds that observed before excitation. In man, the trunk of the vagus may in some persons be excited bj^ pressure, and results produced which correspond with those of electrical ex- citation in animals. Prof. Czermak, of Leipsic, is able, by making pressure at the proper spot on the right side of the neck, to arrest the action of iiis heart for a few moments.' 76. 3. Demonstration of the Influence of certain Afferent Nerves, in reflex Relation with the Inhibi- tory Nerves contained in the Vagus, on the Heart. Bernstein's Experiment. — The inhibitory heart nerves contained in the vagus are in intimate relation, through the heart centre in the medulla oblongata, with certain afferent fibres contained in the sympathetic system ; so that when these fibres are excited, the same effects are produced as if the vagus itself was directly acted upon. This may be shown in the frog as follows: A frog is secured in the supine position. The pleuro-peritoneal cavity is then opened, and tlie intestines and other viscera are removed, great care being taken not to injure the mesentery or the vessels and nerves whicli it con- tains, ^^othing now remains excepting tlie heart resting upon the oesophagus. By carefully dividing the double layer of serous membrane which forms the lateral wall of tlie eisterna magna on both sides (see Chap II.), the ganglionic cliaius (fig. 240) are brought into view along with the rami coin- municantes by which the ganglia are severally connected with the anterior roots of the corresponding spinal nerves. In the thoracic part of the visceral cavity the two aortaj are seen converging downwards, till at the level of the sixth vertebra they meet to form one trunk, from whicli at its origin the me- senteric artery is given off, to be distributed to the stomach and intestines. If now the two aort.-e are raised near their junctions, with the point of the forceps, it is seen that one of ' Populare Vortrage, p. 37. s BY DR. BURDON-SANDEUSON. 283 the ganglia of the cord sends towards the mesenteric artery a branch which meets with its fellow from the correspondino- ganglion of the opposite side, to form a plexus of nervel winch surrounds the artery; and that from or through this plexus a nerve or nerves (nervi. mesenterici) can be traced which follow tlie vessel towards its distribution. It is in these nerves that the fll)res which are in reflex relation with the vagus are contained. To excite them, the best method is to raise the aorta with the forceps from the bodies of the verte- bra?, drawing upwards with them at the same time the two ganglionic cords; then to divide the abdominal aorta and the two cords at the level of the seventh or eighth vertebra, sever- ing at the same time some of the rami communicantes on either side; and lastly, to place the two aortse and the cords winch accompany them, on the exciior in such a position that the two ganglia next the junction are in contact with the electrodes. On opening the key, the heart is arrested in dias- tole, begnining to contract again rliythmically as before, when the excitation is discontinued. To demonstrate that the channels by which stimulation of the mesenteric nerves affects the heart are the vagus nerves and their centres in the me- dulla oblongata, the experiment must be thrice repeated; first, after section of both vagi; secondly, after destruction of the medulla oblongata; and thirdly, after destruction of the brain, the medulla remaining intact. In the first and second cases the eflTect is annulled, in the third it is unaltered.' 77. Reflex Excitation of the Vagus of the Frog by Meohanioal Means: Goltz's Klopfversuch.— It is 'now many years since it was discovered by Goltz that excitation of the ends of the mesenteric nerves by mechanical means produces the same efl'ect as the electrical excitation of their trunks. To show this, a frog is secured on its back, the pleuro-peritoneal cavity opened, and the heart exposed as before. The surface of the intestine is then smartly tapped. After a few moments the heart is arrested in diastole. If the ganglionic cord is then divided on each side opposite thejunction of'^the two aorta?, and the experiment repeated, no effect is produced. Another frog is prepared in the same way, with the exception that both vag^i are divided. On repeating the tapping, the result is negative. The same thing happens if, instead of dividing the vagi, the cord is divided immediately below the medulla. 78. Reflex Excitation of the Vagus in Mammalia.— The constant action of the inhihitory heart nerves in the hio-hei- animals is dependent on the constant action of the centripetal nerves in reflex relation with them. This may be shown as fol- " UntersucUungen fiber den Mechanismus des regiilatorischen Herz- nervensystems." Archiv f. Anat. u. Physiol, 18C4, p. 614. 284 CIBCTJLATIOS OF THE BLmD. ' lows: In a rabbit, the trachea is connected with the apparatus for artificial respiration, and the vagi are exposed in the neck. Thereupon the spinal cord Ls divided immediately below the medulla oblongata. On the cessation of breathing, artificial respiration is commenced. The cervical sympathetics are then divided, and a needle i? inserted in the heart. A succes- sion of observations of the frequency of the heart's action is then made, and both vagi are divided. So acceleration of the palse rate occurs. The purpose of the experiment is to show that when the affer- ent sympathetic nerves which are known to be in reflex relation with the vagus heart nerves are .severed, the same effect is pro- duced on the vagus as if it were itself divided. There Ls no way of accomplishing this directly, without such interference with other nerves as w<5nld affect the heart, and thereby render the result ambiguous. The most complete method would be to remove the whole ganglionic cord on both sides. Without reference to the extreme difficulty of such an operation, it is clear that it would involve the accelerator nerves (gee § ?0;, and thereby perhaps produce an effect the opposite of that which we intended — a slowing instead of an acceleration of the pulse. •So also, when the spinal cord is divided immediately below the medulla oblongata, the effect is modified not only by the de- struction of the accelerator nerves, but by the general paralysis of the vasomotor system. Consequenth' no answer to the question is to be obtained by direct obser^-ation of the changes which are produced by any such operation in the rate of pulsa- tion of the heart, so that the end we have in view can only 1>e accomplished indirectly. We already know that both vagi are in constant action, i. e., that the heart Ls constantlvunder°their inhibitory control ; and that when thLs control is' removed by dividing them, the frequency of the pulse increases. It is ob- vious that this effect can only be witnessed so lonroduce the phenomena of d3'spnrea, the following method, devised by Rosenthal, niaj^ be emplo3'ed. The mercurial gosometer (fig. 251) is filled with oxygen. The animal is tlien allowed to breathe the gas in the wa}' described (§ 95) until it maj'' be reasonably supposed that the air contained in the air-passages is displaced by it. This occurs in the rabbit in about ten respirations. Tlie communication is then opened between the valve B and the receiver, while the exit tube is clipped so tiiat the animal both inspires from the gasometer and expires into it. As the experiment goes on, it is obvious that the propor- tion of carbonic acid increases and must continue to increase, until that gas attains such a tension in the gasometer that no further escape from the blood is possible. At first the volume of gas in the gasometer undqrgoes no sensible diminution, for the animal expires nearly as much of carbonic acid as it inspires of oxygen ; afterwards, as the quantity of carbonic acid gas given off becomes less and less, the cylinder sinks in each inspiration more and more. As soon as this is the case it is of course absolutely certain that the animal is breathing an atmosphere containing a large excess of carbonic acid gas, yet notwithstanding, there is no sign of asph3'xia, the reason being that tlie oxj'gen still exists in the mixture in a propor- tion exceeding that in which it exists in the atmosphere, or at all events, not falling far short of it. When at a still later period the breathing begins to be excessive, the dyspnoea can at first be relieved by increasing the pressure to wliich the gases contained in the gasometer are exposed. This, of course, while it favors the absorption of oxygen, equally favors that of carbonic acid gas ; that the latter has no physiological efl"ect cannot be maintained, but the experiment proves that its effect is very inconsiderable. The direct proof that dyspnoea is dependent on defect of oxygen, is obtained by the analysis of the gases of tlie blood in an animal which has been asphj^xiated by the inhalation of pure nitrogen. Pfliiger has found that an animal (dog) breath- ing nitrogen becomes hyperpnoeic in 15 seconds. In 20 seconds the struggle is at its height, the blood being already very dark. In Pfliiger's experiments, blood was allowed to flow from an BY DR. BURDON-SANDERSON. 335 artery into a recipient for the analysis of its gases, at from lialf aminute to a minute after tlie beginning of tlie inhalation of nitrogen, the animal being already in the second stage of as- phyxia. It was found, for example," that the blood of au animal which before breathing nitrogen contained 18.8 per cent, per vol. of oxygen (at 160 millim. and 0° C.),contanied after breath- ing nitrogen for one minute a me^-e trace of oxygen (0.3 per cent.) ; during the same period the carbonic acid gas had dimin- ished from 47.2 per cent, to 39.4 per cent. These experiments are referred to here on account of their fundamental importance. They are much too difHcult for repetition. 114. Demonstration that the Pulmonary Termina- tions of the Vagus Nerves are Excited by Distension of the Lungs.— It was long ago surmised by physiologists (particularly by Rosenthal) that tlie pulmonary branches of the vagus nerves contain afferent fibres, which are excited by the expansion of that organ, and that tliese fibres take part in the regulation both of the movements of the heart and those of respiration. The proof of this has been lately given by Hering. A dog having been narcotized with morphia or opium, one arm of a T-shaped canula is secured in the trachea, the other being connected with a mercurial manometer. To the stem an India- rubber connector is fitted, which is guarded by a screw clip, and ends in a blowing tube: a cannla is placed in the carotid aud connected with the kymograph. These preparations having been made, an observation of arterial pressure is taken. Tlie clockwork being still in motion, the experimenter distends the lungs of the animal until the distal column of the manometer stands about 30 or 40 millimetres above the other, and then closes the clip. Two important results are produced. In the first place, the inspiratory muscles are thrown out of action, and remain relaxed so long as the distension lasts, while those of expiration are brought into continuous and energetic con- traction ; and secondly, the frequency of the contractions of the heart is more than doubled. In the preceding experiment the circulation is considerably affected by the increased pres- sure exercised by the distended lungs on the heart and great veins ; consequently, the increased frequency of the pulse might be attributed in whole or in part to this circumstance rather than to the pulmonary distension. To meet this objection, the experiment may be modified as follows: A dog is narcotized and respiration maintained artificially, the apparatus being so arranged that at any moment the lungs may be distended as in the last case. This done, the thoracic organs are completely exposed by removing the anterior wall of the chest in the man- ner descriijed in § 49 : it is then seen that the effect of inflation ' Pfluger's Archiv., vol. I. p. 94. 336 ANIMAL HEAT. on the heart is just the same as when the thorax is closed. These results are sufficient to show the pulinonarj' distension and acceleration of the contraction of the heart, stand in the relation to each other of cause to effect. That the influence of the former on the latter is exercised through the nervous sj's- tem, and consequently through the vagi (these being the only known channel by which the lungs are in communication with the nervous centres) is sufficientl3' obvious. Accordingly, we should expect that if this channel were interrupted the effect would be annulled, and experiment proves that it is so. The demonstration is, however, very difficult, for in the dog the pulsations of the heart are already so ra|.)id after section of the vagi that no further acceleration is possible ; a negative result, therefore, would mean nothing. Hering has met this difficulty by carefully exciting the peripheral end of one of the divided nerves after section of both (using Helraholtz's modification), so as to reduce the frequency of the heart's action, and repeat- ing the pulmonary distension under these altered conditions ; the result was still negative. These experiments teach us two important facts relating to the innervation of the lungs, viz., that the pulmonary branches of the vagus contain afferent fibres, the excitation of which by pulmonary distension tends to weaken or paralyze both the inspiratory and cardiac centres in the medulla oblongata; the one action showing itself in the complete cessation of the rhythmical efforts of the inspiratory muscles, the other in the shortening of the diastolic intervals of the heart. The subject requires much fuller investigation than it has j-et received. CHAPTEK XYIII. A^'BIAL HEAT. The temperature of the body is dependent on the relative activity of two sets of processes, viz. : those by which heat is produced or generated, and those by which it'is destroyed or lost. The subject admits of being' correspondingly divided into two parts— the study of the processes, and the study of the resulting state. The former is based on the measurernent of the quantity of heat set free at the surface during a siven period (Calorimetry) ; the second on the measurement o'f the temperature existing in the circulating blood and the tissues at the moment of observation (Thermometry). BY DR. BURDON-SANDERSON. 337 Section I.— Calorimetrt. The production of heat is one of the essential functions of living tissue; consequently, wherever there are livino- cells heat IS generated at all times. We assume, at the outset, that tlie source of production is the sum of the chemical processes which take place in the body ; and that under all circum- stances, so long as the tissues are neither growing nor wasting. the quantity of heat produced by the oxidation of the foo'd consumed IS equal to the quantity which would have been produced had the same quantity of oxidizable substance been converted into similar more or less oxidized products out of the hoay. . 115. There are two distinct methods by which a theoretically complete determination of the quantity of heat products in the body in a given time can be arrived at. The first consists m deducting the heat-producing power (heat value) of the substances discharged from the body in a given time, from the heat value of the substances consumed. The second is based on the actual measurement of the quantity of heat discharcred in a given time. In the former case the difference obtained expresses the amount of heat produced in the period, provided that the animal is in a state of nutritive equilibrium— i e that Its tissues are neither growing nor wasting. In the latter' the measurement gives the desired result, provided that the discharge is exactly equal to the production of heat—i. e., th-it the temperature of the body remains the same. With reference to the first method, as it reposes entirely on chemical and physical operations, some of which do not fall within the scope of this work, while others will be described under other heads, all that is necessary is to make clear the principles of its application. So long as an animal is in nutritive equilibrium (see above) the combustible material actually consumed, i. e., oxidized in its body in a given time may be known by deducting, from the quantity of such material actually swallowed, the quantity discharged in the faeces. This determination is, therefore, purely a question of chemical analysis. The heat-producing powers of the chief constituents of food have been determined approximatively by Frankland, who finds, for example, that one gramme of albumin, in under- going complete combustion into water, carbonic acid, and ammonia, produces heat enough to raise 4998 grammes of water one degree centigrade. This fact we express by stating that 4998 is the heat value of albumen. In like mannet- Frankland has found the heat value of lean beef to be 5103, and of the fat 9069. If, therefore, it were possible to determine how much of any of these substances is consumed, 22 ' 338 AXIJIAL HEAT. say per diem, it is clear that we could readilj' calculate how much heat -would be produced, provided that the consumption, I. e., oxidation, -n-ere complete. As regards the albuminous elements of food, no such complete oxidation takes place, for the elements of these compounds do not leave the organism in the form of ultimate products of oxidation, but in great part in the form of urea and other imperfectly oxidized organic constituents of urine. The quantity of heat actually pro- duced by a given weight of albumin, therefore, falls consider- ably short of its heat value. In order to arrive at this quantity, the deduction pjrevioush' referred to must be made: i. e., from the heat value of the albumin consumed, the heat value of the nitrogenous excreted substances into which it is transformed must be taken : the difference expresses theoreti- cally the exact number of heat units actually- generated by its elements in their passage through the body. As regards the hj-dro-carbons, no such deduction is necessarj', so that in the case of animals which feed exclusively on these compiounds — e. y., bees — the quantity of heat piroduced is at once obtained by estimating the heat value of the food consumed.' Another chemical method of estimating the rate of pirodnc- tion of heat in the body of an animal, is founded on the esti- mation of the discharge of carbonic acid from the lungs and skin. In carnivorous animals this method is of little value, for. as we have seen, so much of the food consumed as consists of albuminous compounds is incompletel}- oxidized, so that there is no definite relation between the consumpition of albu- minous products and the amount of oxidation. In such ani- mals, however, as can be fed entirely on hydro-carbons of known composition, the carbonic acid gas discharged may be taken as an exact index of the heat production — not because the quantity of heat piroduced, as was at flr~t erroneously as- sumed, is equal to the heat which would be disengaged by the oxidation of the quantity of carbon actually contained in the carbonic acid, and of the quantity of hydrogen contained in the corresponding quantity of water — but Ijecause in such an animal the whole of the material consumed is completely oxi- dized ; so that the quantity of carbon discharged as carbonic acid is always equal to the total quantit}- of the same element oxidized. On this account Ijees, which can be fed exclusively ' Zso results can be obtained by this method unle55 the animal i.= in a state of perfect nutritive equilibrium. Tor this reason, it can be seldom applicable in the investigation of pbviiolozical or jjathological questions relating to heat ; for, on account of the length of the periods over which the detenninations must necessarily extend, it gives little or no informa- tion as to the cariations in the production of heat, the appreciation of Tvhich is practically more important than the determination of the means of the quantities produced per hour or day. BY DR. BURDON-SANDERSON. 839 on hydro-carbons, and have the additional advantage that, although they are of variable temperature, their heat^jroduc- tion IS as active as that of warm-blooded animals, are specially adapted for the investigation of the relation between heat pro- dnction and oxidation. Under many circumstances which preclude the use of this method alone, it is of value in combination with that of direct measurement, to be immediately described ; for the informa- tion It affords, even when the nutritive substances consumed are partly nitrogenous, is trustworthy. If the ingestion of nutritive material is regular and uniform, it affords a rough, but otherwise reliable, indication of whatever variations may occur m the activity of the chemical vital processes. It will be readily understood, that these indications occur later than the causes which produce them ; so that it is not until some time after any increase or diminution of oxidation, that the corresponding increase or diminution of the discharge' of carbonic acid manifests itself. The mode of gauging the discharge of carbonic acid in the animal body has been de- scribed in the previous chapter. In the application of the re- sults of such determinations, it must not be forgotten that the absolute values obtained are meaningless. Their use is limited to the interpretation of direct calorimetrical measurements. 116. Direct Estimation of the Quantity of Heat produced by an Animal in a given Time.— The second method (to which alone the term Calorimetry is strictly appli- cable), consists in tlie direct estimation of the quantity of lieat (heat units) given off by an animal in a given time. The subject of observation is placed for a measured period in a chamber, which is so constructed that while it is continuously supplied with air for respiration, it is surrounded on all sides by a mass of water, the weight and temperature of which are known. The construction of such a chamber (Calorimeter) can be readily understood from the diagram, fig. 265. _ A, is a box of zinc plate, in which the animal is placed, the size varying according to the animal it is intended to receive. If for rabbit or small dog, it is 1.5 J inches long by 12 inches wide, and 13 inclies high. It possesses two openings, one of which is in the lid and communicates with a large gasometer, into which air is constantly injected by a Bunsen's water air- pump. The otiier is in one end, and opens into an exit tube (Dj, which after surrounding the box twice, terminates in a flexible connector, by which the air which has passed through the chamber escapes. The section of this tube, the purpose of which is to secure the condensation of the aqueous vapor dis- charged from the lungs and skin, is oblong and rectangular; in order that it ma^' present to the water by which it is sur- rounded as large a surface as possible. The inner box (A) is 340 ANIMAL HEAT. surrounded bj' another, which is of such dimensions that the external surface of the former is separated from the internal surface of the latter by a space of an inch and a half in every direction. This space contains water the weight of which can be readiljr known. The inner box can be fixed into its place by a simple mechanical arrangement. The water-chamber (B) is contained in a wooden case (C), which however is so large that a considerable space intervenes, which is closely packed with tow, the purpose of which is to prevent loss or gain of heat by radiation or conduction, and thus to render the tem- perature of the interior of the apparatus entirely independent of that of the surrounding media. For the same reason the external surface of the water-chamber is of bright tinplate. The interior of the water-chamber is japanned. The zinc inner chamber for the reception of the animal is left as it is. The temperature of the animal having been measured by passing a thermometer an inch and a half into the rectum, it is placed in the box, the exit tube of which has been previously brought into communication with an aspirator. The lid is then rapidly but carefullj^ closed with putty, and the whole placed without loss of time in the water-chamber. The water-chamber is then closed and immediately covered with a layer of tow. In its lid there are two oblong openings for the introduction of stirrers.' The water having been agitated immediately after the introduction of the box containing the animal, a thermometer is introduced by one of the openings already mentioned, which after three minutes is read. The time having been noted, the apparatus is left to itself for fifteen minutes, half an hour, or an hour, and the temperature is again ob- served after aafitation of the water. The results having been noted, the animal is withdrawn with as little delay as possible from the case containing it, and the thermometer is introduced into the rectum to the same distance as before, and read after the same interval of time. In this way obviously four readings are obtained — those of the animal and of the calorimeter at the beginning and end of the given period. To interpret them we must take into ac- count, not only the relative weights of the animal and of the calorimeter, but their several capacities for heat. In the case in which the temperature of the animal remains the same, the amount of production being equal to that of discharge, all that is required is to know how much heat has been communi- cated during the period of observation to the calorimeter. In the opposite case we must, in order to judge of the quantity ' I have lately adopted a better method of agitation, consisting in the injection of air into the space below the chamber A. The construction is such that the whole of the air so used finds its way into the chamber. BY DR. BURDON-SANDERSON. 341 Of heat produced add to or deduct from the quantity commu- nicated the quantity t has borrowed or given off from its o7u body. If the animal loses heat while it is in the chamber be li'tlfci:^ f ">"'^ ''""f'^'y generated, the remainde beig abstracted from , s own body. If it gains, the quantity aSdpT tf -f'^ ^^ ? °"'^' l^'"'''''^"^' g'^^*^" °ffi the remainder il ;drbl .r^" t'^'^^P'^'-'^ture. To make this deduction or addition, as the case may be, two questions must be answered if, ;pnlr T ^'^'-^^^^oes tl'e calorimeter require in order that Its temperature may be raised one deoree ' same^ui;:se? '°" ''' '"''' '' "^^ "^""^^^ ^^l""-*^ f-" *'- In both cases the quantity required is equal to the specific beat multiplied by the weight. The mea« specific lieat of Ihe calorimeter IS obtained by adding together the products of the specific heat and weight of the parts of which it is composed — I. e., the iron case and the water. Supposing, e. g., the iron to weigh 3800 grammes and the water 8600 grammes, the specific heat of iron being 0.114 the product in question is for the iron casing 419.5, while tha for the water is 8600.0. Consequently 9019.5 grLmme-units' of beat are required to raise the whole one degree of temperature Applying the same method to the animal body, the specific heat of which is estimated to be 0.83, we have of course 83 gramme-units as the quantity to be added or deducted for each gramme of weight and degree of variation of temperature Ihe whole process will be readily understood from an ex- ample, the weight of the calorimeter being that given above Temperature of calorimeter— at beginning 9M C, at end ooTo'^P®''^*"'"® ^^ animal_at beginning 39°.2 C, at end Weight of animal, 3200 grammes. From these results we obtain : 1. Units of heat communicated to the calorimeter 9019.5 x 1.6 = 14431 2. Units of heat borrowed from tlie body of the animal -„ , 3200 X 0.83 X 0.9 = 2390 Result 14431 — 2390 = 12041. That is to say, the animal, during the period of observation gave off 12,041 gramme-units of heat. In calorimetrical experiments, the temperature of the water ' The absolute amount of lieat (in gramme-units) required to raise the calorimeter 1° C. of temperature may be ascertained empiricallv by introducing into the calorimeter (in place of the animal) a metal vessel containing a known weight of water at a known temperature— say 40O C— and determimng on the one hand the loss of heat sustained by the water, and on the other, the gain by the calorimeter in a given time 342 ANIMAL HEAT. eboiild, as a rule, be a little higher than that of the surround- ing atmosphere. Not only is this the condition most favour- able to the accuracy of the ob^rvations, but it is most advan- tageous as regards the state of the animal observed. If the temperature is too high, the disengagement of heat from the surface is relatively lessened, so that unless completely com- pensated for by increased evaporation, the bodily temperature of the animal will rise. If, on the other hand, the tempera- ture of the calorimeter is lower than that of the surrounding air, that of the animal sinks so quickly that its condition is no longer normal. It is obviously of great importance that the observations should be made in a room of even tempera- ture, and it is desirable that it should not be too cold. The method above described may be applied not only to the investigation of periodical and other physiological variations of the process of nutrition, but to the investigation of many abnormal states and alterations, such for example as those of fever changes affecting the condition of the surface of the bod^', changes affecting the circulation, respiration or nervous system, and changes produced bj- the action of various drugs.' — For the investigation of fever, tlie pyrexial state ma}' be pro- duced experimentally, either by injecting into the venous sys- tem small quantities (5 to 15 minims) of the exudation liquids of certain acute inflammations ; or by producing a local in- flammation, e. g., by applying croton oil to the surface. Al- though the increase of temperature produced bj- these methods has been carefully investigated by the thermometer, no suffi- cient investigations have as 3'et been made as to the quantity of heat produceendent on the vital conditions of the nerve. CHAPTER XXVIII. STIMULATION OF NERVES. _ Other things being constant, we may now take variations m the contraction of tlie muscle of a nerve-muscle preparation as a measure of variations in tlie condition of the nerve. A muscular contraction is a token of a nervous impulse passino- along the nerve, the extent and character of the one being a measure of the extent and character of the other : a tetanus in the muscle indicates a series of impulses in the nerves, follow- ing each other with not less than a certain velocity. 1. The Effects of the Constant Current.— 06s. I. Ar- range a nerve-muscle preparation in the moist chamber, with the nerve on non-polarizable electrodes, the muscle loaded with 10 or 15 grammes, lever attached, recording surface pre- pared, etc. Have a battery of two or more cells, and between the battery and the electrodes introduce the rheochord (Chap. XIX., sec. VIIL). Let all the plugs be in, and the travelling mercury cups close up. The resistance now offered by the rheochord, compared with that offered by the electrodes, is practically nil ; consequently none of the current from the battery will pass through the latter; there will, therefore, be no contraction in the muscle. Remove one of the plugs, viz., that one the removal of which throws the least resistance into the rheochord. A certain fraction of the current will now pass through the electrodes on account of the resistance thrown into the current through the rheochord by the removal of the plug. If a contraction be the result, let it be recorded; if none, let that fact be recorded too, noting on the recording surface the plug removed. Re- move the plugs one by one, recording the result each time. Replace the plugs one by one, also noting the results. It will bo found that a contraction of the muscle takes place, a nervous impulse is originated, only at the moment when the plug is withdrawn or replaced. It may be present 386 STIMULATION OF NERVES. at both withdrawal or reinsertion, or at either, or at neither; but no contraction occurs in the interval during which the plug or plugs remain away from the board or in their i^lace, provided tliat the current in the battery be constant and tlie condition of the nerve-muscle normal. A nervous impulse is generated in a nerve only when there is a sudden change in the intensity of a constant current j^assing through it (including the changes from and to zero, i. e., the total breaking and making of the current). So long as the current remains uniform in intensity, there is no contraction of the muscle, no nervous impulse generated in the nerve. The contractions so obtained are simple contractions, indica- tive of the advent of a single nervous impulse. Yery often, especially in working with winter frogs in early spring, the con- tractions thus obtained by variations in tlie intensity of a con- stant current are not simple, but tetanic. This is an abnormal result, wliich has not yet been investigated. The contractions obtained above are not onljr variable, inas- much as they come either at a diminution (breaking) or increase (making) of the current, or at both, but also differ in extent, i. e., the nervous impulses differ in intensity. These variations depend on the strength of the current (amount of variation of the current), the direction of the cur- rent, and the condition of the nerve. II. Law of Contraction. — 06k. II. Arrange in the moist chamber a nerve-muscle preparation as fresh and lively as pos- sible. Place the nerve on a pair of non-polarizable electrodes, about a centimetre apart. Insert between the electrodes and a battery of two or more cells, first the commutator, and then the rheochord. Let the positive and negative wires have different colors, the same throughout the whole apparatus in each case, and arrange so that when the handle of the commu- tator is raised, the current is ascending in the nerve ; when depressed, descending. The handle of the comra utator being horizontal, and the plugs of the rheochord all in, withdraw the mercury cups a few de- grees of the scale, and depress the handle of the commutator. If there be any contraction, record it. This is equivalent to the making in the nerve of an extremely feeble descending cur- rent. Then bring the handle of the commutator horizontal, and so break this feeble current, recording any result. After wailing a few minutes, repeat the observation, usino- an ascending current instead of a descending. Thus will be obtained the effects of breaking and making an extremely feeble constant current both ascending and descending. Then shift the mercury cups several degrees, "and repeat the whole observation. This will give the effects of makino- and BY DR. MICHAEL FOSTER. 387 breaking a still feeble but yet rather stronger descentlincr and ascending current. ° Proceed in this way, shifting the mercury cups by stages, until they are brought to the other end of the board ; t1ien remove the plugs one by one, the removal of each plug mark- ing a corresponding augmentation of the strength of the current sent through the electrodes on the nerves. Wait some minutes between each observation to allow the nerve to recover itself. Tabulate the results. They should be such that, throwing the various intensities of current into four categories, they illustrate the following law: Desc en ding. AsceudiDc. Make. Break. Make. Break. Weakest Yes No No No Weak Yes No Yes No Moderate Yes Yes Yes Yes Strong Yes No No Yes where " Yes " means a contraction ; "No," none. The making of the descending current is the first to make itself manifest by its effects, and maintains its pre-eminence throughout the series as the most certain and strongest stimulus. Next, the making of the ascending cwtrent also becomes effi- cient; then the breaking of the descending; lastly, the break- ing of the ascending ; so that with a certain intensity of current which we here call " moderate," a contraction is called forth both by making and breaking both ascending and descending currents. With a further increase of intensity, the contraction which follows upon the making of the ascending current gets less, and finally disappears altogether. The contraction due to breaking the descending current suffers subsequently the same fate, so that with a " strong" current we have only a single contraction with each current ; but it is a contraction on mak- ing in the case of the descending^ on breaking in case of the ascending. We have seen that when a constant current is sent into a nerve, katelectrotonus is established at the negative pole, ane- lectrotonus at the positive. Both conditions remain during the whole time of the passage, and both disappear (with more or less rebound) when the current is broken. It is evident from the above observations that the rise of a nervous impulse is connected with the transition of a nerve from its ordinarj' condition into that of either katelectrotonus or anelectrotonus, or both, or with its return from katelectrotonus or anelectrotonus into its normal condition, and not with its being or remaining in either katelectrotonus or anelectrotonus. 38^ STIMULATION OF NERVES. Turther, it is evident from the different results of breaking and maldng, that the entrance into liatelectrotonus and an°- lectrotonus has not the same relation to the origin of a nervous impulse as has the exit from those states. Lastl.y, from the different behavior of the ascending and descending currents, it appears that the effect of the entrance • into katelectrotonus is not the same as that of the entrance into anelectrotonus, and that the effects of the exits from these states likewise differ. III. Eleetrotonus as affecting Irritability.— Arrano-e a nerve-muscle preparation in the moist chamber, with levei-, etc. Prepare two pair of non-polarizable electrodes. Place the end of the nerve on one pair, about 1 or 2 cm. apart ; connect this, the polarizing pair, with a batteiy of one or two cells the commutator intervening. Place the second pair between the first pair and the muscle, and connect this, the excitino- pair, with an induction coil. "^ When the polarizing current is made a descendino- one, the portion of the nerve on which the exciting electrodes rest, will be in the region of katelectrotonus ; when ascending, in anelec- trotonus. Ohs. III. The polarizing current being shut off (the handle ot the commutator horizontal), pass a single induction (open- ing) shock through the "exciting" pair, and -record the con- traction. Shift the secondary coil, if necessary, until a con- traction of moderate excursion is obtained, and note the dis- tance of the secondary coil from the primary. Now let the polarizing current ascend in the nerve (throucrh the polarizing pair of electrodes) ; the exciting pair will Tc- cordingly now be in the region of anelectrotonus. Neglect the contraction which may be caused by the makino- (and subsequent breaking) of the constant polarizino- current" and while the current is thus passing in an ascendino- direc- tion, send a single induction shock of the same streno-th as before thi-ough the exciting pair, and record the contraction. bhut off the iiolarizing current, and after a few minutes' rest, send a third time the same induction shock throuoh the exciting pair. ° Of the three contractions thus called forth by the same stimulus (the induction shock) under different circumstances, ?}\ '\e found that the second is much smaller than the first but^the third nearly of the same size (it may be larger) as the During the passage of a constant current, the irritability of a nerve is lessened in the anelectrotonic region, the same stimu- lus giving rise to a weaker nervous impulse, and so to a smaller contraction. Obs. IV. Shift the secondary coil until it reaches such a BY DR. MICHAEL FOSTER. 