CBUIDE TO Microscopy, Histology and Embryology IM CORBTELL UBTnTERSITY Qlnrnell Imacraita Htbrarg Jftljata, Nem ^nrfe THE CHARLES EDWARD VAN CLEEF MEMORIAL LIBRARY *5*«^.-^>^.a.w.Cp^.t.c\^. Cornell University Library QH 207.G12M Microscopy, histology and embryology in 3 1924 000 325 484 The original of tliis book is in tlie Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http ://www. arch i ve . o rg/detai Is/cu31 924000325484 M icroscopy, Histo- logy and Embryology IN CORNELL UNIVERSITY A GUIDE TO COURSE 1 Including the Requirements for the Course; an OutHne of the Laboratory Work and the Labo- ratory Reports ; the Questions for Recitations and the Subjects for Lectures and Demonstrations; a Numbered List of the Objects and Sections to be Studied; also a Statement of the Methods and Facilities for Conducting the Course and a List of the Other Courses Offered by the Department BY SIMON HENRY GAGE 1904-1905 COMSTOCK PUBLISHING COMPANY | ITHACA, NEW YORK ^1+ KKaiV'oS^ Ithaca Daily News Press COURSE I Microscopy, Histology and Embryology In Cornell University INTRODUCTION Course i of the Department of Microscopy, Histology and Em- bryology is the beginning or introductory course and serves as a basis for all the advanced work of the department. It is required of first year students in medicine and in veterinary medicine. It is open to other university students after the first year provided they have already pursued one or more courses in zoology or botany. Units or Kxercises. The work is divided into eight hour units or exercises, each unit comprising one lecture or combined lecture and demonstration, one recitation and six hours laboratory work including a laboratory report. When the course extends through- out the college year one exercise is given each week; if the work is concentrated into half a year then two units are given each week. The work is divided as follows: The Microscope and its Accessories 4 units or 32 hours Histology of the Tissues and Organs.. 14 units or 112 hours- Embryology, including the Genital Organs... 14 units or 112 hours Total for the Courses 32 units or 256 hours Method and Facilities for Conducting the Course. Laboratory Work. In this each student will have opportunity to go over the ground himself with the actual specimens or with the actual apparatus and thus gain knowledge at first hand. The lectures and demonstrations are meant to facilitate this personal study .so that it will not require an undue amount of time. Laboratory work must be taken during the assigned hours. Work at other than the regular time can be taken only by special permission. 3 The laboratory is open at all times, however, and the student may, at his convenience, make use of it for the" examination of the prepa- rations and models in the cases and for the consultation of the works of reference. Laboratory Reports. For each unit a laboratory report is re- quired. These reports are meant to represent salient features of the work. They must be handed in by the student within six days from the time the work on any unit begins. The reports will^be examined and marked by the instructors and returned. At the end of the course all are to be put together in order and handed in for final examination and correction. These reports are of the great- est value to each student. They will serve as literary training as well as for stimulating clear and logical thinking and. accuracy in stating scientific observations. Drawings for the Reports. To show something of the character of the drawings desired models will be posted in the laboratory from time to time. In general it may be said that there should be given a drawing at small magnification to show the object as a whole, then somfe of the details should be represented at a much greater magnification. As an aid to neatness the drawings are made either within circles representing in general the field of the microscope, or in oblongs. Delicate lines or broken lines are carried out from the structures to the margin and the name written in full or a letter or numeral is used and the name written out in another part of the sheet. Draw- ings in black and white will answer, but if colored pencils are used a drawing looking more nearly like the stained preparation can be produced. The student should remember, however, that it is of fundamental importance to learn to recognize organs and tissues b3' their structure, and not by some staining reaction. To impress the truth of this statement unstained and fresh preparations are studied, and submitted as "unknowns" (see below). The drawings should be accurate and neat with an indication in a uniform position on the page of the number of the preparations from which they were drawn. The drawings are made from as- signed slides or personal preparations. Much help in pathology will be gained 'by referring back to preparations, drawings and* descriptions of normal tissues and organs. In a word then the preparations and laboratory reports are retained by the student for the aid they will give in future work in histology, physiology or pathology. Recitations. In the recitations the students will be held respon- sible for the questions given in the lists for each unit. These can be fully and adequately understood only by attendance at the lectures and demonstrations, by laboratory work, and finally by a serious study of the text book, and the special papers and mono- graphs referred to from time to time. No Excuses from recitations are received. In case there is some special reason for it, a student may be given permission to change his recitation section, but this permission must/ be obtained in ad- vance. Lectures. — The aim, of the lectures is to present the broader as- pects and the fundamental principles of the subject and to show clearly the connection of this with related subjects. The details can best be obtained by the laboratory work and by the study of a text- book. The lectures are, in most cases, combined with a demonstration with the projection mciroscope, see the following: Demonstrations with the Projection Microscope. — Usually a part of the lecture period of each unit is devoted to a demonstration with the projection microscope of the preparations studied during that unit. Naturally the best possible preparations attainable are Used, and the difficulties are cleared up so that the students may understand and appreciate the specimens studied in the laboratory. For these demonstrations the projection microscope is placed at a distance of about 8 meters (26 feet) from the screen in order to produce the correct magnification for a class of 200 students. Only such objects and details are chosen for these demonstrations as can be clearly seen with a microscope having a low ocular and a 16 mm. objective. The objectives used for the projection microscope range from 100 mm. to 6 mm. equivalent focus, no ocular is employed; and the objects vary from 50 to 2 mtn. in. diameter. Demonstration of Difficult Objects in the Laboratory. — As the projection microscope is not useful for showing fine details these are demonstrated with special microscopes during laboratory hours on specimens not available in sufficient numbers for assigned slides. Specimens Assigned for Study. — Each student is supplied with prepared specimens of all the permanent preparations in the fol- lowing outline. 20 (¥) Heart Pr. 7 5 c: IS S. LO CORNBIX iraivEasiTY Fig I 5 FIG I— Assigned Slide in Histology to Show th"e Method of Numbering and Labeling. The label on the right gives the name of the preparation and the number corresponding to the number in this outline. C. — is for coverglass, and in this case it is IS hundreths mm. thick. The S. stands for the section, which is 10,« (ten microns) thick. Finally, as indicated on the bottom, the preparation is the property of Cornell University. The 20 on the left shows that this particular slide of preparation 75 should be assigned to student No. 20. Each slide bears a printed label and the slides (loo or more) are numbered with a writing diamond, commencing each preparation -with I. Each student is also numbered and he always receives specimens num'bered with his number. If his number were 20 he would receive slide 20 of all the assigned slides. This enables the department to keep track of the assigned slides and to fix re- sponsibility for their loss or injury. At the end of the course the assigned slides are returned by the student and any which are lost or injured must be paid for. Human Tissues and Organs. — For the assigned slides in histol- ogy go per cent, of the preparations are from the human body. The material is obtained from postmortems and from surgical cases. Those from surgical cases are fixed very soon after removal from the patient. Those from necropsies show more or less of a post- mortem change. From the point of view of pure histology this is unfortunate, but for the student of medicine there are some advan- tages. Most of the pathological material which he will subsequently study will show not only pathological changes, but postmortem changes. If he is familiar with postmortem changes in normal tissues and organs he can fairly judge of the additional modifica- tions induced by pathological processes. Human tissues and organs are taken as a standard because the student of medicine will have to deal with human tissues and organs i-n pathology, and then to all students the structure of man is of greater interest than the structure of one of the lower animals. For the specimens studied in Embryology, see pp. 52-55. Specimens Prepared by the Student.— Besides having the assigned slides for study, each student prepares many specimens himself. These he keeps. A part are from the human and a part from some lower animal. Sometimes the same organ, for example the duod'enum, is prepared for a human and the animal body. In this way the student learns to appreciate the fundamental similarity of structure and also any marked differences, as with the duodenum. Part of these specimens are fixed and sectioned by the depart- ment and mounted and stained by the student. A part are prepared from the fresh tissues by the student himself, all the processes re- quired to make preparations by the paraffin and by the collodion methods are thus learned. This is to give the student experience in the necessary manipulations, and a knowledge of the many details necessary for the preparation of specimens in histology and embry- ology. These specimens will be examined by the department at the end of the course and their excellence will help to determine the standing of the student in the laboratory work. "Unknowns."' As soon as the course has proceeded over the "tissues," there will be given to students at frequent intervals unlabeled specimens for them to determine the tissues and organs present. In embryology similar preparations will be given to test the student's knowledge of developing organs. The purpose of this exercise in "unknowns" is to give the student facility in detecting microscopic details, and in deciding on the character of objects in which no special clue is given. Material Equipment. — Most of the material used and the appar- atus necessary for carrying on the course are supplied by the uni- versity, but slides, cover-glasses, drawing paper, etc., which the student will take away with him must be obtained by the student. See the leaflet giving schedule and the requirements for the course, p. ii. Microscopes. — For his laboratory work each student is supplied with a microscope equipped with an Abbe condenser, triple nose- piece, 2 oculars and a i6 mm. and a 3 mm. objective. The depart- ment is well supplied with 2 mm. oil immersion objectives so that each student learns to use them and has one available whenever the object being examined requires it. Students are also taught to use the binocular microscope. Microscopic Accessories. — Besides the microscope constantly used bj the student there are available as needed, a Wollaston's camera lucida for determining magnification, an Abbe camera lucida and Bernhardt's drawing table for drawing, stage, ocular and filar mi- crometers, a polariscope and a micro-spectroscope, and numerous other pieces of apparatus. Text-Books. — Each student is required to supply himseH with a text-book in Histology and one in Embryology. As will be seen by the leaflet giving the schedule of hours etc., a choice of 'books is given. Works of Reference. — On the reading table in the laboratory may be found the standard text-books and the works of reference on all the subjects considered. Here may also be found papers, mono- graphs and Festschrifts to which special reference is made during the course. Standing of Students. — The standing of students is determined by four different factors as follows: 1. The laboratory work, including the determination of "un- knowns." 2. The laboratory reports. 3. The recitations. 4. The examinations. Other Courses Offered by the Department. (From the iCornell University Register, 1904-1905.) 