389 position that tlie induction sliock given becomes tlie mini- mum stimulus requii-ed to produce a muscular contraction, that is, any further removal of the secondary from the pri- mary coil will lead to the absence of all contractions. This minimum stimulus then giving, in the absence of the polarizing current, a slight but obvious contraction, send an ascending polarizing current tlirough the nerve; the contraction will be wholly absent. Remove the polarizing current, and excite again ; the contraction will again make its appearance. Obs. Y. Remove the secondary coil a little furtlier avvav from the primary, so that an induction shock gives no con- traction where the polarizing current is cut off from the nerve. Pass a descending current through the polarizing pair, ^. e., throw the portion of nerve in which the exciting pair rest into katelectrotonus. Again pass the same induction shock as before: a conti'action will follow. Shut off the polarizing current, and after waiting a few minutes, send the induction shock through the exciting pair a third time. No contraction, or at best a very slight one, will be obtained. During the pasaage. of a constant current, the irritahility is increased in the region of katelectrotonus. Obs. Yl. The other arrangements being the same, put the magnetic interrupter into connection with the primary coil. Record the movements of the lever on the revolving cylinder. With a not very strong interrupted current, tlirow tlie mus- cle into tetanus, and as soon as tetanus is established, send an ascending current through the polarizing electrodes for a few seconds onlj', and afterwards close the key of the inter- rupted current. The curve of the tetanus on the recording cylinder will ex- hibit a marked fall (down even to zero if the polarizing current be strong enough) at the moment when the polarizing current breaks into the nerve, and a corresponding rise when the polarizing current is shut off. This is simply another way of showing tlie diminution of irritability in anelectrotonus. Obs. VII. Repeat the observation, using a very weak teta- nizing current, and let the polarizing current be descending. The making of the polarizing current will be marked bj' a rise, and the breaking by a corresponding fall in the tetanus curve, indicating, as before, an increase of irritability in katelectro- tonus. 06s. VIII. Ligature the nerve between the two pair of elec- trodes, and repeat all the observations. The polarizing current will have no effect at all upon tlie results of tlie exciting cur- rent. Otherwise, i^art of the effects described above will have 390 STIMULATION OP NERVES. been due not to vital changes in the nerve, but to escape of current or simple electrical changes. 06s. IX. Having arranged a nerve-muscle preparation with the polarizing, but witliout the exciting pair of electrodes, let the nerve between the electrodes and the muscle hang down in a loop. Let the extreme end of the loop dip into a drop of concen- trated solution of common salt. As soon as the irregular tetanic contractions resulting from the action of saline "fluid on the nerve make their appearance, pass an ascending current tlirough the electrodes. The tetanic spasms will be much less- ened, or cease altogether. Pass a descending current through the electrodes, the spasms will be increased. The general irrUabiUty, therefore, of the nerve is affected in electrotonus,not simply its susceptibility to electrical modi- fications. Obs. X. By introducing a rheochord between the battery and the polarizing electrodes, and by varying the number of cells used, the student will ascertain that the amount of in- crease of irritability in katelectrotonus and decrease in anelec- trotonus depends on the strength of the polarizino- current being greater witli the stronger. ° ' Obs. XI. By placing the polarizing electrodes at a variable distance from each other, it will be found that, with the same strength of current, the effect is greater the longer the piece of nerve between tlie polarizing electrodes. Obs. XII. By shifting the exciting electrodes nearer to and farther from the polarizing electrodes, it will be found that the effects of both anelectrotonus and katelectrotonus are greatest in the immediate neigliborhood of the polarizino- pair, and diminish tlie farther the exciting pair is from thi polarizing. In alUhe above observations, the stimulus, wliether electric or chemical or othei-, is brought to bear on the nerve between the polarizing pair and the muscle. Obs XIII. They may be repeated with the polarizino- pair placed between the exciting pair (or chemical stimulus) and tlie muscle. An ascending current will now throw the reoion of the exciting pair into katelectrotonus, a descendino- T„to anelectrotonus. ° The g-eneral results will be the same, but they will not come out with the same distinctness, for the following reason- When the exciting pair is placed nearer to the muscle tlian tlie polarizing pair, the nerve between the exciting pair and the muscle IS simply in a state of katelectrotonus, the intensity of which diminishes towards the muscle onwards There is nothing between the exciting electrodes and the muscle to BY DR. MICHAEL FOSTER. 391 modify the increase of impulse clue to katelectrotonus. Wheu the exciting pair is on the other side of the polarizing pair, and the region of the exciting pair tlirown into katelectroto- nus, for instance, the increased impulse due to katelectrotonus after passing through the region of katelectrotonus has to make its way through a region of anelectrotonus before it can reach the muscle — it has to struggle in this region against an- tagonistic influences, and whether it reaches the muscle as an impulse greater than, or less than, or simply equal to, that which occurs in a nerve not electrotonized, will depend on the relative amounts of the katelectrotonic increase of irritability and the anelectrotonic decrease of conductivit}'. This will be found to depend largely on the intensity of the polarizing current. If the current be weak, the katelectrotonic increase over the normal impulse (of the non-electrotonized nerve), though less- ened by having to pass through an anelectrotonic region, will be evident as a larger contraction in the muscle. If the polarizing current be strong, the contraction caiised b}^ the impulse originated in the katelectrotonic region will not only not be greater than the normal but will even be less, or may be absent altogether with a very strong (tliree or four Grove cells) polarizing current, owing to the impulse being completely blocked in the anelectrotonic region. Mutatis mutandis, the same results are witnessed when the effect of an anelectrotonic decrease has to pass through a kate- lectrotonic region on its waj' to the muscle. Obs. XIV. By placing the polarizing electrodes sufficiently far apart from each other, the exciting pair may be inserted into the intrapolar region, and the following results ob- tained : — In the intrapolar region, as in the extrapolar, there is an in- crease of irritability in the neighborhood of the negative, and a decrease in the neighborhood of the positive pole. The increase and decrease respectivel_y are greatest close to the poles, and diminish towards a neutral point situate between the poles. With a weak current, this neutral point lies rather nearer to the negative pole than the positive. By increasing the strength of the current it is driven nearer and nearer to the positive pole. IV. Other Variations in Irritability .— TAe farther from the muscle the part of the nerve excited, the greater the contraction. Obs. XV. Arrange a nerve-muscle preparation with two pair of electrodes, one close to the muscle, the other near to the cut end of the nerve. Connect both electrodes with a double key (Chap. XIX., *^92 STIMULATION OP NERVES. sec. IX.), and the double key with an induction coil. Arrano-e for single oi>ening induction shocks. '^ By means of the double key, put the lower electrodes next the muscle m connection with the secondary coil, and find what strength of the current (what position of the secondary coil) just falls short of causing a contraction. Then connect the upper electrodes with the secondary coil in place of the lower ones. Send through these a shock of the same strength as that which sent through the lower elec- foHow ^'■° """'^ "^^ contraction. A distinct contraction will Once more send the same shock through the lower elec- slMiTone ■' ""'" ^'' '' ^'^"''^ ^° contl-action, or a very The same stimulus produces, therefore, more effect when applied to a point farther from the muscle. Obs. XVI. This is partly due to the section of the nerve trunk above the higher electrodes. lai?''bivP^tfi°™"?'''^ destroyed the spinal cord of a frog, and laid baie the sciatic nerve without dividing it, place a uair of electrodes under the main sciatic trunk, send 1 feebK 4 induction shock through them, and reco^ the amount of con! tiaction m the gastrocnemius, or determine the position of the secondary coil, which gives a shock just fallin. short of he strength required to cause a contraction ° Divide the sciatic nerve a little distance above the electrodes and determine, at intervals of 15 minutes, the contractions which result from the application of the 'same stS ulu a Smum°y!m\dr^ ''' ^^^^^"^'^ ^' ''^ ^^-^-^ -^^ ^-^ ^ crease, am\ afterwards to aiminish, the irritability of the ' In th'e ^Lv' "h"" '-r^-" immediately below the seltio, . In the above observations, the student must make sure that the electrodes are exactly similar, so that the differences wliicl come out are not due to any differences of resista ce i he two pair of electrodes or to the electrodes of oi e air be n ' further apart from each other than those of the other etc ^ For this purpose it will be as well, after a series of observa tions, to exchange the electrodes, putting the one pair in tl^e oT Fvu "n' 'H' "''^'^••' "°^^ ^'^P-t^he series.' Obs. ^Vn On the sciatic nerve of a froo- in which the Dram and spinal cord have been destroyed,\and te heart removed so as to stop the circulation, plac'e t"iree pair of ctS e'^rorthe' «■■ "" g-,^---'--:-other cl'eTo the T) virion the nerve, and a third between the other two Divide the nerve above the upper pair Arrange the preparation carefully in the moist chamber. BY DR. MICHAEL FOSTER. 393 Send a, single weak induction sliocli through each pair of electrodes, and record the contraction ; or determine the minimum stimulus for each pair of electrodes. Repeat the observation at intervals during the da}'. It will be found that after the temporary' increase due to section, the irritability graduall_y diminishes from tlie central cut end towards the periphery, the extreme muscular branches being the last to die. Be careful that no part of the nerve is more exposed than others. Obs. XVIII. Repeat the observation in a frog whose brain and spinal cord have been destroyed, but the blood current not interfered witli. The irritability will disappear much more slowly, but in the same centrifugal manner. CHAPTER XXIX. PHENOMENA ACCOMPANYING A NERVOUS IMPULSE. The only phenomenon definitely and certainly known to accompany the passage of a nervous impulse is the negative variation of the nerve current (see Chap. XXVI., sec. II.). In the case of muscle, the negative variation shown in teta- nus by the galvanometer was proved by the rheoscopic frog to consist of a series of successive negative variations (see Chap. XXIV., sec. III.). At first sight a similar proof seems to be afforded by the be- havior of nerves. Obs. I. Prepare a nerve-muscle, and also a separate piece of nerve as long as possible. Place the nerve-muscle b (fig. 291) on a glass plate ; place the nerve a over the nerve of B,in either of the positions shown in fig. 291, 1. II. ; connect the end of A with an induction coil. A single shock sent through A will produce a contraction in b; an interrupted current will throw b into tetanus. 06s. II. Ligature a between the electrodes and the end touch- ing B. No contractions will appear in B on sending shocks through the electrodes. This proves that the results of Obs. I. were not due to any simple electrical conduction through A or to any escape of the current to b by other means. The same thing is shown in the so-called "paradoxical con- traction." Obs. III. In the leg of a frog, the sciatic nerve divides at the 894 PHENOMENA ACCOMPANYING A NERVOUS IMPULSE. lower end of the thigh into the peroneal and tibial branches, l^issect out one, say the peroneal, and divide it at its periphery'. Divide the sciatic trunk high up, and place the peroneal branch on the electrodes of an induction coil. This will virtually con- vert the leg into a preparation similar to fig. 291, III.; the peroneal and tibial branches running, so to speak, side by' side in the sciatic trunk. Irritating the peroneal nerve a, with an interrupted current will produce contractions in the muscles to which the tibial b IS distributed. _ All these " secondary contractions" cease when the nerve a IS ligatured between the electrodes and the nerve b With each making (competent to give rise to a nervous im- pulse) of the exciting current through a, two events take place which must be kept distinct in the mind of the student. First, there is the electrotonic increase (in the anelectrotonic region or decrease (in the katelectrotonic region) of the natural nerve current. This increase or decrease remains during the whole time of the passage of the exciting current, and disappears with tlie breaking. Secondly, there is the yiegatim variation of the natural cur- rent which travels with the nervous impulse indifierently in either direction, and which, in any given point of the nerve is over and gone in an exceedingly short time after the act of making tlie exciting current. During the time of the passage of the (uniformly constant) current, there is no negative variation, as there is no nervous impulse. On breaking the exciting current, a fresh negative variation sweeps along the nerve, if the current is of such a character that the breaking of it gives rise to a nervous impulse. V\ ith a single induction shock there is also the double event of a negative variation, and, as well, of a momentary electro- tonus ; with an interrupted current there is a succession of such double events. In both these cases the secondary contraction, as in Obs. I II., III., may be due to either half of the double event: to the' negative variation or to the electrotonic change; or to both. To winch of them it is really due cannot be deckled bv the use ot such currents only. If, however the electrotonic increase is itself competent to cause a secondary contraction, the contraction ought to be ob- tainable at any period during the passage of an exeitino- con- stant current, at a time when the negative variation is absent. 06i. ly. Connect a (placed on a glass plate) with a constant current of two cells, the positive pole%owirds the lono freeen 1 suspend the nerve of b in such a manner over a that^ when de^ Il'tfl.^ 291) '"^^ "" '' '° ^'' "i^"" ^ "^ '^' P-^^ "°" I °'- BY DR. MICHAEL FOSTER. 395 The exciting current being made, a negative variation sweeps over A and is gone. Tlierc remains, however the anelectrotonic increase of the natural current of A along the whole region from the positive pole to the free end. Now^ let fall b as directed. A contraction in the muscle of b will follow. This can onl^^ be due to the electrotonicalh' increased natural nerve current of a acting as a stimulus to the nerve of b when the circuit is closed by a portion of b, and so causing a nervous impulse just as the closing of any other galvanic current would. And inasmuch as the electric intensity of the electrotonic increase (or decrease) is much greater than that of the negative variation, the secondary contractions iu the 06s. I., II., III. are chiefly due to this cause. CHAPTER XXX. VAEIOUS FORMS OF STIMULxlTION OF MUSCLE AND NERVE. I. Mechanical Stimulation. — A blow, sufficiently strong and sudden, applied to either muscle or nerve, will produce a contraction; and a series of such blows repeated sufficiently rapidly will ]iroduce a tetanus. This maj' be roughly shown bj- striking simply bjr hand, with some thin but blunt instrument, either muscle or nerve. For more exact purposes, the tetanomotor of Heidenhain may- be used, and can be applied equally to muscle or nerve. For a description, see Rosenthal, Electricifatslehre, p. 116. A simpler method is that of Marey's, with a tuning-fork. ' Obs. I. Get readjr a nerve-muscle preparation. Place the nerve on a small piece of India-rubber sheeting stretched quite tight over a ring of wood or metal. The object of the elastic India-rubber is to soften the violence of the blows given. Ar- I'ange a tuning-forlv on a stand, in such a position that the vibrations of the tuning-fork shall take place at right angles to the nerve. Set the fork going, and bring it in slight contact with the nerve. The muscle will at once be thrown into teta- nus, which may be recorded on the cylinder. Obg. II. A muscle (gastrocnemius, or, better, one of the recti) of a frog poisoned with urari, may be placed on the caoutcliouc in place of the nerve. Tetanus will be then obtained by direct mechanical irritation of the muscle itself, without intervention of the nerves. 396 VARIOUS FORMS OF STIMULATION. II. Idio-Muscular Contractions.— O&s. III. Place on some flat surface a nerve-muscle preparation winch has been much exhausted by treatment or by long removal from the boay. Strike the muscle sharply with some thin but blunt instru- ment (handle of scalpel), across the middle of the belly at right angles to its long axis. . A contraction will probably follow—a contraction which, as usual, travels along the whole length of the fibres Wlien the contraction, however, has passed away, the line where the blow fell will be marked by a wheal, i. e., by a local shortenmg and thickening, which lasts for several seconds, but finally disappears. This wheal, this local thickening and short- ening, is the idio-muscular contraction. 06s. IV. Wait till neither muscle nor nerve give any fordi- nary) contraction with an electric stimulus. Strike as before ■ the idio-muscular contraction will still make its appearance! Ihe lelaxation becomes slower the nearer the advent of rigor d-Z!7'eIrl °"''' °^ "'"'''' *'''' idio-muscular contraction „ "^V^'^^™^^^^ ®*^™"^^*i°n of Muscle.— 06s V Care- ully dissect out the sartorius muscle in the front of the thi<.li (fig. 278.5) injuring it as little as possible, and takino- away with It a piece of the pelvis from which it has its origin, "ciamp the piece of pelvis avoiding any entanglement of the fibres of the sartorius itself, and attach the clamp to a stand so that the muscle hangs vertical. If it be desired to record the contrac tions, thrust a fine needle through the middle of the muscle and either bnng the muscle to bear directly on the record n J suiface, steadying it with a shotted thread as in the kvmo° graphion (Chap^XVL, § 33), or make the neecUe mrt'ora" de icate lever. With a sharp pair of scissors, cut off the tn culai fi;"e" " " " '° ^"'' ''"" " transverse' section of mus- Place a drop of any or each of the below-mentioned fluids on Lf ffl^-Tf'-" ^/"'^ ^'^"'^ ^^" ^' ^« l^-'*^ - good convex su face of fluid) and very gradually raise the plate until tiie fluid comes in contact with the muscular surface Immedia eh or Si:Ser^ ^°""^'' ^^-'"°^'^ contraction;^Sthe v^a:^::^^^:^'' ^^^^^'^^ ^'-^^^^ ^« — i- flares meSrsnlts't' ''"'" 'I'^'" '""^''^'^y dilnted; solutions of metallic salts strong solutions of neutral salts of the alkalies • lactic acid ; glycerin, even diluted to a considerable extent ' Obs. VL Ihe vapor of ammonia, even in mere traces acts as a powerful stimulus Place a few drops of ammonia in 'a smaU flat wide-mouthed bottle; cover the top with a greased o^S plate. Protect the muscle from all extraneous^apor ot' am BY DR. MICHAEL FOSTER. 397 moni.i, and bring the closed bottle immediately under it. Tiie mnscle exhibiting no contractions (there being no escape of ammonia), slip away the glass cover from the top of the bottle ; contractions will at once follow. In the above observations, a fresh surface of muscle must be cut after each trial, as tiie body used as stimulus destroys the layer of muscle with whicii it is immediately in contact. Apply tlie substance under trial as soon as possible after making the section, as the surface exposed soon dies. IV. Chemical Stimulation of Nerve.— 06s. YIT. Pre- pare a nerve-muscle witii as long a piece of nerve as possible. Fasten the muscle in the champ, and support the nerve so tliat the end hangs freely down in a vertical position. Bring a drop of one of tlie below-mentioned fluids, on a glass plate, in con- tact with the end of the nerve, allow some millimetres at least of the nerves to be fully immersed in the fluid ; and either take a fresh nerve-muscle for each experiment or cut awajr eacli time all that portion of the nerve which had been previously exposed to the action of the fluid. The movements of the muscle may be recorded as usual. Do not load the muscle with anything more than the lever itself. The following substances applied to a nerve produce con- tractions in its muscles : — Mineral acids, in considerable concentration only ; neutral salts of the alkalis and metallic salts, in considerable concen- tration only; lactic acid, only vihan concentrated; glycerin, only when concentrated. Ammonia hardly acts at all as a stimulus to nerve ; in making trial with this, care must be taken to protect tlie muscle from .all ammonia vapor. V. Thermal Stimulation of Muscle.— 06.s. VIII. Hav- ing arranged a sartorious muscle, as in Ohs. V., bring to the lower cut surface a thin slip of heated metal. On contact taking place, a contraction will result. In this case the lieat is applied to a part only of the muscle. Ohs. IX. Attach a gastrocnemius to a lever (either with the origin of the muscle downwards and the tendon upwards, or in the ordinary position with the tendon playing round a pulley) in such a way that the whole muscle may readilj' be immersed in fluid. Fig. 292 represents a convenient arrange- ment for this and other purposes. The muscle a is fastened to the clamp c, which is part of the bent holder d. This holder moves on the same upriglit as the lever e. The tendon of the muscle is attached by the thread b to the lever, so that its contractions pull tlie lever down. The lever is counter- balanced by weights carried over a pulley. The muscle can thus be readily immersed in or withdrawn from any fluid. Counterbalance the lever with 10 or 15 grammes. 398 INDEPENDENT MUSCULAR IRRITABILITY. Immerse tlie whole of the muscle in a small vessel filled with normal saline solution, and around the small vessel place a large one, through which send a stream of hot water. By means of a thermometer, ascertain the temperature of the saline solution close to the muscle. When the tempera- ture rises to 38"-40° C, the muscle is thrown into tetanus. In this case the temperature of the whole muscle has been raised at as nearly as possible the same time. Immediately that tetanus has set in, withdraw the muscle from the saline solution. The tetanus will speedily pass away, and the muscle will remain alive and irritable. Repeat the observation, but allow the muscle to continue at the temperature of 40° for about two minutes. On removing the solution, the muscle will still remain in a state of tetanic contraction, as indicated by the position of the lever, and from that contraction no relaxation will take place. No stimulus, however strong, will be able to call forth any further contraction. The reaction of the muscle will be found to be acid, and its extensibility diminished. In fact, the muscle will be found to have passed from a state of tetanus into a state of rigor mortis. VI. Thermal Stimulation of Nerves.— 06.s. X. Ar- range the nerve-muscle preparation with the nerve dependent as in 06s. VII. Bring a hot surface to bear on the end of the nerve, or dip the end of the nerve into a hot normal saline solution, or place the end of the nerve in a small quantity of the normal saline solution, the temperature of which gradually raise. In all cases contractions in the muscle will follow. CHAPTER XXXI. UEARI POISONING AND INDEPENDENT MUSCULAR IRRITABILITY. Obs. I. Introduce beneath the skin of the back of a stronassage of sensory, but not of motor impulses. Obs. YI. Carefully cut away the posterior roots on which you have been experimenting. The anterior roots, which are thin- ner than the posterior, will now come into view. Repeat on one of these anterior roots (9th nerve) 06s II Mere touching the nerve will probably produce a movement of the hmd hmb of that side. This result will at all events follow upon ligature and section. Stimulation of the peripheral stump, with even a very feeble stimulus, will produce tetanus in the limb. Obs. VII. Repeat on the anterior root next above Obs III Ao effect whatever will be produced by stimulatino- the cen- tral stump. ° BY DR. MICHAEL FOSTER. 405 The anterior rool.-^ conveij motor impulses centrifugalli/, but not sensor)/ im^^ulsrs eentripetallt/. Ohs. Till. In a fresh, strong frog la.y bare the roots of the spinal nerves and divide the posterior roots of the Tth, 8th, 9th, 10th nerves on tlie right side and tlie corresponding anterior roots on the left side. *• Tlie left leg will remain motionless, being simplj^ drao-ged along by the rest of the body, but never moving of itself. ""[If the brain has been previously destroyed or separated from the spinal cord, the right leg vriil be drawn up as usual (see Chap. XXXIII.), but not the left leg.] Pinching tlie right foot, or otherwise irritating the right leg, will give rise to no movement whatever in any part of the body, will call forth no signs of sensation. Pinching the left foot, or otherwise irritating the left leg, or any part of the body except the riglit leg, will produce move- ments which may occur in any part of the bodv except the left leg itself. In this case the right leg has had all its posterior, the left all its anterior, roots divided. No centripetal impulses pass up from the right leg to the central nervous system ; no centrifugal impulses pass down from the central nervous system to muscles of the left leg. The posterior roots are the channels of tit e centripetal (sen- sory), the anterior of centrifugal (motor) impulses. Recurrent Sensibility.— This is never witnessed in the frog. It can only be shown in the higher animals, the cat or dog being best adapted for the purpose. The method adopted is very similar to the above — the arches of one or two verte- bras being carefully sawn through or cut through with the bone forceps, and the exposed roots being very carefully freed from the connective tissue surrounding them. If the animal be strong, and have thoroughly- recovered from the chloroform and from the operation, irritation of the peripheral stump of the anterior root causes not only contractions in the muscles supplied by the nerve, but also movements in other parts of the bod}- indicative of pain or of sensations. On dividing'the mixed trunk at some little distance from the junction of the roots, the contractions of the muscles supplied by the nerve cease, but the general signs of pain or of sensation still re- main. These disappear when the posterior root is also divided. Hence it is inferred that fibres conveying centripetal impulses pass downward along the anterior root to the mixed trunk, and thence, turning round, run back again to the central ner- vous organ along the posterior root. (For further details, see Bernard, Lejons sur la Pliys. du Systeme Nerveux, Vol. I., p. 62 et seq.) 406 EEFLEX ACTIONS. CHAPTER XXXIII. REFLEX ACTIONS. Reflex actions are best studied in tlie frog, the brain liav- ing first been removed, or at least separated from the spinal cord. The strongest and healthiest frogs should be chosen for the purpose. The student should make himself acquainted ■with the general form of the dried frog's skull. This having been done, the position of the occipito-atlantal articulation may readily be recognized on the living animal. Division of (he Medulla Oblongata.— Raxhig wrapped a cloth round the hind legs and body of the animal, clasp the fore legs round the ring finger of the lei't hand, and hold them in posi- tion by the middle and little fingers, which should also hold tight the cloth. Press down the tip of the frog's nose with the thumb of the same hand, so as to bend the neck as much as possible. If tlie fore-finger of the right hand be now made to glide over the roof of the skull, exactly in the mid-line from before backwards, a slight but distinct" depression will be felt in the neck at the point where the occiput ends, and where the medulla is covered, not by bone, but by the occipito-atlantal membrane. It lies in a line drawn across the skull at a tan- gent to the hinder borders of the two membrana tvmpani. (Fio-. 266, line a-b.) ° The position of this point being satisfactorily ascertained, with a sharp-pointed scalj^el make a small transverse incision across it about a few millimetres long. The incision should not be carried too far on either side. If the blood, which comes freely, be rapidly taken up with a sponge, and the neck be kept well bent, the medulla will be clearly seen. This should now be completely cut across, and the wound be rapidly sponged, in order that the division may be ascertained by actual inspec- tion to be complete. The encephalon may then be completely destroyed by introducing a blunt piece of wire into the wound, and eviscerating the skull. If the wound be then left to itself the bleeding will, in most cases, soon cease ; if not, a small pluo- of wood (the sharpened end of a lucifer match) may be thrust into the skull. This, however, should be avoided if possible. It IS better to conduct the operation in this way, seeing clearly what is being done, than to divide skin, membrane, and^medulla by one thrust, without being able to tell exactly whether the division is complete. a BY DR. MICHAEL FOSTER. 407 Decapitation. — Introduce one blade of a strong pair of scissors into tlie mouth, and bring it, transverse to tlie long axis of the head, as far back as possible. Bring the other blade down to the skin behind the occiput, and quickly cut off the head, being careful that neither blade slips forward. Simple inspection will, at once, determine whether the whole of the encephalon has been removed or no. The bleeding, in manj- cases, is excessive, and must be staunched by astringents or by the actual cautery. Indeed, where decapitation seems desirable, it is far better to employ the galvanic cauture, introducing the loop of platinum wire into the mouth, and brinoino- it out throuirh the oceiinit along the line a-h. fig. 3G6. For the general study of reflex actions, division of the medulla is preferable to decapitation. The large amount of bleeding, the exposure to the air, and possibly other causes, often lead, in the latter case, to abnormal results, ex. gr., pseudo-voluntarjr movements on the one hand, and lack of reaction on the other. Obs. I. Place the frog, immediately after the division of the medulla, on its belly, with its legs extended. In most cases the legs will remain extended, and at first no movements will be produced by stimuli applied to any part of the body. The animal (or rather its spinal cord) is in a state of shock, consequent upon the operation. If the animal be watched, it will be found that after a while the hind legs, apparently without the intervention of any external stimulus, are suddenlj', first one and tlien the other, drawn up to the body, and assume the wonted flexed posture. This is a token that the condition of shock has passed away. If now one of the legs be pulled out, and then let go again, it will be immediately drawn up once more under the body. After the shock has passed away, the legs having been drawn up, the animal w^ill appear to have assumed a natural posture. On observing it more closelj^, however, it will be found that the posture is not quite natural. The line of the back is too horizontal, the iiead lies flat, witli the neck almost touching the table, and the fore limbs spread out ; whereas an entire frog keeps the head and neck raised high up on the almost vertical fore limbs, and the line of the body makes a large angle with the plane of the tal)le. If left to itself, the frog will exhibit no movements whatever, will not stir from the spot in which it is placed unless some external stimulus be brought to bear upon it. This absence of spontaneous movements is most marked, when sudden variations of temperature are avoided, and the skin is not allowed to get dry. Hence it is advisable to place the animal on a dish containing a small quantity of water, and to cover it with a glass shade. 408 REFLEX ACTIONS. If turned over and placed on its back, it remains for an indefinite period in that position, Avitliout malnng any attempt to regain its natural posture. While on its back, the heart may be observed beating, but the respiratory movements will be wholly absent. ^ If thrown into a basin of water, it will sink to the bottom like a lump of lead (unless the lungs be too much distended witli air), without making any attempt whatever to swim. By irritating it in various vrajs, it may be made to execute a variety of movements (see following observations), but can- not, by any means, be made to leap or spring forward. Obs.^ II. With the point of a needle gently stroke the abdominal walls on one side. A slight "twitching of the muscles of the region so stroked will be witnessed. ° This is one of the simplest forms of reflex action. Contraction takes place in muscles on that side of the body only, the afferent nerves of which are affected by the stimulus, and it will be found that the afferent and efferent nerves concerned in the action belong tolerably exactly to the same segment of the spinal cord. On increasing the stimulus gradually by stroking more forcibly, the twitchings will be seen to spread over a wider and wider area, to invade the other side, and finally to pass into the hnider and fore limbs. With a stimulus, sufficiently slight, of an afl^erent nerve, a definite small group of efferent fibres are alone affected by reflex action. On increasing the intensity of the stimulus, the effect spreads into a larger and larger number of efferent fibres. 06s. III. Pass an S hook through the lower jaw, and thus suspend the animal on a suitable upright, with the leo-s and Dody hanging freely down. Or, take a piece of thin wood, about an inch broad and five long ; place the frog, belly downwards, on it, in such a way that the wood reaches no farther down tlian the lower part of the abdomen, and secure the frog to it by two slight India- rubber bands, one immediately below the fore limbs, and the other a httle above the thighs. If the wooden slip be now fastened vertically m an upright, the hind limbs will haucr ;Sen«;"firr^'^'^^^^ ^^^^^' "'^''^ '^'^ '^'^^^^ -" ^^ '-^^^ For most purposes the former simpler- method is sufficient. V\ I en It IS desired to study the movements of the le-^s alone with some accuracy, the latter method must be adopted Ihe legs hanging freely down, and the body being com- pletely at resf: wuh a smooth pair of forceps gently pinch the tip of one of tiie toes. The leg will immediltely be drawn sharp ly up, and af^ter being kept in the flexed position for a variable time, will be slowly dropped again. BY DR. MICHAEL FOSTEK. 409 Eepeat the observation on the other leg. Onl3' that leg, tlie toes of which are pinelied, is drawn up: and if the toes ho not too ronghly treated, no other movement than the drawing up of tlie leg is witnessed. Obs. lY. With more force pinch the folds of the skin aronnd the anus. Both legs will be suddenly corai)letely drawn up, so that the toes of hotli feet arc brought above the forceps, and are then as suddenly and completely extended again. This movement of sudden flexion and extension, that is of kicking, may be repeated rapidly several times as the result of one for- cible pinching of the region in question. Obs. V. Pinch with some force the skin at a point on one side of the loins. The leg of the same side will be suddenly flexed over the back, and brought round back again with a sweeping movement. Obs. VI. The hind limbs hanging down as before, place a watch or other small glass containing very dilute sulpliuric acid (one drop to 20, 30, or 50 CC"', strong enough to give an acid taste) nnderneatli the frog, and bring it close up to one of the feet, so that the extreme tip of the longest toe just dips into the acid. Within a short time, the exact length of time being determined by the strength of the acid and the condition of the frog, the leg will be flexed, and the foot withdrawn. Tei-y frequently the movement, even after the fluid has been taken quite out of the waj', is not confined to a single flexion followed by a relaxation, bnt consists of a series of flexions and relaxations, each succeeding flexion being less marked than its predecessor. Eepeat the observation with varying degrees of acidity, beginning with simple distilled water, and gradiially adding acid. Be careful to wash the foot carefully with water after each observation, to wait some minutes between each applica- tion, and to dip only the tip of tlie toe, and that to tlie same extent in each case. Measnre by means of a metronome, beating very rapid!}', the exact time intervening between the actual entrance of tlie ,toe into the fluid, and its withdrawal. With an acid of a given strength, applied to the same frog under vaiying circumstances, the duration of this interval may be talien as a measure of the power of reflex action. Tiie shorter the interval, the more prone is the cord to reflex actions. In making observations on the length of this interval, it is as well to use very dilute acid, such as will onljr just give a sensation of acidity when applied to the tongue. Obs. YII. Simple water of a sufHciently high temperature (25°-.35°C.) may be used instead of the acid. It has the ad- vantage of being less likely than tlie acid to produce a perma- nent action on the skLii. The difficulty, however, of keeping 410 REFLEX ACTIONS. up exactly the same temperature renders it unsuitable for com- parative experiments. In all the above experiments tbe movements produced bear marks of purpose. As the result of stimulation of a particular region of the surface of tbe body, we find a complicated move- ment, a movement brought about by the contraction of certain muscles and sets of muscles, acting in a definite combination and sequence. The movement thus produced is apparently directed towards an end. Thus when the foot is pinched or irritated by the acid, the resulting movements appear at least directed towards, and frequently actually effect, the withdrawal of the toot from the offending object ; when the flank is pinched, the movement is such as tends to thrust away the points of the forceps ; wlien the anus is pinched to kick awav the forceps, and so on. " This purposeful character of reflex actions may be still more conveniently shown by adopting the following method :— Oba. VIII. Arrange tiie frog with the legs alone free ac- cording to the second method given above. Cut small pieces of blotting-paper about 1 or 2 millimetres square, dip them in strong acetic acid, remove from them all superfluous acid, and then place them on definite regions of the skin. In this way the stimulus may be limited to very small areas chosen at pleasure • and It will be found that very different movements of the hind limbs will be produced by applying the morsel of paper to dif- ferent regions of tlie body. Thus if the morsel be placed on the heel of one foot, both feet will be violently rubbed together, while the legs remain forcibly extended. If the moisel be placed on one flank, it will be rubbed off' by the foot of the same side ; if it be placed in the mid-line of tlie back, either or both feet will be employed to remove it, and so on The student will do well to map out the limbs and body of the frog into small areas, and to determine the characters of the movements, which result from the stimulation of each area. He will in this way find abundant instances of an appa- rent purpose. '- ^ 06.9. ]X It has been seen tliat where the morsel of acid paper is placed say on the right flank, it is the right leo- and the i-ight leg only, which under ordinary circumstances il used to rub ofl: the paper. Choosing a strong frog, in which reflex action has been found to be highly developed, suspend it ac- cording to tlie second method, hold the right leg firmly down or load It with a greater weight than the leg is able to lift, and apply a morsel of acid paper to the right flank. Twitchinag and convulsive movements of tlie right leg are first witnessed and then the left leg is brought up to rub the rio-ht flank I lace a similarly strong frog with powerful reflex capabilities on Its back on the table. BY DR. MICHAEL FOSTER. 411 If a morsel of p >- g ov .3 -^ \_ 11 53 p >- d .2 (a 0. rQ a o -73 |3-S" Ct So t3 CD CO 3 o "8 -^ -^ CD S3 rt rP a j^ pr o £ |5 QJ ^ g'l CO ^ ^ •r^ t 1^ , xn ' ^ ' ' o m -iH CD '3 9" O B5 oi a 3 '0 n .9 a a ■^ m o 3 .a 1 'Sec ^^ d p a s ^ 3 ^ O a: Q CI d" Q .9 1 .2 ■ 0^ ^ d "^ oj d -^ do f3 d rt '0 ;d rt CD ^ £ 2 '0 _2 CO 'P C3 c/j CO .0 ^ tl, ^ d CD Ci CD ■J:^ CO £ g 2 Gj CJ "^ CD -e o o J3 .2 '0 g; CO '0 oj a '0 CD ^ ^ Is £ H fl^ £ iz; , ■^ t , !>i ^ .Q GJ QJ S +^ 9 r^ rd bO rTi o 438 ALBUMINOUS COMPOUNDS. as fibrin, for a long time with water, especially under pressure, in a Papin's digester, in a sealed glass tube, or in a soda-water bottle. By boiling witli dilate sulphuric acid or concentrated hj'drochloric acid, they are produced in a sliorter time. The production of peptones by the digestive ferments will be con- sidered afterwards. 35. Leucine. — Preparation. — It may be obtained by boil- ing fibrin with dilate acid for a long time, or by digesting it with pancreas, but it is more usually got from horn chfps. Boil two parts of lioi-n shavings with five parts of sulphuric acid, previously diluted with thirteen parts of water, for twenty- four hours, loss of water by evaporation being prevented by tlie arrangement shown in fig. 329. Saturate the fluid while hot, with chalk, filter, evaporate the filtrate to half its bulk, add oxahc acid to precipitate the lime, filter and evaporate till a scum forms on the surface, and then set it aside to crystallize. A considerable amount of tyrosine will crystallize out first. Pour off the liquor, let it stand till crystals of leucine form Purify them by boiling witli water and lead hydrate, filter, re- niove the lead by sulphuretted hydrogen, filter, evaporate the filtrate in a water-bath to dryness: dissolve the residue in hot weak alcohol, and let it cool and evaporate till crystallization takes place. Leucine can be formed synthetically, and if wanted pure this IS the best way of obtaining it. For this purpose a mixture of valeral-ammonia, hydrocyanic and hydrochloric acids are boiled together in a retort till the oily ammonium compound has disappeared. The liquid is then evaporated to dryness, the residue is boiled with water and lead hydrate, and the product purified as already directed. _ C7iarfficters.— Leucine forms extremely slender, white, <^listen- lug plates. Allow a drop of a solution in water or alcohol to evaporate on an object-glass and examine it under the micro- scope. It will form round balls, which are either hyaline and strongly resemble fat globules, or exhibit radiatiuo- lines ' Or It may appear as very thin plates grouped in a radiating fas'hion. They differ from urates presenting a similar form in not bein- strongly refractive. ° So/"6i7%._l. Water: Pure leucine dissolves slowly, and is soluble in about twenty-seven parts of cold water. It.c issolves more easily in hot water. When impure it is more easily solu- 2. Alcohol: Pure leucine dissolves in 1040 parts of cohl and 111 800 of hot alcohol. If impure, it is much'more solubl ' rerdif^soire: '"''""' '' ^""«"^^' '^-^ ^' ^^'1"^° --^^> it is 6. Concentrated hydrochloric or sulphuric acids. It is dis- BY DR. LAUDER BRUNTON. 439 solved without decomposition. Neutralize them, and it is precipitated. t Effect of Heat. — At 110^ C. it sublimes unchanged: a higher temperature decomposes it. Put a little leucine into a Avj test-tube and heat it gently. It will rise in white clouds and be deposited on tlie cool part of the tube. Heat the deposit strongly and a strong smell of amj'lamine will be perceived. Decomposition. — When decomposed by heat it yields CO^ XHj, and amylamine. To show this put a portion of leucine into a hard glass bulb, and connect this by means of India-rubber tubing with a glass tube long enough to reach to the bottom of a test-tube. Pre- pare two other similar pieces of glass tubing and three test- tubes, tlie first of wduch should be about half filled with caus- tic baryta solution, the second with Nessler's reagent, and the third with water. Heat tlie bulb containing the leucine, apply- ing the heat first to the upper part of the bulb and graduall}^ moving it downwards, so that as the leucine sublimes its vapor may be strongh' lieated and decomposed. Pass the fumes into the baryta solution, then disconnect the glass tubing, and after attaching a clean piece, pass them into Nessler's reagent and then into water. The baryta will be precipitated as white car- bonate, the Nessler's reagent will become brown, sliowing the presence of ammonia, and the water in the third test-tube will acquire the peculiar smell of amylamine and an alkaline reac- tion. Add to tlie barium solution a little nitric acid. It will become clear and evolve gas, showing that the precipitate was barium carbonate. A minute quantitj' onlj'- of NH^ is disen- gaged when leucine is heated alone, and the coloration of Ness- ler's reagent is therefore very sliglit. If a little lime and caus- tic soda or potash are heated with the leucine much more NH. is given off. 36. Preparation of Nessler's Reagent. — Dissolve 4 grammes of potassium iodide in 250 cub. cent, of distilled w^ater. Set aside a few cub. cent, and add a cold saturated solu- tion of mercuric chloride to the remainder, till the precipitate of mercuric iodide is no longer dissolved on stirring. Add that part of the potassium iodide solution wliich was set aside, to the rest, so as to dissolve the remaining precipitate, and then add mercuric chloride again ver^' gradually', till a slight per- manent precipitate is produced. If a few cub. cent, of the potassium iodide solution were not set aside, great caution would be required in adding the mercuric chloride so as to avoid excess. Dissolve 150 grammes of potassium hydrate in 150 cub. cent, of distilled water, allow the solution to cool, and add it gradually to the potassium iodide solution. Pour the mixture into a measuring-glass or flask, and add distilled water 440 ALBUMINOUS COMPOUNDS. to make np fi litre. Pour it into a large well-stoppered bottle, taking care tliat there is no ammonia near it at tlie time. It will deposit a brown precipitate, and become quite clear and of a pale greenish-3-ellow color. It is then ready for use ; a little of it should be poured into a smaller bottle when wanted. 37. Detection of Leucine in Tissues.— In order to de- tect the presence of leucine, cut up the organ (the pancreas of a sheep or ox, for example) into small pieces witli a large knife or sausage-making machine. Mix it with water and let it stand for a little while, stirring it frequently ; filter it through a piece 01 cloth, and press out the water first with the hand, and then with a screw-press. Extract it with water a second time in the same way. Mix the watery extracts togetlier, acidily slio-htly with acetic acid, and boil, to coagulate the albumin. pTlter- add a solution of lead acetate to the filtrate. JFilter : pass sul- phuretted hydrogen through the filtrate to remove the excess of lead. Filter: evaporate the filtrate to dryness. Extract the residue with boiling alcohol. Filter : evaporate the filtrate to a syi-up, and set it aside for several days to crystallize. If leucine is present, it will crystallize in a day or two in balls or Jvnots, or, possibly, in shining plates, but will not form o-ood crystals. It is not pure, but is mixed with a number of olhcr substances. In order to free it from these, the followino- method IS recommended by Hoppe-Seyler. Dissolve it in ammonia, add lead acetate till no further precipitate is produced Filter • wash the precipitate witli a little water. Suspend it in water and pass sulphuretted hydrogen through it. Filter and evaporate tlie filtrate in the water bath. ' 38. Tests for Leucine — The formation of round lumps or plates IS not sufficient to prove that a substance is leucine and other tests must be applied to them. Before doing so, they should be purified by drying them between two folds of blot- ting-paper, dissolving them in boiling alcohol, and letting them crystallize out again. The following tests may be applied •_ 1. lut a portion into a dry test-tnbe and "heat it over a Bnnsen's burner or spirit-lamp. If it consists of leucine, it will emit the smell of amylamine. ' 2. Schcrer's Test: Tut a small portion of the supposed leucine with a drop of nitric acid on a piece of platinum foi and evaporate It gently. If it is pure leucine, a colorless almost invisible, residue will remain on the foil Add a few d ops of liquor potassa. to it, and heat. It will become yellow u on'Tl?e"bi;iH,o ?"if™^ "^ oily drop, which runslabouT upon tlie loil witliout adhenno- to it. 39. Tyiosine.-Preparatlon.-Boil horn shavings ^-ith dilute sulphuric acid crystallize out the tyrosine, as d reete in the preparation of leucine, wash the crystal^ with cold BY DR. LAUDER BRUNTON. 441 water, dissolve them in ammonia, and allow the solution to evaporate, until the tyrosine crystallizes. It forms fine colorless microscopic needles, with a silky lustre, and without taste or smell. Or digest fibrin witli pancreas, see § 111. Characters. — Let a drop of a solution of tyrosine in hot water evaporate on an object-glass, and examine it under the microscope. Long needle-like crystals will be seen which are often united in single tufts, or in 'radiating groups of tufts. SolubiUty. — 1. Cold water dissolves it with difficulty. 2. Boiling water dissolves it easily. Almost all the tyrosine crystallizes out on cooling. It is insoluble in, .3. Absolute alcohol, 4. Ether. It is easy soluble in, ,5. Ammonia, 6. Liq- uor potasste, T. Concentrated solution of potassium or sodium carbonate, 8. Alcoholic solution of caustic potasli, 9. Concen- trated hydrochloric or sulphuric acid, and, 10. Dilute mineral acid. 11. Acetic acid dissolves it with difficulty. 12. Nitric acid dissolves it. Let the solution stand a while. A jrellow crystalline powder of uitro-tyrosine will separate. Pour off the liquid and add liquor potassa?. to the powder. It will dissolve and form a red solution. 40. Detection of Tyrosine.— Treat the organ exactly as described in the process for the detection of leucine. The dried residue, after it has been extracted with boiling alcohol to remove the leucine, consists of tja-osine. Dissolve It in boil- ing water or ammonia, and let it crystallize out. 41. Tests for Tyrosine. — It is distinguished by its micro- scopic appearance, and by tiie following reactions. 1. Hoflfmann's Test. — Put a little of the solution supposed to contain tyrosine in a test-tube ; add some water, and a few drops of mercuric nitrate solution. Boil it for a little while. If tyrosine is present, the liquid will become rose-colored, and will afterwards deposit a red precipitate. 2. Piria's Test — Pour a few drops of concentrated sulphu- ric acid on two or three pieces of tj-rosine the size of a pin's head in a watch-glass. Gently warm it for a little. Let the solution cool. Mix it with a little water, and add chalk or barium carbonate till all effervescence has ceased. Filter. Evaporate, if necessar}', to a small bulk at a gentle heat, and add a few drops of a neutral solution of ferric chloride. The fluid will become of a beautiful violet. 3. Scherer's Test. — Put a little of the supposed tyrosine, with a drop or two of nitric acid, on a piece of platinum foil, and evaporate gentIJ^ If it is reallj' tyrosine, it will quickly become of a bright yellow color, and will leave a deep 3rellow shining residue. Add a few drops of liquor potassos to it, and it will form a yellowish-red solution. Evaporate, and it will leave a brown residue. 442 CHEMISTRY OP THE TISSUES. CHAPTER XXXYI. CHEMISTRY OF THE TISSUES. 42. Epithelial Tissues.— The epithelial tissues— nails, hair, epideraus, and epithelium, as well as horns and feathers —contain a small quantity of fat, and a substance which con- stitutes the chief part of their bulk, and to which their form is clue. To this substance tlie name of keratin lias been ffiven. it IS prepared by removing the fat, etc., from any of the epi- • lerinal tissues by boiling with ether, alcohol, water, and dilute acid As the elementary analyses of it do not agree, it is quite possible that it is a mixture of several substances, but this is not yet certainly made out. It is nearly allied to albumin, as IS shown by its yielding the same products, leucine and tyro- sine, when decomposed by boiling with dilute sulphuric acid (see § 3oJ. It contains sulphur, which seems to be in a very loose state of combination. Hair, as is well known, becomes blaclvened by lead sidphide when a leaden comb- is used. To show the presence of sulphur, put a few parings of nails into a test-tube; add a little liquor potass*; and boil. Add a little hydrochloric or sulphuric acid to the solution thus obtained. Hydrogen sulphide will be given off, and may be recognized by the smell. ' ^ & j 43 Connective Tissue.— In the group of tissues so desio-- nated, there ai-e several which do not seem very like one anothe? teuch are mucous tissue, reticular and ordinary connective tis- sue adipose tissue, cartilage, bone, and dentine. Their close relation to one another is shown by their being linked tocrether by intermediate forms, by one tissue sometimes passin° into another so that the boundary between them cannot be defined and ,y one occasionally replacing another. They all contain substances which are either derived from albumin or are nearly connected with it, and have received the name of albuminoids .ll^il-nn i""r"" ~^^'"'' ^''''^ nitrogenous, and resemble albuminous bodies in composition, but differ from them in their behavior with acetic acid, potassium ferrocyanide, nitric and ^-°li^"^'°.''- 7^''^' ^'■'^ ™"^-'"' S^^'-^tin, and chondrin V u, ^ucm.— Ihis is found in fretal connective tissue and altioug-li not present in the fasciculi is an important con- stituent of tendon tissue. It occurs also in all mucous secre- tions, and gives them a tenacious character. It is distino-uished by Its solutions not being coagulated or rendered tuibid by BY DR. LAUDER BRUNTON. 443 boiling; b}" giving with acetic acid a precipitate which shrinks together in pure acid, instead of swelling and dissolving as albnminous bodies do. The addition of potassium ferrocj^anide to the acetic acid prevents it from precipitating mucin, so that no turbidity is produced unless albuminous substances are also present. It gives no precipitate with mercuric chloride ; when heated with liquor potasste and cupric sulphate, the solution remains of a clear blue. Preparation, (a) From Salivary Glands. — Wash the sali- vary glands of an ox or sheep well. Cut them up into small pieces. Wash away any remaining blood with a little water. Mix the glandular substance well up with a considerable quan- tit}' of water, and filter through linen. Add acetic acid gradu- all}- to the filtrate, till a precipitate partly fibrous and partly flocculent is obtained. Filter through linen. Wash the pre- cipitate with water, and then with alcohol and ether, to remove the fat. (6) From Tendons. — Free the sinews of the legs of an ox or sheep from mnscle. Wash them well, and cut them up in small pieces. Extract them with water. Put them into a large quan- tit}' of lime or barj'ta water, and let them stand in a closed ves- sel for several daj'S. Filter. Add acetic acid in excess to the filtrate to precipitate the mucin. Wash the white flocculent precipitate with dilute acetic acid and then with dilute alcohol. (e) From Ox Gall. (See § 1.34). Solubility. — 1. Water : — -It does not dissolve, but swells very much; when the mixture is filtered, part of the mucin often passes through, forming a turbid filtrate. The mixture with water is not tenacious, and no foam is produced on shaking it. 2. XaCl solution. Add a little solid NaCl to a mixture of mucin and water. It will become clearer. Put a glass rod into the liquid. It will now be found to be tenacious, and on with- drawing the rod a long thread will follow it from the fliUd. Shake it, and foam will form. Add a large quantity of water to the solution or mixture (for it is not certain which it is), and the mucin will be precipitated. 3. Very dilute hydrochloric acid of less than 1 per cent., or other mineral acid, does not dis- solve mucin. 4. Dilute hydrochloric acid of 5 per cent, partly' dissolves it. Shake the solution and it foams. Add a little NaCl to it, and the mucin will dissolve much more readily. 5. Concentrated'hydrochloric, or other mineral acid, dissolves it completely. 6. Liquor potassse dissolves it; add a little to some mucin, but not enough to dissolve the whole of it. Filter. The filtrate is not tenacious, and is neutral. 7. Baryta and limewater dissolve mucin, and when used in small quantity give, like liquor potass.c, a neutral filtrate. Precipitation of Mucin. — f 1. Boil the neutral or slightly alkaline solution. It will not be altered. , 444 CHEMISTRY OP THE TISSUES. Pnt,^'nff h'^ t-*'"^-', '^"''|- ^ P'-ecipitate will fell. Let it settle. U w 11 *'^t '^\" ""''^ ''°"' °" 8'^''^^'^'^' ^^cetic acid. Generally It will not dissolve. '' t 3. Add acetie acid with solution of potassium ferrocyanide If the mucin is pure no turbidity will appear at first, but will clo so after the solution has stood for some time 4. Add mercuric chloride. No precipitate. 5. Add basic lead acetata A copious precipitate will form. f^eacho,^ ^v^lh Cupnc Oxide—Add liquor potassaj and a little cuprie sulphate to a solution of mucin. The cupric 1 v dratewi be dissolved. Boil. The liquid will stUl remain of a clear blue color. This distinguishes mucin from Xumin ^ K"^!;"';^^ f?''-^^'"' ^^"'•'^l^ gi^e t violet or red colon ' r«iot o'^y Connective Tissue.— Tendons — Sif t!roTan?c"?'*""r,' °^ Collagen.-This suSce loims tile oiganic basis of bones and teeth, and the Drinciml oi^ fibrous part of connective tissue, tendo;is, lig^mints, £ Preparalion. (a) From Bones.-Soak some bones in hvdro h? "the'r; d'^^"'"^ 7'^'^ ' '' ' ^'"-^ "^ '-'Ik o^wate • Sai " safts vliich IrT''"' 'I'T-- ^^'"^ ^^''" ''''^^^'^ tl^e inorganic U m f f deposited HI the bone and impart hardness to Its 01 ignal shape, but be quite soft and pliable The t n p the hnnL s^l s they contain, varies with their size • but if are us % d.T T ""^^'^ '''''''^ °'' ""» 1^°"- such'as ribs aie used, a day or two is sufficient. Wash them well with times °' '^ '"'^'l^ "^ ^'^ter, changing it several other «d(l?itwlll 8we ' ^T,,''"i -;°°''',.;''''''« "<"■'' ■" BY DR. LAUDER BRUNTON. 445 diyiiess on the water bath. Use the third for testing various precipitants. Sohibililtj.—l. Cold water. Dried gelatin will swell, but will not dissolve. 2. Boil the water, it will dissolve. 3. Cold dilute acids, and 4. Cold dilute alkalis, will dissolve it readily. Precipitation.— li is precipitated by 1, tannic acid ; 2, mercuric chloride. Unlike albumin, pure gelatin is not pre- cipitated bj', 1, acetic acid and ferroovanide of potassium ; 2, manj- metallic salts, as lead acetate, cupric or ferric sulphate. It is not precipitated by acids or alkalis. Alteration by Boiling — Boil a solution of gelatin for some time with an acid or alkali and let it cool.'' It will remain fluid and will not form a jell^-. Test its reactions. They will be found the same as before. The same effect is produced by prolonged boiling with water alone. 48. Elastic Tissue.— Elastin.— The elastic fibres which occur in the connective tissue in various parts of the body, and are especially abundant in the middle coats of the aorta and large arteries, and in the ligamentum nucha;., and ligamenta siibfiava, are supposed to consist of elastin. Preparation — Remove the adhering cellular tissue from the fresh ligamentum nuchae of an ox. Cut it into small pieces, and boil it with alcohol and ether to remove the fat. Boil it for 24 hours with water, to dissolve the collagen, renewing the water as it evaporates, or preventing evaporation (see § 207). Boil the residue with concentrated acetic acid for a consider- able time ; remove the acetic acid by boiling with water, and then boil with moderately dilute liquor soda or potassaB till it begins to swell. Remove the alkali by boiling with dilute acetic acid, then with water. Put the residue into cold hydro- chloric acid ; let it remain for 24 hours, and then wash it"with water till the washings have no longer an acid reaction and leave no residue on evaporation. Characters. — The elastin which remains after the treatment just described is yellowish and elastic while moist, but when cliy becomes hard and brittle. Solubilitij. — 1. Put a piece of dry elastin in water. It will swell np but will not dissolve. 2. Boil the water. Unlike the collagen of connective tissue, it will not dissolve. It does not form gelatin, and the water will not gelatinize on cooling. 3. It does not dissolve in alcohol, ether, or acetic acid, though it swells in the latter. 4. Boil it with a strong solution of caustic potash ; it will dissolve. Precipitation. — Neutralize the solution in potash with hj'- drochloric or other acid. No precipitate will fall. Add tannin to the neutral solution. A precipitate will be produced. No other acids cause a precipitate. Reactions. — 1. Xanthoprotein reaction. Put a piece of elas- 446 CHEMISTRY OF THE TISSUES. tin m concentrated nitric acid, and let it staj' some time. It will swell up, then become j-ellow, and lastly form a mucilagi- nons solution. Add ammonia, and it will become a deep orange-red. 2. Millon's reaction. Test a piece of elastin with Millon's reagent." It will become slightlj'- red. Decomposilion. — On boiling elastin with concentrated sul- phuric acid, it is decomposed and yields leucine, but no tyrosine. **49. Cartilage,— Chondrogen.— The intercellular sub- stance of hyaline cartilage, and that which lies between the fibres of fibrocartilage, consists mainly of chondrogen, so named because it is dissolved by boiling in water and forms chondrin. Solubility — Take a piece of costal cartilage of a sheep or ox and test its solubility in the following reagents : 1. Cold water. It is insoluble. When allowed to dry before it is put in water' It swells up slightly. 2. In boiling water, it dissolves. On cooling. It forms a jelly. 3. In acetic acid it is insoluble. When dry, it swells very little in acetic acid. 50. Ch.on6.xin.— Preparation — Boil the costal cartilao-es or trachea of a sheep or ox in water till the perichondrium strips easily off. Remove the perichondrium. Cut up the cartilao-es into veiy small pieces, and boil them with water for several hours. If a Papin's digester is at hand, boil them in it under a pressure of 2-3 atmospheres. Filter while hot. The fil- trate will be strongly opalescent. Put part of it into a beaker and allow it to cool. It will form a jelly. To the remainder ot the filtrate add acetic acid, and the chondrin will be pre- cipitated. ' Solubility.— Tdst the solubility of chondrin, using either that precipitated by acetic acid, or the jelly which formed on cooling, in the following reagents: 1. In cold water it is in- soluljle Heat it, and it is dissolved. It is soluble in 2. Solu- tions of alkaline salts, as sodium sulphate, and is easily solu- ble m ... Dilute mineral acids, 4. Liquor potassffi,and 5. Liquor ammonia. It is insoluble in 6. Alcohol, and 7. Ether Prenpitation.-AM to a warm solution of chondrin in water, t 1. Acetic acid. It will be precipitated, t 2 Add to this a little sodium chloride or sulphate. The precipitate will redissolve. 3. Add sodium sulphate to a watery solution of chondrin, and afterwards acetic acid. No precipitate will fall. 4. Dilute hydrochloric or other mineral acid. The chondrin is precipitated and is dissolved by excess of acid. 5. Alum pre- cipitates chondrin ; excess dissolves it. 6. Lead acetate, 7. Sil- ver mtrate 8 Chlorine water, all precipitate chondrin. Meet of Boiling.-Boil a watery solution of chondrin for a long time. Let it cool, and it will be found to have lost its BY DR. LAUDER BRUNTON. 447 power of gelatinizing, but it will give the otliev renctions just as before. Decomposition of Ghondrin. — By boiling with concentrated hydrochloric acid, chondrin is decomposed, and yields grape sugar, and certain nitrogenous substances, 'ihe presence of grape sugar may be tested by the reactions given in § "It or § 155. 51. Distinctive Characters of Mucin, Chondrin, Gelatin, and Albumin. Mucin. — Precipitated b_y acetic acid, the precipitate is not dissolved bj- sodium sulphate. Chondrin. — Precipitated by acetic acid, the precipitate is dissolved \)y sodium sulphate. Gelatin. — Not precipitated by acetic acid, nor by acetic acid and potassium ferrocyanide. Albumin. — Dissolved by acetic acid, the solution is i)recipi- tated by potassium ferrocyanide, or by the addition of alkaline salts and heat. Gelatin and Chondrin are most generally recognized bj' their hot solutions forming a jelly on cooling; but as they are both deprived of this property b}' long boiling or boiling with acids, this test is not alwa^'s to be depended on. ** 52. Bone. — When bone is subjected to the action of acids, the earthy salts are removed. The remainder, to which tlie name ossein has been given, consists chiefly of gelatigenous substance. The earthy salts are tribasic calcium, and tnague- sium phosphates, calcium carbonate, and small quantities of calcium fluoride. To remove the earthy salts, and leave the ossein, place a bone for some time at a low temperature in very dilute hj'drochloric acid. When treated with warm dilute h3'drochloric acid, bone gives out COj and is apt to separate into lamellre. Tlie ossein is soft, flexible, and elastic while moist, but becomes hard when dry. It retains the form of the bone. In its chemical characters it resembles the gelatigenous substance from con- nective tissue. To get the earthy salts, incinerate the bone, when tiie organic substance will be consumed, and thej^ will remain behind, mixed with other salts formed during the combustion, for here as in other cases the salts in the ash diifer considerablj' from those which exist in the tissue. ** 53. Adipose Tissue. — Fats. — Fats difl^er from each other in appearance and consistence. Their general properties may be conveniently studied in olive oil, for which cod liver oil or train oil may be substituted, if an animal fat is desired. Solubilily. — Fats are insoluble in 1. Water, and 2. Cold al- cohol. I 3. Hot alcohol. Warm a test-tube containing oil and alcohol over a spirit-lamp or Bunseu's burner. As the 448 CHEMISTRY OF THE TISSUES. spirit becomes warm, part of the oil will be dissolved Pour off some of the dear alcoholic solution into another tube and cool It. It will become milky from the deposition of oil. f 4 Cold ether. Shake a little oil with ether and it will dissolve readdy. The test-tube containing the ether must not be brought near a flame, as its vapor is readily inflammable. 5. Lhloroiorra ; 6. Oil of turpentine, and other volatile oils, also dissolve fat readily. * Emuhionizing of i^a/s.— Shake a little oil with a solution of albumin in a test-tube. The oil will become finely divided and torm a milky-looking fluid or emulsion. Put a drop of this under the microscope, and it will be found to consist of minute globules of fat. The globules in the emulsion unite again and form large globules, but very slowly. Add a little acetic acul to the emulsion and shake it. The globules will unite much more quickly. Repeat the experiment^yith a solu- tion of gelatin. This also will emulsionize the fat. i?earf«o«._Wash a piece of lard in water and press a piece of litmus paper against it, or melt it in a test-tube, and put a diop of It or of olive oil on the pai,er. Its reaction will be Gomposition of Fats.-V^t consists of a triatomic radicle propenyl or glyceryl, combined with three atoms of a mona- tomic fatty acid. The glyceryl may be displaced by inorganic bases, such as potassium, lead, etc., and glycervl hydrate or glyceryl alcohol (glycerin) is produced, 'fhe replacement of glycerin by other basis is termed saponification Boil two and a lialf grammes of olive oil with one gramme of very finely powdered lead oxide, and about fifty cubTc centi- metres of water in a beaker or evaporating dish for some hours, stirring the mixture well to prevent the lead oxide from T ,o ?o l" n "k-"' ^"^^■'^Pl'^^'^^g the water as it evaporates. s^thth v^il '°',"^'"' ^'''^ ^^'' ^""''y ""'''^ '" the oil, formino. a sghtly yellowish mass, and the glycerin will be set free. To obtain the glyc^nn, filter the fluid ; pass sulphuretted hydrogen hrough the fi trate, add a little animal charcoal to decolonize ratJtlffilSe.'"' ' "''^ ^" ' "^^^'^ ^'^^ ' A^^^' --' -'-^1- taS? aiS^r^:S!^nSs" ^^ ^ ''"'''' '^''' '-''' ^ --^ J;'SSrl vs. ^h^itSsir^^'^ ^'-^«'' '' -^- Solvent Power—It dissolves many metallic oxides. Add a little liquor potasste to a solution of copper sulphate of lead acetate, a precipitate will tall. Add a little glycerin, and the precipitate will redissolve. ^ ' ^ It .also acts to some extent as a solvent for fatty acids DecompoHttion.-Ynt a little glycerin, free from watei^ into BY DR. LAUDER BRUNTON. 449 a test-tube, with glacial phosphoric acid or acid potassium suli)hate, aud heat. The glycerin will be decomposed, and yield water and acrolein or acrol, a body which has an extremely unpleasant smell, and causes great irritation of the nose and eyes. Test for Glycerin. — As no other bodj^ yields acrolein when decomposed in the way just mentioned, its formation serves as a test for glycerin ; and as it is very pungent, small quantities of glycerin can easily be detected. 55. Muscle.' — For the structure of muscle, see Chap. IV. Beactioii. — Muscles which have been at rest have an amphi- cromatic reaction; i. e., thej^ change red litmus to bine, aud also blue litmus to red. They do not alter the color of blue litmus so much as that of red, and they are therefore alkaline. Alteration in the Reaction by Contraction. — The reliction changes to acid after contraction of the muscle or after death. See Chap. XX., Obs. VI. 58. Composition of Muscle. — The Sarcolemma is usually said to agree with elastic tissue in its characters, and to jdeld no gelatin, but it has been recently stated to be solu- ble, though slowly, in alkalies and acids, as well as in gastric juice, and would thus more nearl^^ resemble connective tissue. 57. Sareous Elements. — Little is known regarding the chemical composition of the sareous elements, except that they swell slightl}', and lose their power of double refraction when boiled or when heated with alkalies or very dilute acids. Alcohol does not alter them. t 58. Muscle Plasma. — When muscles are subjected to pressure at 0° C, a fluid termed muscle plasma is obtained. The plasma of muscles resembles the plasma of the blood, in possessing the power of coagulating spontaneouslj-, aud sepa- rating into a clot, and serum. To this clot, corresponding to the fibrin of the blood, the name myosin has been given. Co- agulation of the plasma causes the muscles to lose their elas- ticity and become stiff and hard, and tiuis gives rise to rigor mortis. After some time, decomposition sets in, and the mus- cles again become soft and flexible. Muscle plasma is some- what troublesome to obtain, as it coagulates too quickly in the muscles of warm-blooded animals to allow of its preparation from them, and the muscles of frogs, in which it coagulates more slowly, are not alwaj's to be had in sufficient quantity. Preparation. — Prepare a freezing mixture bj^ mixing to- gether equal parts of salt and snow, or pounded ice. Intro- duce it into a large beaker, and plunge a platinum crucible or small tin box into it. Fill another beaker with half per cent, salt solution, and put it in a vessel containing snow or ice. Prepare several frogs in thefollowing manner: Open the thorax, cut off the apex of the heart, push a canula up into the aortic 29 450 CHEMISTRY OP THE TISSUES. bulb, aud inject a half per cent, salt solution through it, in the manner directed for artificial circulation in Chap. XVI § 45 till the fluid which issues from the veins is quite colorless' Gut away the muscles close to their attachments, and wash them with half per cent, salt solution cooled to 0° C When washed, squeeze them tightly together into a ball, and tie them up m a piece of thin linen ; put them into the crucible or tin box. As the muscles of each frog are prepared add them to those in the crucible, and let it remain in the freezino- mixture until they are all frozen quite hard. Take a sharp knife and pool It m the freezing mixture ; cut the frozen mass of muscle into very thin slices ; throw them into a mortar cooled in the same way, and break them up small. Tie them up in a piece of strong hnen, and put them into a strong screw-press. As the temperature of the muscle is gradually raised by the ]IZ I'fi ';' Pf T- ^' ^^"^* "^^ collected in a vessel cooled n ice, and filtered through paper moistened with cold half per cent, sa t solution, and collected in a cold beaker. The funnel maj. be kept cold during filtration by placing it in a double cop per filtering stand of the form shown in figrsSG, but filled wM snow or pounded ice, instead of hot watei' As the fil ersTet soon choked, they must be frequently renewed. Tl le fi tefed 2=.;:, flS'^'^ '-''''''''' -' «P^^---' ^3-P3-, buS ^eacZ?-o« Its reaction is alkaline, like that of muscle. Coagulation of ilusde P/asma.-Transfer a little plasma from t^e beaker to cooled test-tubes and observe the following It will coagulate spontaneously when allowed to stand at the tempera ure of the room, and form a gelatinous clot which will begin at the sides of the tube, and extend inwards.' i3y stirring a coagulum is obtained, which is flocculent and not h)n-ous hke the fibrine of blood. ^^^^ni, ana Heat greatly accelerates its coagulation, and at 40° it coagulates almost instantaneously. Cold water coagulates it at once, so that the plasmi when SlltntVc'eS'"","'"'^ '''^f' ''^'''- ^«^^^ ^S^oUuion IL 1 V *"' ""^""^ coagulates it, but a solution of five per cent does not. Dilute hydrochloric acid of ten er cent coagulates it at once, but dissolves the coaguhim and forms syntonin almost immediately. o^"um, ana loims ** 59. Examination of the Aqueous Extract nf Muscle -In order to obtain an aqueous extract of Se a dog niust be killed by decapitation, and the Wood en^^^^^^^^ from the vessels of the lower extremities by artific al c rciK t.on. For this purpose open the abdomen quickly and in ert a canula m the aorta. Inject ten per cent. NaCl olu onT o BY DR. LAUDER BRUNTON. 451 it till the blood returns coloiiess by the vena cava. Cut off some of the muscles of the thigh quickly, and mince them up small. This is best done liy a sausage-making machine. Mix the mass with distilled water, stir it up well, and let it stand for a quarter of an hour. Filter it through linen, aiding its filtration by pressure. ** 60. Albuminous Substances in Muscle.— Alkali Albuminate— The watery extract thus obtained contains alkali albuminate. It is at first alkaline or neutral, but after- wards becomes acid, and the alkali .albuminate is then thrown down as a flocculent precipitate. The source of the acid is not known. If the extract has been made from muscle which has^ already become acid, this precipitate will not fall. To a portion of the extract add dilute hydrochloric, acetic, or lactic acid very gradually. A flocculent precipitate will fall. ^ Repeat the last experiment, using exactly the same quanti- ties of extract and acid, but add a little sodium phosphate to the extract before acidulating it. No precipitate will fall. See § 15. Albumins — Besides alkali albuminate, the extract contains two other albuminous substances, one of which coagulates at 45° C, the other at 15° C. Filter the fluid from which the alkali albuminate has been precipitated either by the develop- ment or the addition of acid. Put some in a test-tube and warm it in a water bath to 45° C. A precipitate will form. The coagulation is not affected at all by previously rendering the liquid neutral or alkaline. Let the fluid stand till the precipitate subsides, and then remove it by filtration, and warm the filtrate to TO" C. A second coagulation will take place. ** 61. Myosin. — Free the remainder of the muscles from fascia, tendons, fat, nerves, and vessels, and cut them up small. Put the mass of finely-divided muscle into five or six times its weight of water and stir it well. Let it stand for several hours and then strain it through a linen cloth, and express the fluid with the aid of a screw-press. Treat the muscles a second time with water in the same way, and strain and press again. Unite all the fluids thus obtained and keep them for examination. Wash the muscle, which remains on the linen, with water, as before, till it becomes of a grayish color, and the water is no longer colored. Throw it into a mortar, and rub it up with ten per cent, salt solution in sufficient quantity to prevent it from being too thick and to allow it to flow tolerably easily. Let it stand for several hours; Alter, first through linen, then through paper, and add to the filtrate several pieces of rock salt. As the salt dissolves, the myosin, which is insoluble in a concentrated NaC 452 CHEMISTRY OP THE TISSUES. solution is precipitated in flocculi. If any salt remains undis- solved after the myosin seems fnllj' precipitated, remove it, and tlien filter the solution. The m_yosin which contains a laro-e amount of NaCl remains on the filter. In order to free it fro°n this, dry it as well as possible by pressing it l)etween folds of filtering paper ; dissolve it in a little water, and throw the solu- tion into a lai'ge beaker full of water, when it will again be pre- cipitated. Let it stand for a day, pour off the clearluid as well as possible, and then collect the precipitate on a filter. After the greater part of the water has passed through the filter, but while the precipitate is still moist, remove it into a beaker, as it cannot be separated from tlie filter after it becomes dry. Sohibility. —Test the solubility of the moist myosin in the following reagents : f 1. Ten per cent. NaCl solution. The myosin will dissolve. Put some sodium chloride in substance into the solution. As it dissolves, and the solution becomes saturated, the myosin will be precipitated. It is soluble in 2. Solution of sodium sulphate or other neutral salt ; .3. Verv dilute liquor potassffi ; and 4. Yery dilute hydrochloric acid. " Achon of Acids and Alkalies — dilute acid and alkalies dis- solve myosin, as has just been seen. At first it is simply dis- solved, but IS very soon converted into acid albumin or alkali albuminate. Divide the solutions of myosin in dilute liquor potassffi and dilute hydrochloric acid just made, into two por- tions, add salt solution immediately to one portion of each put in a drop of litmus, and neutralize both. No precipitate will fall, for the myosin being unchanged is soluble in the salt solu- tion. Let the other portions stand for ten minutes, and then treat them m the same way. A precipitate will fall on neutral- izing them, for the myosin, being now converted into alkali al- buminate and syntonin, is no longer soluble in NaCl solution Coagulahon of Myosin.