4. Research in Histology and Embryology. Laboratory work eight or more actual hours per week with seminary throughout the year. This course is designed for those preparing theses for the baccalaureate or advanced degrees and for those wishing to under- take special investigations in histologic and embryology. Profes- sor Gage and Mr. Thro. Course 4 is open only to those who have taken course i or its equivalent in some other university. Drawing (course I, in Indus- trial Drawing and Art, or its equivalent) and a reading knowledge of French and German are indispensible for the most successful work in this course. Subjecfis for theses should be decided upon as early as possible so that material in suitable stages of development and physiologic activity may be prepared. 5. Structure and Physiology of the Cell. ..First h'alf-year. Two lectures per week at hours to be arranged. This course is de- signed for students of biology and medicine, and gives the funda- mental facts and principles '^relating to- cell structure and activity, especially in their bearing on general problems of biology and theories of evolution and- heredity. Open to students who have had satisfactory courses in zoology, botany or physiology, or course l. Dr. Kinglsbury. 7. -Seminary. One lecture or seminary each week at an hour to be arranged. At the seminary there will be presented reports of special methods and the results of advanced work. Professor Gage. 8. Structure, Development and Physiology of the Nervous System and the Organs of Special Sense. Credit 3 hours. Pro- fessor Gage, Dr. Kerr and Dr. Kingsbury. The course consists of three parts: (A) Gross Anatomy with special reference to medicine and surgery, I>r. Kerr; (B) Histol- ogy and Development, Prof. Gage and Inisitructor Thro; (C) Physiology, Dr. Kingsbury. The instruction in each part consists of laboratory work, dem- onstrations or lectures and recitations. The gross anatomy, his- tology and development are given during the latter part of the first term, and are immediately followed by the physiology in the fir.sit part of the second term. The course is only open to students who have done work in hutnan or comparative anatomy and have completed course i. It is a regular part of the curriculum of second year students in medicine. PART I-THE MICROSCOPE AND ITS ACCESSORIES Aim. The purpose of this part of the course is to give the student something of a mastery of the modern microscope and its most essential accessories. As the microscope is one of the most important aids in biology and medicine it seems worth while to learn its capabilities and limitations early in the student's sci- entific career. Before beginning work in Microscopy the student must supply Ifimself with the book on the microscope and the material indicated on p. ii of the leaflet giving the schedule, etc. UNIT I The Microscope and the Function, of Each Part. Laboratory Work 1. Clean your slides and cover-glasses during odd moments of the first two weeks. For cleaning the covers use 95% alcohol containing I per cent, or 2 per cent, hydrochloric acid; for the slides use the same or distilled water containing 5 per cent ammonia. You will find stock solutions on the shelves over the sinks in the labora- tory. 2. Read in the book on the Microscope §§i-io. 3. Perforin the first experiment in §11. Try the others if you have time. A special simple microscope like that in Fig. 20 will be furnished for the other experiments. 4. Read §§12-46. 5. Perform the experiments in §§47-48. 6. Read §§49-52. Perform the experiments in §§53-59. • Read §§60-69. 9. Perform the experiments in §§70-75. 10. Read §§76-103. Recitations 1. What is a microscope? 2. What is a compound microscope, a simple microscope? 3. What is the focus of a lens? Where is it? 4. What is a principal and w'hat a secondary axis? 10 5- What is the function of each part of a compound microscope? 6. How construct the two images of a compound microscope see §io). 7. Which of these images is erect, and which inverted? 8. What are the mechanical parts of a compound microscope? 9. How are oculars and objectives designated? 10. What is meant by equivalent focus? 11. What is chromatic aberration? What is spheric^ aberration? 12. What is refraction? Why is a stick apparently bent up in water? \\'hich way is the ray of light bent? 13. What is the function of an objective? Of an ocular? 14. What is the eye-point? Is it real or only apparent? 15. What is a real image? What is a virtual image? Figs. 14, 15, §10. Laboratory Report 1. Give a diagram of a double convex lens of 20 mm. focus showing the formation of a real image (see Figs. 14, 15 and §10). 2. With the same lens show the formation of a virtual image. 3. Give diagrams showing what is meant by equivalent focus. For the'sim{)le lens use one of 25 mm. focus. 11 UNIT II Interpretation of Appearances. Laboratory Work 1. Read §§111-127. 2. Read repeatedly §129. 3. Perform the experiments in §§130, 131, 133. 4. Read §134- 5. Perform the experiments in §§I3S, 136, 137, 138, 139, 140. 6. Read §§141, 142. 7. Perform the experiments in §143. 8. Read §§144, HS, 146, I47- 9. Perform the experiments in §§148, 149, 150. 10. Look at the demonstration of §151. 11. Perform the experiment in §152. 12. Readi §153 and look at as many objects there mentioned as the time will permit. 13. Learn to use the binocular microscope. Compare the ap- pearances of the same object as seen with the binocular and the monocular microscope. Recitation 1. In using the mirror which gives the -greater illumination, the plane or the concave side? Why? 2. H'ow focus? How get an object in the field of a high objective? 3. What is the field of a microscope? 4. What is meant by working distance? How does it com- pare with focal distance? 5. Discuss the care of the microscope and of the eyes. 6. What is the interpretation of appearances? 7. How can one detect dust in the -ocular? In the specimen? 8. How can one determine the presence, of dirt on the ob- jective? 9. How is the relative position of objects under the microscope determined? 10. How do air bubbles look under the microscope by trans- mitted light, by reflected light? 11. .How do oil globules look and why? 12 12. What determines the distinctness with Which an object under the microscope can be seen? (Its color and refractive inde^j as compared with the mounting medium). 13. Compare apparent and real velocity under the microscope. 14. Which way does i current seem to flow under the micro- scope? 15. What is pedesis? What forms of matter exhibit it? 16. How could you distinguish pedetic movement from the move- ment of living objects? 17. Muscae volitantes, why is it necessary to know about them? 18. iGive five rules for .microscopic observation and the inter- pretation of appearances. 19. What is a binocular microscope? 20. What are its advantages and its disadvantages? Laboratory Report 1. Give a diagram showing the use of the plane and of the concave mirror with daylight. 2. Give a diagram showing working and focal distance. 3. Give a diagram illustrating the real and' the apparent velocity under the microscope. 4. Give a diagram showing cotton, wool and silk fibres. 5. Describe the difference in appearance of the same object seer^ with a binocular and with a monocular microscope. 13 UNIT III Magnification with the Microscope. Laboratory Work_ 1. Read §§104-106. 2. Perform the experiments in §§107-108 with the homogeneous immersion objective. A condenser must be used in these experi- ments. 3. Read about the use of the condenser and the proper dia- phragm to use (§§83, 84, 88, 89). 4. Read §§154, ISS- (The images on the screen with the pro- jection microscope are illustrations of real images). 5. Get the magnification of the tripod magnifier §§156, IS7. 6. Get the magni'fication of the compound microscope and fill out the table on the special sheet (§§158-163). Recitation 1. What is an immersion objective? 2. What is a water immersion objective? 3. What is a homogeneous immersion' objective? 4. What is an objective called where no liquid is used? 5. What is a condenser? What kind of a condenser is on your microscope? ; 6. What diaphragm should be used with a condenser, and how can one determine the proper size? 7. Which mirror should be used' with daylight? With lamp light? 8. Give examples of real images with the microscope, with the projection microscope. 9. If an ocular is used can one get a real image with the projection microscope? 10. What is magnification? Is it expressed in diameters or in areas? 11. What is a stage micrometer? 12. How can one obtain the magnification of a simple micro- scope? 13. How obtain the magnification of a compound microscope? 14. How can the magnification of a compound microscope be varied? 15. What is the standard distance for measuring the image? 16. Why is a standard distance necessary? 17. Can one obtain the magnification at any other distance? 18. What is the field of a microscope? How can it be varied} 19. How can the actual size of the field be obtained? (See §§So, SI)- 14 20. What is the difference between the actual and the apparent size of the field with the microscope? Laboratory Report 1. Fill out the table of magnifications. 2. Determine the size of the field with your two objectives. IS UNIT IV Micrometry and Drawing. Laboratory Work I. Read §164-170. 2. Determine the ocular micrometer valuation for both ob- jectives using an ocular micrometer with fixed lines (§§171, 172). 3. Fill out the table for the high ocular (X8) with both objectives. 4. Get the ocular micrometer valuation of a filar micrometer (See ?I74).. 5. Find the size of a blood corpuscle by §168 and §173. 6. Make a drawing of a blood corpuscle or a part of the fly's wing with an Abbe Camera lucid'a. You might try the same with a Wollaston's camera lucida. Do not forget to give the scale of the drawing (§186) for both cameras. 7. Alount a fly's wing in balsam (§§255, 256). It would be better to draw this preparation than the assigned one. Recitation 1. What is micrometry? Four ways? 2. What is an ocular micrometer? 3. What is a filar micrometer? What are its advantages? 4. What is meant by ocular micrometer valuation? 5. How is the ocular micrometer valuation found? 6. What would vary the ocular micrometer valuation? 7. What is the unit of measure in micrometry? 8. How can one draw with the microscope? 9. What is a camera lucid'a and what are the two forms? 10. On what law in optics does the WoUaston camera depend? (See ?ioo). 11. On what law does the Abbe camera depend? 12. How can one determine the scale at which a drawing is made when the camera lucid'a is used? 13. How could one determine the magnification of the image on the screen when the projection microscope is used? 14. How should one arrange the lines of the two micrometers in getting ocular micrometer valuation (see Fig. 108). 15. In getting the magnifying power how should one place; the dividers on the lines of the micrometer? 16. What are adjustable objectives? 17. Are the objectives used by you adjustable? 16 Laboratory Report I. Fill out the sheet, giving the ocular micrometer valuation with the two objectives, one or both oculars as you have time. 2. Make a drawing of some object, preferably the fly's wing mounted by you. Do not forget to give the scale of the drawing. If you have time make the drawing of the same object with the Abbe and with the Wollaston camera lucida. 3. In using the Wollaston camera lucida where do the pencil and image appear to be? 4. In using the Albbe camera lucida where do pencil and image seem to be, i. e., are they under the microscope or on the drawing board? 5. Problem in refraction. Give all the data in your report. (See PP- 52-54). Suppose a ray of light at an angle of 45 degrees meets a surface of glass of an index of refraction of 1.60, what would be the angle of the ray of light after entering the glass? If you have time work out the critical angle for water, index 1.33 andi lof a glass with an index of 1.60. See §100. 17 PART II-HISTOLOGY Aim. The aim or purpose of the work in Histology is three- fold: (i) As a completion or supplement to Anatomy, in which the finer structure of man and the domestic animals is clearly demonstrated; (2) As an aid to Physiology by showing the rela- tions of structure and function, and especially the structural feat- ures characteristic of states of physiological activity; (3) As a preparation for Pathology by showing the normal structure and the variations of the same due to age and to physiological activity. Variations superadded to these muisit then be either pathological or postmortem. DIVISION A ORIGIN OF THE BODY; CELLS AND TISSUES Before beginning this work the student must supplj^ himself with the material and with one of the books on histology listed on p. ii of the leaflet giving the time schedule, etc. UNIT y Origin of the Body; the iCell and Epithelium. Laboratory Work Preparations will be supplied to the student to bring out clearly the fact (a) that the body is derived from the ovum; (b) that the ceil is the unit of structure; (c) that the ovum is a cell; (d) that the ovum divides or segments and forms many cells; (e) that these cells of the ovum finally arrange themselves in an orderly and definite way to form the so-called germ layers; (f) that the cells of the germ layers differentiate and form the various tissues of which the organs are composed, viz.:(i) epithelium, (2) blood and lymph, (3) the connective tissues, (4) the muscular and (s) the nervous tissues. 1. Ovum of the star-fish (Asterias) to represent the cell from which the body of the star-fish originates and as an example of the typical cell of Schwann. (There are many ova in the section of the ovary given you). la. Section of Amphioxus showing the ova in the body. 2. A young ovum of Amblystoma (demonstration). 3- Ovum of Amblystoma divided into a few cells. , 18 ' 4. Ovum of the Amblystoma divided into many cells. 5. Ovum of Amblystoma showing the germ layers and the be- ginning of the organs. Epithelium. Definition. This is a tissue composed of cells and cell cement. It is found covering all free surfaces of the body except the articular cartilage of synovial joints. Anatomical Classification (a) Simple. An epithelium one cell thick. All the cells reach the basement substance, and all or most of the cells reach the free surface. (b) Stratified. An epithelium several cells thick (often 20 to 50). Only the deepest cells are in contact with the basement sub- stance, and only the ectal layer reaches the free surface. (c) 'Massed. Epithelium in the form of large masses, as the liver of mammals, nails, hoofs, hairs and some horns. Physiological Classification (a) Protective; (b) Motile; (c) Absorbing; (d) Secretory or Execretory; (e) Sensory; (f) Germinal. Besides the names given albiove, epithelium is often classified according to the shape of the cells composing it, as squamous, columnar, cubical, etc. Consult your book on histology. 6. Section of the papilla of a kidney (Homo or horse) to show a simple epithelium composed of low columnar or cubical cells. The stratified epithelium of the renal pelvis may show in this preparation. If so compare it with the epithelium of the lip (15). 7. Section of the small intestine of a cat to show a simple columnar epithelium. Compare the striated border of the cells with ihe ciliated end of the ciliated cells. 8. Section of the ileum of man to show a simple columnar epithelium and the basement membrane. In this preparation the cells ido not cover all the free surface. That is because a part of the cells were shed before the organ was put into the fixer. (See for fixing the Micr. §284). 9. Isolated (Columnar epithelium cells from the intestine to show the individual cells. 10. (M'esentery of the cat. Silver nitrate was used to stain the cell cement so that the outlines of the cells would be sharply defined. This preparation illustrates a simple epithelium of the scaly, pavement or squamous type. Such a simple epithelium, found on serous surfaces, is sometimes called Endothelium instead of epithelium. 11. Isolated cells from the trachea of a horse. These ciliated cells illustrate the constituents of a motile epithelium. 19 12. Living ciliated epithelium from a frog's mouth or esophagus. This preparation is to show the function of the cilia. 13. Gross prepaTation of a ciliated surface to show the strength of the current. 14. Section of the soft palate of the cat to show on the respira- tory side a ciliated and on the oral side a stratified epithelium. In the substance of the soft palate are many tubular glands. These are cut at various angles. The cells are simple columnar epithelial cells and illustrate the epithelium of this form of gland. 15. Section of a human lip. This illustrates a stratified epi- thelium fcrming the epidermis on the outside and the epithelium of the mucosa on the inside. This kind of epithelium is pre- eminently protective. 16. Isolated surface cells of a stratified epithelium. For this moisten the end of your finger and scrape the inside 'of your own cheek. Mount the scrapings on a slide and put on a cover- glass. Examine with the low and then with the high objective. By pressing on one edge of the cover with one of your dissecting needles perhaps you can get the cells to turn over and thus find out that they are very thin. On account of the thinness of the surface cells such an epithelium as that lining the oral cavity is sometimes called a stratified squamous epithelium. Compare^he surface cells with those on the mesentery. For a permanent preparation put a drop of alumcarmine-eosin- glycerine at the edge of the cover-glass (see Micr. §§261, 263, 253.) 17. Preparation of the deeper cells of a stratified epithelium to show intercellular bridges. For this dissociate the lip of a horse ('Micr. §260). Scrape off the surface cells with a scalpel and discard them. Scrape off some of the deeper cells and m'ount them on a slide in soiTie of the dissociator. Cover and examine with the 3-mm. objective. The cells are irregularly rounded and they will be seen to be covered all over with little spines like a chestnut burr. The spines are little processes passing from cell to cell. From the prickly appearance they are often called prickle cells. A permanent preparation may be prepared as described for (16). In studying the various organs later on, all the forms of epithelium will be found, and some organs will be met with very frequently. Recitation on the Celt and Epithelium 1. What is the typical cell of modern histology? Example. 2. What is the cell of Schwann? Who was Schwann? 3. What tissues make up the body? 4. What is an epithelium? Where could one find an epi- thelium? 5- What i= a simple epithelium? Give examples. 6. What is a stratified epithelium? Give examples. 7. Give examples of massed epithelia. * 8. What is an endothelium? 9. Compare epithelium and epidermis. Where are they found? 10. Give an anatomical classification of epithelia. 11. Give examples of each form. 12. Give a physiological classification of epitlielia and examples. 13. Where and what is a motile epithelium? 14. iCompare a ciliated epithelium and one writh a striated border. Give situation of each. 15. Compare the surface and deeper layers of a stratified' epi- thelium. 16. What are intercellular bridges? Prickle cells? Examples. 17. What is intercellular substance in epithelium called? 18. How is this substance deeply stained? 19. From what is the body originally derived? 20. How is this brought about? Laboratory Report on the Cell and Epithelium 1. I>raw the star-fish ovum. Name all the parts. 2. Draw the simple epithelium of the kidney (6). 3. Satne for (8) to show basement membrane. 4. Draw ciliated cells (11). Compare with cells with a striated border (7). 5. Draw a stratified epithelium (14 or 15). 6. Draw the surface cells from your cheek, and the prickle cells from- the deeper layers of the horse's lip (16, 17). 7. Describe and figure what you saw in studying ciliated epi- thelium from the frog's mouth (12, 13). UNIT VI Blood and Lymph. Blood and lymph differ from the other tissues in the body in having the intercellular substance liquid instead of solid or semi- solid. The cells in blood are the leucocytes, the red corpuscles, and bodies of unknown character (blood plates). The cells of lymph are leucocytes. The liquid portion of both blood and lymph is called plasma. The lymph and blood mingle in the great veins of the neck. (For the origin of the lymphatic vessels, see later under embryology). As the distributing medium for nourishment and the collecting medium for the waste of the body, blood and lymph are of prime importance physiologically; and from the part played by them in diseased conditions they are also of prime importance patho- logically. One must learn to recognize the corpuscles of tlood and lymph with absolute certainty and readiness wherever they are found. Laboratory Work on Blood and Lymph Non-Mammalian Blood Corpuscles. i8. iPut a drop of blood from a recently pithed frog on a clean slide and cover it. Note the form and structure of the red cor- puscles. They will not look very red in this thin preparation. 19. Look through the preparation for the leucocytes.- As they are without color and of a refractive index not very .dififerent from the plasma one must be careful tO' light properly ('Micr. §83). 20. Put a drop of 2 per cent, acetic acid at the edge of the cover. It will run under and diffuse. Note the effect and compare with what is said on hemolysins by Dr. Ewing (Clinical Path- ology of the Blood, pp. 24, 144). 21. Study the stained preparation of Necturus blood, and the blood of the hen. Remember that in all non-mammilian vertebrates the red blood corpuscles are nucleated, and in all, except the lamprey, they are elliptical discs. In the lamprey they are nucleated, but in shape are circular biconcave discs like the red corpuscles of mammals. Com- pare the camelidae (17). 22. Amoeboid movements of leucocytes. On a fresh preparation of «rog blood study the white corpuscles and see their amoeboid movement. Do not fail -to see this and to make drawings of the same corpuscle at intervals. Mammalian Blood iCorpuscles, Read what your book on histology says about the blood and then try to aee as many of the structural appearances as possible in the preparations made by you. The best source for the mam- malian blood is the student's own vascular system. Remember, however, that in drawing blood only sterile instruments should be used. If a needle is used flame it first. If Dr. 'Moore's hemos- path is preferred sterilize the lancet with s% carbolic acid, then wash off with distilled water and wipe with absorbent cottton. Clean the place to be pricked with 95% alcohol. One may draw the blood from the ear lobe or from a finger. Get enough blood tO' fill the space under the cover. It is time saving to make several preparations at one bleeding. 23. Study the fresh human blood prepared as for the frog and make out the form and arrangement of the red. corpuscles. 24. Use 2 per cent, acetic acid and see the effect on the red and on the white corpuscles or leucocytes. 24a. Use 2 per cent, salt solution and note the crenation of the corpuscles. An isotonic solution would produce no appreciable effect. 25. Amoeboid movement. Study the leucocyte in a fresh prepa- ration. If the red corpuscles obscure the white ones, press on the cover with the finger covered with lens paper and press out some of the blood. If the room is conifortably warm (20° C) the leucocytes will show the ameboid movement without using a warm stage. This is more satisfactory after the preparation has been made 20 minutes or more. 26. Permanent preparations. Make two or three spread films of blood on covers or slides (see iCamac's directions in the Ref. Hand-book, Vol. II, p. 38 and Dr. Ewing's in the Clinical Path- ology of the Blood, pp. 53-54)- (a) Stain one film with eosin i minute, wash off with water and stain 2-5 minutes with hematoxilin. Wash with water and allow the preparation to dry in the air. Mount in balsam dry (see ;\IicT. §256). (b)' Stain one preparation 2 minutes with Jenner's stain. Wash with distilled water till the preparation looks reddish; blot oflE the water, let dry and mount as in (a). This preparation will show the blood plates as well as the other elements. 27. Fibrin. When the plasma of the blood or lymph coagu- lates or clots it divides into a liquid (serum) and a filamentous solid (fibrin). To demonstrate this one of the fresh preparations made in the beginning should foe left 10 minutes or longer in a moist ahamber or with a piece of m'oist blotting paper pressed lightly on the slide. When ready to complete the preparation, put a drop or two of the distilled water at the edge of the cover-glass and lift it up with a dissecting needle. Use the pipette and wash the film gently with distilled water. Stain two minutes or more wifli eosin. Do not wash with water after staining but blot up the eosin very carefully and let the preparation dry. It should be mounted in air (see Micr. §§247, 246a). A dry preparation need not be mounted immediately if one' has not time. 28. Hemin crystals. For these put so,me powdered dry blood on a slide, add a granule of common salt (NaCl), put on a cover-, glass and fill the space under it with glacial acetic acid. Heat the slide over a lamp till the acid almost boils. Addi a drop of fresh acid and heat again. Let the preparation cool. Lift up the cover and let the acid evaporate. There should be multitudes of hemin crystals iboth on the slide and on the cover-glass. Study dry, then mount in balsam (Micr. §256). 29. Ingestion of foreign particles by leucocytes. For this a mixture is made consisting of: lamp-black, I gram; gum arable, I gram; common salt (NaCl), I gram; water, 100 cc. From 10 to 20 cc. of this is injected', by means of a 'hypodermic syringe, into the abdominal cavity of a kitten or other small animal. After 24 hours the abdominal lymph will be crowded with leucocytes which have engulfed some of the carbon. Spread preparations are made and dried as for Wood, only the films need not be so thin. It is well also to have a slight afnount of blood mixed with the lymph. The dried films may be studied without staining, or they may be stained with eosin or with eosin methylene blue. If unstained, mount dry (Micr. §246a) ; if the film has been stained mount in balsam (Micr. §256). The significance of the ingesting action of leucocytes may be seen by consulting Ewing, Pathology of the Blood, p. 138. 