— \. Boil a NaCl solution of myosin ■ It will coagulate. 2. Add alcohol to its NaCl solution, and a similar coagulum will form. Effect of Drying.— m-K A myosin is tough and difficult to powder, and almost insoluble in NaCl solution ** 62. Extractive Matters in Muscle.— The cold watery extract of muscle contains, beside the albuminous mat- ters creatine, creatinine, hypoxanthine (sarkin), xanthine uric acid, inosic acid (apparently not always present), glucose ino- s te salts of lactic acid, and volatile fatty acids and acid piios- phates of the alkalies. Unless a largo quantity of muscle can be got It will be better to use Liebig's extract for the prepara- tion of these substances. Put the watery extract of muscle in a tin kettle; heat It quickly to boiling, so as to coagulate the albumin. Filter it through a linen cloth. Let the itltrate be- come quite cool, and add acetate of lead to it as lono- as a nre cipitate IS formed. Excess of lead must be avoided as much as BY DR. LAUBBR BRUNTON. 45a possible. Collect the precipitate on a filter, and keep it for after examination. . . ...... (a) 63. Creatine. — ^Precipitate an}' lead present in the filtrate bj' hj'drogen sulphide: filter; evaporate the filtrate to a thin 83'rup on the water-bath. Pnt it in a cool place for several days, and the creatine will separate in short colorless crystals. Let it stand till no more crj^stals are deposited ; pour oft" the mother liquor from the crystals, and add to it two or three times its volume of alcohol of 88 per cent., so as to cause tlie sus- pended creatine to be deposited. Filter it, and wash the crys- tals with a little alcohol. Wash ofl' the crj'stals which still re- main on the evaporating dish with the alcohol which drops from the filter, throw them also on the filter, and wash them with a little alcohol. Collect the filtrates, mix them and put them aside. ......... (b) Dissolve the crystals in a little boiling water, and allow the solution to cool, when the creatine will crystallize out in color- less transparent and lustrous oblique rhombic prisms, which, when gently heated on a piece of platinum foil, lose water of crystallization, and become dull and whitish. Soluhility. — Creatine is sparingly soluble in cold water; easily soluble in boiling water ; almost insoluble in strong alco- hol; insoluble in ether. Eeaction — The solution in hot water lias a neutral reaction, and bitter taste. Tent. — Creatine has no very characteristic reactions, and it is best recognized by converting it into creatinine. If it is pure, no precipitate will fall on the addition of zinc chloride to its solutions, but if mixed with creatinine a precipitate will be produced. Decomposition. — When it is boiled for a considerable time with caustic baryta, creatinine decomposes into urea and sar- cosin. If tlie boiling is continued still longer, the urea decom- poses into carbonic acid and ammonia. This reaction is very interesting as indicating one source of urea in the body. When boiled with water for a long time or with acids, it loses water and is converted into creatinine. 64. Creatinine. — Boil creatine for half an hour with dilute hydrochloric acid ; neutralize with hydrated lead oxide ; filter ; evaporate the filtrate to dryness on the water-bath. Extract the residue witli alcohol, and evaporate the extract. The crea- tinine will crjrstallize in colorless lustrous prisms, which, when heated on platinum foil, do not dry like creatine. Solubility. — It is soluble in water, especially when hot. Un- like creatine, it is soluble in hot alcohol. Reaction. — Test the watery solution with litmus or turmeric paper ; it will be found strongly alkaline. It has a taste like dilute ammonia. ■^^^ CHEMISTRY OF THE TISSUES. Characters.— Greatinine acts like a strong alkali, and forms double salts with metals. The most important is its compound with zinc chloride. Add to an alcoholic or not very dilute watery solation of creatine, a concentrated syrupy solution of zmc chloride free from hydrochloric acid ; a precipitate of warty granules will fall at once if the solution is concentrated ■ but if dilute, groups of needles will slowly form. The o-ranules are seen under the microscope to consist of radiating" ..roups of fine need es They are very sparingly soluble in coM water • rarrcids."' ' '"'°'"''' "^ '''''''''' ' ^"* ''"'-y ^<^1"^1^ - '^^i"e: This test is sufficient to distinguish creatinine. It is fur- ther precipitated by silver nitrate, by mercuric chloride ad by niercuric nitrate with the gradual addition of sodium cLao fron?the^mtrnt''e /,^yP°^,^°thine).-Evaporate the alcohol 4Xi It ! Hiine I ^'°'' * '' water-bath ; dilute it with water; in , Hn l^">f ^'°^ ^y fimmonia, and then add an ammoniaca solution of silver nitrate. Sarkin will be precipitated Le the tat on w t/''''P''"'' "■''''''''■' ''^''' it severa/times by decan! tation w h water containing ammonia; throw it on a smooth "rb^ttom^rfhr^rif '' *'"r"-"';'-^' ' ^"^'^ ^ gi-B 1-00^1^^ acid of 1 i^n "■' '^"'i ''*''^ t'^^' precipitate with nitiic acid of 1.100 sp. gr. into a small flask. Heat it to boilin " and add more nitric acid till the whole is dissolved T^f fl i should be kept nearly boiling. Som:timera few flakes of Mlver chloride remain undissolved. Decant the linn.vi f them into a beaker, and let it stand foi s x ho rs T do^b" mtiate of silver and hypoxanthine will crystallize ^ut solution of silver nitrate to remove hfe T d SusoeTd tb'"' in water, and pass hydrogen sulphide thioughit p' ter from bei:y;™Sd '^;xs':^:;^'-^ ^-- ^^«^- "- ^ in iiZ^!^^;~^::jt TS:cc::^"T ''^ ^^-^^^ ^-^-p--- of silver and xanthine wilT;il Wa^ h;' ^"1"^'""**' "*''"*'-'''*^ pend it in boilina ^atTan 1 dJ "^ l'^'''"^'''"^" 5 «"«- phide. Filter and evapomt Sr'^'T- " ^T, h^^'-^gen sul- scaly film. evaporate. The xanthine will separate as a Ad?f ^ii^rSt^ic^^ii^ifr:./^ ^t^^"'"; • '' ^"^ ^^-^i-- capsule; evaporate to drvne. a" ^f,-^^"^!""'^ '" * porcelain Add a drop of cLustic sod to -^ ancHt wH. ?"'"*^ "'"1 ^'^"^^i"- it, and the color will changfto 'purple i^d '°'" "'• '^''' BY DR. LAUDER BRUNTON. 455 Put liquor soda; in a watch-glass with a little chloride of lime ; stir it, and introduce a portion of xantliine. A ring will form round it, at first dark green, but soon becoming brown, and then disappearing. 67. Uric Acid. — Suspend the lead precipitate (a) in water ; decompose it completel}^ 113^ hydrogen-sulphide; filter; concen- trate the filtrate in a water-bath. IJric acid will separate gradu- ally. Filter, and set the filtrate aside (d). Wash the crystals on the filter with a little water and then witli alcohol. If desired, thej' may be further purified by dissolving them in a little liquor sodffi, precipitating by ammonium chloride ; filtering and decomposing by dilate hj'drochloric acid. Mm-exide Test. — Put a small portion of uric acid on a watch- glass, with one or two drops of nitric acid, and evaporate to drj^ness at a moderate temperature. A j^ellow residue will re- main, which becomes red when quite dry. Put a drop of am- monia on tlie side of the glass, and let it run gentljr down to the uric acid, which will then become of a beautiful purple. If a drop of liquor potassaj or liquor sodse is used instead of am- monia, a bluish-violet color will be produced. Inosite. — Evaporate the filtrate (d) till a permanent tur- biditj' is produced bj^ the addition of alcohol. Then add its own volume of alcohol to it and warm it, when the turbidity will disappear. Set it aside for several days. Inosite may then crystallize out. If it does not, add ether ; and if still no crystals form, evaporate almost to dryness ; add a little nitric acid, evaporate to dryness ; moisten it with calcium chloride, and evaporate to dr^aiess again. If inosite is present, a rosy red spot will remain. If crystals have been formed, dissolve some in water, in which they are easily soluble, and apply the same test. 68. Brain. — The brain contains cholesteriu, lecithin, and cerebrin, besides albuminous substances, which chiefly form the axis cylinders, and are insoluble in water. Cerebrin probably belongs to the white substance of nerves. The specific gravity of the brain may be ascertained in the manner directed in App. § 216, and the amount of water it contains by weighing it, drying it in a hot chamber, or over sulphuric acid, and estimating the loss. To separate the sub- stances contained in the brain, remove the membranes and ves- sels as much as possible from it, wash its surface with water, and rub it to a paste in a mortar. Mix it with great excess of alcohol, and let it stand for several days, stirring it frequently. Separate the alcohol by filtration, and set it aside for tlie pre- paration of lecithin. ....... (a) Rub up the brain again, and extract it with large quantities of ether, as long as they take up much lecithin or cholesteriu. ^ 4a6 CHEMISTRY OF THE TISSUES. This is known by evaporating a small quantity of the eth ler ex- each time it is taken from the brain. Put the ether aside ; ex- ti-aet the bram with hot alcohol several times, and filter it hot On cooling, eerel)rin will crystallize out, mixed with lecitliin 69. Cerehiin.— Purification— Fihei- off the alcohol from the cr3-stals, wash them with cold ether, and l)oil them for an Iini,''.r H '^'^^ '^T:'- ^'"'^ ^^^ *''''°"gh the liquid to pre- fir t w,>l ",T''r^^T^= ^'^'"'^ ^'''^ '""'^^ the precipitate fiist with cold water and then with cold alcohol. Put the pre- cipi ate m a beaker with alcohol and heat it, to extract the cerebi-in from it, and filter it hot. On coolin., crystals of iriTohTi at'^^''"^' 7'ii°" ^"^"^^^ '- ^=-" '^i-'-i-i ^- ml drie ; i 1 to crystallize out again, washed with ether, and (iiied at a moderate temperature Cerebrin forms a white hygroscopic powder. Put a little on From the mode of preparation, it is evident that it is inso- ove'l f"^' ^1" '°^"'t ''^ ''''' '■^I'^^l'^l' ^"'1 that it i not de- stioyed by boiling with baryta water starch.'' '" ''''*"■■ ^' '"'" '^""''^y ^^'^^ "P' somewhat like Decomposition.— When treated with acids or with h^T boS;:^!;:.;^';:,!::"'^ wii? t' r ^'°°'"\^^^ ^-- '^ -^^ precipitate will fan " '^^ decomposed, and a smeary nio'^t1^e'bama~mt«".' T' ''^^ *'™"-"'^ ^'^ filtrate to re- alcohol. Add to ^h a c'ohobcT' '". 'V^"^^^' '^^t™^'^ ^-itl' ^ precipitate ^^^SS^J^^^Sj^Z^jr^ ^f tinum may be removpil h,r i,,..i,.. '"-"= iviu lau. iiie pla- BY DR. LAUDER BRUNTON. 457 CHAPTER XXXVII. DIGESTION. Section I.— Saliv.i and its Secretions. 72. Mode of obtaining Mixed Saliva.— To obtain a sufficient quantity of human saliva for examination, the secre- tion of the salivary glands must be stimulated artiflcially. For this purpose any of the mechanical or chemical stimuli to be mentioned in § 85 may be used. To avoid the rislv of the sahva becoming altered by mixture with the substance used to quiclien its secretion, the mechanical stimuli sliould be pre- ferred. There is no objection, however, to the employment of ether vai^or. ** 73. Examination of Mixed Sa.liva.—A2}pearance.~ Saliva IS transparent or opalescent. It sometimes deposits a white precipitate almost immediately after it has been col- lected. When poured from one vessel to another, it is seen to be more or less viscid, in consequence of which it is gen- erally filled with air-bubbles. If none are present, they°are readily produced by blowing into the liquid tiirough a narrow glass tube, when it is seen that they take a long time to subside. If tlie saliva is allowed to stand long, a thin pelli- cle of carbonate of lime forms on its surface. Microscopical Examination. — Saliva contains numerous air-bubbles, pave- ment epithelium cells from the mouth, and round cell's (sali- vary corpuscles) resembling lymph corpuscles, within which are numerous granules in constant movement. ** 74. Determination of the Amount of Water and of Solids. — Take a small porcelain crucible with a lid, drv it in an air-bath at 100° C, put it under a bell-j.ar over a dish containing strong sulphuric acid till it is quite cool, then weigh it immediately and note its weight carefully. After weighing it, replace it in the air-b.ath for another hour, cool it and weigh it again as before. If the weight is less the second time than the first, the process must be repeated till no further loss of weight occurs. Introduce some saliva into it and weigh again. The amount of saliva used is ascertained by de- ducting the weight of the crucible alone from the weight of the crucible and its contents, thus : — 458 DIGESTION. Weight of crucible and saliva 33.562 grm. Weight of crucible alone 23.296 grin. 10.266 = weight of saliva used. Evaporate tlie saliva to dryness either in the air-bath or over a water-bath, but finish the desiccation in the air-bath. Cool and weigh the cracih)le as before. The amount of solid residue is determined in the same way as that of the saliva itself, thus : — Weight of crucible and dried residue 23.342 grm. Weight of crucible alone 23.296 grm. Difference .046 grm. =weight of residue. The amount of water is found by subtracting the weight of the solid residue from that of the saliva used, thus : Weight of saliva used 10.266 Weight of solid residue .046 10^220 weight of water. Hence percentage of water = ^^^■^'^^ ^ ^00 ^ go c „„(j 10.266 Percentage of solid residue = ^■^^^'' ^ ^'^'^ = 44 10.266 * 75. Qualitative Investigation of Inorganic Con- stituents.— For this purpose the saliva must be filtered so as to separate the epithelium and mucus. It contains carbo- nates, chlorides, phosphates and sulphates of potassium, sodium, calcium, and magnesium, and in most cases also potassium sulphocyanide. The presence of these several salts may be demonstrated as follows : Carbonates If a drop of saliva IS placed on an object-glass and covered in the usual way, and a drop of acetic acid added, bubbles of gas will be seen to form under the cover-glass. Chlorides.— The saliva 18 acidulated strongly with nitric acid, after which solution of silver nitrate is added ; the precipitate formed is insoluble in excess of acid, but dissolves readily in ammonia. Sulphates. — Ihe turbidity produced by solution of barium, chloride, or nitrate docs not disappear when nitric acid is added, and the liquid IS boiled. Potasmcm.-U^ little saliva is gently evapo- rated on a platinum wire and then heated in the flame of a Bunsen's lamp the flame seen through blue glass exhibits a violet color. Sodmm.-Withont the glass it presents the well- known yellow color due to the presence of sodium. Calcium may be precipitated as oxalate by the addition of ammonium oxRinte Magnesium as ammoniaco-magnesian phosphate To obtain the latter, ammonium chloride, and ammonia must first BY DR. LAUDER BUUNTON. 459 be added, then sodium phosphate. Potassium Sulphocyamde. — ihis IS generally, though not invariably, present in mixed saliva. It IS derived from tlie saliva secreted by the parotid gland, and is not contained in that of the submaxillary gland 10 show its presence, add a drop of solution of perchlortde of n-on, so very dilute as to be almost colorless, to a little saliva m a porcelain crucible or capsule, and stir it. A reddish color s developed, which remains unchanged after the addition of hydrochloric acid, but is at once removed by a solution of cor- rosive sublimate. Perchloride of iron gives a similar color with acetic acid and with meconic acid, but the color produced in the former case is destroyed by hydrochloric acid and in the latter by mercuric chloride. When undiluted perchloride ot iron IS used, the color is deep red, and may be shown to persons at a little distance. If the test does not at first suc- ceed, the saliva should be evaporated to one-third of its bulk and the test then api^lied. ' To determine the iMrceniage of inorganic salts, the dry resi- as inT74 ''*' '"^'°''''''*^^^ ('"^^ § 214), weighed, and calculated, * 76. Organic Constituents.— These are albumin, mucin ptyalni Albumin.— U saliva is strongly acidified -with nitric' acid, It becomes turbid, but no precipitate is formed. On then boiling It becomes clearer, and the color changes to yellow • the addition ot ammonia changes the yellow to oranoe-red' It to another portion a mixture of acetic acid and potassium lerroeyanide is added, a white precipitate is produced. Saliva contains two albuminous bodies— albumin proper dissolved in salts, ^m\glohulin. Globulin is precipitated from dilute solu- tions by 00„ ordinary albumin is not. To separate them, a stream of carbonic acid gas must be passed through saliva, di- luted with a large quantity of water, for some time. A very fine flocculent precipitate is formed, which tends to disappear when the turbid liquid is agitated with air. After the precipi- tate has settled, tho liquid may be decanted off with a syphon and, if needful, filtered ; it can then be proved to contain albu- min by the addition of acetic acid and ferroeyanide of potas- sium. This process requires considerable care. Ilucin To this body is due the stickiness and tenacity of saliva. If acetic acid is gradually added to saliva while it is stirred with a glass rod, it becomes more and more tenacious, and finally the mucin separates in white stringy flakes ; these must be washed with water and acetic acid, and tested by the reactions o-iven m § 45. '^ ** 77. Action of Saliva on Starch Paste.— Saliva con- verts starch into sugar. To show this, prepare some thin mucilage by rubbing up a little starch with cold water into a smooth paste and pouring a large quantity of boiling water 460 DIGESTION. over it (one grain of starch to one hnndred centimetres of water), or b^- boiling it in a flask or large test-tube, and then allowing it to cool. Filter the saliva to be used, and distribute it in three test-tubes, introducing into the first, starch mucilage alone — into the second, saliva — and into the third, saliva with about three times its bulk of starch paste. Mix them well together by agitation. Then put all three for a few minutes into a water-bath at 40° C, or warm them gently over a spirit- lamp. Add to each of them liquor potassaj in excess, and a drop or two of solution of cupric sulphate. In the first and second, a light blue precipitate will be thrown down, and the liquid will remain colorless ; but in the third, the precipitate just formed will be redissolved, and give a blue solution. If now the liquids arc boiled, the precipitate in the first tube, containing starch paste, alone will be blackened, but the liquid will remain colorless. In the second, containing saliva, the precipitate will be partly dissolved, and give to the fluid a violet color, due to albumin in the saliva, § 12. In the third, a yellow or orange precipitate will be formed. This reaction' which is known as Troramer's test, shows that there is no sugar either in the saliva or starch used, but that it is formed by the action of the one on the other. Bapidity of conuersion of starch into sugar. — Bidder and Schmidt erroneously con- sidered that the conversion of starch into sugar was almost instantaneous. To illustrate this view, introduce saliva into a small beaker. Place it in a water-bath at 40° C, and when it is_ warmed through, let a little dilute starch mucilage, colored with iodine, fall into it drop by drop. As each drop falls it becomes decolorized. The disappearance of the blue color is not dependent on the conversion of starch into sugar, but on the conversion of the iodine into hydriodic acid. ° Other or- ganic fluids, such as the urine of dogs, according to Schifi', ex- hibit the same reaction, which is probably due^'to their 'con- taining deoxidizing substances, for the same effect is produced by sulphurous acid or morphia, both of which absorb oxygen readily. This may bo shown by putting starch mucilao-e colored with a little iodine into a test-tube and diluting it tUl It forms a clear blue transparent solution. If it is now^placed in the warm bath at 40° C, it will remain unaltered, but will at once lose its color on the addition of either of the reducino- agents above mentioned. '^ * 78 Effect of Temperature on the Diastatie Action o± Saliva.— lake four test-tubes, and carefully introduce a little saliva into each witli a pipette. Put the first into a mix- ture of snow or ice and salt, the second into a test-tube rack on the table, the third into a water-bath at 40° C. ; boil the fourth briskly for two or three minutes, and then allow it to cool. Then add starch paste to each of them, and allow them BY DE. LAUDER BRUNTON. 461 to remain where they are for five or ten minutes. Take a part of the fluid from each, and test it for sugar, either by Trom- mer's or Moore's teets. (See § 155.) None will be found in the first or fourth, a little in the second, and more in the third. Thus we learn that saliva does not act, or acts very slowly, at the freezing point, that it acts at tlie temperature of the air, and still more quickly at the temperature of the body. Now place the first and fourth test-tubes in the water-bath at 40 C, allow them to remain for several minutes, and test again for sugar. It will be fouud in the first but not in the fourth. This shows that the power of saliva to transform starch into sugar, is merely suspended by exposure to a very low temperature, but is totally' destroyed b^' boiling. * 79. Influence of Acids and Alkalies on the Dias- tatic Action of Saliva.^Dilute aci^s do not arrest the action of saliva upon starch ; stronger acids do so for a time, but when they are neutralized the auction again goes on. Take three test-tubes, and put into each equal parts of saliva and starch paste. Add to the first its own bulk of water, to the second a similar proportion of distilled water, containing 0.C5 per cent, of commercial hydrochloric acid, and to the third the same quantity of dilute acid of 10 per cent., and keep them for five minutes at 40° C. Add liquor potass® to the first and second, and test for sugar. It will be found in nearly equal quantity in both. Take part of the fluid in the third tube, and test it for sugar. None will be found. Neutralize the remainder with carbonate of potash, carefully avoiding excess, and replace the test-tube in the water-bath for a little while. On again testing it, sugar will be found to be present.— As the greater part of the starch we eat is not transformed into sugar in the mouth, but is swallowed un- changed, it is important for us to know whether the trans- formation goes on in the stomach or whether it is arrested by the acid gastric juice. The strength of the dilute acid just employed (0.2 of real hydrochloric acid) is nearly the same as that of the gastric juice, and the experiment shows that in the healthy stomach the conversion of starch into sugar may go on rapidl3^ In some pathological conditions the acidity of the gastric juice is abnormally increased, and the action of the saliva may be suspended so long as the food remains in the stomach, but when the acid is neutralized by the intestinal secretion, the action will go on again. Alkalies. — Caustic potash and soda, when added to the saliva in excess, put a stop to its action on starch, and its diastatic power is not restored by neutralization. Its action is suspended by sodium and potassium carbonates, ammonia and lime-water, but restored by neutralization. Put saliva in two test-tubes and add to one several drops of liquor potassaj. 462 DMESTION. and to the other a few drops of a solution of potassium car- bonate, mix a little starch mucilage with both, and let them stand in a water-bath at 40' C. for half an hour. Test a small portion of the liquid from both tubes, and having ascertained that neither contains sugar, put a drop of litmus solution in each, and neutralize with dilute hydrochloric acid. After both have stood for another half hour, sugar will be found in the one to which the carbonate was added, but not in the other. * 80 Action of Saliva on Raw Starch.— As has been seen, the saliva rapidly converts starch mucilage into sugar, but it does not act so quickly on raw starch? The starch grannies consist of a number of layers arranged in an eccentric manner round a point called the hilum. These layers consist alternately of two substances which have been termr-d respec- tively, starch-cellulose and starch-granulose. The latter is colored blue by iodine alone ; the former is not colored unless the granules have been previously acted on by sulphuric acid or zinc chloride. When starch is digested with saliva, the granulose only is dissolved, and although the starch (Granules still retain their form, they are no longer colored "blue by lodme. ■' To show this, potato starch must be mixed with saliva, and subjected for two or three days to a temperature of .^5'^ G ihe sahva used must be decanted off, and a fresh quantity added every two or thre« hours. The starch is prepared for tlie purpose by placing a quantity of the pulp obtained by scraping the cut surface of a raw potato on a bit of calico stretched over the mouth of a beaker, and then washinrr it with a gentle stream of water. The starch rrfanules pass through into the beaker, leaving a fibrous residue on the calico. 81. Artificial Saliva.— As ptyalin is present, ready tormed, m the salivary glands, a fluid which, like saliva, will convert starch into sugar, can be obtained by makinr. an infu- sion of the glands. _ Take the salivary glands of an ox, sheep, rabbit, or guinea- pig Remove the cellular tissue from them', chop them up fine, and let them stand with a little water upon them for several hours, (strain through muslin and filter. The filtrate mav be_^used instead of saliva for the experiments already S'ibeT n«n5= P?^r^*'°'' f Ptyalin from the' Salivary Glands.-I tyalin may Ije separated from the infusion of the glands in the same manner as from saliva, but as it dissolve; very readily m glycerin, it is much more advantageous to ex- tract it by that agent For this purpose prepare the salivaiy gland,s of an ox or sheep, as above direcLd. Pla^c the we f minced gland m a flask, and cover it with absolute ak-oho Cork the mouth of the flask, and let it stand for twen^'four BY I)R. LAUDER BRUNTON. 403 hours Then, having poiired off the liquid, squeeze tlie re- mamcler in a cloth, so as to get rid of as much of the alcoholic extract as possible. The cake so obtained must now be mixed with as much glycerhi as will cover it in a beaker, and allowed to remain for several days, during which the mixture may be occasionally stirred. At the end of this period, the whole must be stramed through muslin, and tlien filtered thron-h paper. In the filtrate, ptyalin is precipitated by tlie ad.litiSn ot alcohol in excess. The precipitate, after having been col- lected by subsidence and decantation, must be dried over sul- phuric acid. 83. Separation of Ptyalin from Saliva.— The method employed for separating ptyalin as well as otlier ferments from the secretions in wliich they are contained, depends on the fact tliat when a copious precipitate is produced in the fluid, tlie fer- ment adheres to the particles of the precipitate, and is carried down along with them. It does not, however, adliere very closely to the precipitate, and can readily be washed off. Tlie precipitate employed to carry down ptyalin is calcium phos- phate Ilus carries down witii it not only the ptyalin, but also the albumin in the saliva. Tlie albumin, however, adheres more closely than the ptyalin to the precipitate, so that the ptyalin is dissolved away by the first wash -water, while the albumin remains adherent. Collect a considerable quantity of saliva by filling the mouth with ether; while fresh, acidify it strongly with phosphoric acid, so that the precipitate to be pro- duced may be voluminous; then add milk of lime till the fluid has a faintly alkaline reaction, and filter. When the fluid has drained from the precipitate, remove the latter into a fresh Ijcaker, add to it a little water, not exceeding in amount the saliva origmally employed, stir it well and filter ao-ain. Add to the filtrate an excess of alcohol. After some "time a fine white flocculent precipitate will separate, which must be col- lected in a filter and dried over sulphuric acid. It then forms a snow-white powder, and consists of ptyalin mixed with some inorganic salts. To obtain it free from ash, dissolve it in water and precipitate it again by absolute alcohol. Pour off the alco- hol, dissolve again in water, and precipitate again. Repeat tliis several times, collect the precipitate on a filter, wash with dilute alcohol, and then with a little water, and finally dry it at a low temperature, under a bell-jar over sulphuric acid. * 84. Properties of Ptyalin.— Tlie reactions of ptyalin may be examined either in the filtered aqueous solution of the calcium phosphate precipitate, or in solutions of pure ptyalin. Ptyahn diflfers entirely from albumin in its reactions. 1. Add nitric acid ; there is no precipitate. Boil the liquid, allow it to cool, and add ammonia. No yellow color is produced. 2. Add to several portions in test-tubes, mercuric chloride; 464 DiOESxroN. tannic acid ; acetic acid and solution of potassium ferrocyanide ; platinum chloride ; solution of iodine. Xo precipitate appears in any case, but the iodine produces a yellow color. S. Add lead acetate, and to another quantity basic lead ace- tate. In both cases a i^recipitate is formed after a time, and on filtration it is found that the filtrate is without action on starch, the ptyalin having been carried down with the precipitate. 4. Add liquor potassseand cupric sulphate. No reduction of the copper oxide occurs. ** 85 Secretion of Saliva. — The secretion of saliva goes on very slowly or ceases entirely when the glands are not under the influence of some stimulus. Tlie stimulus may be either mechanical, chemical, electrical, or mental. The student may estimate the eifect of different stimuli by experiments on him- self, thus: Swallow all the saliva contained in the mouth, so as to empty it completely. At the end of two minutes spit out the saliva which has collected in the mouth into a .small beaker previously counterpoised {see § 21.5) and weigh it. Again empty the mouth, apply the stimulus and collect the saliva for two minutes more, and weigh as before. By the comparison of the two, the action of the stimulus may be judged of. The best modes of stimulation are the following : 1. Mechanical — Roll a pebble or glass stopper in the mouth, and attempt to chew it. 2. C'AemzcaZ.— Touch the tongue (1) with a crystal of tartaric or citric acid, or (2) of sodium carbonate; (.3), fill the mouth with ether vapor, allowing it to pass back into the pharynx, and retaining it for some time in the mouth. .3. Electrical.— "Vouch the tongue and inside of the cheeks with the electrodes of Du Bois Reymond's induction coil. The effect which a stimulus applied to the mouth produces in man, on the secretion from the parotid and submaxillary glands, may be studied with greater precision by means of a canula or syringe. If a syringe is used, its nozzle must end in a funnel-shaped dilatation. This is applied to the papilla at the orifice of Wharton's or Stenson's ducts, and gentle traction made upon the piston. A stimulus may be applied to the mouth, and the rate at which the saliva flows afterwards ob- served. It is, however, more satisfactory to use a canula, which with a httle practice, can be introduced into the ducts with great ease. *86. Mode of Collecting the Secretions of the Sali- vary Glands unmixed in mz.Ta..—ImerUon of a Canula into the Submaxillary Liuct.—Dra.^v out a narrow glass tube to a fine point, and at the place where it seems small enouo-h to enter the orifice of the duct, notch it with a triancrular file break it off; round the edges at the border of a glass flame and allow It to cool. To insert a canula thus prepared into his own BY DE. LAUDER BEUNTON. 465 submaxillary duct, the studout must now place himself before a mirror, with a bright light directed into the mouth. Fill the mouth with vapor of ether, or chew a piece of pyrethrum. Turn the end of the tongue back against the palate. At the root of the frxnum lingux a papilla with a little black dot is seen at each side of the middle line. From these two dots, which mark the orifices of Wharton's ducts, the saliva will be seen to issue. Insert the end of the cauula into one of them, and hold it steadily in its place. The entrance of the canula is attended with an unpleasant sensation, not amounting to pain. At first the canula fills pretty rapidly, but as the effect of the ether passes off, the flow soon diminishes. If it is desired to collect the secretion, a piece of India-rubber tubing must be attached to the wider end of the canula before inserting it. Imertion of a Canula into the Parotid 'huct.— As it is hardly possible to insert a canula into one's own parotid duct, a second person must be employed, who should sit opposite a good light and chew pyrethrum root as before. The method is as follows : Draw one angle of the mouth outwards and forwards so as to stretch the cheek. Opposite the second molar tooth of the upper j^aw the small papilla is seen which marks the orifice of Stenson's duct. Insert the canula and hold it steadily but carefully in its place, then a third person may blow into the mouth some vapor of ether, or introduce a little diluted tincture of pyrethrum. By these methods a sufficient quantity of secretion can be collected for the investigation of the leading properties of the two secretions. Both possess the property of determining the transformation of starch and sugar. 87. Study of the Secretions of the Salivary Glands in Rabbits. — The ducts of the salivary glands in rabbits are too small to allow of the easy introduction of a canula, but the secretion may be readily studied by cutting the duct across. The saliva escapes from the cut end and collects in drops. When the secretion is slight, it may be rendered readily visible by putting over the end of the duct a piece of bibulous paper reddened with litmus. The saliva is absorbed by the paper, and produces a blue spot, which increases in size, more or less rapidly, according to the rate of secretion. * Farofid Gland — The duct runs from behind forwards across the masseter muscle about its middle, covered by fascia. It has branches of the facial nerve on each side of it, and is parallel with the transverse facial artery. At the anterior edge of the masseter it takes a direction towards the middle line, in order to enter the mouth. If a vertical incision is made in a line with the cornea through the skiu and fascia of the cheek down to the masseter, 30 466 DIGESTION. the facial nerves and transverse facial artery are cut across as well as the duet. As soon as the bleeding has ceased, the discharge of saliva from the cut end may be investigated in the manner directed in § 90. 88. Investigation of the Secretions of the Salivary- Glands in the Dog. Permanent Salivary Fistulge.— Permanent iistulaj may be made either with or without insert- ing a cannla in the duet. In the method to be described, that of Schifr, no canula is used. Permanent Suhmaxillary Fin- tida.~The animal having been placed on the table, and its head secured with the aid of Bernard's holder, it is put under the influence of chloroform.' Shave the hair from the under surface of the lower jaw. Make an incision along the inner border of the ramus of the lower jaw, extending forwards from the anterior margin of tlie digastric muscle, and dividiuo- the skin and platysma. Secure every vein that presents it"- self with two ligatures, and divide it between them. Divide the mylohyoid muscle cautiously. Underneath it will be found the submaxillary and sublingual ducts, which run side by side, the submaxillary being somewhat larger and nearer the ramus of the jaw. Isolate the duct and divide it as near as possible to Its entrance into the mouth. Close the wound with sutures leaving the end of the duct projecting. To prevent its retrac- tion, pass a suture through it. When the wound heals, the end ot the duct will come away, leaving a fistulous opening Examine it daily, and if it has a tendencv to close, pass stine probe into it and along the duct. Permanent Sublingual fistula.— This is made in the same way as a submaxillary fistula, and the same animal may be ortlie head'' *'''' *'''° ^'^"^* ''"""^'^ ^^ "'' <^PP°site sides 89. Parotid Fistula.-The animal having been secured thP £r, T ^'! °''«f°^™ ''^ before, the hair.is clipped from the cheek between the orbit and tlie angle of the moi th. On running the finger along the lower bolder of the zyaomaVic arch from behind forwards, its anterior and inferioiroo s^ felt at Its insertion into the superior maxilla, forming an arch of which the convexity is directed backwards. At the end of this arch between its insertion into the maxillary bone and the alveolus of the second molar tooth, a little depression is =iS' aS^i^S^:^ i"f " fi'^^^^^T^x BY DR. LAUDER BRUNTON. 467 felt. Exactly on a level with this depression, and in a line with the insertion of the zygomatic arch, make an incision through the skin, cutting obliquely in a direction from the inner canthus of the eye towards the angle of the mouth. On dividing tlie subcutaneous cellular tissue, the facial vein and artery, a nerve, and the parotid duct will be found all together. The duct lies most deeply and runs from behind forwards, -while the artery, with its accompanying vein, pass from above downwards. It is of a pearly white color. Isolate it, and divide it as near the moutli as possible. The wound must be closed round the duct, and the duct secured in it by a suture, just as in the case of the submaxillary gland. * 90. EfFect of Stimuli on Secretion.— In animals with permanent flstulte, whether parotid or submaxillary, it can be demonstrated that these glands do not secrete excepting when secretion is excited by stimulants. The stimulation may con- sist in the introduction into the mouth of sapid substances, such as vinegar (which, in common with acid substances in general, acts most on the parotid), quinine, or colocynth, or of ether, or in electrical excitation of the tongue. The action of mental stimuli may be also shown, as, e. g., by placing a bone before the nose of a fasting dog without allowing himto reach it. From Schiff's experiments, it appears that this kind of stimulation has no effect on either the parotid or submaxillar}'. The mastication of a bone produces an abundant secretion from both glands, but mastication of a tasteless substance, as, e. 