30. Blood plates. 31. Hemoglobin crystals of Necturus. 32. Blood with the spectroscope showing arterial and venous blood CM'icr. §210, and Fig. 122). 33. Blood of the lamprey to show the nucleated biconcave red corpuscles of this animal. It is the exception among non-mam- mals. Compare with the camelidae. 34. Blood corpuscles of the camel to show the elliptical cor- puscles of the camel family. They are non-nucleated like the rest of the adult m'ammals. The leucocytes appear to be like those of ordinary mammals. 35. Nucleated red blood corpuscles of an embryo mammal. • Even in the adult the red corpuscles are developed from nucleated cells. See discussion in your books. 24 Recitation on Blood and Lymph 1. What is blood? What are its constituents? 2. What is lymph? Of what is it composed? 3. What connection is there 'between blood and lymph? 4. Character of the red blood corpuscles of non-mammals? 5. Character of the red blood corpuscles of mammals? 6. Give the exceptions. 7. What- are leucocytes? What are they sometimes called in the blood? 8. W'here could one find leucocytes in the body? 9. Where could the red corpuscles be found? 10. What are blood plates? Size? No. per cmtn.? 11. What is meant by ingestion of foreign particles by leu- cocytes, and what is it supposed to signify? 12. What becomes of the leucocytes after they ingest — particles of carbon for example? 13. Number per cmm. and size of the Ted corpuscles in man? In horse? 14. Number per cmm. and size of leucocytes in man? Are the leucocytes larger or smaller than the red ones in the frog? 15. Give a classification of the leucocytes (a) from their mor- phology; (b) staining properties. 16. Are leucocytes found in the blood of embryos? 17. What is amoeboid movement? Where seen in mammals? 18. Compare leucocytes and pus. Who was Cohnheim? 19. W'hat is fibrin? What serum? 20. W'hat part of the blood crystallizes? Name two kinds of blood crystals? Medico-legal importance? 21. Discuss ways of detecting blood and of determining what animal it came from. (See Woodward; Ref. Handbook, Vol H; and Ewing on the Clinical Pathology of the Blood, pp. 23-30). Laboratory Report on Blood and Lymph 1. Make a drawing of the Mood of the frog showing the red and the white corpuscles. 2. Show the amoeboid movement in the frog's leucocytes. 3. Show the amoeboid movement in human leucocytes; also idraw red corpuscles. 4. Draw some of the ingested leucocytes. 5. Give drawings of lamprey and of came'I blood and state to what they are exceptions. 25 UNIT VII Bone and Cartilage Laboratory Work 36. Hyaline Cartilage. For this make several free hand sections of fresh cartilage. i\Iount the sections on a slide in normal salt solu- tion or in ^ % alum solution. Study the sections carefully to see the relative amount of ceiUular and intercellular substance. This preparation also illustrates free hand sectioning. 37. , Elastic Cartilage. Study a stainfd section of eilastic cartil- age from the ear. Compare the ground or intercellular substance with that of hyaline cartilage. 38. Fibro-Cartilage. This will be furnished. It is from the intervertebral region. Here the fibers are white fibrous tissue instead of elastic tissue. There may be hyaline cartilage and boiie in the preparation also. Compare with 36, 37. 39. Embryonal Cartilage. This will be found in the vertebra of the 15 mm. pig section given tO' illustrate nucleated red Mood corpuscles. Compare the relative number of cells in this and in 36. This cartilage represents temporary hyaline cartilage. 40. Compact Bone. 'Make a preparation of a transection of the human femur or of some large bone of one of the idomestic animals. Do this with a fiJe, keeping the section wet with water. File the section down until it is, in parts at least, not more than 8 to lo-iooth mm. thick (8o/n to loo/x.) You will then be 'shown how to mount it in hard balsam so that the air may be retained in the canaliculi, etc. Use the cover-glass measurer to determine the thickness of the sections. 41. Decalcified Bone. Study a section of a bone which has been decalcified to show the compact and spongy bone and the relations of the periosteum. Note the relation of the bone marrow to the rest of the bone. Recitation on Bone and Cartilage 1. W'hat is cartilage? 2. What are its four varieties? 3. State where and when the different forms of cartilage may be found. 4. What is embryonal cartilage, when and where is it to be found? 5. Compare elastic and fibro-cartilage, and state where they ar< located. 6. What and where is hyaline cartilage. 7. What is meant by permanent and what by temporary car- tilage? 8. Which is the more abundant in cartilage, the celiular or the intercellular substance? 9. Compare adult and embroyonal cartilage. ID. What is bone? II 12 13 14 15 16 17 18 19 20. Are there any cells in bone? Compare compact and spong}' iboiie. WRat is periostal bone and where found? What are haversian canals? Who was Havexs? W'hat is bone marrow? Red marrow? Yellow marnow? What are lacunae? What are canaliculi? \\'ith what da they communicate? What is decalcified bone? What happens to bone if it is burned in air? Laboratory Report on Bo7ie and Cartilage 1. Make a drawing of the hyaline cartilage, free hand section. 2. Draw the embryonal cartilage also. If these were put within one circle, giving a semicircle to each the ■difference would be very striking. 3. Draw the transection of decaikified bone. It should sihow compact and spongy bone, the bone marrow and periosteum. UNIT VIII Embryonal and Fibrous Tissue. Laboratory Work 42. Embryonal Connective Tissue. Study the section of the 15 mm. embryo pig for this. Note especially the numerous cells with anastomosing processes. It is a network of cells, .and cell processes. 43. W'hite Fibrous Tissue. In the adult body nearly pure white fibrous tissue may be found in tendons and ligaments. In tendons tihe fiber bundles are parallel, and the connective tissue cells are in rows between the bundles. This is well shown in the tendon from the -mouse's tail. Note that if seen on edge the cells are narrow; if facewise they are elongated plates with the nuclei mostly at the ends. 44. Elastic Tissue. This in its almost pure form is seen in the ligamentum nuchae of the domestic animals (horse, etc., not in man and cat). Study a transection stained with picrofudhsin. The red part belongs to the white fibrous tissue, the yellow is elastic. 45. Preparation of teased out elastic fibers to show the branch- ing. MiQunt in water 46. Mixed Fibrous and Elastic Tissue. For this the so-called areolar tissue connecting the skin and underlying parts, the muscles, etc., form good examples. Study a permanent preparation to get an idea of the cells and fiber bundles. 47. Preparation of fresh areolar tissue. Make this by spreading on. a dry slide part of an artificial edema from the subcutaneous tissue of a kitten or other animal. Study this first with a low and then with a high power. As the' elements are uncolored and slightly more refracting than the surrounding medium care must be used in lighting. (Micr. last part of §83). 48. Add some 2% acetic acid to this preparation. The acid will make the white fibrous tissue very transparent but it wM not aflfe'ct the elastic tisue; the nuclei of the cells will stand ont clearly also. Note the clearly defined elastic fibers. Some of them may be seen to branch. White fibers do not branch. 49- Reticular Tissue. This is a form of connective tissue mak- ing a net work in lymphatic glands and lymphoid tissue generally. It is al'so found in many other organs. It is apparently midway between elastic and white fibrous tissue as it has properties of both. For a good example of the network of connective tissue in organs examine the section oif spleen with the splenic tissue washed out. 28 so. Adipose Tissue. This is connective tissue with fat in many of the tissue cells between the fibers. This tissue will appear fre- quently in the sections you will study, and you s'hould become so familiar with the appearance of fat and of the empty fat cells that you will never mistake this tissue for any other, lung for example. Study the preparations in which the fat has been dissolved out of the cells. 51. Section of tissue with the fat stained with osmic acid. 52. Massed connective tissue in the cornea and sclerotic. Study the silvered cornea for cell spaces and joining channe.ls. 53. Pigment Cells. Study a preparation from the peritoneum of necturus to see the greatly branched pigment cells in the connective tissue of non-mammals. 54. Study a preparation from a mammal showing the pigment cells. I Recitation on Fibrous Tissue 1. What is connective tissue? 2. Where is it found in the body? 3. Which is preponderant, the ceiHular or intercellular substance? 4. What is white fibrous tissue? S- Do the fibers of this form of tissue anastomose? 6. Describe the arrangement of the fiber bundles in tendons, in ligaments. 7. Describe the tendon cells. 8. What is elastic tissue. Where is it found? 9. Is there an elastic ligamentum nuchae In man? 10. Compare the elastic and white fibers. 11. What is reticulum, and wihere found? 12. What is areolar tissue, and where found? 13. W'hat elements are found in areolar tissue? 14. W'hat is' the effect of acetic acid on areolar tissue? * 15. What is adipose tissue? 16. W'here is adipose tissue possibly present in the body?. I". Descr'ibe the appearance of adipose tissue in ordinary sec- tions, f 18. How does it appear after osmic acid'? 19. What are pigment cells? Where found in non-mammals? 20. Where can one find pigment cells in mammals? In man? Laboratory Report on Fibrous Tissues 1. Draw the areolar tisue in the permanent preparation. 2. Draw the areolar tissue in the fres'h preparation after the action of acetic acid. 3. Draw adipose tissue with the fat dissolved out and with the fat stained with osmic acid. 4. Draw pigment cells from Necturus. 5. Draw pigment cells from a mammal. 29 UNIT IX muscular Tissue / Laboratory Work 55. Striated Muscle. A small mass of striated fibers will be given you in clearer. Pull them apart with needles, drain oflt the excess clearer and mount in Canada balsam. Study the preparation and determine as far as possible all the structural features. 56. Transection of Sartorius. — Study this prepared section to see the arrangement of the entire muscle with its" connective tissue. (On the outside epimysium; around the bundles or fascicles, per- imysium, and' between the fibers, endiomysium). Vessels and nerves are also present. 57. Muscle Spindles. There is a muscle spindle in section shown within the small black ring of the preparation of sartorius. Note the connective tissue envelope and the intrafusal fibers. Compare them with the ordinary muscle fibers. There are several other spindles in the section. 58. Size and Number of the Fibers in the Newborn and the Adult. 'Compare sections of the sartorius of a child with that from the adult. It is easy to see the difference in size of the fibers. For the numbers in the new born and the adult see Ref. Hand- book, Med'.., Sciences, vol. vi., p. 24. 59. Red and' Pale Muscl'e. Compare the naked eye 'appearance of red and of p.ale muscle; also study sections of these tw© varieties. Compare the structure and the physiology. 60. Cardiac Muscle. Study a preparation of isolated cardiac* muscle, cells (Homo at birth, veal). Compare with striated muscle. 61. Section of Cardiac Muscle from the Adult. Compare with the s'artorius. ^ 62. Plain Muscle. Study isolated muscle cells from the intes- tine. Compare with skeiletal and cardiac muscle. 63. Plain Mus'cle in Section. For this study the section of human ileum and ureter. Compare with the sections of sartorius and of heart muscle. 64. Gross Dissection of Skeletal and of Plain Muscle, Take a piece of intestine and some skeletal muscle in which the connec- tive tissue hasi been softened in nitric acid. It will be easy to separate the structural elements. 'By using needles it is not difficult to get isolated fibers on a slide. One can thus pass from naked eye to microscopic structure with the same specimen. 30 Recitation on Muscle 1. What is the physiologic character of muscular tissue? 2. What is striated muscle? Where is it? 3. Why is it called skeletal muscle? 4- What is cardiac muscle and where is it? 5. What is plain muscle and where in the body is it? 6. Which form of muscle is voluntary? 7. What is epimysium? 8. What is perimysium? 9. What is endomysium? 10. What is the sarcolemma? Which kind of muscle possesses it? 11. What is a tendon? 12. What are the relations of muscle fiber land tendon? 13. What are fascicles? 14. What are fibers? 15. What are fibrillae? In which form of muscle are they present? 16. V\'hat is the sarcoplasm? I/- How many nuclei are there in the different foTms of muscle fibers? 18. Is a striated fiber a cell? 19. How long may a striated fiber be? 20. What is the retetion of the fibers to one another in a skeletal muscle? 21. What is the relation of the fibers or cells in cardiac muscle? 22. What is the relation of the plain muscle fibers? 23. Are cardiac and plain muscle fibers cells? 24. In a section of cardiac or of plain muscle will each fiber show a nucleus? 25. Compare the position of the nuclei in different forms of muscle? 26. What are muscle spindles? 27. What are intrafusal fibers? 28. 'Compare the number and size of the striated fibers in a skeletal muscle of an adult and of a new-born animal of the same species. (See Ref. Handbook, vol. vi., p. 24.) Laboratory Report on Muscle 1. Draw a transection of the sartorius, and beside it a diagram of an isolated fiber showing striations. 2. Draw a section of cardiac muscle .and of a single cell. .3. Draw a section of plain muscle from the ileum, and one or more isolated fibers. 4. Give diagrams and state the views as to the relation of muscle fiber and tendon. 31 UNIT X Nervous Tissue.* Laboratory Work 65. Isolated Nerve Cells. Study isolated nerve cells from the niyel (spinal cord) to illustrate multipolar cells. 66. Nerve Cellsi of the Brain. Study these in isolation prepar- ations and in a Golgi preparation. In this last the neurite can be seen. 67. Myelinic Nerve Fibers. These will! be given you in clearer. Prepare them .as for the isolated striated muscle (SS)- 68. Amyelinic Nerve Fibers. These will be demonstrated under a special microscope. In the preparation will also be so'me mye- linic nerve fibers so that the difference may 'be seen with absolute clearness. 69. Sciatic Nerve in Section. Study this to see the sectional views of myelinic fibers and the connective tissue of a large nerve. Compare with the sartorius muscle. 70. |Peripheral Ganglion. Study a section of a spinal or sym- pathic ganglion. 71. Ganglia of Viscera. For an example study the section of human ileum. Between the muscular layers sections of ganglia will be found. 72. Compare the visceral ganglia in the rabbit's intestine. Here you will see them face view instead of in section. 73. Mbtor Nerve End. Study a gold stained motor nerve-end in striated muscle. 74. Sensory Nerve Ending. Study an example in epithelium and in connective tissue. (In connective tissue select a Pacinian body from the human finger or from the cat's mesentery or a tactile body from the human finger). Recitation on Nervous Tissue What are nerve cells? Where are nerve cells found in the body? What kind of processes do nerve cells possess? What are neurites? What are dendrites? Do all nerve cells possess neurites? How many? Do all nerve ceWs possess dendrites? The number? What are nerve fibers? *In the second year a special course is given upon the nervous system and the organs of sense (see course 8, p. 8.) 32 g. What are myelinic (medullated) nerve fibers? Where are they? 10. What are amyelinic (non-med'ullated) nerve fibers Where may they Ibe found? 11. How do nerve fibers arise? Are they independent elements? 12. How do nerve fibers end in the tissues? 13. How do nerve fibers end in nervous tissue? 14. What is a sensory nerve ending? Give an example, (a) in epithelium, (b) connective tissue. 15. What are motor nerve endings? Give an example. 16. iCompare all the parts of a nerve and of a muscle (select as examples the sartorius muscle and the sciatic nerve). 17. What is epineurium, perineurium, endoneurium? Compare with the connective tissue of muscle. 18. What is an axiscylinder? the neurolemma? The myeline or white substance of Schwann. 19. What are nodes of Ranvier? 20. What is the neurone theory? Laboratory Report on Nervous Tissue 1. Draw a nerve cell from the myel. 2. Draw a nerve cell from the brain and show the neurite. 3. Draw a motor nerve ending of striated muscle. 4. Draw a sensory nerve ending in epithelium and in con- nective tissue. 5. Draw ii myelinic and an amyelinic nerve fiber. 6. Draw a transection of the sciatic nerve. 33 DIVISION B MICROSCOPIC ANATOMY, OR HISTOI.OGY OF THE OE.GANS AND SYSTEMS UNIT XI The Vascular System. Laboratory Work 7S. Heart. Study a section of the entire wall of the heart — au- ricle or ventricle — showing the endocardium, myocardium and ecto- cardium (epicardium.) ji). 'Columnae Carnae. Study a section of one of these for the endocardium on the surface and the muscular and connective tissue within. •JJ. Auriculo-Ventricular Valve. Study a section of a norma! auriculo-ventricular valve. Compare with one in which the edges are thickened. 78. Aorta and Vasa Vasorum. Study a section of aorta to gain an idea of the structural features of an elastic artery and of the vessels, vasa vasorum, of the large vascular trunks. 79. Miuscular Type of Artery. Nearly all t'he smaller arteries have aburtdant plain muscle in the media. Study a transection of one. In the sections of organs in your later work you will meet arteries cut at alt angles. It is very important to know these structures so thoroughly that they will be recognized instantly. 80. 'Vein. Study a section of vein and compare with the efastic and the muscular art^ery. 81. Lymph Vessel. Study a section of a lymph vessel and com- pare it with an artery and a vein. There are numerous lymph vessels in the various ograns, but they are rarely distinguished as vessels unless they are specially injected or distended. 82. iCapilfery Network. Examine this in an injected preparaition. Compare the capillary mesh with the form of the structural elements in .the organ or tissue examined. 83. Lymph Gland. Study a section of a lymph gland. If t'he lymph sinuses or channels are not too much crowded with leu- cocytes they will be easily found and their reticular meshwork seen. 84. Hemolymph Glands. Study a section of one of these. In an ordinary lymph gland' there is an abundant blood supply, but the blood is in distinct and independent vessels. In hemolymph glands the blood may be found in the sinuses. Roughly speaking, a hemo- lymph gland is one with blood instead of lymph in the sinuses. 85. Peyer's Patch. A section of this from the ileum of the cat will be studied. It is an example of a condensation of lymphoid 34 tissue— that is tissue like a lymphatic gland. Diffuse lymphoid tissue is very common in the entire digestive and respiratory ap- paratus. 86. Tonsil. This is largely a lymphoid organ. Study a section. The oral surface should be covered by stratified epithelium. 87. Spleen. This is a very complex organ. There is much lym- phoid tissue in it. See Dr. Mall's article on tlie spleen in Vol. VII of .the Ref. Hand-Book. 88. Thymus. Study the section of a new born child's thymus. Compare it with lymphoid tissue. 89. Vascular Epithelium. Examine the preparation of vascular epithelium stained by nitrate of silver. 90. Circulation of the Blood. There will be opportunity to study the circulation of the blood in the gills of Neoturus. A low power will be used for the general features and a 2^ mm. water immersion for the corpuscles. Note especially the relative number of red and w'hite corpuscles and the flexibility of the red corpuscles. Recitation on the Vascular System 1. What common structural element is found in all vessels? 2. What is the vascular system? 3. What is the bl'ood vascular system? 4. What is the lymph vascular system? 5. What is the heart? Its structure? 6. What are arteries? Structure of the different types? 7. What are veins? Structure? 8. What are lymph vessels? Structure. Presence of valves? 9. What are capillaries? Structure? 10. Compare blood and lymph capillaries? 11. What are lymphatic glands? Structure? 12. What are hemolymph glands? Structure and comparison with lymph glands? 13. W'hat is a iPeyer's patch? What is difftise lymphoid tissue? 14. What is a tonsil? Its structure? 15. What is the spleen? Its structure? 16. Thymus, its structure? 17. Compare the circulation of the blood with the circulation of the lymph. 18. Who discovered the circulation of the blood? ' 19. What are lacteals? Who discovered them? For 18-19 see Chapman's Physiology and the article Lymphatics in the Ref. Hand Book. 20. Where are the blood vessels found in the body ? 21. Where are they absent? 35 Laboratory Report on the Vascular System 1. Draw the sectiom of the heart wall (7S). 2. Draw 76 and compare with 7S- State what structures attach to the columnae carneae? 3. Draw the muscular artery. State how it differs from an elastic artery. 4. Draw a section of the lymph gland. S- Draw the section of hemolymph gland. 36 UNIT XII Digestive System. Laboratory Work 91. Soft Palate. This section illustrates the stratified epithelium of the oral cavity, also glandular tissue in the mucosa. The epithe- lium facing the nasal cavity is ciliated (compare 14 under epithe- lium).. 92. Tongue. Transverse section to show the muscles and the covering epithelium. There may be some glands in the lingual substance also. 93. Esophagus. Near the pharyngeal end the muscularis is striated. Note the epitlielium and look for glands and for visceral ganglia, also sections of nerves and of blood vessels. 94. Esophagus. The section is somewhere in the gastric half. How could this be determined? Look for all the structures men- tioned in 93. 95. Esophagus of Dog. This is especially instructive for showing the gland's in the mucosa. The section is in the gastric half. 96. Esophagus and Ston;iach. This section is longitudinal and includes esophagus and stomach. It shows very strikingly the change in the epithelium. 97. Cardiac Stomach. This is to show the gastric tubules and the central and border cells. In addition the muscular and other tissues s'hould be studied carefully. 98.' Pyloric Stomach. Compare with the cardiac stomach. 99. Pepsinogen Granules. Study a section of stomach fixed in osmic acid. The pepsinogen granules will show as brownish granules in the chief or central cells of the gastric tubules. Thes'e granules are believed to transform into the aotive pepsin so char- acteristic of the gastric juice. 100. Duodenum. Study a section of the human duodenum for the prominent valvulae conniventes, and also for the other struc- tures characteristic of the duodenum. loi. Duodenum of Cat or Dog. This section will show well the structure of the duodenum including the B'runner's glands. Note that there are no valvulae conniventes. This last structural arrange- ment seems to be characteristic of man. 102. Fat Absorption. For this preparation a cat or frog is fed with fatty food and afte-ri some hours (about 24 for the frog, 3 to 6 with the cat), the intestine is placed in osmic acid or a fixer con- taining osmic acid. This blackens the fat and one can then see the globules of fat traversing the epithelial cells. O.f course the intestinal epitfhelium absorbs other food constituents, but the ab- sorption of fat is easiest to demonstrate. 37 103. Large Intestine.— Note in this the absence of villi, and the character of the epithelum in comparison with the small intestine. 104. Musculature of the Large Intestine. iCoimpare the unifO'rm musculature of the dog's or cat's intestine with the muscular bands in the human intestine. Gross preparation. 105. Appendix. Study a transection of human appendix and compare with the small and with the large intestine. 106. Vascula.r Supply of the Alimentary Canal. Study prepara- tions of the small 'and of the large mtestine in which the blood vessels haveibeen injected with colored gelatin. This will give an idea of the imimense vascularity of the digestive tract. 107. Lacteals. The lymphatics of the intestine are often called lacteals. Compare them with the blood vessels in a preparation in which both vessels are injected with dififerently colored gelatin. Recitation on the Digestive Tube 1. Name all the parts of the digestive tube. 2. What is t'he oral cavity and into what does it open? 3. What is the tongue? Its structure? 4. What are the teeth? (Their development will te studied in the course on embryology). 5. What are the passages leading from the pharynx? 6. What is the character of the epithelium in the mouth? 7. What is the esiopbagus, and the character of its epithelium? 8. Discuss the musculature of the esophagus (a) in man, (b) in dog, (c) in bors'e, (d) in the ruminants. 9. Where is t'he cardiac stomach? 10. Compare the stomach of a man and a horse? 11. Compare the stomach of a cow or sheep with man's. 12. Discuss the glands of the pyloric stomach. Compare with tbos'e in. the cardiac region. 13. Discuss the musculature of the stomach. 14. Compare the duodenum of man and cat? 15. What are villi? iValvulae conniventes? 16. What are crypts of Lieberkuehn? Where are they found? 17. What is the muscul'aris mucosae, and where is it? 18. Where can one find' lymphoid tissue in the alimentary canal? 19. What is the structure of t'he appendix? 20. What is the structure of the large intestine? Compare man and dog. 21. What are zymogen granules? Where found? 22. What are pepsinogen granules? Where are they found? 23. Discuss fat absorption. 