'aC10=5XaCl + CO^+2Hp + 2y. The carbonic acid which is generated in the reaction is absorbed h)y the solution of sodium hypochlorite. Instead of sodium hypochlorite, the similar salt 'A potaaHium, or calci.o,ra might be used in this experiment. ** 186. Separation of uric acid fC.H.X^O,) from Urine. — Place 200 cubic centimetres of urine in a narrow glass cylinder, and add two or three cubic centimetres of pure nitric acid. After twenty-foar hours a brick colored or brown sedi- ment will have subsided, which consists of crj'stals of uric acid, strongly tinted with the coloring matter of urine. These pre- sent, under the microscope, the most various forms, the more common being rhombic tables or columns and lozenge-shaped crystals ; the yellow or brown color which such crj'stals jxw- sess is very characteristic of uric acid. Decant the urine from the red sediment of uric acid, which may be freely' washed with distilled water, as uric add requires 14,000 times its weight of cold and 1800 times its wei^rht of hot water to dissolve it. The sediment may then be c^jlTected on filtering i)aijer and subjected to the following tests : 1. Place a small quantity of the crj-stals on a microscopic slide, and add a drop of liquor potass*. The crystals dissolve, and a solution of urate of potassium is obtained fC'.H K^' (),). Now add carefully an excess of nitric or hydrochloric! acid, when uric acid will be again obtained in the form of crystals, which may l»e further examined. It may be well to state that uric acid often occurs as a de- jx.sit in urine which has not been artificially acidified, and that the crjBtallographic characters of the substance are very various and sometimes puzzling. The typical crystals of uric acid are undoubtedly rhombic plates with extremely obtuse angles ; the typical form is, however, very fref^uently modified; thus spin- dle-shaped figures are forme^l by the rounding of the obtuse angles, or the primary form is so modified that needles are formed which occur in groups Tfig. 30.ii;. Not at all unfrequently BY BR. LAUDER BRUNTON. 537 wc have the primaiy form so modified that the crystals resemble hexagonal plates. Experience gained bj- a frequent comparison ■with accurate drawings of the various forms of crystals of uric acid, can alone enable the observer rapidly to identify uric acid. When any doubts exist as to the identity, it is well to dissolve the suspected crystals in liquor potassse, and to proceed as directed above, for bj' neutralizing an alkaline urate with acid, some of the commoner, and therefore easily identified shapes of uric acid crystals, are obtained. 2. Place a very small quantity of the reddish crystalline deposit in a watch glass ; add four or five drops of nitric acid and heat very cautiously over a small spirit-lamp flame. The uric acid will dissolve, and on evaporating to dryness, a red- disli-3'ellow residue is obtained. On exposing this residue to the vapor of ammonia, or adding, by means of a thin glass rod, a small quantity of solution of ammonia, a beautiful purple- red color is developed, which, on the subsequent addition of a little solution of caustic potash, assumes a violet tint. This reaction has received the name of the Murexide Test. *187. Separation of Hippurio Acid (C,H„NO,).— After urea, hippuric acid is the organic compound present in largest quantity in the urine of man, the mean quantitj' excreted per diem amounting at least to one gramme. The difficulties at- tending the separation of hippuric acid from the urine of man are, however, great, and it is therefore advisable that the stu- dent should learn to isolate this substance when it is present In larger quantities than normal in the urine. As the ui'ine of herbivora contains large quantities of hippuric acid, it may be advantageous to use for the experiment to be described cows' or horses' urine, or the urine of men in whom an excessive excretion of hippuric acid has been induced ; this maybe done by administering to a man ten or fifteen grammes of benzoic acid ten or twelve hours before the urine is collected. It is a fact worthy of remembrance tliat when ben2ioic acid is administered to healthy men, large quantities of hippuric (gly- co-beuzoic) acid are excreted. There appears to be alwa3's in the system a quantity of glycocine (C.jH3(NH2) OJ, which al- though it is never excreted as such, is capable of being seized upon by the radical of benzoic acid, so as to yield hippuric acid. By comparing the formulae of glycocine and hippuric acid, ex- hibited below, it will be seen that the latter can be represented as derived from the former by the substitution of (CjH^O) for H, thus: — Glycocine C,,H,(NH,)0, Hippuric acid C,H,(NH,)(C.H,0)0,. Take 200 cubic centimetres of the fresh urine of the cow and concentrate it, by heating on tlie water-bath, to forty cubic 538 THE SECRETIONS. centimetres. Then add hj'drochloric acid, and set aside until next day. A large quantity of liippuric acid will have separa- ted in the form of a brown crystalline mass. Wash with cold water, press the crystalline mass between folds of filtering paper ; dissolve in as little boiling water as possible, add a little pure animal charcoal {i. e., animal charcoal which has been in contact with dilute hydrochloric acid for many daj's, and then thoroughly washed with water), and filter. The filtrate should be concentrated and allowed to crystallize. (For other methods of separating hippuric acid, especially when existing in small quantities, the reader is referred to Hoppe-Seyler's " Handbuch der physiologisch- und patholo- gisch-chemischen Analyse, 1870, p. 157). Having obtained nearlj' pure hijjpuric acid, the following experiments may be tried : — 1. Dissolve a fragment in boiling water, and allow a drop of the solution to crystallize on a microscope slide. The acid usually separates in the form of transparent prisms which are single, or occur in radiating groups, and generally present four sides parallel to their long axis ; their ends are terminated by two or four planes. Their primary form is a right rhombic prism (fig. 31.3). 2. Heat a fragment of hippuric acid in a small glass tube, with a little soda-lime ; the ammonia wdiich is given off, and which can readily be detected bj^ its odor, proves that the body under examination contains nitrogen. 3. Mix a fragment of hippuric acid with strong nitric acid in a small porcelain crucible. Boil and then evaporate to dryness ; on heating the residue, a very characteristic odor of nitro-beuzol is developed. * 188. Separation of Creatinine (C,H-N,0) from Urine. — To 300 cubic centimetres of urine add milk of lime until the reaction of the fluid is decidedly alkaline. Then add a solution of chloride of calcium as long as a precipitate falls. After the precipitate has been allowed partially to subside, filter, evaporate the filtrate to dryness in a basin or the water- bath, and add to the yet warm residue thirty or forty cubic centimetres of 95 per cent, alcohol. Stir and decant the con- tents of the basin into a beaker, taking care to add the alco- holic washings of the basin. Set aside the beaker in a cool place. Filter and wash the insoluble residue with a little more spirit. If the filtrate and washings amount to more than 50 c. c, concentrate at a gentle heat to that volume. Allow the fluid to cool, and then add half a cubic centimetre of an alco- holic solution of chloride of zinc, absolutely free from the least trace of acid, and stir for some time. Set the beaker aside for three or four days in a cellar. At the end of that time the whole of the creatinine will have separated in combination BY DR. LAUDER BRUNTON. 539 with zinc chloride. It should be collected on a Alter and Avashed wilii pure spirit; the substance left on the filter con- sists of chemically pure chloride of zinc-creatinine (CjH,N30)j, ZnCl.^. This most characteristic compound is very slightly soluble in cold water and insoluble in cold alcohol ; it cr^rstal- lizes from urine in the form of bundles of needles. From chloride of zinc-creatinine, the pure substance is obtained by boiling with freshly prepared and thoroughly washed hydrate oxide of lead for half an hour or longer. On filtering the fluid, and evaporating to dryness, creatinine is obtained, which may be dissolved in alcohol and crystallized. Creatinine is vei'y soluble in cold alcohol. The following experiments may be performed with it:— 1. When a few drops of a solution are allowed to evaporate spontaneously, colorless prisms are obtained (fig. 302). 2. Tlie taste of the solution is strongly alkaline. 3. The reaction to test-paper is intensely alkaline. 4. A concentrated solution of chloride of zinc added to creatinine, causes the immediate precipitation of the zinc com- pound, which is always crystalline. ** 189. Separation of the Coloring matters of Urine. — Under various names, among others that of Urohse- matine, different writers have described the substance, or mixture of substances, which the}' considered to be the cause of the color of healthj' urine (Scherer, Harley, Heller). We are now perfectlj^ convinced that no one coloring matter, capa- ble of accounting for the normal, golden, or amber color of human urine, has been separated. The following experiments may be performed, as they throw some light on the reactions of the normal urinary coloring matter :— 1. Take 200 cubic centimetres of urine and precipitate with neutral acetate of lead ; an abundant precipitate falls, which consists of lead salts of acids present in the urine, and which contains a portion of the urinary coloring matter. Filter, and observe that the filtrate from this precipitate is not altogether colorless. Add to the filtrate basic acetate of lead, when a further precipitate will form, which, when separated, leaves a colorless filtrate. Now unite the j^recipitates caused by neutral and basic acetates of lead, and treat the mixture with alcohol acidulated with hydrochloric acid. A red fluid will be obtained, which, on filtration and evaporation, yields a reddish-black residue, insoluble in water. That this is not, as was supposed, the coloring matter of urine, is now admitted. The researches of Dr. Harley, although failing to discover any one normal urinary coloring matter, show 540 THE SECRETIONS. that the so-called iirohsematine contains a mixture of several pigmentary substances. 2. Passing from urohsematine, the student's attention is to be drawn to the constant presence in urine of a very well- defined body — viz., indican, or white indigo (CjjHjjiSfjO,) — which may readilj^ be converted into indigo-blue and indigo- red. To the indican present in urine, Heller, who first dis- covered its presence, without, however, being aware of its nature, gave the name of Uroxanthine, and to the indigo-bhie and indigo-red obtained from it, the names of Uroglaucine and Urrhodin respectively. For the method of obtaining indican, the reader is referred to Hoppe-Sejder (op. cit. p. 163) ; it will be sufficient if the student performs the following experiments: — Precipitate 100 cubic centimetres of perfectly fresh urine with acetate of lead. The fluid is filtered. The filtrate con- tains the whole of the indican. A strong solution of ammonia is added, which precipitates hydrated lead oxide, together with indican. The precipitate is collected on a filter, washed with water and dilute dydrochloric acid. Very often the filter is seen to contain blue particles, in consequence of the production of indigo-blue, which contrasts with the chloride of lead with which it is mixed. The filtrate, when left to itself for twenty -four hours, gener- ally becomes covered with a bluish-purple film, consisting of indigo. 3. Several hundred cubic centimetres of pure urine are pre- cipitated by acetate of lead and then filtered ; the filtrate is treated with excess of sulphuretted hydrogen, boiled and filtered; the filtrate is now poured into an equal volume of pure and strong hydrochloric acid. The fluid becomes either violet or indigo-blue ; it is allowed to stand for twelve hours, and diluted with an equal volume of water. After about twenty-four hours, a deposit will generally have formed, which is collected on a filter, washed, and dried. When treated with ether, the deposit will generally yield to it a red coloring matter, whilst indigo is left behind, and is to be purified by solution in boiling alcohol. The student will remember that indigo-blue only difl'ers from indican in the possession of two additional atoms of hydro- gen,— Indican, or white indigo C ,H N O . Indigotin, or blue indigo .... o"'h"n"0^ In the production of indigo-blue from indican there are other substances formed, such as a form of sugar, which is an isomer of glucose, but unfermentable, and the imperfectly BY DR. LAUDER BRUNTON. 541 investigated body, indigo-red, which has alreadj' been alluded to.' The following reactions may be tried with indigo-blue : — (a) Shake a fragment of indigo-blue with ether ; the sub- stance is found to be very scantily soluble. Ether, however, dissolves enough to acquire a faint blue tint. (b) Place a fragment in a narrow glass tube and heat ; it "will sublime and be deposited in the cool part of the tube. If the latter be very narrow and thin, it may be examined microscopicalljf. The sublimate of indigo is then seen to con- sist of microscopic needles and plates. Methods foe the Quantitative Analysis of Urine. ** 190. Determinationofthetotalquantity of Urine passed in a given time. — Before describing briefly the methods which are emploj'ed for the determination of the more important urinary constituents, attention must be drawn to the fact that, as a general rule, quantitative analj'sis of urine throws little or no light on the rate and character of the tis- sue changes going on in the animal body, unless the anal^ysis be made of a specimen of urine which represents the average excretion of a known period, during which the conditions of the animal have been ascertained as accurately as possible. These remarks will be better understood when it is stated that we can obtain the most valuable information relating to the urinary secretion if we collect, mix, and then measure the whole of the urine passed in twenty-four hours Having ascertained the total volume of urine passed in twenty-four hours, two hundred cubic centimetres will suffice for tlie great majority of quantitative analyses. The urine of man must be collected in perfectly clean glass vessels which in accurate experiments, should, before being used, be washed with dilute sulphuric acid, and then with water. The collecting-vessel may be graduated or not ; in the latter case, the urine is carefully poured, if necessary, in suc- cessive portions, after being mixed, into a cylinder capable of holding a litre of water, and divided into 200 parts ; so that each division indicates 6 cubic centimetres. It is frequently of use to collect the urine of dogs and rab- bits, especially when experiments are made on the physiological action of drugs. ' In many cases of disease, urine contains so mucli indican, that the following reaction may be observed : — To five cubic centimetres of fuming hydrochloric acid, add from one to two cubic centimetres of urine. A violet color is produced, which passes into red. 542 THE SECRETIONS. In these cases, cages are employed, whose walls are marie partly of sheet iron or zinc, and partly of wire netting. The floor of the cage should be made of thick glass rods (about four-tenths of an inch in diameter), placed very closely together. These rods are so arranged that the spaces between them will allow urine to trickle away, whilst the solid excreta are re- tained. The glass rods are firmly inserted into the wooden base of the cage ; this is furnished with a drawer, into which is accu- rately fitted a fiat glass or porcelain dish, such as is used by photographers in washing photographs. The dish is perforated by a hole, in which a tube (preferably of glass) is accurately fitted, and leads to the collecting vessels outside. If care be taken to wash the glass-rod bottom of the cage and the collecting-glass dish placed beneath It, the urine may be collected in a state of great purity. ** 191. Determination of the specific gravity of Urine. — This may be effected in either of the two ways de- scribed in App. § 216, for the determination of the specific gravity of fluids, viz., by means of a hydrometer or with the specific gravity bottle. The hydrometer employed for taking the specific gravity of urine is called a urinometer; in this country its stem is usually divided so as to indicate densities ranging from 1000 to 1060 (water being 1000) ; it is preferable to use two urinometers : one indicating densities from 1000 to 1030, the other from 1030 to 1060. The length of the stem being the same as that of the ordinary instruments, the accuracy of the reading will be much increased. Before using a urinometer, its accuracy should be checked by immersing it in fluids of known specific gravity. If the specific gravity of three samples of urine be accurately taken with the bottle, data are obtained for checkino- the accuracy of the urinometer. Although, under certain circumstances, important informa- tion may be obtained by a determination of the specific gravity of an isolated sample of urine, generally it is only when the specific gravity of a sample of the mixed and measured urine of the twenty -four hours is ascertained, that we learn much from the experiment. A knowledge of the specific gravity enables one to form a near approximation to the total quantity of solid matter ex- creted by the kidneys in a given time. It has been empirically determined that the specific gravity of urine generally bears a close relation to the solid matters which it contains in solution. Sir Robert Christison pointed out, many years ago, that if the whole numbers which express the diflTerence between the density of a sample of urine and the density of water (expressed as 1000) be multiplied by the factor BY DR. LAUDER BRUNTON. 543 'J. 33, the product represents very closely' the weight of the total .solids contained in 1000 parts, by weight, of urine. Subsequent observers have determined that whilst Christison's formula yields very correct results when applied to urines of specific gravities aljove 1018, for urines of lower specific gravity greater accuracy is obtained by substituting the factor 2 for 2.33. The following example will suffice to show the method of calculating approximately the total solid matter excreted in the urine in twent3'-four hours : — A man passes in twenty-four hours 15*?5 cubic centimetres of urine of specific gravity 1023, and it is desired to obtain an approximate estimate of the total urinary solids. tst. We find the total solids (expressed in any particular units of weight) contained in 1000 parts (expressed in the same units of weight) by Dr. Christison's formula, thus, if the unit be the gramme, and the quantity of solid matter in 1000 grammes be represented by x, X = (1023 — 1000) 2.33 = 53.59. 2d. We require to know the weight of the whole of urine. As its density is 1023, and the quantity 1516 cubic centimetres, the weight ill grammes is at once found by the following proportion : — 1000 : 1023 :: 15Y5 : x 1023 X 1515 !„,, X ^= = Ibll. 1000 3d. Knowing the weight in grammes of the ui'ine of twenty- four hours, and the approximate weight of total solid matters in 1000 parts, by weight, of urine, we obtain the total solids passed in twenty-four hours expressed in grammes: — 1000 : 53.59 :: 1611 : x X = 86.33 grammes. It is to be noted that the result obtained by such calcula- tions is merel}' an approximation to the actual number which would be ascertained by the direct method, to be immediately described ; the approximation is, however, sufficiently close to be useful. 192. Determination of the Total Solid Matters con- tained in Urine. — If we know the total volume of urine passed in twenty-four hours, and it be desired to ascertain, by direct weighing, the total quantity of solid matter contained in it, 10 or 15 cubic centimetres of the mixed urine are poured from a ver^' accurately graduated pipette into a weighed porce- lain or glass capsule, which is heated over the water-bath. 544 THE SECRETIONS. or in the water oven (fig. 339), until a nearly dry residue is obtained. The capsule with its contents is then heated in an air oven whose temperature is maintained at 120° C. The capsule is, after some time, allowed to cool in an exsiccator (fig. 340) and rapidly weighed. The drying and weighing should be repeated until the weight of the capsule and residue is constant. In order to secure accuracy, the capsule in which the evaporation is carried on should be fitted with a ground glass plate, which should be placed over it, when it is" trans- ferred from the air oven to the exsiccator, and from the ex- siccator to the balance. It is absolutely essential that the weighing should be con- ducted with the greatest possible rapidity, as the dried urinary solids are highly hygroscopic. Instead of measuring the urine used in the analysis, a weighed quantity may be taken. ** 193. Determination of the Amount of Chlorine contained in Urine. By Liebig'n Method — It has been already mentioned that when a solution of mercuric nitrate is added to a solution of urea, a dense white precipitate is formed, which consists of compounds of urea with mercuric oxide. If the solution of mercuric nitrate be sufBciently diluted, and be added in sufficient quantity, the compound formed con- tains four molecules of mercuric oxide for each molecule of urea. If, however, a solution of mercuric nitrate be added to a solution of urea and chloride of sodium, no precipitate will at first be formed, the reaction between the urea and oxide of mercury not occurring until the double decomposition between the mercuric nitrate and sodium chloride has been completed thus: — ' Hg 2N03 + 2NaCl=Hg Cl, + 2NaN03. As soon, however, as this has occurred, a white precipitate of the mercuric oxide and urea compound falls. Liebig's method of determining tlie amount of chlorine in urine is based upon the reactions which have been referred to In order to enable the student to determine the amount of chlorine by Liebig's method, we shall describe, in the first place, the method of preparing the standard solution of nitrate of mercury, and, in the second place, the method to be fol- lowed in determining by its aid the quantity of chlorine in urine. Preparation of standard solution of mercuric nitrate for the estimation of chlorine in Urine. The following solutions are required : 1st. A solution of mercuric nitrate of such a strength that BY DR. LAUDER BRUNTON. 645 one cubic centimetre shall correspouil to 10 millio-rammes (0.010 gvm.) of sodium chloride. " This solution may be made by dissolving twenty grammes of perfectly pure metallic merciiiy in boiling nitric acid, until a drop of the acid fluid does not cause a precipitate when added to a solution of common salt. The acid fluid is concentrated by heating over a water-bath until it is of syrupy consistence. It IS then diluted with nearly a litre of distilled water. Unless a great excess of nitric acid has remained after the evaporation, a white precipitate, consisting of a basic nitrate of mercury, will fall, and must be separated by filtration. Be- iore performing the latter operation, a few drops of nitric acid may, however, be added, as they will cause the re-solution of a considerable part of the precipitate, without rendering the liquid too acid. The solntion of mercuric nitrate thus "made must be set aside until the other reagents which are required for determining its strength are prepared. 2d. A solution made by dissolving in distilled water 20 grammes of pure sodium cloride and diluting to one litre. The salt is fused before being weighed. Ten cubic centimetres of this solution contain 0.200 o-rm of NaCl. 3d. A solution made by dissolving 4 grammes of pure urea in distilled water and diluting to 100 c. c. 4th. A solution of sodium sulphate, saturated at ordinary temperatures. In order to determine the strength of the solution of mer- curic nitrate, it is poured into a burette (preferably a Mohr's burette, witli glass -stopcock) of a capacity of 50 cubic centi- metres, and divided into lOths of a cubic centimetre. Ten cubic centimetres of the standard solution of chloride of sodium are then measured by means of a pipette, and poured into a glass beaker. To this is added 3 cubic centimetres of the solution of urea, and 5 cubic centimetres of the solution of sulphate of sodium. The solution of nitrate of mercury is now allowed to flow gently into the beaker ; as the drops fall into the fluid con- tained in the latter, a white precipitate is seen to form, which, however, dissolves at once, or when the fluid is stirred. On adding more of the solution of nitrate of mercury, the fluid becomes opalescent but no precipitate occurs until the reaction is completed, i.e., until the whole of the chloride of sodium has been decomposed. The number of cubic centimetres of the solution of mercuric nitrate which has been added is read off; if, for example, 12.7 cubic centimetres of the solution had to be added in order to induce a permanent precipitate, we conclude that this quantity of solution contains the quantity of mercuric nitrate required 35 546 THE SECRETIONS. to decompose 0.200 gramme of NaCl. As it is convenient to have a solution of which 10 cubic centimetres shall be equiva- lent to 0.100 gramme of NaCl, we must take our solution and dilute it to the required extent. In the assumed case, 12.7 cubic centimetres contained as mucli of the mercurial salt as correspond to 0.200 gramme of NaCl, i.e., as much as would be required in 20 cubic centimetres of solution. If we there- fore diluted 12.7 cubic centimetres with 7.3 cubic centimetres of water, we should obtain 20 cubic centimetres of a solution of which 10 cubic centimetres would be exactly capable of de- composing 0.100 gramme of NaCl. But as in preparing such a standard solution we deal with large quantities of fluid, it is well to effect the dilution of the whole at once. Thus let us suppose that we have- 800 cubic centimetres of the solution, of which 12.7 cubic centimetres are equivalent to 0.200 gramme of NaCl. As 12.1 cubic centimetres require the addition of 7.3 cubic centimetres of water, it is easy to find how much 800 cubic centimetres require, viz., 459.8 cubic centimetres. If we then measure out very accurately this quantity of distilled water, and add it to our solution, we obtain 1259.8 cubic centimetres of a solution of which 10 cubic centimetres represent 100 milli- grammes of NaCl, or 60.65 milligrammes of CI. Having made the standard solution of nitrate of mercury for the estimation of chlorine, we must, before analyzing urine, prepare a solution which we shall designate as Baryta Mixture. This is prepared by mixing two volumes of a solution of barium nitrate, saturated in the cold, with one volume of a solution of caustic barj'ta (barium hydrate), similarly saturated. Two volumes of the urine to be analyzed (saj' 40 cubic centi- metres) are now mixed with one volume (sa}' 20 cubic centi- metres) of baryta mixture. An abundant precipitate falls, consisting chiefly of a mixture of phosphate, sulphate, and car- bonate of barium. (This removal of phosphates is essential, as these salts are precipitated by the solution of nitrate of mercury.) The fluid in which the precipitate has formed is filtered, care being taken that the filter is not moistened. As the filtrate contains one-third' of its volume of baryta mixture, it is convenient to take for analysis 15 cubic centi- metres. This quantity will exactly correspond to 10 cubic cen- timetres of urine. It is convenient, therefore, to have, in addi- tion to pipettes graduated so as to deliver 20 and 40 cubic centimetres, one which delivers exactly 15 cubic centimetres of fluid. The measured portion of filtrate is very slightly acidified by adding, drop by drop, exceedingly dilute nitric acid, and then the solution of nitrate of mercury is allowed to BY DR. LAUDER BRUNTON. 547 flow in, at first rather rapidly, afterwards guttatim, until a per- manent and dense cloud, not aflected by vigorous stirrino- makes its appearance. °' The number of cubic centimetres used, multiplied by 0.010. indicates the amount of chlorine, in fractions of a gramme, cal- culated as NaCl, contained in 10 cubic centimetres of urine. Thus, if 8.56 cubic centimetres of the standard solution of chlorine were added, the quantity of CI, calculated as NaCl in 10 cubic centimetres, would be 0.085 gramme. It must be remarked that if a urine contains albumin, this substance must be removed by boiling and filtration before the determination of chlorine by Liebig's method can be efl'ected. 194. Determination of chlorine by means of nitrate of silver. —In cases where the quantity of chlorine is exceedingly small, the following method is much to be preferred to that already described. Ten cubic centimetres of urine are placed in a platinum cap- sule, together with 2 grammes of pure potassium nitrate (quite free from chlorine), and evaporated to dryness. The residue is ignited at a moderate heat until the whole of the carbon has disappeared. The crucible is allowed to cool, and the saline mass which it contains is dissolved in distilled water, a little nitric acid being added. The estimation of chlorine may then be effected by those methods which are to be found described in text-books on chemical analysis. The chief of these methods consist (a) in precipitating the chlorine as chloride of silver, etc., washing, burning, and weighing the precipitate ; and (6) in adding to the neutralized solution of the chloride, mixed with a drop of potassium chromate, a standard solution of nitrate of silver. The nitrate of silver causes a white precipitate of chloride of silver, when added to such a solution, until the whole of the chlorine has been precipitated. Then, however, the addition of a single drop more produces a deep salmon-red color, due to the formation of silver chromate. ** 195. Determination of the amount of Urea found in Urine. I. By Liebig's Method — In order to determine the amount of urea by Liebig's method, we require (a) baryta mixture as used in the determination of the amount of CI in urine, and (b) a standard solution of nitrate of mercury, prepared in the same manner as that used for CI determinations, but containing much more mercury. In making this solution, dissolve about 15 grammes of pure mercury in pure nitric acid, adopting all the precautions previouslj' suggested, and dilute to the volume of one litre. In order to grade the solution of mercuric nitrate for urea, we must pour into a beaker 10 cubic centimetres of a standard 548 THE SECRETIONS. aqueous solution of pure urea, containing 2 grammes of per- fectly pure urea in 100 cubic centimetres. The quantity of so- lution in tlie beaker will then contain 0.200 gramme of urea. The solution of mercuric nitrate is then added and the fluid stirred ; an abundant snow-white precipitate falls. When the precipitation appears to be nearly completed, a drop of the fluid holding the precipitate in suspension is added to a drop of solution of sodium carbonate on a porcelain slab. If the urea be not completely precipitated, no change of color will be ob- served when the two fluids are mixed. The mercuric nitrate solution is then added drop by drop, and the process of testing with the solution of Na^CO, on tlie slab repeated from time to time. At last a yellow color will appear. This will indicate that the solution of mercury has been added in excess. The number of cubic centimetres of solution added indicates the number of c. c. which are equivalent to 0.200 gramme of urea. As it is convenient to have a solution of mercuric nitrate, of which 10 cubic centimetres shall precipitate 100 milligrammes of urea (0.100), or 1 cubic centimetre 10 milligrammes, it is essential to dilute the solution which has been prepared, in the same manner as was indicated in the case of the solution for the determination of chlorine. Having prepared the solution of mercuric nitrate for urea, and the baryta mixture, the analysis of urine can be rapidly effected. 40 cubic centimetres of urine are mixed with 20 cubic centimetres of baryta mixture; 15 cubic centimetres of the fil- trate are precipitated with the mercury solution, until a yellow reaction with solution of Na^CO^ is obtained. The number of cubic centimetres of the mercury solution used, minus 2 and multiplied by 0.010 gramme, indicates very closely the amount of urea, expressed in fractions of a gramme, contained in 10 cubic centimetres of urine, provided that the urine be of average composition, i. e., that it contains no ab- normal substances, that the amount of chlorine in it be about the average, and that it be neither very concentrated nor very dilute. The statements made in the preceding paragraph indicate many circumstances which have to be taken into account, and many corrections which have to be introduced in order to give to Liebig's method the accuracy of which it is capable. In pointing out these corrections, an explanation must be given of the empirical statement, '■'■that the number of cubic centimetres of mercury solution used, minus 2, and multiplied by 0.01 grm., indicates very closely the amount of urea, ex- pressed in fractions of a gramme, contained in 10 cubic centi- metres of urine." The reason for subtracting 2 cubic centi- metres is, that in average urines this volume of the solution is BY DR. LAUDER BRUNTON. 549 required to decompose the chlorides, and does not, therefore, take part in the urea reaction. If this correction be constantly introduced in a series of ob- servations, and, as has been alread}' pointed out, the nrine be not of very exceptional composition, results are obtained wiiich are very nearly correct, and which are comparable the one with the other. If, however, the urine in cases of pneumonia or of fevers were under investigation, the error introduced by the application of this arbitrary correction would generally be very great. In such cases we must adopt a more scientific method of avoiding tiie error introduced by the presence of chlorides. We must in the first place determine, by the tttcuidard solution of mercuric nitrate for chlorine, the amount of chlorine, calcu- lated as NaCl present in 10 cubic centimetres of the urine, i.e., in 15 cubic centimetres of the filtrate obtained on mixing two volumes of urine with one volume of baryta mixture, and we must then remove the whole of the CI from a fresh quantity of filtrate by a standard solution of nitrate of silver. To do this we require a solution of nitrate of silver exactly equivalent to the solution of nitrate of mercury which has been used. If 11.601 grammes of fused silver nitrate be dissolved in distilled water, and diluted to the A'olumeof 1 litre, the solution will be of the required strength, i. e., 1 cubic centimetre will exactly precipitate 0.010 gramme of chloride of sodium. Take .30 cubic centimetres of the filtrate from the mixture of bar3fta mixture and urine, and, having added a drop of nitric acid, pour in from a burette, or from a finely divided pipette, twice as many cubic centimetres of the nitrate of silver solu- tion as tiie number of cubic centimetres of nitrate of mercury solution required in the chlorine determination. A precipitate of chloride of silver will fall, and the. filtrate may now be sub- jected to analj^sis for urea. An exam^jle will help to make the course of these operations clear. Forty cubic centimetres of the urine of a boy suffering from typiius fever were mixed with 20 cubic centimetres of baryta mixture, and tiie fluid was filtered. 15 cubic centimetres of the filtrate was placed in a beaker, and the standard solution of mercury for chlorine was added, until a permanent and dense cloud had formed. The number of cubic centimetres added was 4.5. As each cubic centimetre of the standard solution corresponds to 0.010 gramme of CI calculated as NaCl, the quantity in 10 cubic centimetres amounted to 0.045 gramme. 30 cubic centimetres of the filtrate from the baryta mixture and urine were now taken and treated with 4.5 X 2, i. e., 9 cubic centimetres of nitrate of silver solution. The fluid was filtered. Now 39 cubic centimetres of the mixture of urine, baryta so- 550 THE SECRETIONS. liition, and silver nitrate solution, contained 20 cubic centi- metres of urine. On, therefore, taking ^-^ or 19.5 cubic centi- metres of the filtrate, after the precipitation of the chloride of silver, we obtained a quantity of fluid which contained all the urea present in 10 cubic centimetres of the original urine. It may be well to state that when, as in many cases of acute disease, the amount of chlorine present is very small, nearly accurate results are obtained, if no correction for chlorine be introduced. Other corrections must be introduced into Liebig's method under peculiar circumstances : these will be stated dogmati- cally, the student being referred to larger books for their ex- planation. 1st. "When, in determining the amount of urea in 15 cubic centimetres of mixture of urine and baryta solution, the num- ber of cubic centimetres of mercury solution added exceeds 30, we must repeat the operation, adding to 15 cubic centimetres of the fluid a quantity of distilled water equal to the difference between 30 and the number required in the first operation. 2d. When the amount of solution of nitrate of mercury added to 15 cubic centimetres of the filtrate from the mixture of urine and baryta mixture, is less than 30 cubic centimetres, 0.1 cubic centimetre must be subtracted from the amount of mercury solution required, for every 5 cubic centimetres less than 30 cubic centimetres. This correction is of little importance. II. Davy's method for the determination of Urea. This excellent method is based upon tlie fact already men- tioned, that when a solution of urea (CHjN,,0), such as urine, is treated with a solution of hypochlorite, it splits up into car- bonic acid, water, and nitrogen gas. If the mixture be effected in a long graduated tube, and this be inverted and placed over mercury, the whole of the N accumulates on the surface of the fluid, the carbonic acid being absorbed by the solution of hy- pochlorite used. Fi-om the volume of N evolved the quantity of urea present may be calculated. (For details of this method the reader is referred to a Treatise on the Pathology of the Urine, by Dr. Thudichum, London: Churchill, 1858. f Davy's process is, like Liebig's, not absolutely correct. Uric acid, and other nitrogenous substances present'in urine, are de- composed by hypochlorites ; as their quantity is, however, com- paratively very small, the error introduced is not large. The writer can vouch, from personal observations, of the o-reat accu- racy of this method when applied to Solutions of pure urea, and believes that, if carried out with the apparatus devised by Dr. Hiifner for the determination of urea by solutions of alkaline hypobromites, it would prove the most useful and reliable method for the determination of urea. BY DR. LAUDER BRUNTON. 551 * 196. Determination of the Amount of Uric Acid in Urine. — Uric acid is usually determined by precipitation with dilute nitric or hydrochloric acid, the crystalline precipi- tate being washed, dried, and weighed. Take 200 c. c. of the urine and add to it 5 c. c. of dilute hy- drochloric acid of density 1.11. Set aside in a cellar for 24 Lours. Collect the uric acid on a weighed filter, and wash thoroughly with distilled water. Dry the filter and uric acid in a water oven at a temperature of 100° C. Allow the dried filter to cool under an exsiccator (in watch glasses, etc.) and weigh. The weight of the filter and uric acid, minus the weight of the filter paper, gives the amount of uric acid precipitated. To this must, however, be added the quantity of uric acid which has been held in solution by the urine and hj'drochloric acid, and by the washings of the filter. The whole of these fluids are therefore mixed and measured, and for every 100 c. c. 0.0038 grammes of uric acid must be calculated (Neubauer). The number thus calculated, added to that of the uric acid col- lected on a filter, gives the amount of uric acid contained in the urine. The number is, however, only an approximation to the truth.' **197. Determination of the Amount of Phosphoric Acid contained in Urine. — The phosphoric acid contained in urine exists partly in a state of combination with the alka- line earths, magnesia, and lime, but chiefly in combination with alkalies. If we render the urine alkaline by the addition of am- monia, the former are precipitated, leaving the alkaline phos- phates in solution. It is customary to state the amount of phosphoric anhydride corresponding to phosphoric acid in the urine. In determining the quantity of phosphoric acid in urine, we may merely determine the total quantity existing in the fluid, or we may determine the total quantity first, and then the quantity which remains after the precipitation of the earthy phosphates. The volumetric method for the determination of phosphoric acid in urine is based upon the following reactions : — (a) When a solution of a phosphate acidulated with acetic acid is treated with a solution of nitrate or acetate of uranium, a precipitate falls which is composed of uranium phosphate. (b) When a soluble salt of uranium is added to a solution of potassium ferrocyanide, a reddish-brown precipitate or color is developed. Preparation of Standard Solutions of Uranium, etc. — Before preparing this solution, it is advisable to make a standard solu- ' The reader is referred to tlie recent researches of Dr. Salkowsky, in Virchow's Archiv. Bd. 53, and of Maly, Pflliger's Archiv. 1873, vol. vi. p. 301. 652 THE SECRETIONS. tion of a phosphate. For this purpose, 10.085 grammes of well crystallized sodium phosphate (Na,HPO, + 12H,0) are dis- solved in distilled water, and the solution diluted to one litre. Fifty cubic centimetres contain 0.1 gramme of P^Oj. Then 100 grammes of sodium acetate are dissolved in 900 c.c, of distilled water, and 100 c.c, of acetic acid added. The solution of uranium acetate is made by dissolving com- mercial uranic oxide in acetic acid, diluting and filtering; or, instead, a solution of uranium nitrate may be made by dissolv- ing the crystallized salt in water, and diluting. The solutions are intended to contain 20.3 grammes of ura'nic oxide in one litre of solution. Having obtained the solution of uranium acetate or nitrate, its strength is determined in the following manner: 50 c.c. of the standard solution of sodium phosphate are placed in a beaker, and 5 c. c, of the acid solution of sodium acetate added. The uranium solution is poured from an accurately graduated burette, until precipitation ceases. Then a few drops of a solution of potassium ferrocyanide are placed on a porcelain slab, and after each addition of uranium solution to the phos- phate, a drop of the mixture is taken up by means of a glass rod and brought in contact with the ferrocyanide. As soon as an excess of uranium solution has been added, the character- istic reddish-brown color of uranium ferrocyanide is observed. It is convenient to graduate the solution of uranium so that 20 cubic centimetres shall be exactly equal to 50 c. c. of the standard solution of phospliate of soda, i.e., to 0.1 gramme of In analyzing urine by means of solutions of uranium, it is convenient to operate on 50 c. c. This quantity of urine is treated with the acetate of sodium solution and heated on the water-bath to a temperature approaching 100° C. ; it is then treated with the solution of uranium as previously described 198. Determination of the Quantity of Sulphuric Acid m Urine.— The quantity of sulphuric acid in urine is best determined by precipitating with chloride of barium and weighing the dried and burned precipitate of barium sulphate • Irom this the amount of sulphuric acid can be calculated It 18 usual to state the amount of sulphuric anhydride (SO ) cor- responding to the sulphuric acid existing in the urine For details as to the precaution to be used in determinino- the amount of sulphuric acid by precipitation, the student i1 referred to Fresenius's Quantitative Analysis. The manipula- tions involved in such an analysis, however simple it may be can only be learned in a laboratory devoted to pure «hemistrv. It has been suggested that the sulphuric acid in urine should be determined by means of a standard solution of chloride of harium ; the metliod is one, however, which is tedious and BY DR. LAUDER BRUNTON. 553 which cannot be recommendefl, even on the score of rapidity, as preferable to the one first described. ** 199. Detection of Sugar in Urine.— It is still a mat- ter of doubt whether the urine in health contain,? sugar; the processes which have been suggested, for the separation of this substance, bj- those who maintain its constant occurrence in healtliy urine, are, however, complicated ; and, as they have led to very various results in the hands of different observers, their consideration would be out of place in this book. (See Pfliiger's Archiv. fiir Physiol. V. pp. 359 and 315.) When present in abnormal quantities in urine, as in diabetes, glucose may be very readily detected. The following expei'i- ments will be sufficient to make the student acquainted with the more common reactions. Exper-iment 1. Take 5 cubic centimetres of diabetic urine, or of a solution of grape-sugar, and add to it two or three drops of a solution of copper sulphate, so that a very slight green tinge is perceptible ; then add to the fluid a solution of caustic soda, or potash, until the precipitate of hydrate copper oxide, at first formed, is redissolved. The fluid, which has assumed a blue tint, is now boiled, when an abundant precipitate of cuprous oxide falls ; before this has separated, the fluid in which the precipitation is effected be- comes opaque, and presents a reddish-yellow color. This is known as Trommer's test {nee § 77 and § 12). 2. To five cubic centimetres of urine add nearly an equal volume of a solution of caustic soda, or potash, ancf boil. The fluid will assume at first a light-yellow, then an amber, and lastly a dark-brown coloration. This is known as More's test. 3. Some diabetic urine is mixed with a little brewer's yeast, and the mixture is poured into a test-tube half full of mercury • the orifice of tiie tube is closed with the thumb, and the tube is inverted into a capsule containing mercury. After a period of twenty-four hours, at ordinary tempera- tures, the test-tube will be found to contain large quantities of carbonic acid gas, which can be readily' absorbed by passino- up into the tube a fragment of caustic potash. In addition to these tests, the student maj' with advantao-e determine, by means of a polariscope, that diabetic urine pos- sesses the property of rotating the plane of jDolarized light to the right, ** 200. Determination of the Quantity of Sugar in Urine. — This may be best eflTected by one of the two follow- ing methods : firstly, by determining to what extent a known depth of the saccharine fluid rotates the plane of polarized light to the rigiit; or, secondly, bj' determining the quantity of urine which has to be boiled with a standard solution of 554 THE SECRETIONS. a cupric salt, in order to reduce the whole of the copper to the condition of red cuprous oxide. In order to determine the quantity of sugar by the last method, which is known as that of Fehling, we require to prepare a standard solution in the following manner : 34.65 grammes of pure and well crj^stallized copper sulphate are dissolved in about 160 cubic centimetres of water, and 113 grammes of Rochelle salts (tartrate of potash and soda) are dissolved in about 600 cubic centimetres of solution of caustic soda, having a specific gravity of 1120. The solution of sul- phate of copper is added gradually to the alkaline solution of Rochelle salts, the fluid being continually stirred. A deep blue solution is thus obtained, which is diluted with distilled water to the volume of one litre. Ten cubic centimetres of this solution are reduced by 0.05 gramme of diabetic sugar. The following is the process which has to be followed in determining the quantity of sugar in urine: — The urine to be examined is diluted to a known extent ; thus in the case of a diabetic urine, having a specific gravity of 1040, 100 cubic centimetres are diluted with distilled water to the volume of 1000 cubic centimetres. Ten cubic centimetres of the standard copper solution are then accurately measured out and poured into a porcelain capsule. Forty cubic centimetres of distilled water are added, and the solution in the capsule boiled. The previously diluted urine is then allowed to flow in from a burette ; after a few cubic centimetres have been added, the fluid in the capsule is briskly boiled, and then the application of heat discontinued for a few seconds. The solution, which, after the saccharine fluid has been boiled with it, assumes a red color, deposits a red sediment of cuprous oxide, whilst the supernatant fluid retains a more or less blue color, in consequence of a portion of the copper remaining in solution. Successive portions of the diluted urine are then added, and the fluid boiled after each addition. As the operation proceeds, the addition of the diluted urine is performed with great care[ only a few drops being poured in at a time. A point is at last reached when the bottom of the capsule is coated with a de- posit of red cuprous oxide, and when, on tilting the capsule so as to bring the fluid, which it contains, over the clean white sides, no tint of blue is perceived. The number of cubic centimetres of sugar solution added is then read off and marked. It is advisable, however, to pur- sue the operation one step further. A few more drops of diluted urine are added to the contents of the basin, which are again boiled, and if necessary, the addition is repeated until the boiled fluid becomes faintly opaque and of a yellowish BY DR. LAUDER BRUNTON. 555 color. These appearances prove that a sliglit excess of sugar solution has been added. The number of cubic centimetres°of diluted urine added is again read off. If the arithmetic mean of the first and second results be now taken, a number will be obtained which represents, very accurately, the volume of the dilute urine, in cubic centimetres, which was capable of re- ducing the whole of the copper in ten cubic centimetres of the standard solution employed. Now, as this volume of copper solution is reducible by exactly 0.05 gramme of dia- betic sugar, this quantity must have' been present in the volume of diluted urine made use of. An example will render the calculations required intelligible : The urine of a diabetic patient was found to have a specific gravity of 1035. 100 cubic centimetres were placed in a litre flask, and distilled water added until the fluid exactly measured 1000 c. c. Ten cubic centimetres of standard copper solution required 30.49 c. c. of the diluted urine in order to be completely reduced, or 30.49 c. c. of the diluted urine contained 0.06 gramme of sugar. As the urine had been diluted to ten times its original bulk, the same volume of the undiluted urine would contain ten times as much sugar, i. e., 0.5 gramme of sugar. From these data we can easily ascertain how much sugar was passed in the twenty-four hours. Thus, if the quantity of urine passed in twenty-four hours, in the case under consideration, amounted to 3000 cubic centimetres, the amount of sugar passed during the same period would be at once found by the following proportion : — 30.49 : 0.5 : : 3000 : x = 49.19 grammes. The student, in carrying out the process just described, must be careful to dilute the urine to a sufficient extent. In cases where the percentage of sugar is very large, it is, for instance, convenient to dilute the urine twenty times instead of ten. ** 201. Detection of Albumin in Urine. — Except in very exceptional cases, which need not be alluded to here, the only albuminous body proper which appears in urine possesses the reaction of serum albumin. Accordingly, when albumi- nous urine is boiled, it is found to be coagulable, i. e., the albumin separates in the insoluble form, and the coagulated albumin is insoluble in niti'ic acid. Nitric acid, when added alone to urine containing albumin, likewise precipitates that substance, and the precipitate is not dispelled by heat. It must be stated, however, that in certain cases, when nitric acid produces a mere haze, this may disappear on boiling, although it be really due to a trace of albumin. Albuminous urine possesses the property of rotating the plane of polarization to the left. 556 THE SECRETIOXS. * 202. Determination of the Amount of Albumin in Urine. — A known volume of the urine, say 50 or 100 cubic centimetres, is boiled ; if tlie reaction is alkaline or neutral, a trace of acetic acid being previously added, the albumin sepa- rates freely and is collected on a weighed filter. The substance on the filter is repeatedly washed with boiling water, and after being allowed to drain, it is dried, first in a water oven at 100'"^ C, and afterwards in an air oven at 120° C. The weight of the filter and albumin, minus the weight of the filter, fur- nishes us Tvith the quantity of albumin (with adhering salts) present in the quantity of urine taken for analysis. When a large number of determinations of albumin in urine have to be made, it is advisable to make use of the polariscope. The extent to which the plane of polarized light is rotated to the left bears a strict relation to the quantity of albumin present in a fluid, providing the depth of fluid examined be the same, and that no other substance (e. g., sugar) be present, exerting an opposite action on polarized light. ** 203. Detection of Bile-coloring Matter in Urine. — TVheu a large quantity of bilirubin is present in urine it may be separated from it by agitating the fluid with chloroform, decanting, evaporating the chloroform solution, dissolving the residue in pure chloroform, and alloiving the fluid to evaporate spontaneously. In this way red rhombic prisms of bilirubin may be obtained. In all cases where bile-coloring matter is present, we can de- tect it by the well known reaction with nitric acid (Gmelin's reaction). If strong nitric acid, containing nitrous acid, be added to a thin stratum of urine containing bile, in a flat por- celain dish, a succession of beautiful tints is perceived. The fluid is seen at flrst to be green, then blue and violet ; it then assumes a rather dirty claret, and ultimatelv a dirty yellow color (see § 13.5). In cases where a very satisfactory search for traces of bili- rubin is to be made, it is advisable to separate it from the urine, by means of chloroform, and then to test the evaporated residue •with nitric acid. A property which is very characteristic of urine or other animal fluids colored by bile pigment, is that of staining, of a yellow color, linen which is moistened with it. ** 204, Separation and Detection of Bile Acids in Urine. — Four or five hundred cubic centimetres of urine are treated with acetate of lead until a precipitate ceases to fall, and then solution of ammonia is added. The precipitate is collected on a filter, washed with water, and allowed to drain. The filter paper, with the very bulkv precipitate which it con- tains, is then boiled in a flask, with alcohol, and the solution is filtered wliilst hot. A few drops of solution of sodium carbo- nate being added, the fluid is evaporated to dryness on the BY DR. LAUDER BRUNTON. 557 water-bath. The residue is boiled with absolute alcohol, and the solution is eoiieeiitraled to a small volume. On addinr may be removed during part of the process to allow freer access of air, but towards the end it should again be rephieed so that the heat within the crucible may become greater. AVilh the same view, the blowpipe flame may be substituted for lliat of (he Bunsen's burner. The crucilile is then allowed to cool somewhat on the triangle, but ^vhile still warm must be placed over snlpliuric acid, and left there till cold. The weight of ash left by a good filter is very inconsiderable ; but it may be ascertained by burning a dozen filters and dividing the weight of the ash by the number. Filters may he almost completely deprived of ash by extracting them with dilate hydrochloric acid, and washing them with water till the acid reaction completely disappears. 215. Weighing. — The balances most useful in a physiological lal)ora- tory are a fine analytical balance to carry 100 grammes in each pan, and turn easily with half a milligramme or less, and a large balance to carry sc\-enty l-:ilogrammes, and turn with a fe^v grammes. Fine balances are always protected by glass covers, to prevent the access of dust and protect the instrument from draughts of air, etc. Inside this, a vessel containing chloride of calcium is often placed to keep the air dry. The doors of the case should be only opened when the substance or weights are to he adjusted, and should be closed while the beam is oscillatiug. It is convenient to lay the weights on a sheet of paper on the floor of the balance, and to marlc the weiglit of each on that part of the paper W'here it lies. They must never be touched with the fingers, only with forceps. It is advisable alw^ays to place the weights in the same pan (the right) of the balance, and the substance to be weighed in tlie other. The placing of heavy -weights on a fine balance should be avoided, even though they may not exceed the weiglit which tlie instru- ment is constructed to carry. Nothing should he placed on the pans or tal^en from them wliile the beam is oscillatiug. It is not necessary to wait each time till the index stops moving in order to see whether there is any difference between the weights in the pans ; for this is ascer- tained much more axactly by observing whether the index oscillates farther on one side of the zero marls; than on the other, than by noticing its position when at rest. After weighing, add together the weights "which are absent from their places on the paper. Note down the weight (It once, and cheek it by adding the weights together as they are lif"fed from the pan and replaced. No weight should ever be allowed to remain on the balance after weigliing. Substances arc generally weiglied in watch-glasses, small crucibles or small flasks. These may be either weighed separatelj', and their weight deducted from the total weiglit, or the}' may be counterpoised. To save the trouble of weighing them each time, they may be carefully weighed once for all, and their weight noted and marked on them with a diamond, or, if thejf are of porcelain, in inlc. Wlien a crucible with its lid is used, it is usual to put correspond- ing marks on tlie crucible and its lid, so that the same may be used each time. Counterpoises may be made in various ways. The most con- venient is to choose a jiiece of brass of about the size of the brass weight which corresponds most closely to the weight of the vessel to be coun- terpoised, and reduce it by careful fihng till the weights are exactly ef(ual. If only required for temporary use, a pill-hox partly filled with small shot will suffice. 216. Specific Gravity. — The specific gravity of a solid or liquid is its weight compared with that of an equal bulk of distilled water. AN'ater and other liquids, however, slirink when cooled, and expand 568 APPENDIX. ■n'ben heated, so that the weiglit of a given bulk varies with the tempe- rature. If a vessel containing, for example, a cubic inch is filled with a fluid at a moderate temperature and cooled, the liquid will shrink, and more must be poured in to fill up the space. If, on the contrary, it be warmed, the hquid will run over. The weight of the cubic inch of cold liquid will be greater than that of the liquid at the original temperature by the quantity poured in, while that of the hot liquid will be less by that which has run over. It is therefore absolutelj'- necessary to com- pare the weights of bodies at the same temperature. Specific gravities are in this country estimated at 15-' C. or 00° F. Specific Oramty of Liquids. — The specific gravity of a liquid maybe ascertained by the use of the specific gravity'bottle, the hydrometer, or specific gravity beads. The iSpecifl.o Oraeily Bottle. — This is a small bottle which contains a known volume of liquid ; one form of bottle (fig. 343) contains its pro- per quantity when it is filled perfectly full, another form (fig. 344) when filled up to a mark on the neck, which is long and thin. The bottle hav- ing been charged with the liquid, of which the specific gravity is to be determined, the weight of its contents is determined by the balance, for which purpose it must first be counterpoised. The quotient obtained by dividing the weight of the liquid by the weight of the same bulk of water at the same temperature is its specific gravity. It is difficult to fill an ordinary bottle completely and to put in the stopper without get- ting in an air-bubble, which would of course alter the weiaht of the contents and so give false results. To obviate this difficulty ,''the stop- per of a specific gravity bottle has a hole bored up through its middle, so that when the bottle is filled and the stopper put in, any air or fluid that may be present in the neck passes up through the hole, and tlius both the bottle and the hole in the stopper are completely filled with fluid. Before weighing the empty bottle or making a counterpoise for it, it must be thoroughly dried. Specific gravity bottles of this kind are usually constructed to contain from 50 to 100 grammes of distilled water at 15° C. Counterpoises are always sold with them. Before using them, the accuracy both of the counterpoise and of the capacity of the bottle must be tested. For the latter purpose, the bottle must be filled and then immersed in a beaker containing distilled water at a tem- perature a few degrees higher than 15^^ C, and allowed to remain until a thermometer standing in the water indicates that the required tempe- rature has been reached. The bottle must then l)e removed from the beaker and weighed against the counterpoise, its outside haviu"- been first carefully wiped dry. The weight is that of the distilled %'ater contained m the bottle at 1.5'-' C. In weighing the contents of the bot- tie when charged with any liquid of which the specific gravity is to be determined, the same method is to be followed, with thc^ exception that the bottle must not be completely immersed in the liquid contained in the beaker. If then w indicate the weight of the M'ater and to' that of the same volume of the other liquid at the same temperature, its specific gravity = - i Sometimes it is diflrcult to get a suflicient quantity of liquid to fill the specific gravity bottle just described. When this is tlie case, a suecific as in so as gravity bottle may be made out of a test-tube, by drawinr^ it out the accompanying figure (fig. 345), and then fiattening the'liotton; „„ „. to make It stand by heating it and pressing it against a piece of iron. A sera eh is to be made on the narro-sv part of the neck, up to which the bottle IS to be filled with water at 15-' 0., and weighed a-ainst a couulerpoise asbef^ore. In all other respects the procedure is thiU which has been already described. BY DR. LAUDEK BRUNTON. 569 Tlte Hydrometer. — The hj'drometer is an elongated glass bulb -(vbich is weighed at one end so as to malve it float upright, and is prolonged at t)ie other end into a stem, graduated in sueh a manner tliat the number of the division up to wliioh tlie instrument sinks expresses the specific gravity of tlie liquid in which it is placed. As every instrument reads accurately only at the temperature for wliicli it is constructed, the liquid must be brought to the pro]ier temperature before the instrument is used. Ill using the hydrometer, the liquid must be jilaoed in a cylin- drical glass vessel, deep enough and wide enough to allow the instru- ment to float freely in it without coming in contact with the sides or bottom. The froth, if any, is then to be removed from the sui'face with a piece of blotting-paper, and the hydrometer allowed gently to sink into the lic[uid. The mark on the scale, which coincides with its sur- face, indicates the specific gravity. To read this correctly, the eye must be brought to a level with the surfixce of the liquid. "When this is the ease, the surface presents the form of a meniscus, assuming the aspect of an ellipse when the eye is either raised or lowered. To insure accuracy, the reading should be repeated once or twice, the hydrometer being down in the liquid between each two observations. Sperific Gravity of Solids. — The specific gravity of a solid mass, the substance of which is insoluble, is ascertained by weighing it flrst in air and then in water. The difterence between these weights is equal to the weight of its own bulk of the water which it displaces. The specific gravity is therefore got by dividing the weight of the solid in air by the difference between its weight in air and water. The weight of solids may also be ascertained by immersing them in fluids of known densitj^ till they float. Thus the best way of ascertaining the specific gravity of the substance of the brain, or any other organ, is to prepare a graduated series of solutions of common salt of different densities, and to immerse the solid, first in one, and then in another, till a solution is found in which it floats indifferently at anj height. 217. Volumetrical Analysis. — For volnmetrical analyses, measuring flasks, measuring glasses, pipettes, burettes, and other accessory appa- ratus are required. Pleasuring Flasks. — These flasks, of the form shown in fig. 34G, are used for dissolving substances for the jDreparation of standard solutions, etc. They should have tolerably wide mouths, and be furnished with well-fitting stoppers, so that they may be shaken without risk of loss. The graduation mark should be just below the middle of the neck. Flasks are used of capacities varying from 100 centimetres to a litre. Oradweited cylinders, such as that shown in fig. 347, generally called test-mixers, are used for the same purpose. Pipettes. — A pipette is a glass tube of the shape shown in fig. 348, and when filled up to the mark on the neck it should deliver the exact quan- tity of fluid which is marked upon it. Some pipettes are graduated so as to let the exact c^uantity run out by its own weight ; others, to de- liver the right amount only when the liquid is blown forcibly out. The former are to be preferred. Another kind of pipette is graduated along the greater part of its length, so as to deliver different quantities at will, but it is not so accurate as the others. In using pipettes, the liquid to be measured is to be put into a test-glass or small beaker ; the lower end of the pipette is then immersed in the liciuid, which is to be sucked up till it stands somewhat above the mark on the neck of the pipette. The upper eud of the pipette must then be quickly covered with the moistened tip of the forefinger, so as to prevent the liquid from flowing out. The mark on the neck is next brought to a level with the eye, and the tip of the finger geutlj' raised so as to allow the liquid to escape slowly till it stands opposite the mark. It is then allowed to run out into a clean 570 APPENDIX. beaker, and the last few drops removed from the point of the pipette by touching it against the side of the bealier. Burettes. — These are used for delivering standard solutions. There are several forms of burette, but the most convenient is that of Mohr. It consists of a graduated tube, to whose lower end an India-rubber tube is attached, which can be opened and shut by a spring clip (fig. 349), so that the operator can let the solution run out or stop it at will. The bu- rette is supported in an upright position on a stand made for the purpose (fig. 3.52). To prevent dust getting in, a polished marble should be placed on its upper end. In many cases the spring clip answers well, but when nitrate of mercury is used it attacks the clip, and bichromate of potash destroys the India-rubber. For such hquids a burette fur- nished with a glass stopcock is to be preferred. A burette should be filled by allowing the liquid to flow gently into it while it is held in an inclined position in the hand till it stands above the zero mark. The in- strument is then replaced. If any air-bubbles are present, they must be allowed to break, or removed by a glass rod. The solution is then al- lowed to flow out till its level corresponds to the zero mark on the burette. Rules for Beading Burettes and other Graduated Instruments used in Volumetrical Analysis.— 'WlienWquiA is contained in a narrow tube, its surface is higher at the edges where it touches the glass than elsewhere ; and if we examine the curved surface by transmitted light, it seems to be formed of several zones or bands, the lowest of which is dark (tig. 350). To avoid errors and uncertainty, the under border of the dailc zone is always regarded as indicating the level at which the liquid stands. In reading, the eye must of course be exactly level with the surftice, otherwise the reading will be either too high or too low. The under surface of the liquid is more easily seen if a card, with its under half blackened, while itsupper half remains white, be held behind the liquid, so that the division between the black and white parts is about one-eighth of an inch below its surface. The lower surface of the liquid then seems to be bounded by a sharp black line (Sutton). Burettes may be read very easily and with great accuracy by using Erdmann's float (fig. 351). This is an elongated glass bulb, weighted with mercury at its lower end, so that it floats upright. Its diameter being a very little less than the calibre of the burette which contains it, it moves freely, but at the same time steadily, up and down. A horizontal mark round its middle is taken as indicating the height at which the liquid stands, the absolute height being disregarded. Litmus Solution.— The solution used in the neutralization of albumi- nous liquids is prepared by dissolving a little litmus in distilled water decanting the liquid from the sediment, and diluting it as required For determmatious of the strength of acid, the litmus solution is made by putting 10 grammes of solid litmus into half a litre of distilled water, let- ting It stand for a few liours in a warm place, decanting the clear fluid adding a few drops of dilute nitric acid so as to produce a violet color' and preserving it in an open bottle with a narrow neck. If the color sliould at any time partially disappear, it may be restored by exiiosino- the liquid to the air in an open bottle (Sutton). Volumetric Solution of Soda.— Fill a burette with solution of soda and cautiously drop this into 6.3 grammes of purified oxalic acid in crvs- tals, quite dry but not effloresced, dissolved in about 70 c c of distilled water, until the acid is exactly neutralized, as indicated by litmus Note he number of grain measures (n) of soda solution used, and havin- then introduced 900 c. c. of it into a graduated jar, augment this quantity by the addition of water until it becomes '^'^°>^^'^'^ n ^ re c. jj^ c. c. if, for example, » = 93, the 900 cub. cent, should be augmented to '"^'^^^ 1*1*^ = 967.7 BY DK. LAUDER BRUNTON. 571 cub. cent. 100 cub. cent, contain T\[tli of un equivalent in grammes (4 .H-rammcs) of h.ydratc of soda, and will neutralize -j'„tli of an equivalent in grammes of an acid. Soda solution for estimating the acidity of gastric juice is made by di- luting 100 c. c. of the above solution to the bulk of a litre. 218. Polariscope. — There are several organic substances whose solutions possess the powerof eirevmipolarization, i. e., of rotating to one side or another the plane of polarization of a ray of polarized light passing througli them. Some of thenr, such as glucose, cane sugar, and tartaric acid, turn it to the right hand, while others, such as albumin, uncrystal- lizable sugar, and oil of turpentine, turn it to the left. As the amount of rotation increases in proportion to the concentration of the solution and the thickness of the stratum througli which the ray passes, it is easy to ascertain the quantity of a substance held in solution by simply observing tlie extent to which a ray is rotated in passing through a stratum of a de- finite thickness. The apparatus used for this purpose is shown in tig. Ij.TS. It consists of a stand in which are placed t-wo Nicol's prisms, a and h. The prism 6 is fixed, but that at a is movable, and the extent to which it is rotated is indicated on a graduated circular disk s s by an index x. "When the two prisms are placed exactly in the same position, the ray, which has been polarized by 6 passes readily through «, and the field of vision of an observer, looking into the instrumeiit''at a, is illuminated. As a is turned round on its axis, the field becomes dimmer and dimmer till tlie two pirisms are turned crosswise to each other, when the polar- ized ray by b is entirely stopped by «, and the field consequently be- comes quite dark. At this time the index stands at zero. If a glass ' tube, containing a solution of sugar or albumin, is then placed in the space 0, the polarized ray will pass through it, and in doing so will have its plane of polarization more or less rotated, so that it will no longer be entirely stopped by the prism a. In order, therefore, to stop it again and produce a dark field, this prism must be rotated to a corre-- sponding degree, and the extent of rotation is read off on the graduated disk. As it is ditHcult to determine exaotljr the position of a, at which the field is darkest, some additions have been made to this instrument by Soleil and Ventzke, which make their saccharimeler more complica- ted, but gi'eatly increase its exactitude. The first of these is a plate of quartz, q, composed of two pieces, whose line of junction is exactly in the middle of the field of vision. One piece rotates light to the right hand, while the other turns it to the left. Wlien a solution of sugar is placed in the space o o, it increases the action of that lialf of the jdate which rotates to the right, and lessens tlie action of the other lialf which rotates to the left, and the two-halves of the field of vision become of a different color. This difference can be removed by turning tlie prism 0, but this is more easily effected by means of the compensator n. The chief parts of this are figured separatel)'. It consists of two equal prisms (;■ and r') of left-handed quartz, whose surfiiees (e and c') are cut perpendicularly to the optic axis of the crj^stal. Taken together they form a plate bounded by parallel surfaces, and tliej' can be made to slide on one another by means of a rack and pinion, i', so as to in- crease or diminish its thickness at will. One of the frames in wliich these is fixed has a scale, I, and the other a vernier, n. When tlie zero of this corresponds to the zero on the scale, the left-handed rotation of the two prisms is compensated by a plate of right-handed quartz, p, and the field then appears of an uniform color, but as soon as the prisms are moved this compensation ceases, and the two halves become differently colored. The same effect is produced by putting a solution of sugar into 0. The screw b is then turned till the effect of the sugar is counter- balanced and the amount of rotation read off on the scale. At this end, bl'J, APPENDIX. a, is a telescopic adjustment, to enable the division between the two halves of the quartz to be clearly seen. In using this instrument, tlie end b sliould be placed opposite the brightest part of a lamp flame, and it is advisable to cover the tiame with an earthenware cylinder having an aperture which just admits tlie end of the sacoharimeter, so as to shut otf all light except tliat which passes through the instrument. The zero of the vernier having been placed opposite that of the scale, the operator looks into the end a, and adjusts the telescope till the dark line in the centre of the field is clearl}^ defined. If the two sides of the field are of exactly the same tint, he , may proceed with the operation, but if they are not, he must adjust them by means of a screw and key, which are not represented in the engraving. The tube is then to be filled with the fluid to be examined, and its end closed by a piece of glass and a metal cap, which should not be screwed too tightly. The fluid must be transparent, and as colorless as possible. A light yellow color does not interfere with the accuracy of the determination, but a red or brown color impairs it seriously. Three tubes, 1, 2, and | a decimetre in length, are generally supplied with each instrument, and the longer the tube used, the more exact is the determination. Dark fluids may be examined in the shorter tubes, but if very dark they should be diluted before examina- tion. The tube is then placed in the space o o, and the rack v is turned till the two halves of the field present exactly the same tint. By turn- ing the prism a, different colors of the field may be obtained ; a pale rose color is that in which differences of the two halves can be most readily observed. The distance to which the zero of the vernier has been moved from that of the scale to one or other side, indicates the amount of dextro- or lajvo-rotation. The compensator is so graduated that cacli degree of the scale corresponds to one gramme of sugar or albumin in 130 cub. cent, of fluid when a tube one decimetre long is used. When tubes of a different length are employed, the number- of degrees must be divided by the length of the tube in order to find out the strength of the solution. As sugar and albumin rotate the rays in a different direction, their amount cannot be determined when both are present in a solution, the instrument then indicating merely the differ- ence between tlieir rotating power. In such a case the albumin must be removed and the amount of sugar determined. The difference between the rotation caused by the sugar alone and the sugar and albumin together, will then of course give the rotation due to allnmiin. This iustruurent may also be used for distinguishing between substances', such as albuminous bodies, which nearly resemble each other in their general characters and reactions, but have different powers of rotation or specific rotation. The specifie rotation of a substance is the extent to which a solution of one gramme in one cubic centimetre, contained in a tube one decimetre long, will rotate a ray of light passing throu"-h It. To indicate rotation of light to the right, a -f is prefixed to tlie number of degrees through which the beam is turned, and a — to indi cate rotation to the left. The specific rotation of sugar is + .56^ ■ that of albumin — .56°. To find out the specific rotation of any substance with the saccharimeter, the following formula is used aioiroe- Seyler) : — (aj=± 50=4- pl («) J 13 the usual symbol for the specific rotation for vellow lio-ht n is the rotation indicated on the scale, p the weight of "tlie substlmce in grammes contained in 100 cub. cent, of the solution, and I the len"1h BY DR. LAUDER BKUNTON. 