24. Discuss central or chief cells and border cells. 38 25. - Compare th'e lymph and the blood vessels in the alimienta.r.y canal. (See the article !^ymphatics in the Ref. Hand Book. Study the colored plates froim Mall. Laboratory Report on the Digestive Tube Each student may hand in a report, selecting the subjects for drawings and discussion himself. Draw 'and di-scuss what seems to you most important and interesting. 39 UNIT XIII The Digestive System. (Continued.) Laboratory Work io8. Serous Salivary Gland. For this study a section of the parotid. This is almost purely serous in all mammals. 109. Mucous Glands. Mucous glands are much more widely distributed in the digestive and respiratory systems than are serous glands. Study the soft palate of the cat for a go,od example. A special preparation of some mucous gland will be given you also. Note particularly the border cells or crescents of Gianuzzi (See Amer. J. Anat. ii, p. 439). no. Mixed Serous and Mucous Glands. Some glands have a part of the gland tis,sue of the mucows and a part of the serous type. For an example study the submaxillary of man. In the same field one may often see the clear mucous and the darker, more granular serous gland substance. Look in the works on phy- siology for the difference in appearance of the cells of glands de- pending upon their state of functional activity. 111. Pancreas. Study a section of the human pancreas. Com- pare with the salivary glands. 112. Pancreas of Cat. Study a section of pancreas fixed by vascular injection of mercuric chlorid to get a clear view of the structural details. There may be in this section the duodenum also. 113. Bodies or Islets of Langerhans. Study a preparation of pancreas showing the structural features of these bodies. For their origin see American Journal of Anatom}-, Vol. ii., p. 451. 114. Trypsinogen Granules. For these study a preparation of pancreas which was fixed in some osmium mixture. The tryp- sinogen granules will be brownish, and their number will depend on the state of functional activity of the gland. This is the zymo- gen giving rise to the ferment of the pancreatic juice. 115. Liver. For an example showing the outline of the lobules most distinctly study a section of pig's liver. Here the inter- lobular connective tissue is abundant and this serves to mark off the boundaries of the lobules clearly. Search the preparation for a dobule cut 'transversely and for one cut longitudinally. iiSa. Human Liver. Study a preparation of human liver to get an idea of its structure. Compare the interlobular connective tissue with that in the pig. Few animals have the liver lobules so clearly marked as the pig. 116 Glycogen. Study a section of liver fixed in absolute alcohol to see the glycogen stained mahogany IDrown by iodin. 40 After a meal of carbohydrate food has been absorbed the liver cells are loaded with glycogen. Who discovered the glycogenic func- tion of the liver? Is glycogen found in any place besides the liver cells? 117. Bile Capillaries. Study the demonstration showing the bile capillaries gorged with the yellowish bile (cow's liver in Texas fever.) Recitation on the Digestive Glands 1. What glands open into the oral cavity? 2. What are the two main types of salivary glands? 3. What are the border cells or crescents of Gianuzzi or demi- lunes of Heidenhain? 4. Where are these border cells found? 5. What are the three hypotheses concerning the significance of these cells. 6. State where one could find mucous and where serous glands. 7. Is the submaxillary in man mucous or serous? 8. Is the submaxillary serous in any animal? 9. What is the pancreas and into what do its ducts open? 10. Compare the structure of the pancreas and of the salivary glands. To which type does it belong? 11. Under what conditions would one find most trypsinogen in the pancreas? 12. What is the difference between zymogen and trypsinogen? 13. What is the difference between zymogen and mucigen? 14. What are the areas or bodies or islets ^;:'i^!!t^¥:^^^;f4'^'r-^'i!fikji, ,^;. v>*;,-,^.-^i.^ <^ sg) "as v^ \aS5 -«® \S3 M^ x;® 11 3t ,' a. la 43 1. 3 la 23 / 1 4 u 34 / ( s u 35 i 16 i« 1 ■' 17 P i j 18 1 / i ^ 19 1 I'i 10 20 1 / \ S^i«.«i&TTr=--J33s=J-i-= f-l^in-hr^iT^^^V.^-'v-r^^^.-^V-iri-^ Fig. 4 FIG. 4. — Series of an Embryo. This shows part of a tray containing a complete series of an embryo on 26 slides. It shows also the method of outlining the exact space on the tray required to accommodate the 26 slides. If this space is not full when the series is inspected it is known that a part is missing. Preparation of the Embryos and Arrangement of the Sections. — The sizes selected represent the total length along the longest axis when tbe embryo is fresh or after fixation, not the length of the sections on the slide. Before sectioning each embryo is photographed, and the photo- graph accompanies each series so that the student may get the exact appearance of the embryo. For class work the embryos are stained in toto by paracarmine or borax carmine. They are sectioned in paraffin. The arrangement of the embryo for sectioning and the arrange- ment of the sections on the slide are given in the Microscope, pth edition, p. 192. Special Developmental Features in the Diffe'rent Embryos. — Under the various subjects in the laboratory work on embryology 57 references are given to the pig embryo where the structure can be best seen, as, see Pigs I and II, or see Pigs IV and VI. The stu- dent soon learns about where to look for the different structures. F'or the help of the instructors they have made out a more exact system of reference's, and for each point called for they have added the slide of the series for each of the groups. This is necessary, they communicate iim adult life? Recitation on the Stomodeum, Hypophysis, Teeth, Salivary Glands and the Palate. 1. Wihait i's the sitomodeum? W'here is it and ■wthien- formedl? 2. Names of the wall of tissue between the stomodeum and en- teron? 3. What does this tissue consist of? 4. At wlhat period oain the oral plate be fou-n'd, (a) in tad- poles, (b) in pig embryos, (c) in c^t embryos, (d) in human em- bryos ? 5. What is the r-elatiive position- of the oral 'pilate anid the niw- toicho-rd? 6 What is Seesse'I's pocket? Where is dt? ' 7. What an'd where is Rathke's pocket? 8. Wlhat is the proictod'euim? 9. What is the name and structure of the wall of tissue ibetween the proctodeum and enteron? 10. At what stage ojf idlevelopm-ent does tihe anal -m-emib-nane dis- appear (a) in 'the pig, (b) lih the eanb'ryo calf, (c) in the ihuman emibryo? 11. Wha-t germ layer lines th-e stomodeu-m anid proctodfiumi? 12. How can o-ne tell the boundary between ectoderm and- entov- dierm- in the aduil't mouth and- pTiarnyx? 13. What is the oral part of the pituitary body? From what does it originate? 14. Wihait is the po-sition- of the oral invagination giving rise to -the hypophysis? 15. Where can oine fiffld the hypophysis in adivaniced' emibryo* and in tihe adluJ't? 69 i6. What fo'nniis the 'caudal portion loifi the hyipioph5nsi&? 17. What is the first step in the develapment olf the teetlh? 18. From what do the teetlh develop? 19. What is the name .of the string of epithelium connecting the tooth germ with the o-ral epitheliuim? 20. What part of a tooth is developed, from the dental shelf? What is the enamel organ? 21. What part is -develolped froim' mesoiderm? 22. Compaire denitine anidi bone? 23. Oo'mplare loidomitohlasits anid OBteolblasts'? 24. Is tihere any true bone conniected with tihe teeth? 'Where is it anid' its name? 25. Coimpiare the origin of the permiaiiient and the miilk tee*h? 26. Compare the origin of the premolars and the true molars. 27. Ho'w are the salivary glands developed? 28. If the loral invagination giving rise to them' is solid how do the glands come to' have ducts? 29. What oitiher glands are connected with the mioiuth? 30. iFroim what germ' layer ane the sallivary anfd buccal glands developed? Why should! 'there be any doubt aiboiut the germ layer giving rise to these glands? 31. What is the palate and how is it developed? Laboratory Report on the Stomodeum, etc. 1. Draw the cephalic end "of the tadpole and show the stomo- deum and oral plate. Same for the chick. 2. Give a drawing sbowlnig the relation of the ora'l epithelium .and hypophysis. 3. Give a drawing of the tooth germs in prep. 146. If your preparation does not show, these well the instructors will give ycU' another preparation. ' 4. Draw the developing tooth in the jaw of a new-born kitten? 70 UNIT XXII Tongue, Tonsils, Branchial Pouches, Eustachian Tubes, Thymus, Thyroids, Lungs. Laboratary Work 213. Tongue. For the connections of the tongue, study the sagittal sections in Pigs III, IV. For the relation of the tongue to the nasal c'hamber 'before the development of the paJate see Pig II, IV, V. In Pig VI, the palate has been formed and the tongue will be found confined to the oral cavity. 214. Brandhial Pouches. Study Pig II. In' reptiles, birds and mamimals there is always a wall or plate of tissue comparable 'with the oral. plate between tbe ectodermi'c and the entodermic branch- ial pouches. In fis'hes and amphibia some at least of these break down and thus establish passages between the exterior and the pharynx (branchial fissures or gill 'slits). (See Minot, p. 19.) Each branchial pcuch is bounded 'by two branchial or gill arches and the branchial pouch is consequently ibehind the corresponding g'i'M arch. FoT exam'ple, tlhe first branchial' pouch is caudad 'Of or behind the first 'branchial arch, and so on. 215. Eustachian. Tubes. These may be seen in Pig IV, V. They are the persistent first entodermic brandhia'I pouches. The external auditory meatus is the first ectodermic 'branchial pouch. 216. Thymus. This arises from the third entodermic branch- ial pouches. Look for it in Pig II. For the evidence that the thymus gives rise to the leucocytes of the body see Beard and Nussbaum. Anatomischer Anzeiger, Vol. XVIII, p. 550; XIX, p. 6. 217. Thyroids. Pig V and VI will show stages in the thyroid. The fhyroid is single in adult man, 'but i'n' most animals it is a double organ, and arises by several protons or rudiments in man as well as in animals. There is a median proton opposite the s,ec- ond branchial pouch and the main lateral protons arise from the fourth branchial pouches. Th« epithelial bodies arising from the third and fourth 'branchial p'ouches and finally joining the thyroids are believed to be the parathyiro'id protons. 218. Lungs. For various stages in the development of the lungs andi the air passages study all the series, (Pigs- II-VI.) Remem'bor that in the pig tteire is a small third brondhial tiibe. 71 Recitation on the Branchial Pouches, the Lungs, etc. 1. How many protons, rudiments O't anlages are there for the developing tongue? 2. What is the most cephalic proton called? At the level of what branchial pouch does it arise? 3. Is this rudiment paired or unpaired? 4. Give the position of origin of the caudal or posterior proton of the tongue. Is it paired or siingle? 5. In the adult what structures are 'believed to indicate the junction of the various protons of the tongue? 6. Discuss the developiment of the tcnsils. 7. With what ibranchial pouch are they associated? 8. What are the branchial or gill pouches? Where are they? 9. Are the branchial pouches single or are they paired? 10. Are the branchial pouches lined by ectoa'erm or by ento- derm? 11. How many pairs of ibranchial pouches are there in mam- mals? 12. In what groups of animals are tliere real giU slits opening from t'hie pha'rynx to the exterior? 13. What is the eustachian tube and its relation to the branch- ial pouches? Is it paired or single? 14. What is the thymus? Give som'e evidence as to its sup- posed function. 15. How many protons does it have and where are theyi? 16. H'O'w many protons are there for the thyroid? 17. Are these protons single or paired? 18. What is their relatio^n to the ibranchial pouches? 19. From what are the lungs developed? 20. Is there a single or a paired proton from the pharyngeal cavity for the lungs? 21. Describe the steps from the origin until the two lungs are formed. 22. How many bronchial tubes are there in man? 23. How eairly are the primary lobes of the lung's indicated? ■zi,. How many bronchial tubes have the pig and cow? 25. Which part of the respiratory organs originate from ento- derm ? 26. From what region of the alimentary canal (enteron) does the respiratory proton arise? 27. Compare the embryonic and the adult lung? 28. Is the esophagus ciliated in any stage oi development in mammals? Laboratory Report on the Lungs, etc. 1. Give a series of drawings showing the tougiue 'before and after the formation of the palate. Show also the epiglottis and the laryngeal connection with the pharynx. (Pig VI.) 2. Draw developing lung tissue and compare it with the adult lung! tissue. (You have an excellent preparation of adult lung, injected and uninjected.) 