573 of the tube employed. Tlie specific rotation of ditfercnt nlbmninons liodics for yellow liglit, as given by Iloppe-Seyler for scrum albumin, is — 5G^\ and for egg albumin ^ 35'3.5. The conversion of serum albumin into acid albumin by phosphoric or acetic acid increases its specific rotation to — 71^^, and a solution in liydrochloric acid has a rotation of — 78^.7. Serum albumin, treated with caustic potash, has a rotation of — 86° ; egg albumin, — 47° ; and coagulated egg albumin, treated in the same way, — 5S'-\8, for yellow liglit. 574 LIST OF IKSTRUMENTS, ETC. List of the most Important Instruments and Apparatus REFERRED TO IN THIS WORK, AVITH INFORMATION AS TO WHERE THEY CAN BE OBTAINED. I. HISTOLOGY. MiCKOSCOPES.— ir«r/ft«cA,-§- Co., 31 Place Dauphine, ParU ; and Carl Zeiss, Jena, for tlie best; BemrJu, 17 Grossbeeren Straue, Berlin; and Wasserlein Bessel Sirasse, Berlin, for good instru- nents at a lower price. Warm Stages, In.jecting Appaeatus, Strikges and Canul^., Tike Scissors and Forceps, Steel Clips, ETC.—Hawlislei/, 4 Blenheim Street, Bond Street. IlATcniNQ OvEis.— Jordan, WelU Street, Oxford Street. Soluble Prussian-blue.— iI/fflr;sEN-'s CojirRESSED Air AYater-pujip.— Dfsai/a, Unirersitdts-Me- clianiker, Heidelberg. RosE^-THAL's Apparatus, Pettbkkofer's Absorptiox Tubes, Bun- SEN-'s Aspirators, TLic.—Cetti^- Co., 11 Brooke Street, Ilolborn. Calorimeter. — Jordan, Wells Street. III. PHYSIOLOGY OF THE NERVOUS SYSTEM. Galvakometers and Shukts, Du Bois Retmoxd's Induction Ap- paratus, Rheocdokd, Commutator, Wippe and other Electrical Apparatus. — Elliott^- Co., St. Martinis Lane. Moist Chamber, Marking Key, Marey's Myograph, etc. — Haioks- ley, 4 Blenheim Street. Batteries. — Lund, 13 Brooke Street, Ilolborn. lY. DIGESTION AND SECRETION. Gastric and other Canul^. — Ilaiokski/, 4 Blenheim Street. Bunsen's Regulator. — Ceiti, 11 Brooke Street. Water-baths for Digestion. — .Jordan, Wells Street. Beakers, Test-tubes, and Glass Apparatus. — Poioell and Sons, Whitefriars Glass Works. Chemical Apparatus. — Griffin, 32 Garriek Street, Gonent Garden ; and Jackson, Bishopsgate Street Wit/iin. Soleil's Polarization Apparatus, as adapted by Yentzke, for THE Quantitative Determination op Grape Sugar and Albumin. — LtiJimeSf Co., Berlin. Apparatus for Yolumetrical Analysis, and Titrated Solu- tions. — Sutton §• Co., Norwich. INDEX, Absolute firterint pressure, Measure- ment of, 22o Absorptiou by the liver, 505 internal, by veins, 296 by veins and lymphatics, 203 Accelerator, Nerves of heart, 280 Acetic acid, Action of, on fibrous tis- sues, 47 Acid albumin, or syntonin, 432 albumin, 430 Preparation of solution of, 433 Acids, Action of, on blood, 29 Adenoid tissue, 59 Adipose tissue, Chemistry of, 447 Albumin, Alteration of, by acids, 432 by alkalies, 429 Coagulation of, 424 Decomposition of, 430 Detection of, 420 in urine, 555 Determination of amount of, in urine, 550 Dry, solubility of, 423 Mode of separating, from milk, 528 Preservation of, 423 Properties of, 421 Pare, preparation of, 422 Solution to be used in testing, 422 Tests for traces of, in solution, 428 Albuminates, 435 Albuminoids, Chemistry of, 442 Albuminous bodies. Coagulated, 430 in solution, 437 Precipitation of, 424 Separation of, from other substances in solution, 427 Synopsis of, 435 compounds, 421 Products of digestion of, 483 substances in muscle, 451 37 Alkali albuminates, 429, 435 and syntonin. Distinction be- tween, 435 should contain no sulphur, 432 Alkalies, Action of, on blood, 30 Alvergniat's pump, 205 Amoeboid cells, 49 Amyloid, 430 Analysis of blood gases, 210-214 Aniline for coloring sections, 107 Animal heat, 336 Apnoea, 328 Areolar tissue, 47 Arterial pressure, 218 Changes of, in each cardiac period, 224 Expansive movements ac- companying change of, 220 Influence of, on frequency of heart contractions, 285 pulse, Experiments with schema relating to forms of, 234 schema or artificial artery, 230 Arteries, Observation of, during ex- citation of the cord, 251 Circulation in, 217 smallest. Phenomena of circula- tion in, 238 Artery, Artificial, or arterial schema, 230 Asphyxia by complete occlusion of the trachea, 329 by slow suffocation, 330 State of circulation in, 332 Auerbach's ganglia, 86 Beale's solution for coloring sections, 107 Bernard's method of determining oxygen in blood, 216 Bernstein's experiment, 282 Bile, 494 578 INDEX. Bile acids, 490 Sepiiration and detection of, in ui'ine, 556 Pettenkofer's test for, 499 Action of, 504 Composition of, 494 General cliavacter of, 494 pigments, Relation of, to bo3mo- globin, 497 Tests for, 494 precipitates, syntonin and pepsin, 501 Secretion of, 504 Billarj' listula, Mode of producing, in gaineapigs, 505 Bilirubin, 496 Preparation of, from bile, 496 from gall stones, 496 Properties of, 496 Biliverdin, 497 Properties of, 497 Bladder, Epithelium of, 42 Blastoderm, Formation of lamellas of, 104 of chick, Lamellce of, 105 Blood, 175 Action of acids on, 29 of alkalies on, 30 of boracic acid on, 30 of carbonic acid gas on, 32 of cold on, 188 of crystallized ox-bile on, 189 of electricity on, 33, 189 of gases on, 31 of heat on, 188 of water on, 180 Chemical changes of, in dyspnoea and asphyxia, 333 Circulation of, 217 coloring matter, 187 Condition aifecting coagulation of, 183 corpuscle of mammalia, Action of salt solution on, 28 crystals, 34 Detection of, in urine, 550 Gases of, 204 method of analysis, 210 method of rendering laky or transparent, 187 Method of transferring, from artery or vein, to yacuum, 208 Mode of testing for sugar in, 509 of frog, Filtration of, 176 Quantitative determination of haj- moglobin in, 192 Quantitative analysis of, 199 Bloodvessels, Endothelium of, 118 Bloodvessels, Muscular coat of, 120 ^'erves of, 121 of intestine, 139 Structure of, 118 Bone, 03 Chemistry of, 447 Develojornent of, 64 Inflammation of. 170 Preparation of gelatigenous sub- stances from, 444 Boracic acid. Action of, on blood, 30 Brain and spinal cord, Ganglion cells of, 83 Chemistry of, 455 Ganglion cells of, hemispheres, 85 Branched cells (connective tissue cor- puscles), 51 corpuscles of skin, 55 of tail of tadpole, 55 Brunner's glands, 138 Calorimetrj', 337 Capillary circulation in mammalia, 240 Carbonic acid gas, .Action of, on blood, 32 Discharge of, by an ani- mal in a given time, 311 Cardiac impulse, 203 Cardiograph, 265 Carmine, Coloring of sections by, 106 for injecting, 113 Mass, Gerlach's, 113 Cartilage, hyaline, 60 inflammation of, 170 Yellow, 62 Casein, 435 Mode of separating, from milk, 528 Cells, Amojboid, 49 Fat, 57 Nerve, 82 Pigment, 56 Tendon, 58 Cellular elements of centrum tendi- neum in relation to lymphatics, 127 Cellular, Elements of, connective tis- sue, 49 Centrum tendineum. Cellular elements of, 127 Cerebral hemispheres, Remov.al of, in bird, 417 Cerebrin, 456 Cerebro-spinal nervous centres of vas- cular system, influence of, 245 INDEX. 579 Changes of nrterial pvessuvc during ench cardiac period, '2'2i Chicle, Cleavage cavity of, 1C4 Lamella^ of blastoderm of, 105 Chloride of gold, Preparation of cor- nea with, 58 Chlorine, Determiaation of, iu urine, 503 Cholesterin, 503 Cholic acid, 503 Chondriu, Decomposition of, 447 Chondrin, Effect of boiling on, 44G Precipitation of, 446 Preparation of, 440 Solubility of, 440 Chondrogen, 440 Solubility of, 446 Chorda tympani and vascular fila- ments of submasiUary glaud. Simul- taneous section of, 472 Chorda tympani, Direct and refJex excitation of, 471 Ciliary motion, Effects of reagents on, 35 Study of, in situ, 36 Ciliated cylindrical epithelium, 35 epithelium, 37 Circulation, Artificial, '2i'2 Capillary, in mammalia, 240 in arteries, 217 Influence of respiration on, 324 Microscopical study of, 121 Phenomena of, in smallest arte- ries, 238 State of, in asphysia, 332 Study of, in cold-blooded ani- mals, 121 Studj' of, in mesentery, 121 in tail of tadpole, 122 in tongue, 122 in web of frog's foot, 121 Cleavage cavity in ova of fish and amphibia, 101 of chick, 104 process in ova of fish and am- phibia, 159 Coagulation of albumin, 424 of blood, 183 ■ of muscle plasma, 450 of myosin, 452 Cold, Action of, on blood, 188 Cold-blooded animals. Study of cir- culation in, 121 Coloring of sections, 100 Colorless blood corpuscles, 17 Colorless corpuscles. Action of dis- tilled water on, 27 Amoeboid movements of, 17 Colorless corpuscles, Applicalion of lirpiid reagents tu, L'l; Effects of w.irmth on, 23 Feeding of, 25 of nmn, 25 Varieties of, 18 Commutator, 354 Conjunctiva and menibrana nictitans, Nerves of, 112 Connective tissue. Cellular elements of, 40 corpuscles, 51 and fat cells. Transition forms between, 58 Development of, 50 tissues, 46 Chemistry of, 442 Constant current. Arrangement of electrical apparatus for, 357 Contraction as a function of stiuiulns, 307 Contractions, Idio-muscular, 395 Cornea, Fixed corpuscles of, 52 Inflammation of, 171 Nerves of, 91 Preparation of, with chloride of gold, 53 Treatment of, with nitrate of silver, 52 Corpitscles, Branched, of skin, 55 of tail of tadpole, 55 Fixed, of cornea, 52 Granular, 21 Corpuscles of blood. Separation of, from liquor sanguinis, by subsi- dence, 177 Cranial and spinal nerves, G-anglia of, 82 Creatine, 453 Decomposition of, 453 Reaction of, 453 Solubility of, 453 Tests for, 453 Creatinine, 453 Characters of, 454 Reaction of, 453 Separation of, from urine, 538 Solubility of, 453 Crystallized bile, 500 composition, 500 Action of, on blood, 189 Curare, Poisoning by, 398 Current, electric, interrupted by means of an oscillating rod/ 360 Current, electric, with definite inter- ruptions by means of the metro- nome, 300 580 INDEX. Cylindrical ciliated cpltlieliuni, 35 ei^ithelium, nou-ciliated, 38 Dammar varnish, Preparation of, 108 Death, after section of both vagi, 317 DeTelopment of bone tissue, G4 of connective tissue, 50 Dialysis, 5G5 Diaphragm, demonstration of lym- phatics by injection, 126 Diaphragm, Lymphatics of centrum tendineum of, 123 Diastatic action of saliva. Effect of temperature on, 460 Digestion, 457 and secretion, 421 Effects of temperature on, 486 in the stomach, 475 intestines, 515 Method of making a temporary fistula, 51 5 Digestion in the intestines, Method of making a permanent fistula, 516 Digestion of the stomach by itself, 491 during life, 491 Organs of, 135 Strength of acid required for, 486 Digestive action of Pepsin, 483 Discus proligerus and ovum, 148 Dorsalis pedis. Excitation of, 256 Drying, 566 Dyspeptone, 484 Dyspnoja, 328 Egg albumin, 435 Elastic tissue, 47 Chemistry of, 445 Elastin, 445 Characters of, 445 Decomposition of, 446 Precipitation of, 445 Preparation of, 445 Reactions of, 445 Solubility of, 445 Electric currents of nruscles, .376 Natural, 376 Negative variations of, 380 of nerves, 381 Natural, 381 Negative variations of 381 Electrical measurement of tempera- ture, 344 stimulation of nerve and muscle 364 Electricity, Action of, on blood, 33 Electrodes, 352 Non-polarizable, 353 Electrotonus, 382 as affecting irritability, 388 Embedding in gum and gelatine, 105 in was and oil, 103 of tissues for cutting sections, 1 03 Embryology, 158 Endocardial pressure, 268 curve, Modifications of, 270 in mammalia, 273 Investigation of, in heart of frog, 208 Variations of, during each cardiac period, 209 Endothelium and epithelium, 35 Inflammation of, 170 of bloodvessels, 118 of serous membranes, 43 Silver method of exhibiting, 43 Epithelial tissues. Chemistry of, 442 Epithelium and endothelium, 35 of ovary, 147 Ciliated forms of, 37 Cylindrical ciliated, 35 non-ciliated, 38 Inflammation of, 109 of bladder, 42 of kidneys, 144 of malpighiau corpuscles, 145 of villi of intestines, 39 pavement, 40 Excitation and section of spinal cord in rabbit, 248 Direct, of spinal cord in frog, 246 of dorsalis pedis, 250 of nerves of external ear of rab- bit, 255 of superior laryngeal nerve 322 of central end of one vagus after section of both, 321 of vascular nerves of submax- illary gland, 472 Extractive matters in muscle, 452 Evaporation, 561 Method of retarding, 27 Fallopian tubes, 148 Uterus and vagina, 148 Fat cells, 57 and connective tissue cor- puscles, Transition, forms between, 58 Fats, 447 Composition of. 448 Emulsionizing of, 448 Reactions of, 448 INDEX. 581 Fats. Solubilitj' of, 447 Feeding of colorless corpuscles, 25 Fibre cells, 8pirnl, .S" Fibria niid plasma, Properties of, 178 Influence of swelling of, on its digestion, 487 Fibrinogen and paj-aglobulin, Esperi- meuts relating to, 179 Fibrinogenic substance, 435 Fibrino-plastic substance, 435 Fibrins, 435 Fibro-cartilage, 62 Fibrous tissue, 46 tissues. Action of acetic acid on, 47 Effect of maceration on, 47 Filtration, 563 of frog's blood, 176 Fixed corpuscles of the cornea, 52 Follicles, Graafian, 148 of intestine. Solitary and agmi- natcd, 132 of Feyer, 138 Frankland-Sprengel pump, 207 Frog, Injection of, during life, 110 Muscular nerve endings of, 98 Respiratory movements of, 298 Study of movements of heart in, 260 Ganglia, Auerbacb's, 86 of the cranial and spinal nerves, 82 Ganglion cells of brain and spinal cord, 83 of hemispheres of brain, 85 of sympathetic system, 85 Reproduction of, 88 Gases, Action of, on blood, 31 of arterial blood of dog, Analysis of, 214 of blood, 204 Gastric fistula, Establishment of, 475 Operation for, 476 Gastric juice, Action of, 479 on gelatine, 485 Artificial, 479 Effects of stimuli on secre- tion of, 493 Estimation of acid in, 478 Examination of, 477 Secretion of, 490 To determine the nature of acid in, 478 Geissler's pump, 206 Gelatin, 444 Action of gastric juice on, 485 Alteration of, by boiling, 445 Precipitation of, 445 Gelatin, Preparation of, 444 Solubility of, 415 t.ielatigenons substance, 444 Characters of, 444 Preparation of, from bone, 444 Preparation of, from ten- dons, 444 Solubility of, 444 Genital organs, 147 of male, 149 Gerlach's carmine mass, 113 Gland, thymus, 132 Glands, Lymphatic, system, 130 of Brunner, 138 Parotid, 473 Salivary and pancreatic, 135 Sebaceous, 143 Sweat, 142 Globulins, 435 Glycerin, 448 Decomposition of, 448 Solubility of, 448 Solvent powers of, 448 Test for, 449 Glycocholic acid, 501 Glycogen, 50G Conver'n of, into grape sugar, 512 Influence of food on amount of, in liver, 512 Preparation of, 510 Properties of, 511 Glycogenic function of liver. Mode of demonstrating, 508 Glycosuria, 513 produced by puncture of floor of fourth ventricle, 514 ' Graafian follicles, 148 Granular corpuscles, 21 Gum or gelatin. Embedding in, 105 Ha;matin, 197 Iltematoin, 198 Hiiemin, 196 crystals, 34 Hasmoglobin, 34 Chemical properties of, 192 Determination of quantity by es- timation of its iron, 202 Optical properties of, 194 Preparation of, 183 Quantitative determination of, in blood, 201 Hair, 144 Hardened tissues. Preparations of sections from, 100 Hearing, Organ of, 154 Heart, 200 582 INDEX. Heart, Examination of, after deatli by asphyxia, 333 Function of depressor nerve of, 291 Inhibitory nerves of, 279 Influence of temperature on, 278 Intrinsic nervous system of, 274 Movements of, 260 sounds, Investigation of, 2C(5 Study of movements of, in frog, 260 in mammalia, 262 Heat, Action of, on blood, 188 produced by an animal in a given time. Estimation of, 339 Hemispheres of brain. Ganglion cells of, 85 Heynsius' experiment, 182 Hippuric acid. Separation of, from ' urine, 537 Hofmann's tests for tyrosine, 441 Hyaline cartilage, GO Hypoxanthine, 454 Idio-muscular contractions, 395 Ignition, 506 Impulse, Cardiac, 263 Inflammation of bone, 170 of cartilage, 170 of cornea, 171 of endothelium, 170 of epithelium, 109 of tongue of frog, 173 Inflammatory changes in liver cells, 171 in tadpole's tail, 173 Inflamed tissue. Study of, 169 Inhibitory influence of parts of the brain on reflex actions of the spinal cord, 418 Inhibitory nerves of the heart, 270 Injected tissues. Treatment of, 118 Injecting with carmine, 113 "with Prussian blue, 112 Injection after death, 112 Apparatus and instruments for 114 of lymphatic glands and mucous membranes, 130 of the frog during life, 110 of the small mammalia during life. 111 of solution of nitrate of silver, 118 Innervation of respiratory movements 315 Inosite, 455 Inspiratory muscles: Diaphragm, 304 Intercostal, 305 Internal absorption by veins, 296 Interrupted electric current, 359 Intestinal fistula, 522 juice, 522 Actions of, 524 Artificial, 523 Intestine, epithelium of villi, 39 Large, 139 Movements of, 525 Small, 137 Solitary and agminated follicles of, 132 Intra-thoracic pressure. Measurement of 303 Intrinsic nervous system of the heart, 274 Kidneys, Epithelium of, 144 Isolation of tubes of, 145 Kymographic observation. Rules and precautions in, 220 Kymograph, Mercurial, 219 S spring, zzo Lecithin, 456 Leucine, 438 Tests for, 440 Liquor sanguinis, 175 Liver, 139 Absorption by, 505 Functions of, 404 Influence of food on amount of glycogen contained in, 512 Glycogenic function of 508 Separation of diastatic ferment from, 513 Lymphatic glands, Structure of, 130 system, 123 vessels, Stomata of, 125 Structure of, 130 Lymphatics of diaphragm, 126 of omentum and mesentery, 128 Male genital organs, 149 Malpighiau corpuscles, Epithelium of, 145 Manipulation, Practical notes on, 559 of glass tubing, 559 Marking lever, 355 Jlechanical stimulation of muscle and nerve, 364, 395 Medulla oblongata. Division of, 400 Excitation of, 252-254 Section of, within the cra- nium, 251 Medullary sheath of nerve fibres, 80 Meissner's bodies or tactile corpus- cles, 00 INDEX. 583 Meissiiev's plexus, 8G Jlenibrana nictitaus and conjunctiva, Nei-ves of, 912 Mesentery, 129 and omentum. Lymphatic system of, 1:28 Study of circulation in, 121 Tiletapeptoue, 484 Methtemoglobin, 19G Jlicroscopical study of circulation, 121 IMilk, 52G Characters of, 520 Constituents of, 027 Fata of, 529 jMicroscopical examination of, 520 Mode of estimating butter in, 529 separating albumin from, 528 separating casein from, 528 Sugar in, 528 Moreau's experiment on intestinal secretion, 524 Motion, Ciliary study of, in situ, 30 Mouth, Mucous membrane of, 135 Mucin, 442 Mucous and serous membranes, Neryes of, 95 Mucous membrane of mouth, tongue, pharynx, and oesophagus, 135 Murexide test for uric acid, 455 Muscle, Albuminous substance in, 451 and nerve, Mechanical stimula- tion of, 395 Aqueous extract of, 450 Chemical stimulation of, 396 Chemistry of, 449 corpuscles, 73 curve, 365 Exhaustion of, 306 Striped, 67 Unstriped, 65 plasma, 449 Reaction of, 449 Thermal stimulation of, 397 Muscles of respiration. Action of, 304 Muscular coat of bloodvessels, 120 Muscular contraction. Influence of temperature on, 300 Influence of veratrin, etc., on, 307 Phenomena and laws of, 365 Wave of, 309 work done, 368 Muscular fibre. Arrangement and di- vision of, 75 Muscular fibres, Examination of, in polarized light, 75 Muscular fibres, Suhstance of, 07 Nerves of, 90 nerve endings, 97-99 tissue, 05 Myosin, 435 Nnres and larynx. Movements of, 307 Xessler's reagent, Preparation of, 439 Neurilemma, 81 Nenrin, 450 Nerve cells, 82 Peripheral, 90 chamber, 352 Chemical stimulation of, 397 endings, 89 fibres, 79 Axis-cylinder, 79 Medullary sheath, 80 non-meduUated, 82 Schwann's sheath, 81 Nerves, Influence of, on secretion of stomach, 492 Nerves of liloodvessels, 121 of conjunctiva and membrana nictitans, 92 of cornea, 91 of mucous and serous membranes, 95 of peritoneum, 90 of septum cisternfe of mesentery of frog and newt, 95 of skin, 93 of striped muscle, 97 of tadpole's tail, 94 of unstriped muscular fibre, 96 Stimulation of, 385 Thermal stimulation of, 398 Vasomotor functions of, 244 Nervous system, Tissues of, 79 Omentum and mesentery. Lymphatics of, 128 Optic lobes. Irritation of, 418 Organs of digestion, 135 of respiration, 133 of special sense, 150 Ova of fish and amphibia, Process of cleavage in, 159 Ovary, Epithelium and endothelium of, 147 stroma of, 148 Ovum and discus proligerus, 148 Pancreas and salivary glands, 135 Pancreatic ferments. Glycerin solu- tion of, 518 Pancreatic ferments. Isolation of, 520 juice, 515-521 584 INDEX. Paraglobulin und fibrinogeu, Expei-i- ments relating to, T79 Parapcptone, 483 Parotid duct, Insertion of canula in, 465 fistula, 466 glands, 473 Peritoneum, Nerves of, 96 Peyer's follicles, 138 Phosphoric acid. Estimation of, in urine, 551 Picric acid, Coloring of sections by, 107 Pigment cells, 56 Piria's test for tyrosine, 441 Plasma, or liquor sanguinis, 175 Polariscope, 571 Polarized light, Examination of mus- cular fibres in, 75 Precipitates.ffashing of, on filters, 265 Precipitation, 562 Pressure, Arterial, 218 Endocardial, 268 produced by secretion, 471 Prussian blue for injecting, 112 Pseudo-stomata, 128 Ptyalin, 462-3 Pulse, Arterial, experiments relating to forms of, 234 Pumps, Alvergniat's, Geissler's, and Frankland-Sprengel, 207 Recording tuning-fork, 357 Pecurreut sensibility, 405 PieSex actions, 406 excitation of medulla oblongata 252-254 of vagus, 283 of vaso-motor centres, 252 Kespiration, 208 Influence of, on circulation, 324 Organs of, 133 Respiratory movements, Innervation of, 315 of frog, 298 Roots of spinal nerves, Functions of 402 Saliva and its secretion, 457 Action of, 459-462 Artificial, 462 Efli'ect of temperature on dias- tatic action of, 460 Inorganic constituents of, 458 Organic, 459 Secretion of, after decapitation 475 Separation of ptyalin from, 403 [ Salivary fistulcc, 466 glands and pancreas, 135 Preparation of mucin from, 443 Secretion of, in rabbit, 465 secretion. Stimulation of, 464 Sarcolemma, 72 Sarcous elements, 449 Sarkin, 454 Scherer's test for leucine, 440 tyrosine, 441 Schwann's sheath, 81 Sebaceous glands, 143 Secretion of gastric juice, 490 of saliva, 464 of stomach. Influence of nerves on, 492 Section of both vagi in the neck, 315 of medulla oblongata vfithin the cranium, 251 Sections, Coloring of, 106 Mounting of, 107 of fresh tissues. Preparation of, 100 of hardened tissues, Preparation of, 106 Semicircular canals. Division of, 420 Sensibility, Recurrent, 405 Serous membranes, 43 Serum albumin, 423 Skin, 141 Branched corpuscles of, 55 Nerves of, 93 Sight, Organ of, 150 Silver, Solution for injecting, 114, 118 Smell, Organ of, 157 Sounds of the heart, 266 Special sense. Organs of, 150 Specific gravity, 567 Sphygmograph, 227 Uses of, 229 Spinal and cranial nerves. Ganglia of. 82. cord. Excitation of, 246, 248. Spiral fibre cells, 87 Splanchnic nerves, Vaso-motor func- tions of, 258 Spleen, 140 Spring kymograph, 225 Starch paste, Action of saliva on, 459 Stimulation of muscles and nerve= 364, 385. Stomach, 136 Digestion of, during life, 491 Strieker's warm stage, 22 Striped muscle, 67 Nerves of, 97 Stroma of ovary, 148 INDEX. 585 SubinaxiUavy fisttila, 466 giinglion, Functions of, 473 gland, Excitation of vaso-motor nerves of, 471 Investigation of functions of, 4G7 Sugai', Detection of, in urine, 553 Testing for, in blood, 509 Sweat glands, 142 Sympathetic system. Ganglia of, 85,80 nerve, Vaso-motor functions of cervical portion of, 257 Syntonin, or acid albumin, 432 Tactile corpuscles, 90 Tannin, Action of, on blood, 31 Taste, Organ of, 155 Taurocholic acid, 502 Taurine, 502 Teeth, 135 Temperature, Distribution of, in body, 348 Electrical measurement of, 344 Tendons, Preparation of gelatigenous substance from, 441 of mucin from, 443 Tetanus, 371 Curve of, 371 effects of exhaustion, 372 Thermal stimulation of muscle and nerve, 364, 397-8 , Thermometry, 343 Thymus gland, 132 Tissues, Chemistry of, 442 Process of teasing, 46 Tongue, Mucous membrane of, 135 of frog. Inflammation of, 173 Study of circulation in, 122 Traube's curves, 320 Tuning-fork, 357 Tyrosine, 440 Preparation of, by pancreatic digestion, 521 Tests for, 441 Unstriped muscle, 65 Nerves of, 96 Urari, Poisoning by (see also Curare), 398 Urea, Determination of, in urine, 547 i?reparation of, from urine, 534 Ureter, pelvis of kidney, and bladder, 147 Uric acid, 455 Determination of, in urine, 551 Urinary apparatus, 144 deposits, 533 38 Urine, 531 Detection of blood in, 557 Constituents of, 534 Determination of albumin in, 556 of chlorine in, 549 of phosphoric acid in, 551 of sugar in, 553 of sulphuric acid in, 552 of urea in, 547 quantity passed in a given time, 541 Keactions of, 531, 533 Separation of bile acids from, 656 of coloring matters from, 539 of creatinine from, 538 of hippuric acid from, 537 Specific gravity of, 542 Uterus, Fallopian tubes, and vagina, 148 Vagus and splanchnic nerves. Influ- ence of, on stomach, 493 nerve. Influence of, on heart, 279-80 Reflex excitation of, 283 Valves, Study of, in dead heart, 267 Varnished rabbits, Increased dis- charge of heat from, 342 Vascular system. Methods of inject- ing, 110 Vasomotor, Centre reflex excitation of, 252 functions of splanchnic nerves, 258 of cervical portion of the sympathetic, 257 nerves, Excitation and division of, 250 Functions of, 244 Veins and lymphatics. Absorption by, 293 Internal absorption by, 290 Villi of intestine. Epithelium of, 39 Vitellin, 435 Volumetrical analysis, 569 Warm stage, 22 Wax and oil, Embedding in, 103 Web of frog's foot. Circulation in, 121 Weighing, 567 Xanthine, 454 Yellow cartilage, 02 PHILADELPHIA: No. 25 South Sixth Street, April, 1873. CATALOGUE OF NEW WORKS AND NEW EDITIONS RECENTLY PUBLISHED BY LINDSAY & BLAKISTON; TOGETHER WITH A CONDENSED LIST OF ALL THEIR PUBLICATIONS. TEXT-BOOKS AND MANUALS PUBLISHED BY LINDSAY & BLAKISTON, Philadelphia. AITKEN'S Science and Practice of Medicine. 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Two volumes, royal octavo, bound in cloth, price, . . 1 12.00 " " " " leather, . . 14.00 Vov eighteen months Dr. .Vitken has been engaged in again carefully revising this Great ' Work, and aduhig to it many valualjle additions and improvements, amounting in the ag- gregate ahnost to a volume of new matter, included in -wliieli will be found the adojition and incorporation in the text of the " Nciv Nomenclature of the lioijul i'ollrge of J'/iysiciaiis of London;" to whicli are added the Dcjinitions and the Foreign Equivalents for theirlinglish names ; the New Classification of Disease as adopted by the itoyal (.'oUcge of Physicians, &c. The American editor, Meredith Clymer, M. D., has also added to it many valuable articles, with special reference to the wants of the American Prac- titioner. The work is now, by almost universal consent, both in England and the United States, acknowledged to be in advance of all other works on TJie Seience and Praetice of Medicine. It is a most thorough and complete Text-book for students of medicine, following such a systematic arrairgement as will give them a consistent view of the main facts, doctrines, and practice of meilioine, in accordance with accurate physiological and pathological principles and the present state of science. For the practitioner it will be found equally acceptable as a work of reference. ALLINGHAM (william), F. R. C. S., Surgeon to St, IVIarl<'s Hospital for Fistula, ic, FISTUL\, HEMORRHOIDS, PAINFUL ULCER, STRICT- LTRE, PROLAPSUS, and other Diseases of the Rectum, their Diagnosis and Treatment. Second Edition, Revised and Enlarged by the Author. Price ^2.00 This book has been well received by the Profession; the first edition sold rap- idly ; the present one has been revised by the author, and some additions made, chiefly as to the mode of treatment. The Medical Pre&s and C'irculnr, speaking of it, says : " No book on this special suljject can at all approach Mr. AUingham's in precision, clearness, and jiractical good sense." The London Lancet : " As a practical guide to the treatment of aflfections of the lower bowel, this hook is worthy of all commendation." The Edinburgh Monthly : " We cordially recommend it as well deserving the careful study of Physicians and Surgeons." ATTHILL (lombe), M. D., Fellow and Examiner in Midwifery, King and Queen's College of Physicians, Dublin. CLINICAL LECTURES ON DISEASES PECULIAR TO WO- MEN. Second Edition, Revised and Enlarged, with Six Litliooraphic Plates and other Illustrations on Wood. Price . . . ° «2.2C The value and popularity of this book is proved by the rapid sale of the first edition which was exhausted in less than a year from the time of its publication. It appears to possess three great merits : First, It treats of the diseases very common to females Second it treats of them m a thoroughly clinical and 2Jractical manner. Third, It is concise orif- laal, and illustrated by numerous cases from the author's own experience. His style is cleJr and the volume is the result of the author's large and accurate clinical observation recorded in a remarkable, perspicuous, and terse manner, and is conspicuous for the best qualities of a practical guide to the student and practitioner. — i'rtiMA Medical Journal. ARNOTT (henry), M. D., Assistant Surgeon and Lecturer at St, Thomas' Hospital. CANCER: ITS VARIETIES, THEIR HISTOLOGY AND DIAGNOSIS. Illustrated by Five Lithographic Plates and Twenty- two Wood Engravings. Price $2.2^ The chief ahn of the author has been to aid diagnosis, simplify microscopical work and ^. .ll'fvin? f ''' " 1'"'"''' f' tlie various morliid growths, that have all, until i comparat vely recent date, been generically called cancer. i '^-'j' It is an excellent resume of our present knowledge of the minute anatomy of cancer and IS enriched by origmal drawings in tlie author's best manner. ' ADAAiS (WILLIAM), F. R. C. S., Surgeon to the Royal Orthopedic and Great Northern Hospitals. ^^^MFw^^ii ■^'^\ CAUSES, PATHOLOGY, AND TREAT- MEN I . Being the Jacksonian Prize Essay of the Royal Colle-e of Surgeons. A New Revised and Enlarged Edition, with 106 Illustrations engraved on Wood, and Six Lithographic Plates. A large Octavo Volume. Price . . ^^ go. 00 ADAMS (ROBERT), M.D., Regius Professor of Surgery in the University of Dublin, &c., &c, RHEUMATIC GOUT, or CHRONIC RHEUMATIC ARTHI?T TIS OF AIX THE JOINTS. The Second Edhit lutuat J^b; numerous Woodcuts, and a quarto Atlas of Plates Price Volumes, ^o.oo BASH AM (w. R.), M. D., F. R. C. R, Senior Physician to the Westminster Hospital, &c. ^^^NFV? Tv^if T^^f *^^2^^2 ^1' DISEASES OF THE KID- NEYS. With Ten large Plates. Sixty Illustrations. Price ^'00 of these cases,.witfi -i-.^o^^SnilulSit^ir^^^dl^llS-'^^^^llSj:-,' 2 BLACK (d. CAMPBELL), M. D., L. R. C. S, Edinburgh, Member of the General Council of the University of Glasgow, &c,, &c, THE FUNCTIONAL DISEASES OF THE RENAL, URINARY, and Reproductive Organs, with a General View of Urinarj' Pathology. Price ........... |2.so CONTENTS. t'hap. 4. On the Patholoey and Treatment fif Noeturnal Kimresis, and y|»en)Kitic Ineoulinencc. " .'i. Sterility in tlie Male. *' (I. Male Irnpcitenee, " 7. Anomalous Uretliral Discharffea. Chap. 1. On the Conditions that atTeet the Serfotiou of the Urine, "with special , reference to Suppi-ession. " 2. Eetention of L'rine; its Varieties, Causes, and Treatment. " 3. Irritaljle Bladder, Strangury. The style of the author is clear, easy, and agreeable, . . . his work is a valuahle contri- bution to medical science, and being jienned in (bat disposition of nnprejudiced philosophical inqniry which should always guide a true jiliysieian, ailmirably embodies the s^firit of its opening qnotation from Professor Huxley. — Fhiluda. Med. Times. BEASLEY (henry). THE BOOK OF PRESCRIPTIONS. Containing over 3000 Prescriptions, collected from the Practice of the most Eminent Physi- cians and Surgeons — English, French, and American; comprising also a Compendious History of the Materia Medica, Lists of the Doses of all OfTicinal and Established Preparations, and an Index of Diseases and their Remedies. Fourth Edition, Revised and Enlarged. Price, ^2.50 This XEW edition of Dr. Bea-sley's Prescription Book, although presented in a mnch more com]iaot form and at a greatly rednced price, has been thoroughly revised, and an account of all the new medicines lately introduced, with the forranlas of the new Pharmacopoeias adiled. Carefully selecting from the mass of materials at his disposal, the author has aimed to compile a volume sntfieiently comprehensive, in which both physician and drnggist, prescriber and compounder, may find nnder the head of each remedy the manner in -vvhicli that remedy may be most effectively administered, or combined with other medicines in the treatment of disease. The alphabetical arrangement of the boolc renders this easy. A short description of each medicine is also given, and a list of the doses in which its several pre- parations may be prescribed. BY SAME AUTHOR. THE POCKET FORMULARY: A Synopsis of the British and Foreign Pharmacopoeias. Ninth Revised Edition. Price . '^2.50 THE DRUGGIST'S GENERAL RECEIPT BOOK and VETERI- NARY FORMULARY. Seventh Edition. Price. . . ^3.50 BEALE (LIONELS.), M. D. DISEASE GERMS: AND ON THE TREATMENT OF DIS- EASES CAUSED BY THEM. Part L — SUPPOSED NATURE OF DISEASE GERMS. P-VRT II. — REAL NATURE OF DISEASE GERMS. PAitTlII. — THE DESTRUCTION OF DISEASE GERMS, Second Edition, much enlarged, with Twenty-eight full -page Plates, containing 117 Illustrations, many of them colored. Demy Octavo. Price $S-°o This new edition, besides including the contents revised and enlarged of the two former volnmes published by Dr. Beale on Disease Germs, has an entirely new part added on " The Destruction of Disease Germs." 3 BEALE (LIONEL s.j, M. D., F. R. S. BIOPLASM. A Contribution to the Physiology of Life, or an Intro- duction to the Study of Physiology and Medicine, for Students. AVith Numerous Illustrations. Price ?3-oo This Tolume is intended as a Text-Book for Students of Physiology, explaimns the nature of some of the most important ehanges which are characteristic of and peculiar to living beings, rechnical terms have been, as far as possible, avoided, while the subject is ren- throu^'hou't th^'bOTk''' ''"'"''''*''"' *° *'"" '■'='"''''' ^^ "'« numerous illustrations interspersed OTHER WORKS by Dr. BEALE. HOW TO WORK WITH THE MICROSCOPE. A Complete Manual of Microscopical Manipulation. Fourth Edition.' Eighth Thousand. Over 400 Illustrations. Price .... I7.50 ON KIDNEY DISEASES, URINARY DEPOSITS AND CAL- CULOUS DISORDERS. Third Edition. 70 Plates, 41^ Figures P"=^ $10.00 BIDDLE (JOHN E.), M. D., Professor of Materia Medica and Therapeutics in tlie Jefferson iHedical Coiiege, Philadelpliia, &e MATERIA MEDICA, FOR THE USE OF STUDENTS Wi^h Illustrations. Fifth Edition, Revised and Enlarged. Price §4 00 11 Ju^V"'''' ""'' *'^"™"gl''y '-e^ised edition of Professor Biddle's work has incornorated in of an elementary work on the subiftt Thnln '''™™ ?*" '"'='""" *° '^-^'"* '" *'>« '™'^ in our Medical s^Cls ^^t^^Itl^'^:^:^^t^%^^Jl'rf^ -f text-books in a condensed form, all that is most valmhl/ a, l^ui i' . 1^ Y''' ^'t ^^"""^ *" contain, to the (..urse of lectures on AlXia S l ' Tai ''^"PPlj'ltadents witli a reliable guide the United States. °'' ^"^ ^^elivered at the various Medical schools in BLOXAM (c. L.), Professor of Chemistry in King's Coiiege, London, CHEMISTRY, INORGANIC AND ORGANIC. W^ith Experi ments and a Comparison of Equivalent and Molecular FormulaT W th ^76^Engravings on Wood. Second Edition, carefully revised. Octavo <^^s:^z^^r^^z:^^:j:z:^'t:v^.^:^ *°t>^!^'^ book suffiSn«° devoted special attention to Metlllu?A a d s?me otl . 1 ""u"'''' J^'^"""'^^"°- ^e has also order to a.lapt it totliewant, of pr ctkll n „; n1 °, !' I^^nehes of applied Chemistry, in ments, well chosen, and many o'f the^uitT new ^.S ^eilSSen!*' ''''' '"'" '''^P"''- CHAVASSE (p. HENRY), F.R.C.S., Author of Advice to a Wife, Advice to a iVIother, &c ^™NG 0?i ?Sl d""- ,"™'f'^'- CULTURE AND TRAIN- valu'e of'hrf;chdcrto mVES^d ''f l>'^'i '■^ 'arge circulation, th! This book IS a sequel or comj.anion to them and itwill hpf 'f^n very generally recognized, to all who have the care of families, and who' want to bri ' t n '-""l ^T "^''''^ ^"'^ important men and women. It is full of fresh thoughts and j^-aSA/it^^aS.''' *° ^'"''^' ""''''"^ CLARK (f. le gros), F. R. S., Senior Surgeon to St, Thomas's Hospital. OUTLINES OF SURGERY AND SURGICAL PATHOLOGY, including the Diagnosis and Treatment of Obscure and Urgent Cases, and tlie Surgical Anatomy of some laiportant Structures and Regions. Assisted by W. W. Wacstaffe, F. R. C. S., Resident Assistant-Surgeon of, and Joint Lecturer on Anatomy at, St. Thomas's Hospital. Second Edition, Revised and Enlarged. Price .... ^4.25 This edition brings the worlc up to the highest level of our present knowledge, incorjiorat- ing all that is sound and recent in Physiology so far as it relates to sul)jects rei|uiring its aid. It is not alone an admirable exposition of tlie principles of Surgery, but a trusty guide to the emergencies of Practice. We cannot too highly estimate the ability to condense and the results of a ripened experience furnished to us here in a readable and practical form. — Mt'd, Tiines and Gazette, COOLEY (a. J.). CYCLOPyEDIA OF PRACTICAL RECEIPTS. Containing Pro- cesses and Collateral Information in the Arts, Manufactures, Profes- sions, and Trades, including Medicine, Pharmacy, and Domestic Economy; designed as a General Book of Reference for the Manufac- turer, Tradesman, Amateur, and Heads of Families. The Fifth Edi- tion, Revised and partly Rewritten by Richard V. Tuson, F.C.S., &c. Over 1000 royal-octavo pages, double columns. With Illustrations. Price ........... |io.oo Every part of this edition has been subjected to a thorough and complete revision by the editor, assisted by other scientific gentlemen. In the chemical ])ortion of the book, every subject of practical importance has been retained, corrected, and added to; to the name of every suljstance of established composition a formula has been attached; while to the Phar- maceutist its value has been greatly increased by tlie additions which have been made from the British, Indian, and United States Pharmacopceias. CLYMER (MEREDITH), M. D., Fellow of the College of Physicians of Philadelphia. EPIDEMIC CEREBRO-SPINAL MENINGITIS. With an Ap- piendix on Some Points on the Causes of the Disease as shown by the History of the Present Epidemic in the City of New York. With a Map of the City Of New York, showing the Localities, printed in Colors, of Cerebro-Spinal Meningitis in the Epidemic of 1872, made under the direction of Moreau Morris, M. D., City Sanitary Inspector of the Health Department. Price . ■ . . . . $1.00 This exceedingly interesting little volume contains a summary of the clinical history and pathology of cerebro-spinal m'eningitis, with an abstract of all the epidemics of the disorder which have happened in this country and in Europe. It contains much valuable informa- tion, and is a contribution to medical literature thatcannotfail to serve a scientific and useful purpose. DOBELL (HORACE), M. D., Senior Physician to the Hospital. WINTER COUGH (CATARRH, BRONCHITIS, EMPHYSEMA, ASTHMA). Lectures Delivered at the Royal Hospital for Diseases of the Chest. New and Enlarged Edirion, with Colored Plates. Octavo. Price ^3-50 This work has been thoroughly revised. Two new Lectures have been added — viz.. Lecture IV., "On the Natural (bourse of Neglected Winter Cough, and on the Interdepen- dence of Winter Cough with other Diseases ; " Lecture IX., " On Change of Climate in Winter Cough." Also addii;ional matter on Post-nasal Catarrh, Ear-Cough, Artificial Respiration as a means of Treatment, Laryngoscopy, New Methods and Instruments in Treating of Emphy- sema, a good Index, and Colored Plates, with appended Diagnostic Physical signs. DUNGLISON (robley), M. D., Late Professor of Institutes of Medicine, &c,, in the Jefferson Medical College, Philadelphia,' HISTORY OF MEDICINE. From the Earliest Ages to the Com- mencement of the Nineteenth Century. Now first Collected and Ar- ranged from the Original Manuscript, by his son, Richard J. Dungli- SON. M. D. Price t^.Ko The publication of a postliuraous worlv by this di.stingui.slied autlior and teacher must be a matter of general interest lo the profession, to whose advancement he devoted so many years of his valuable life. The great success of his excellent treatises in the various depart- ments of medicine form a memorable cliapter in the history of American literature. As a condensed history of the jirogress of medicine, presenting the main facts in systematic order the book is an excellent one. The editor has added a section in American MedicalHistory' which gives greater completeness to the work. ' ELAM (CHARLES), M. D., Author of "A Physician's Problems," &c, CEREBRIA AND OTHER DISEASES OF THE BRAIN. CONTENTS. Chap. 1 Introduction. | Chap. 8. Chronic Inflammation of the Brain 2. (jeneral Observations on the Studv " 9. Softening of the Brain. « o /'*' ''^^'''''^'O"** "f *e Brain. " " 10. Tubercular Meningitis.' 