3. Give a figure of the early bronchial tubes m man and' ia the pig. State from which pig and from which slides of the set the knowledge of the pig's tubes is derived. For the human consult the ibooks, the models and carefully observe the demon'stratioti. DIVISION D THE MESODERM AND ITS DERIVATIVES UNIT XXIII. The M'esodfirm and its Derivatives; Connective Tissue, Skeleton and Joints; Muscular System. Laboratory Work. 319. Primitive Streak. For the primitive streak and the fusion of the germ layers at this point studly the cau'dlal part o'f Pig I, and sections' of a 16- to 20-hour chick. Remember that cephalad of the primitive streak the mesoderm is at first in two lateral sheets not crossing the dorsal middle line, and caudad of the primitive streak, and the blastopore in amphibia, the middle layer is not divide in'to two lateral sheets. 220. Mesoblastic Somites or Primitive Segments. For these study an entire chick e'mbryo of 30 to 36 hours incubation, mounted diorsal sidle up. 'Also sections of t'he same stage. Pig I shows well the soraiites or se;gtmenitS' in section. '221. Somatopleure. The mesoderm' beyond the primitive seg- ments dielaminates, one lamina going with the ectoderm and one with the entoderm. The ectoderm and the lamina of the meso- derm form the somatopleure. Study Pig I and 36-hour chick. 222. Splanchnopleure. This is the entoderm and' the ventral lamina of mesoderm. Study specimens as in 221. 223. Coelom, Splamchnocoele. The delamination or splitting of the mesoderm gives rise to spaces and produces the coelom. The ' ventral coelom^ or splanchno'coele is the cavity or space produced by the separation of the lateral mesoblast to form the somatopleure andl the splanchnopleure. Same specimens. 224. Mesot'helium and' Mesenchyme. The original mass or sheet of mesoderm is not in the form of an epithelium, but in the formiation o'f the ceolom the cells covering the free surfaces form an epithelial layer which is designated mesothelium. AM the other cells of the mesoderm form the mesenchyma. (Minot, p. 35). 225. Connective Tissue. iConnective tissue isi foundi in all parts of embryos except the very youngest. The branched and stellate cells of the embryonic tissue are very clearly shown in Pigs II-VI, especially just beneath the ectoderm. 74 226. Cartilaginous Skeleton. For the formation of cartilage from mesenchyma study Pigs II to VI. In II there iwill be merely a co-ndensation of cells at the points where cartilages are to be formed, as in the limbs' and the bodies of the vertebrae. All steps ■may be seen in the different ages. 228. Bone formed from Cartilaginous Protons. Most of the bones of the skeleton are represented by cartilage in the embryo. Study all the pigs in^ situations where skeletal parts should be. In sections of the manus or pes may be seen the skeletal rparts in cartilaige with some centers of ossification. Study preparation No. 38. ' For steps in the development of bone consult your books on histology. 22g. '^leimbrane Bone. For the membrane which finally ossifies to form the vault of the cranium study Pigs V and VI. iNote that the membrane is attached at the two ends to the cartilages of the primordial cranium. 230. Joints. Joints are formed in the skeleton most simply by the persistence of some of the mesenchyma, while on both sidles it is transformied into cartilage or advances .to bone. Such joints are called' amphiarthrodial. For excellent examples examine the sag- ittal sections in the region of the vertebral column. 231. Diarthrodial Joints. The .true joints with synovial cavities begin as described for amphiarthrodial joints, but ultimately the mesenchyma joining the two ends of 'cartilage disappears except around the circumference. This leaves a cavity and the joint sur- faces are free. It is to be remembered that all articular surfaces of true joints are covered with cartilage (articular cartilage^ throughout life. Studly the limbs of Pig VI for various steps i-' true joint formation. .The best method of demonstrating the form- ation erf true joints is to make a longitudinal section of a limb of an embryo somewhat further advanced than Pig VI. 232. Skeletal Muscles. The skeletal muscles develop from a part of the primitive segiments. They are best seen in sagittal sec- tions. For the persistence of the segmental arrangiment study the intercostal muscles in Pig VI. 233. Embryonic Muscle. For a stage in muscular dJevelopment showing striations on the periphery and an undifferentiated core, ex- amine a transectio'n of muscle from a somewhat more a-dvanced embryo than Pig VI. Remember that striations are not necessary ■for contraction, for thei heart beats before any striations can be demonstrated in the cardiac cells. 75 234- Visceral Muscles. The muscles of the alimentary canal, the hear.t and' same other organs are not deiveloped from the myotomes or muscle plates but from the splanchnic layer of mesoderm. In studying the heart, alimentary canal, etc., one will see such tnusclc. Recitation on Mesenchyme, Skeleton and Muscle. 1. Is the mesoderm a primary layer of the embryo? 2. Where are all three layers fused? 3. What is the mesoderm ? 4. Is it paired or single ? 5. What are primitive segments, mesoblastic somites, proto- vertelbrae? 6. W'hat is a sclerotome or skeletogenous plate? 7. What is a myotome or muscle plate? 8. What is a dermatome or cutis plate? 9. What is the splanchnoipleure? ID. What is the somatoipleure? 11. What is the ooelom? the splanchnocoele? 12. What is mesothelium? 13. What is mesenchyma? 14. How is soft connective tissue formed? 15. How is cartilage formed and from what? 16. Oif what is the skeleton composed? What do the sclero- tomes have to do with the s'keleton? 17. What kindi of skeletons are there in the animal kingdom? 18. iD'o all mammals have a' cartilaginous skeleton in some stage of development? 19. How is cartilage developedi? 20. W'hat kind of bones are there in the adult? 21. How is bone developed from cartilage? 22. Is embryonic bone compact or spongy? 23. What are centers of ossification? 24. Compare ostedblasts and the cells within the lacunae of bone. 25. What bones in the adult were not represented by cartilaigie in the embryo? 26. What are membrane bones Where are they found in mam- mals? 27. Compare the formation of periosteal bone and olf .membrane bone. What and' w'here is the primordial skull? 28. How are joints formed; (a) Amphiarthrodial, (b) Diar- throdial? 29. From w'hat are the skeletal muscles developed? 30. In what forms do the skeletal muscles retain their segmental arrangement? • 31. Where in man and other mammals can one find segmental muscles in the adult? 32. How many pairs of ri/bs are present hypothetically? 33. By what are these riibs represented in the cervical regioil; in the lumbar region.' 34. Give the steps in the histogenesis of a skeletal muscle fiber. 35. Are the embrjfonic fibers larger or smaller than the adult fibers? Are they more or less numerous in a given muscle? 36. From what are the muscles of the heart developed? 37. What is the origin of the muscles of the alimentary canal? 38. From what are the muscles of the, genito-urinary organs de- rived? Laboratory Report. I. Draw your section of the 36-hour chick showing the som^ato- pleure and' the splanchnopleure. 2. Draw an embryonic joint showing the formation of a true joint. 3.' Draw a section (Pig VI) showing the muscles- in segments. 4. Draw a section showing the cartilage of the primordial skull and the membrane which will form membrane bone (Piigi V). 17 UNIT XXIV Blood; Blood Vascular System and Heart; Ljmiphatics. 235. Nucleated Red Blood Corpuscles. — In mammalian embryos the first red' corpuscles are nucleated. In Pig II all of the red corpuscles are nucleated. In Pigs V and VI, a part of them are nucleated and) a part non-nucleated. Look in the heart and the large vessels for the corpuscles. 236. Development of Red Corpuscles in the Adult. In the adult the ired corpuscles begin as nucleated cells, but in normal conditions the nuclei are lost 'before entering the general circulatiom. The seat 'of development is the red marrow of the bones. Study a sec- tion of the red marrow of the guinea pig. 237. Development of blood vessels. Study the area vasculosa of the 20-36-hour chick for the blood islands and net works of the earliest blood' vessels. These also contain the first red blood corpuscles. 238. Development of the 'Heart. In birds and mammals and' in many other animals the heart commences to develop while the em- bryo is spread out as a s'heet om the yolk. It begins as a tube in each splanchnopleure. This condition is well seen in chick eim- bryos' of about 20 hours. It also shows in mammalian embryos of the same relative stage of development. It will be demonstrated in Pig I, as well as in chick embryos. 239. Double aorta. All the vessels are developed symmetrically, that is in pairs, except the postcava. Hence in the beginning there aire two aortae. Cephalad of fhe arm buds in Pig II one will see the two aortic arches. They join opposite the arm buds. Find the point of junction. 240. Aortic arches. For these study Pig II and the models. 241. Lymphatics. For the development of the lymphatics, study the figures and the text of Dr. Sabin's article in Vol. I of the Journal of Anatomy. Note thait the lymphatics develop later than the blood vessels' and are outgrowths of them. 242. Leucocytes. The blood in the youngest embryos contains no leucocytes. Leucocytes do' not appear until the lymphatics begin to develop and not until the thymus appears. For the evi- dence that the thymus gives oirigin to 'the leucocytes, see Beard, Anat. Anz., Vol. 18, p. 550, 573.;NusBbaum, same, Vol. ig., p. 6. 78 Recitation on the Blood and Vascular System. 1. Where does the blood first appear in birds and mammals? 2. W'hat are blood islands and where are they? 3. How and where dio the red corpuscles develop in the adult? 4. What other cells can one find in the red marrow? 5. What are two special seats of red corpuscle production in the embryo? 6. What is' meant by a hematopoietic organ? Give an exa.mipk. 7. How is the heart developed in birds and mammals? 8. Give an example of an animal in which it is developed differently. 9. Does the hear*- belong to the somatopleure or to the splanch- nopleure? ID. How many aortae are present at first? 11. What are the vitelline arteries and where do they go? 12. What are the vitelline veins and where do' they go? 13. How many descending venae cavae (precavas) are there. 14. How many postcavas ? What are the constituents of the pos'tcava? 15. What are the ducts of Cuvier? 16. How does the heart become a single organ If it develops froTn two tubes? 17. How does the adult heart acquire its septum dividing it into right and' left chambers? 18. How are the lymphatic vessels developed? 19. Where do the leucocytes come from? 20. When are leucocytes found in the hlood? Laboratory Work on the Vascular System 1. Draw the different cells found in the red marrow. 2. Draw the junction of the two aortic arches. Draw also the two arches and the single aorta after the fusion. (Pig II). 3. Draw a section of the ventricles in Pig IV, and state how the two ventricles in the adult differ from' those in the emibryo. 79 UNIT XXV. The Urinary Organs; The Genital Organs. 243. Pronephros. The pponepferos or head kidney will be dem- onstrated in the Lamprey and in 'the Human embryo. 244. jNIesonephros and Glomeruli. The mesonep'hros or Wolf- fian body miay Ibe seen in all the (Pigs. The glomeruli or vascular tufts are especially abundant near the mesal side. The tubular and segmental character of the first rudiments will be demonstrated in the human embryo, the embryo cat and the embryo shark. 245. The Wolffian Duct. The duct of the primitive kidney may be seen im |Pigs II, V and VI. For its entrance into the lallantois or genito-urinary sinus, see Pigs II and V in the pelvic region. 246. Metanephros or True Kidney and Ureter. This is present only in amniota, Reptiles, Birds and Mammals. The true kidbey in various stages can be seen in Pigs II, V and VI. It is in ai very early condition in Pig II. The ureter may be followed to its 'origin in all the specimens. Study the models of the uro-genital system. 247. Genital Ridge. This may be seen as a thickening and a deeply staining projection on the mesal edge of the mesonephros in all the Pigs, but it is especially well shown in the transections (Pigs II, V). 248. Miuellerian Ducts. Study the models, and the Demonstra- tions. 249. Cloaca. Study the Models, and note the relative position of the different parts. Remember that in many animals the cloaca is a permanent feature of Wheir organization. . 250. The Genito-Urinary Sinus. For this study Pig II, and for the prominent perineal body dividing the cloaca into rectum and genito-urinary sinus study Pig. III. 251. The Fallopian Tubes and Uterus. Study the models and the demonstrations. Remember that in man the oviducts open di- rectly into the body of the uterus, but in most animals the body ol£ the uterus is small and the horns of the uterus are relatively large. In animals with multiple Ibirths like the pig, the pig embryos are scattered along the horns of the uterus like peas in a pod. 252. The Ovary and Parovarium. Demonstration. 