3. On some Conditions connected with " H. Organic and Pseudo-organicDiseases the Circulation in the Brain. of the Brain " 4. On the received Nosology of the " 12. Symptomatolot^-. « r ^ !?'"■, • " 13- Baralvsis as a Svuiiitom. 5, 6^ Cerebria. " 14. The Treatment of Inflammation of 7. -fartial Acute Cerebritis. | the Brain ^'"'=" ■. . . 52.50 FOTHERGILL (j. milker), M. D. THE HEART AND ITS DISEASES, AND THEIR TRE'lT- MEjST. With Illustrations. Octavo. Price . . . <-.oo , This work gives to the reader a concise view of Cardiac Diseases, uniting the most recent mformation as to the cause of heart-disease, with German Pathology and the latest advaoces in Therapeutics It is designed to fill the gap between our standa'rd works and th; mesen? position of our knowledge in diseases of the heart. piesenu BY SAME AUTHOR. ^^^.^'J^LIS. Its Mode of Action and its Use, illustratino- the Effect of Remedial Agents over Diseased Conditions of the Heart Price .... ^ ■ GANT (FREDERICK J.), F. R. C. S., Suro-eon to the Royal Free Hospital, &c, THE IRRITABLE BLADDER. Its Causes and Curative Treat- ment ;inch,ding a Practical V,e^y of Urinary Pathology, Deposits, and Calculi. Ihird Edition, Revised and Enlarged. With New Ilh strn tions. Price " It more complete and practically useful. ^juiuouai matter as to make 6 GODFREY (benjamin), M. D. DISEASES OF HAIR. A Popular Treatise upon the Affections of the Hair System, with Advice upon the Preservation and Manage- ment of Hair. Price ;^i-5o CONTENTS. CnAPTEK 1. Introduction. 2. Anatoni-\' and Physiolociy of Hair. 3. Excess of Hair. 4. Baldness. 5. Triehionosis Cana. (i. Albinism. 7. Hair in the Wrong Place. 8. Vei^e- table Parasitic Diseases. 9. Morbus Paxtoiiii. 10. Cliignon Fuagiis. 11. Plica Poloniea. 12. Diseases of Color of tlie Hair. 13. Pityriasis. 14. I'htheiriasis. 15. Distases of Hair- Follicles. 16. Trichiasis Ciliorum. 17. Color of Hair in relation to Character and Disease. It;. Cleanliness. ISi. Plair-Dyes. 20. The Beard. HARLEY (GEORGE), M. D., F. R. C. P., Physician to University Coilege Hospital. THE URINE AND ITS DERANGEMENTS: With the Applica- tion of Physiological Chemistry to the Diagnosis and Treatment of Constitutional as well as Local Diseases; being a Course of Lectures delivered at University College. With Engravings. Price ^2-75 CONTENTS. 1. AVliat is Urine ? 2. Changes in the Composition of the Urine, induced by Food, Drink, Medicine, and Disease. 3. Urea, Ammonfemia, XTrEemia. 4. Uric Acid. 5. Hippuric Acid, Chloride of Sodium. Urolnematin, Abnormal Pigments in Urine. 7. Phosphoric Acid, Phosphatic Gravel and Calculi. 8. Oxalic Acid, 0.\aluria, ]Mulberry Calculi. 9. Inosite in Urine, Crcatin and Creatinine, Cholesterin, Cystin, Xanthin, Leuciu, Tyrosin. 10. Diabetes Mellitus. 11. Albuminuria. On the whole, we have here a valuable addition to tire library of the practising physician; not only for tlie information which it contains, but also for the suggestive way in which many oi' the subjects are treated, as well as for the fact that it contains the ideas of one who thoroughly believes in the future capabilities of Therapeutics based on Physiological facts, and in the important service to be rendered by Chemistry to Physiolo,gical investigation. American JouvimI of tliG Medical Science. HABERSHON (s. c), M. D., Physician to Guy's Hospital, &c. ON THE DISEASES OF THE LIVER. Their Pathology and Treatment. Being the Lettsonian Lectures, delivered at the Medical Society of London, 1872. Price ..... ^1-50 These Lectures contain within a brief compass a large amount of information and many practical suggestions that cannot fail to be of great value to every practitioner. Dublin Medical Journal. HEWITT (graily), M. D., Physician to the British Lying-in Hospital, and Lecturer on Diseases of Women and Children, &c. THE DIAGNOSIS, PATHOLOGY, AND TREATMENT OF DISEASES OF WOMEN, including the Diagnosis of Pregnancy. Founded on a Course of Lectures delivered at St. Mary's Hospital Medical School. The Third Edition, Revised and Enlarged, with new Illustrations. Octavo. Price in Cloth . . . IS-oo " Leather . . . 6.00 This new edition of Dr. Plewitt's book has been so much modified, that it may be considered substantially a new book ; very much of the matter has been entirely rewritten, and the whole work has been rearranged in such a manner as to present a most decided im})rovement over previous editions. Dr. Hewitt is the leading clinical teacher on Diseases of AVomen in London, and the characteristic attention paid to Diagnosis by him has given his work great popularity there. It may unquestionably be considered the most valuable guide to correct Diagnosis ta be found in tlie English language. 7 HEWSOIS' (addinfxl,) M. D. Attending Surgeon Pennsylvania Hospital, &.c. EARTH AS A TOPICAL APPLICATION IN SURGERY. Being a full Exposition of its use in all the Cases requiring Topical Applications admitted in the Surgical Wards of the Pennsylvania Hospi- tal during a period of Six Months. With Four full-page Illustrations. CONTEXTS. Preface; Introduction ; Histories of Cases; Comments as to the Effeeta of the Contact of TK Tnfl ' ' -t-fl^rts on Tarn ; Its Powr as a Deodorizer ; Its Influence oyer Inflammation ; Its Influence over Putrefiict.on ; Its Influence over the Healins Processes; Modus Cperandi ot the Earth ; As a Deodorizer and other Putrefaction; In its Effects on Livino- Parts ^^"'^"' ^2.50 It presents the results of researches by the author into the action of Earth as a surgical dressnig, a.id embraces the histories of over ninety cases whicli occurred in the wards of the iennsylvania Hospital some three years since, but whose publication has been delayed for m'.n", ' ''"'•'"T f 7?SH"^'^ *"" ^^ subsequeht experience, and of interpreting their meaning by a caret nl study ot the various subjects which they involve. t= e r HODGE (HUGH L.), M. D. Emeritus Professor in ttie University of Pennsylvania, HODGE ON FOETICIDE, OR CRIMINAL ABORTION Fourth Edition. Price, in paper covers, . . . . $0. 30 " flexible cloth, .... 0.50 This little book is intended to place in the hands of professional men and others the means n^cjr^r s^^rii^"^^"'^' ^^^ '"""^''^ '"" -^^ "^^ -'^'^ of thi^in r KIRKES (WILLIAM senhouse), M. D HAND BOOK OF PHYSIOLOGY. The Eighth London Edition t wTb • ^^T'''''■ ""^^^l'- ^■^■^■S-' Lecturer on Phvstology,' &c. With 241 Illustrations. Price . ' ..^'^•^ * * ' ' * *^J ■ ^^ LEBER & ROTTENSTEIN (drs ) ''''^JI^fl^^^T^l^''^ '^S CAUSES. An Investigation into he Influence of Fungi in the destruction of the Teeth translated bv HOMAS H. Chandler, D.M.D,, Professor of Mechan cLl DentTstrv n Pnc? °' "' ""'^'"^ University. With Illustrations Octav" ev™;C?^U:d ;;™t;™f *:n'^:^,2Lrtytr^^ "^ ^^^^^^ Ca^es.^ d'^ original, and by authors writmg on tlte subject.^ ^ prolession, who have seen it in tile LEGG (j. wickham), M. D. Member of the Royal College of Physicians, &c. A GUIDE TO THE EXAMINATION OF THE IJRTNF tt the Practitionerand Student. Third Editionr^L^CloJi^PnS .I^l ed^?oJ;i;?;s^!:*{];e"r:!Jzx^:i^^,^i^^'t^;^,^:j--^ p^-fy exhaustion of;:' It can confidently be commended to the^tadln" I^riafe ^nd TeUabir 'ui^i:''*'" '" '"^ ^^'"'-'• 8 LEWIN (dr. GEORGE). Professor at the Fr.-Wilh, University, and Surgeon-in-Chief of the Syphilitic Wards and Sl(in Diseases of the Charity Hospital, Berlin. THE TREATMENT OF SYPHILIS by Subcutaneous Sublimate Injections. With a Lithographic Plate illustrating the Mode and Proper Place of administering the Injections, and of the Syringe used for the purpose. Translated by Carl Prcecler, M.D., late Surgeon in the Prussian Service, and E. H. Gale, M.D., late Surgeon in the United States Army. Price ........ ^2.25 The great mimber of cases treated, some fourteen linnili-cil, -within a period of four years, in the wards of the Cliarity Hospital, Berlin, only twenty of whieh were returned on account of Syphilitic relapses, certainly entitles the nietliod of treatment advocated hy this distinguished syphilographer to the attention of all physicians under whose notice syphilitic cases come. LIZARS (JOHN), M. D. Late Professor cf Surgery in the Royal College of Surgeons, Edinburgh. THE USE AND ABUSE OF TOBACCO. From the Eighth Edinburgh Edition. 121110. Price, in flexible cloth, . Jo. 60 This little work contains a History of the introduction of Tobacco, its general characteris- tics; practical observations upon its etfects on the system; the opinion of celebrated profes- sional men in regard to it, together with cases illustrating its deleterious influence, &c., &c. MACNAMARA (c.). Surgeon to the Ophthalmic Hospital, and Professor of Ophthalmic Medicine in the Medical College, Calcutta. MANUAL OF THE DISEASES OF THE EYE. The Second Edition, carefully Revised; with Additions, and numerous Colored Plates, Diagrams of tlie Eye, many Illustrations on Wood, Snellen's Test Types, &c., &c. Price . . . . . . ^5.00 " This work when first published took its place in medical literature as the most complete, condensed, and well-arranged manual on ophthalmic surgery^ in the English language. Arranged especially for medical students, it became, however, the work of reference for the busy practitioner, who could obtain nearly all that was best worth knowing on this subject, tersely stated, and easilv found by the aid of the excellent margdnal notes on the contents of the paragrai")hs." — Philadelphia Medical Tiinea. MACKENZIE (morell), M. D. Physician to the Hospital for Diseases of the Throat, London, &,c. GROWTHS IN THE LARYNX. Their History, Causes, Symp- toms, Diagnosis, Pathology, Prognosis, and Treatment. With Reports and Analysis of One Hundred Consecutive Cases treated by the Author ; and a Tabular Statement of every published case treated since the in- vention of the Laryngoscope. With numerous Colored and other Illustrations. Octavo. Price ...... ^3.00 Dr. JIackenzie's position has given him great advantages and a large experience in the treatment of Diseases of the Throat, and for many years lie has been regarded as a leading authority in this department of Surgery. The Illustrations have been prei)ared with great care and expense. OTHER ^A/ORKS BY SAME AUTHOR. THE LARYNGOSCOPE IN DISEASES OF THE THROAT. With an Appendix on Rhinoscopy, and an Essay on Hoarseness and Loss of A^oice. With Additions by J. Solis Cohen, and Numerous Illustrations on Wood and Stone. Price .... ?3-oo PHARMACOPCEIA OF THE HOSPITAL for Diseases of the Throat; with One Hundred and Fifty Formulje for Gargles, &c., &c. Price . . . . . . . . . . .J1.25 9 MAUNDER (c. f.), F. R. C. S. Surgeon to the London Hospital; formerly Demonstrator of Anatomy at Guy's Hospital. OPERATIVE SURGERY. Second Edition, with One Hundred and Sixty-four Engravings on Wood. CONTEXTS. Chap. 1. Cornpress, Splint, Bandage Strap' " 2, Ligature Operations on the Vascular System. 4. ( 'iterations on Arteries. 5. Ligature of special ditto, (j. f.'perations on the iJoues. Price Chap. 7. 0])erations on the Surface of the Body. 8. Amj)utation. " 9. Lower E.xtremity. " 10. Upper ditto. " 11. Special Operations. ^2,50 MARTIN (joHNH.). Author of Microscopic Objects, &.c. A MANUAL OF MICROSCOPIC MOUNTING. With Notes on the Collection and Exammation of Objects, and upwards of One Hun- dred Illustrations on Stone and Wood, drawn by the Author Price . . ^.00 ,^„ } '' "■"'' '" ™""^, *'"" '*'* *'*!'= indicates. It gives a description of the apparatus neces- sary for microscopical research, as well as the methods of priparation ami preservL" the various objects. It is a complete and well-illustrated worl. o,/ its subilot which is daily MEADOWS (ALFRED), M. D. Physician to the Hospital for Women, and to the General Lying-in Hospital, &c. MANUAL OF MIDWIFERY. A New Text-Book. Including the Signs and Symptoms of Pregnancy, Obstetric Operations, Diseases of f clitTon'P'w .t''''' '^'- ' ^^u ^'''' ^™"'^^'^ f™^^ '1^= Second London lidition. With numerous Ilkistrations. Price ^. 00 Illustrations are numerous and well executj!! "*'''""' *"' '^'^ ^'-^^tif^^ii^i'- The MILLER (JAME.S), F.R. C.S. Professor of Surgery University of Edinburgh. ALCOHOL, ITS PLACE AND POWER. From the Nineteenth Glasgow Edition. i2mo. Cloth flexible. Price ^^'neteenth view of the subject that could be freel7L'semTn\ted'atn';r*iTlSL^r""*"'° "" ""'^"^^ REYNOLDS (j. ru.s,sell), M. D. Of University College, London. LECTURES ON THE CLINICAL USES OF ELECTRTCTTV Delivered at the University College. Post octavo Pril^e ^^'^g^To f'^''n'i'T^::^^^:i:^^:^ in smaH bulh and clear readable feebly convey the highly practlcalLudgeAer4p^f^i;;^rnt^h-^:^S:S*C^ -t-dmburgh JlcdicalJounial, January, 1872.' RINDFLEISCH (dr. edward). Professor of Pathological ^^atonly| University of Bonn. TEXT-BOOK OF PATHOLOGICAL HISTOLOGY. An Intro- duction to the Study of Pathological Anatomy. Translated from the German, by Wm. C. Kloman, M.D., assisted by F. T. Miles, M.D., Professor of x\natomy, University of Maryland, &c., &c. Containing Two Hundred and Eight elaborately executed Microscopical Illustra- tions. Octavo. Price, bound in Cloth, .... ^6.00 " " Leather, . . . .7.00 This is now confessedly the leading book, and the only complete one on the subject in the English language. The London Lancet says of it : " Eiudfieisch's work forms a mine wliich no pathological writer or student can aflbrd to neglect, wdio desires to interpret aright }>athological strucfural changes, and his book is consequently well known to readers of Ger- man mellical literature. \\'liat makes it especially valuable is the fact that it w as originated, as its author himself tells us, more at tlie microscoj'c than at the writing-table. Altogether the book is tlie result of honest hard labor. It is admirably as well as profusely illustrated, furnished with a capital Index, and got up in a way thut is worthy of what must continue to be the standard book of the kind." ROBERTS (FREDERICK T.)., M. D., B. Sc. Assistant Ptiysician and Teacher of Clinical Medicine in the University College Hospital 1 Assistant Physician Brompton Consumption Hospital, &c. A HAND -ROOK OF THE THEORY AND PRACTICE OF MEDICINE. 8vo. Nearly ready. RICHARDSON (joseph), D. D. S. Professor of Mechanical Dentistry in the Ohio College of Dental Surgery, &c. A PRACTICAL TREATISE ON MECHANICAL DENTISTRY. Second Edition, much enlarged. With over 150 beautifully executed Illustrations. Octavo. Leather ^4-5o- This work does infinite credit to its author. Its comprehensive style has in no way inter- fered with most elaborate details ; and the numerous and beautifully executed woodcuts with which it is illustrated render this volume as attractive as its instructions are easily under- stood. — Sdinburgh Med. Journal. ROSS (jAMEs), M. D. THE GRAFT THEORY OF DISEASE. Being an Application of Mr. Darwin's Hypothesis of Pangenesis to the Explanation of the Phenomena of the Zymotic Diseases. CONTENTS. Chap. 1. The Germ Theory. Chap. 4, 5. The Zymotic Diseases. ^ " ' The Graft Theory. " 6. The Inherited Local Diseases. " 3! Life, Health, anil Disease. The " 7. The Inherited Diathetic Diseases. General Diseases. " 8. Classification and C onclusion. Price ^4-00 RYAN (MICHAEL), M. D. Member of the Royal College of Physicians, PHILOSOPHY OF MARRIAGE, in its Social, Moral, and Physi- cal Relations ; with an Account of the Diseases of the Genito-Urinary Organs, &c. Price $i.oo This is a philosophical discussion of the whole subject of Marriage, its influences and results in all their varied aspects, together w-ith a medical history of the reproductive func- tions of the vegetable and animal kingdoms, and of the abuses and disorders resulting from it in the latter. It is intended both for the professional and general reader. 11 SVVERINGEN (hiram v.). Member American Pharmaceutical Association, &c PHARMACEUTICAL LEXICON. A Dictionary of Pharmaceu- tical Science Containing a concise explanation of the various subjects and terms of Pharmacy, with appropriate selections from the- collateral sciences. Permute for officinal, empirical, and dietetic preparations: selections from the prescriptions of the most eminent physicians of ii,urope and America; an alphabetical list of diseases and their defini- tions; an account of the various modes in use for the preservation of dead bodies for interment or dissection; tables of signs and abbrevia- tions, weights and measures, doses, antidotes to poisons, &:c., &c and tLZ I °f ;=""o^''3', a few leaves from a dispensatory published in the seventeenth century. Designed as a guide for the Pharmaceutist Druggist, Physician, &c. Nearly ready. ccuiisi, BURDON-SANDERSON (j.), M.D. Professor of Practical Physiology in University College, London, HANDBOOK FOR THE PHYSIOLOGICAL LABORATORY Ik^ITmV^T''''^ f°^,Students in Physiology and Histologjfby E Klein, M.D. formerly Privat-Docent in Histology in the Univer- f^rnL^pTf- EditedbyJ.BuRDON-SANBERsoN. Containing it full-page Plates, or over 350 Illustrations. 2. vols. , . . Price, fo!oo SAVAGE (henry), M. D., F. R. C. S. ^UT, CT.^r^Jr"^''"^ ''^^'"'^" *° '^' ^'"^^"*^" ^''' "°=Pit^'- London. THE SURGERY, SURGICAL PA TROT nrv j c • , , Edition, greatly enlarged. A quarto volume. Mce $0.^0 TANNER (THOMAS HAWKEs),M.D., F R C S &c MEMORANDA OF POISONS am ' j ' ' , " '' tion. Price ^'^^^'J^^- A New and much enlarged Edi- , This manual is intenrJed to assist the praotitir.no,. ;„ ti, ^- ' • ' ' • ^°-75 ing, and especially to prevent his attributinl to natar^lrli '"""'' '""^ treatment of poison- istration of deadly drugs. irioutm,, to natural disease symptoms due to the admin- " /t?""^ T ^'''^*^'^^- ^"D THEIR TREATMENT TO THOROWGOOD (j. c), M. D. Physician to tlie City of London Hospital for Diseases of the Chest, and to the West London Hospital, &c. NOTES ON ASTHMA. Its various Forms, their Nature and Treatment, including Hay Asthma, with an Appendix of Formulae, &c. Second Edition. Price . . . . . . • fi-75 TOMES (JOHN), F. R. S. Late Dental Surgeon to the Middlesex and Dental Hospitals, Sic. A SYSTEM OF DENTAL SURGERY. The Second Revised and Enlarged Edition, by Charles S. Toimes, M.A., Lecturer on Dental Anatomy and Physiology, and Assistant Dental Surgeon to the Dental Hospital of London. With 263 Illustrations. Price . . ^5-oo Tliis book ha'! been for some time out of print in tliis country. Tlie material progress made ill the science of Dental Sur^'ery since its first publication has rendered large additions and many reyisions necessary to tlie'New Edition : in order to bring it fully up to the time; this has teen done without increasing the size of the book more than possible. Many improye- nients, hoiveyer, will be found added to the Text, and some Sixty new illustrations are in- corporated in the volume. TROUSSEAU (a.), M. D. Professor of Clinical Medicine to the Faculty of Medicine, Paris i Physician to the Hotel Dieu, &c., SiC. LECTURES ON CLINICAL MEDICINE. Delivered at the Hotel Dieu, Paris. Vol. I. Translated with Notes and Appendices, by P. Victor Bazine, M.D., London and Paris. Vols. IL, III., IV., and v.. Translated from the Third Revised and Enlarged Edition, under the auspices of the Sydenham Society, by John Rose Cormack, M.D., Edinburgh; M.D., Paris, F.R.S.E., &c. Price of Vols, i, 2, and 3, each, $5-°° " " 4 and 5 " 4 00 This edition of Trousseau's Lectures, so favorably received, as well by the profession of the United States as abroad, is published in this country in coiinectio)i with the New Sydenham Society. The \Vokk is kow complete ; each volume can be furnished separately. TUKE (DANIEL s.), M. D. Associate Author of "A Manual of Psychological Medicine," &c. ILLUSTRATIONS OF THE INFLUENCE OF THE MIND UPON THE BODY. Octavo. Price .... ^4-oo The author shows very clearly in this book the curative influence of the mind as well as its elTect in causing disease, and the use of the imagination and emotions as therapentic agents. His object is also to turn to the use of legitimate medicine the means so frequently einployed successfully in many systems of quackery. TIBBITS (HERBERT), M. D. Medical Superintendent of the National Hospital for the Paralyzed and Epileptic, &c. A HANDBOOK OF MEDICAL ELECTRICITY. With Sixty- four large Illustrations. Small octavo. Price . . - $2.25 The author of this volume is the translator of Duchenne's great work on ''Localized Elec- trization." Avoiding contested points in electro-physiology and therapeutics, he has pe- pared this handbook as containing all that is essential for the busy practitioner to know, not ^n y when, but in EXPLICIT ANlTrCLL DETAIL, how to use Electricity in the treatment ot disease, and to make the practitioner as much at home in the use of his electrical as, his other medical instruments. Id WILSON (GEORGE), M. A., M. D. Medical Officer to ttie Convict Prison at Portsmouth. A HANDBOOK OF HYGIENE AND SANITARY SCIENCE With Engravings. CONTENTS. Chai^. 1. Introductory — Public Healtii and PreventalJle Disease. 2. Food — CoListructiou of Dietaries; Examination ; Eifects of Un- wholesome Food. 3. Air : its Impurities ; Unwholesome Trades. 4. Ventilation and Warming. 6. Examination of Air. 6. Water, Waterworks, Water Analy- sis. 7. Eifects of Impure Water on Public Health. 8. DiFellings, Structural Arrange _rnents, Dwellings of the Poor Price tage, and Contagious Diseases Hospitals. Chap. 10. Eemoval of Sewage and Eefuse Matter. 11. Purification and Utilization of Sewage. 12. Eifects of Improved Sewerage and Drainage on Public Health. 13. Preventive Measures; Disinfec- ,, tiou ; Management of Epidemics. 14. Duties of Medical Officers of Health. Appendix I. Excerpts from the various ^.oo WARD (STEPHEN H.), M.D., F. R. C. P. Pfiysician to the Seaman's Hospital, &c,, &c. '^'^ .S"" AFFECTIONS OF THE LIVER and Intestinal Canal ■ ^ith Remarks on Ague and its Sequete, Scurvy, Purpura, &c. of the diseases treated will ^n^":^' t^r^^ ^^^i..^^^ Z^_ description WALKER (ALEXANDER) in the breeding of animals. wlTlluX°tTons°' ^pTi^-P^"^";^ ^^^;^l WEDL (carl), M. D. T^T7M'r AT r, , ^'°^'''°' °^ "'"°'°^^' ^'■' '" t^" U"i""=ity of Vienna. ^'^Jeti^l p'elTe^c^^o^SeT;A7a^ '^'V^.F -^^ ''^ ^-*- ^ith in th Dental 's^hSi oftT 1 i^"- ^"^ ^^"^^'^^^^ ^"^ Therapeudcs Illustrations. ""^p".*^ University, Cambridge. With 105 This work exhibits laborious ;esear:h amr'd-"l ' ^'■'° ' ^'^'''''' ^^-So covers the entire field of Anatomv Ph, ^1 medjcal culture of no ordinary character It Prof. Wedl, has thoroughlv ma "ered «ie " F' f"*^ .Pathology of the Teeth. The auihor very valuable material left Cthe late Dr w^f"*',,'''?'? ^""^ ■'?>-'^«t benefit to the hook the versrty of Vienna, the -ult';^ the {^i?L^«t^k ^^^^^^^^^^ ''^ "- uSt JUST READY. A HAND-BOOK PHYSIOLOGICAL LABORATORY. BY E. KLEIN, M. D., ASSISTANT PROFESSOR IN THE PATHOLOGICAL LABORATORY OF THR BROWN INSTITUTION, LONDON, FORMERLY PRIVAT-DOCENT IN HISTOLOGY IN THE UNIVERSITY OF VIENNA; J. BURDON-SANDERSON, M. D., F. R. S., PROFESSOR OF PRACTICAL PHYSIOLOGY IN THE UNIVERSITY COLLEGE, LONDON ; MICHAEL FOSTER, M. A., M. D., F. R. S., FELLOW OF, AND PRELECTOR OF PHYSIOLOGY IN, TRINITY COLLEGE, CAMBRIDGE ; AND T. LAUDER BRUNTON, M. D., D. Sc, LECTURER ON MATERIA MEDICA IN THE MEDICAL COLLEGE OF ST. BARTHOLOMEW'S HOSPITAL, LONDON. EDITED BY J. BURDON-SANDERSON. ONE HUNDRED AND THIRTY-THREE PLATES. CONTAINING THREE HUNDRED AND FIFTY-THREE ILLUSTRATIONS. IN TWO VOLUMES. VOL. I. TEXT. VOL. II. ILLUSTRATIONS. PHILADELPHIA: LINDSAY & BLAKISTON. iS73- EXTRACT FROM THE PREFACE OF SANDERSON'S HAND-BOOK. This book is intended for beginners in physiological work. It is a book of methods, not a compendium of the science of physiology, and consequently claims a place rather in the laboratory than in the study. But although designed for workers, the authors believe that it will be found not the less useful to those who desire to inform themselves by reading as to the extent to whicli the science is based on experiment, and as to the nature of the experiments which chiefly deserve to be regarded as fundamental. The practical purpose of the book has been strictly kept in view, both in the arrangement and in the selection of the subjects. Many subjects are entu-ely omitted which form important chapters in every text-book. They have been left out either because they do not admit of experimental demon- stration, or because the experiments required are of too difficult or compli- cated a character to be either shown to a class or performed by a beginner. The mode of arrangement will be found to be somewhat different in the four sections into which the work is divided. This difference, although in part attributable to difference of authorship, is mainly due to the peculiarities of the modes of demonstration required in the several subjects. As regards the physiology of the nerve and muscle, it is sufficient to refer the reader to the author's introduction for an exposition of the method fol- lowed. In the histological part will be found a purely objective description of anatomical facts and methods. Substituting chemical for anatomical, the same thing might be said of the chapters relating to the chemical func- tions. Here, where minuteness of description is essential, great pains have been taken to give the student the most ample details as regards materials for work, instruments and methods. In the chapter on the blood, the same object has been kept in view, but in those relating to the mechanical func- tions of circulation and respiration, where either man or the higher animals must be for the most part the subjects of observation, and where conse- quently the conditions of experiment are complicated by the interference of the nervous system to an extent which it is often difficult to estimate, it has been found impossible to avoid entering somewhat more largely into theoretical explanations. CONTEXTS SANDERSON'S HAND-BOOK. Chap. I. II. III. HISTOLOGY. Blood Corpuscles. Epithelium and Endothelium. CoNNECTi\'E Tissues. -PART I. Ch.-vp. IV, Muscular Tissues. A'. Tissues of THE Nervous System. HISTOLOGY. — P.\RT II. VI. Prepar.\tion of the Compound Tissues. VII. V.iscuLAR System. VIII. Ly-mph.vpic System. IX. Organs of Respiration. X. ORG.A.NS of Digestion. XI. Skin, Cutaneous Glands, and Genito-Urinary Api'aratus. XII. Organs of Special Sense. XIII. Embryology-. XIV. Appendix. — Study' of Inflamed Tissues. PHYSIOLOGY. — PART I. Blood, Circulation, Respir.\tion, and Animal Heat. XV. The Blood. i XVII. Respiration. XVI. Tpie Circulation of Blood. I XVIII. Animal He.vt. PHYSIOLOGY. — PART II. Functions of Muscle and Nerve. XIX. XX. XXI. XXII. XXIII. XXIV. XXV. XXVI. XXVII. General Directions. General Properties of Muscle .AT Rest. Preliminary' Observations on the Stimul.ation of Nerve and Muscle. Phenomen.a and Laws of Mus- cular Contraction. The Wave of Muscular Con- traction. Tet.\nus. Electric Currents of Muscles, Electric Currents of Nerves, EllciroToncs. XXVIII. Stimulation of Nerves. XXIX. Phenomena accompanying A Nervous Impulse. XXX. Various Forms of Stlmul.a- TioN OF Muscle and Nerve. XXXI. Urari Poisoning and Inde- pendent iluscULAR Irri- tability. XXXII. The Functions of the Roots of Spinal Nerves. XXXIII. Refle-X Actions. XXXIV. On some Functkins of Cer- tain Parts of the Ence- phalon. PHYSIOLOGY. — PART III. Digestion and Secretion. XXXV. Albuminous Compounds. XXXVI. Chemistry of the Tissues. XXXVII. Digestion. XXXVIII. The Secretions. XXXIX. Appendlx, — Notes on Ma- NIPULATIO.N. The illustrations to the book, which consist of One Hundred and Twenty-Three Octavo pages, and include over Three Hundred and Fifty Figures, each having appropriate letter-press explanations attached with references to the Text, when necessary, are bound in a separate volume for more convenient reference. They have been executed in the most elaborate manner by the engraver, and printed on a finely-sized cream- tinted paper. A list of them, covering fourteen octavo pages, is included in the volume. In the volume of Text there is also a list of the more important instruments or apparatus referred to iiT the work, with informa- tion as to where they may be obtained. Price of the Two Volumes ....... ^ Hewitt's Diagnosis, Pathology, and Treatment of tlie Diseases of Women. THE THIKD EDITION. Revised, Enlarged, Rearranged, and Mostly Rewritten; with Many New Illustrations. OPINIONS OF THE PEES3 ON THE THIKD EDITION. The changes and additions wliicli have been made, as well as the general rearrange- ment of the whole subject matter, render tliis new edition an essentially new work. — Chicago Med. Examine}'. It forms a volume of 740 pages, numerously illustrated, and though called a new edition, it is really a new work. The style is attractive and practical, the mechanical execution of the work creditable, and as a reliable guide in the treatment of diseases peculiar to women it has no superior. — Canada Lancet. It now forms a complete and systematic treatise, admirable in arrangement, beautiful in appearance, and rich in the wisdom that comes from ample experience, mature thought and active industry. — Leavenworth Herald. He has really rewritten the former edition, embodying his extensive clinical experi- ence, making tliis edition a most complete and thorough work on all that pertains to the pathology and treatment of diseases peculiar to women. — Cincinnati Medical New.i. For those who desire full instruction and careful illustration in this department nothing can equal the work before us; the philosophy of mechanics, and the modes of applica- tion are fully presented. — Buffalo Medical and Surgical Journal. It is unquestionably one of the most valuable guides to a correct diagnosis to be found in the English language. — Richmond and Louisville Journal. The latest, best, and most authoritative exponent of a well-defined bia.s that powerfully affects a zealous class of gynecologists ... We hail Dr. Graily Hewitt's work as the lineal successor to Simpson's. — Brit. Med. Jour. The style is clear and very readable, and it gives evidence throughout of honest hard work ; not that of the office book-worm, but of the careful clinical observer. — Canada Med. and Surg. Jour. This new edition is remarkably full, and affords instruction in every department of the science and art of gynecology. The topics embraced in the volume cover the whole ground of sexual disorders, and our friends will find it one of the best works for consul- tation. — Lancet and Observer. We have derived from this work in hours of doubt and perplexity great comfort and assistance. The present edition is not merely a reprint, but in many and important respects a new work, containing certain generalizations on the important questions of the pathology of diseases of the Uterus, which involve the adoption of new views concern- ing the pathology and treatment of others. The arrangement of the former edition de- vised to facilitate the study of the subject, particularly the Diagnosis, has been very much modified in this edition. Many new and gr.aphic illustrations are added. — Firowim Clinical Record. In the diagnosis of the various uterine disorders, great attention has been paid. Dr Hewitt has endeavored to render this easy of accomplishment, for his descriptions and symptoms of disease are as carefully and minutely rendered as to at once become appa- rent as the work of a diligent and painstaking observer. — Canada Medical Record The author treats systematically and generally, and with sufficient fulness, on all sub- jects within the sphere of gynecology, and many of the more difficult subje'cta are illus- trated with well-executed woodcuts. It undoubtedly occupies the front rank among syeteraatic treatises on the diseases of women. — Michigan University Journal. " Tlie most thorough and Practical Work on the subjrd now oe/ore ike Profcssiony Meigs and Pepper's Practical Treatise on the Diseases of Children. roui'tli Edition, tlioroughly Eevised and greatly Enlarged. By J. FoKSYTii Meigs, M. D., Felloiv of the College of Physicians^ of Philadelphia, &c., &c., and William Pepper, M. D., Physician to the Philadelphia Eoapital, d-c, tt-c, forming a Royal Octavo Volume of over 900 pages. Price, bound in Cloth, . . ' . $fi OO " " Leather, . . . "j 00 l)r. Meigs' work lias been out of print for some years. The rapij sale of the three previous editions, and tbe great demand for a new'edition. is sufficient evidence of its great popularity ; ivhile the very large practice of many years' standing of the author in the speciality of " Diseases of Cliiklren," imparts to it a value unequalled, probably by any other work on the same subject now before the Profession. This present edition has been almost entirely rewritten and rearranged, and no effort or labor has been spared by either Drs. Jleigs or Pepper, to make it represent fully in its most advanced state the present condition of Medicine as applied to Children's Diseases. The entire work has been subjected to careful revision. Several of the articles, as those on Eclampsia, Chorea, and Parasitic Skin Diseases, have been much enlarged ; and others, as the various articles on the Diseases of the Stomach and Intestines, and 'hat on Eczematous .Affections, entirely rewritten. In addition, articles have been added upon the following important subjects: Diseases of the Heart. Facial Paralysis. Cyanosis. llheumatism. Diseases of the Cascum and Appendix. Diphtheria. Intussusception. Mumps. Chronic Hydrocephalus. Kickets. Tetanus Nasceulium. Tuberculosis. Atrophic Infantile Paralysis. Infantile Syphilis. Progressive Paralysis, with apparent Hy- Typhoid Fever, pertrophy of the Muscles. Sclerema. The new matter thus added amounts to nearly 200 pages. It has been the effort of the authors, while endeavoring to make the work fully represent the slate of our knowl- edge upon the subjects treated of, to retain its eminently practical character; and with this view, an unusually large amount of space has been devoted to the consideration of the treatment of each disease. "This is the fourth edition of Meigs on Diseases of Children, greatly enharged and improved by chapters upon a large number of new subjects, and also by a very copious index, which facilitates reference, and makes the work more serviceable to the Prac- titioner. As now enlarged, it is one of the most complete and comprehensive worlvs of its class, and will meet the wants of the Profession in this department most admirably.' . — Buffalo Med. and Surg. Journal. "It is very comprehensive, and embraces most of the maladies incident to childhood and infancy. We consider it a very safe, reliable, and suggestive guide, being quite large and full in detail, embracing almost everything pertaining to the subject, making it a very useful book both foi' reference and study." — Medical Archives. "It forms the most complete and comprehensive work upon the diseases of children published in this country. It has for years been one of the standard authorities, and in its present enlarged form will still more command attention. It presents the latest views of pathology and treatment, and takes into consideration many subjects which were entirely omitted in the previous editions." — Detroil Journal of Medicine, ^-c. "It is satisfactory to note that the authors have brought up their work to the level ef the pathological knowledge of the day, and that their therapeutical notions are equally advanced. The authors are enrolled among the more enlightened therapeut- ists of our time. One cannot fail to be struck throughout the treatise with the vei-y judicious advice given by the authors on various points of treatment. The work, as a ivhole, is entitled to rank with the best." — Medical Repertory. Rindfleisch's Text-Book of Pathological Histology. 208 Illustrations. An Introduction to the Study of Pathological Anatomy. By Dr. Edward RiNDFLEiscii, 0. 0. Professor of Pathological Anatomy in Bonn. Translated from the Second German Edition, by Wm. C. Kloman, M. D., assisted by F. T. Miles, M. D., Professor of Anatomy, Uni- versity of Maryland, &c., &c. CONTENTS. Introduction, Author'a and Editor's Prefaces. General Part. 1. Decomposition and Degener.-ition of Tissues. 2. Pathological New Formations. Special Part. 1. Anomalies of the Blood and the Places 9. Anomalies of the OTories. of its Formation, especially of the Spleen and Lymphatic Glands. 2. Anomalies of the Circulatory Appa- ratus. 3. Anomalies of Serous Membranes. 4. " the Skin. ^- " Mucous Membranes. 6. " the Lung. 7. " " Lirer. 8- " " Kidney. Index and Bibliography. Containing 208 Ekbonitoly Executed Microscopical Illustration. Cue volume, octavo. Price, cloth, $6.00; sheep, 87.00. re^lJ"";'"""?'' ''"':?'"" "' Pathological Histology, so justly celebraied in Germany, where U ,s considered the most complele .and thorough work of lis kind :XrmTMedtrf'l"r"''^''i-'""°°'" -^-'-yi^igMy valued and com,„e, i (he ho rr, n .r '? '" ''"' '"""''^' "''"^ °f "'>°"^ '^^'^ -^ot only familiar w„h "rL'h'of m:dt?srd;""°^'' '-' "-•^''- - ^ --^- -^ P-^-sor of .1 The translators are both gentlemen who bv their m^t P.ln.>«*;^» i. u Cit 1 r 11 i 1 « ^ "J i-'^^Jir pasL euucation nave been rtpf^nl -irl^r fitted for the task of translating the work Dr Klomnn fm™ "^ oeen pecuh.irly f^miliar w,th tt,e German langu^e, while Prrf^nirTas mal^^tsuSecronr:? specal study, both gentlemen being also practical microscopis.s. Tl^-Tubl ers therefore offer a translation of this truly valuable work to the Me.l .,1 P '" the United States, feeling the utmost contidence thalin both ,^ ^''^'J'"'^' Pr«f^^«'«n ■" prove acceptable to them. In their Preface iLt , ? " ""'^ ''^''^ '' "'" English reiding portion of the Medical Po;e ^™.?'""'" ^"^ = " '" P.-esenting the work of Prof. lindfleisch, the trans la rs I .Z I m' ""'t^'"" °' ^"^ "''-""<' merits of the book itself, ^nd the fact that it filn '° ? "^^ necessary. The literature upon tbe sub eet of Patho 'deal 1 1!,,!^"""'' •''.^"P '° °"'- ""^^ ^<=^<'''^ centive for undertaking Ihe labor of SLo^^ThTL^rtrfV; "' "T": '"" by Chance, is, in many points, antiquated and the ^7 """''»" "^^"«^' «>-^"»l"'ed translated by Hacklev, occupies the Vounar.t tll.Zl IT ""^ °' '"'■"'"'"'• of Surgical Pathology." Partially, and is professedly a work This book is translated and published in this cnimtv^ k • , the author. """""^^ ^^ 'P«="il arrangement witi 10. " " Testicles. ■II' " " Mammas. 12. " " Prostate Glan.l. 13- " " S,alivary Gl.inds. 14. " " Thyroid Gland. 1^- " " Suprarenal Cap- sules. 16- " " Osseous System. 1"- " " Nervous System. 1^- " " Muscular System. CONDENSED LIST OF ALL THE MEDICAL PUBLICATIONS OF LINDSAY & BLAKISTON, PHILADELPHIA. AITKEN'S SCIENCE AND PRACTICE OF MEDICINE. Third American, from the Sixth London Edition. In Two Voliimes, Koval Octavo. Over 2000 pages. With a Colored Map, Lithographic Plate, and nearly Two Hundred Illustrations on Wood Cloth, $12; Leather, $14.00. ATTHILL'S CLINICAL LECTURES ON DISEASES PECULIAR TO WOilEjSr. Second Edition, Revised and Enlarged, with Illustrations. . $2.25. ARNOTT ON CANCER, its Varieties, their Histology and Diagnosis. With Illustrations. ......... $2.25. ACTON ON THE FUNCTIONS AND DISORDERS OF THE REPRO- DUCTIVE OEGAKS. Third American Edition. Octavo. . . . $3.00. ACTON ON PROSTITUTION, in its Moral, Social, and Sanitary Aspects. Second Edition. ......... $5.00. 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