253. The Testis and the Epididymis. Demonstration. 254. The Ducts of the Ovary and the Testis. Demonstration. 80 255- The external Genitalia in the two Sexes. Study the models and demonstrations. Constilt the tables in your books for the homologies of th-e different parts. Recitation on the Uro-genital Organs. 1. Why are the urinary and genital organs so closely united in , anatomical and medical discussions? 2. What is the pronephros? In what animals is it found, and in which of these is it functional? 3. What is the mesonephros or Wolffian body ? 4. What is the duct of the last called? Does the pronephros have a duct? If so what is it called? 5. In what animals is a mesonephros functional, (a) at some special time, (b) throughout life? 6. Are there glomeruli in the mesonephros? 7. Where does the d^uct of the mesonephros empty? 8. What does it become in the adult? 9. What is the metanephros? From what does it arise? In what animals is it found? What is its duct? 10. What is the genital ridge? 11. Into what does the genital ridge develop? 12. What is the duct of the testis? What of the ovary? 13. What part of the testis is supposed to originate ifrom the Wolffian body? What part of the ovary? 14. What does the Wolffian duct become in the adult of the two sexes? 15. What does the Muellerian duct become in the adult ? 16. What is the cloaca, and in what animals 'does it persist? 17. What is the genito-urinary sinus, and how is it derived? 18. Compare a cross section of a male and of a !female embryo just beyiond the neck of the bladder? 19. How is the uterus formed from the Muellerian ducts ? 20. From what germ layer are the epithelial linings of the genital passages derived? Compare male and female? 21. Where is the prostate developed? Is it found in the female? 22. From what germ layer are the kidneys developed? The I>ronephros, the mesonephros? 23. Is the muscle of the genito-urinary organs from splanch- nopleure or somatopleure? Laboratory Report on the Genito-urinary Organs. I. Draw the mesonephros and the genital ridge ini Pig. V or II, under a low power. Draw some of the nephric tubules of a speci- men showing clearly the details under a high power. Include a glomerulus in the higher poTver drawing. 81 2. Draw the Genito-Urinary Sinus of Pig. Ill, and show its relation to the alimentary canal. Give a skeit'th' also olf the cloaca as shown in Pig. II and the models for comparisiom. 3. Discuss the origin of the epithelium for all parts of the genito-urinary organs. Same for the muscle. Give references to .specimens and to toooks in support of your conclusions. DIVISION E THE ECTODERM AND ITS DERIVATIVES UNIT XXVI. Epidermis, Hairs, Nails, Sweat, Sebaceous and Milk Glands. Laboratory Work. 256. Ectoderm. This shows in all embryos. Its primitive con- dition or early condition may be seen in the medullary stage of the Amblystoma, in the sections of chick and' in Pig I. 257. Epidermis and Epitrichium. This is present in all the pigs. For the epitrichium see Minot, pp. 181, 232. It shows with great clearness in a human embryo of 45 mm. length. Note the diflferr ence in thickness in the epidermis in different regions in the larger pigs- 258. Nails, (Claws and Hoofs). These show in quite advanced embryos 259. Hairs. For the developing hairs study the preparation of the child's arm and the eyelids of the same child (No. 275). In Pig VI developing hairs may be found under the lower jaw. Study the developing tactile hairs (whiskers) of the kitten. 260. Sebaceous Glands. These are most easily seen as lateral- outgrowths from the hair protons. The early stages show well in the eyelids of the child' (Nio>. 275). For their fully developed con- dition re-examine the sections of the lip (Homo and kitten). 261. Sweat Glands. For an early condition of these study the transection of a new-born child's finger tip. If one studies the palmar aspect of the finger there will be no danger of confusing the protons of sweat glands and of hairs. 262. Milk Ridge and Mammary Glands. For the milk ridge and the mammary glands study the entire pigs available. For sections of the glandular protons study Pig Vand Pig VI. These glandular protons may be most easily found near the umbilical cord. 263. Mammary Gland of New-Born Child. This will show the definite, nearly globular form of the entire gland, and also the gland' tubules. Recitation on the Epidermis and its Appendages . 1. From what is the epidermis derived? 2. What other structure or structures belong to the same germ layer? 83 3. What is the epitrichium? When does it appear and when does it disappear? 4. How are the iiails developed? 5. How do the hoofs of animals differ from the nails? 6. What is the part answering to the ventral plate 'Of the hoof, in animals with nails? 7. Compare the claws of animals with nails and .with hoofs. 8. From what germ layer are the hairs developed? 9. From what part of the epidermis is the hair shaft developed? 10. From what the inner root sheath? 11. What part does the mesoderm form? What is the hair papilla? 12. In the ox where do the hairs develop first? 13. Are hairs developed over the entire epidermal surface in man? 14. What are the sebaceous glands and where are they de- veloped? 15. Are sebaceous glands found only in connection with hairs? 16. How is their secretion produced? 17. What is the milk ridge? Is it found in man? 18. How are the mammae developed from this rid'ge? 19. Compare the mammilla in cow, cat and Homo. 20. What regions of the milk ridge develop mammary glands in the different domestic animals and in man? In the elephants? Laboratory Report on the Epidermis 1. Draw the eyelid's of the child and show the developing hairs and sebaceous glands. • 2. Draw the milk ridge of the pig indicating the points of de- velopment of the glairds. Draw also a section of the early proton in Pig V or VI. 84 UNIT XXVII The Central Nervous System, Spinal GEinglia and Nerves; Sym- pathic Ganglia and Nerves.* L aboratory Work . 2&i,. Medullary Plate. For the Neural or medullary plate of the ectoderm examine the early stage of the Amblystoma (m^ullary plate stage), the sections of chick embryos and Pig I. In these different preparations the neural plate may be seen as a nearly flat plate and in various stages of tube formation. 265. Neural Tube, Brain and Myel. For the general view the entire 36-hour chick is excellent. The brain will be seen as an en- largement of the neural tube .at the cephalic end. All the pig sec- tions show the neural tube either in longitudinal, oblique or tran- sections. Study the sections in different regions of the embryos to see the modifications. Make a special study to determine the character of the roof, floor and sides of the neural tube in different regions. 266. Brain Flexures. The three great bends or flexures in the brain, — Neck bend, Pons bend, and Head bend, — are clearly shown in Pigs III and VI. 267. Spinal Ganglia. For the origin of the spinal ganglia from the neural crest study transections of a chick of 30 to 40 hours in- cubation. Depending upon the stage, the ganglionic crest will show as a mass of cells on the dorsal side just beneath the ecto- derm or as two bud-like projections from the dorsal edge of the neural tube. Various stages of the ganglion formation may be seen in the dif- ferent pigs. Study Pig II more especially. In Pigs III and VI, the great ganglia in the head region may be seen, and also very clearly the ganglia in' the brachial regions and' sacral regions. In Pig IV, the ganglia of the two sides show well with the neural tube between. 268. Dorsal and Ventral Nerve Roots. For these study es- pecially Pig II. Opposite the arm buds is a favorable situation. One can here see the spinal ganglia with the roots passing to the dorsal side of the myel. The ventral root also shows and its *For the advanced course upon the nervous system and the or- gans of sense see course 8, p. 8. somewhat pear-shaped imass of nerve cells on the ventro-lateral margin of the myel. It is to be remembered that the nerve cells giving rise to the ventral root are in the ventro-lateral part of the myel itself, while those giving rise to the dorsal root are in the spinal ganglion outside the myel. 269. Sympathic Ganglia and Nerves. In the section of Pig II showing most clearly the dorsal and ventral roots of the spinal nerve there will be seen passing from the nerve trunk one large branch dorsad. This is the dorsal primary division of the trunk. The part extending nearly straight venttfad is the ventral p:rim.a.ry division. Extending either from the trunk or from the ventral division, a small branch extends ventro-mesad', and near the aorta ends in a cluster of deeply staining cells. The cluster of deeply staining cells is the proton of a sympathic ganglion, and the nerve extending to it is the ramus communicans visoeralis. Recitation on the Neural Tube, Ganglia and Nerves. 1. From what germ layer is the entire nervous system dl- veloped? 2. In what region of the embryo can the proton of this system be found? 3. What is the proton of the central nervous system called? 4. Where is it situated? 5. Is the brain part of the neural tube? Is the neural tube ever connected with the archenteron? What is the name of the canal uniting the two? What are the three primary cerebral vesicles? What part or parts of the adult brain develop from the first? From the second? From the third? 10. What and where are the flexures of the train? 11. What is the neural crest. What is the ganglionic ridge? 12. From what are the spinal ganglia developed? 13. From what source are the nerves of the ventral root. 14. Where are the nerve cells giving rise to the dorsal root? 15. What is a nerve trunk? What is ,a single nerve fiber? 16. What are the two primary divisions of the nerve trunk? 17. What is the origin of the sympathic ganglia? What is the name of the branch connfcting the sympathic and spinal nerves? 18. In a transection of an embryonic myel what parts may be seen? 19. Compare the roof and floor with the sides. 20. Compare the roof, floor and sides in the brain. 86 21. How do the plexuses of the brain apparently get inside the ventricles? 22. Are there any holes in the neural tube in the adult? Laboratory Report on the Nervous System. 1. Draw a transection of an embryo and show the myel, the nerve. roots, the nerve trunk, the two primary divisions of the trunk and the branch to the sympathic ganglion. Name the other organs shown in the section. 2. Draw a section through the myel and name the parts. 3. Draw sections of the Amblystoma, a chick and Pig I, to show the neural plate and its co.n'nection with the ectoderm. 87 UNIT XXVIII. The Eye, Ear and Nose * Laboratory Work 270. The Optic Vesicles. The outgrowths of the first cerebral vesicle to form the optic vesicles are most satisfactorily shown m the entire 36-hour chick. Examine the models of the human em- bryo also. 271. The Optic Cup and the Lens. These are admirably shown in Pig II. The lens in this stage is a hollow sphere. The cells forming the wall are of nearly equal size, and the ectoderm is almost in contact with the lens. The formation of the lens vesicle will be shown in the demonstration. For other stages in the de- velopment of the optic cup and the lens study the older pigs. 272. Optic Stalk and Nerve, Choroid Fissure. For these study the older pigs and the demonstrations. 273. Cornea and Sclerotic. Pigs IV, V and VI show these well. 274. Eyelids and Conjunctiva. Study Pigs IV to VI, also the entire pigs and note that the eye is not covered with lids at first. The cornea is always covered with ectoderm, however. 275. Fusion of the Eye-Lid's. For this study a section of the lids of a 125 mim. human fetus or the two lids of a pig of the proper size. Remember also that some animals are born with the lids still fused. Note carefully the character of the connecting sub- stance. For comparison study the lids of a child near birth after the con- nection between the lids has disappeared. 276. Otic Vesicle. For the closed vesicle study Pig II. For later stages study Pigs III and IV. The origin of the vesicle from the ectoderm will be demonstrated. 277. Labyrinth. For the semicircular canals and other parts of the internal ear study the entire series of pigs and the models of the development of the ear. 278. Eustachian Tube, Middle and External Ear. Study the larger pigs for these. Note the connection of the Eustachian tube with the primitive pharynx. Note also the external meatus. Re- miember that, these passages are the persistent first entodermal and *During the second year the nervous system^ and organs of sense are more fully treated. See course 8, p. 8. ectoderma'. gill pouches. They are divicfed by a partition, the tym- panic membrane, lined internal^- by entoderm and externally by ectoderm. Study the entire pigs for the external ear, also sections of Pigs V, VI. 279. Xose. For the nasal pits or ectodermic invaginations to form the nasal cavities study Pig II. 28a Xasal and Oral Cavities. These are at first independlent. For this see the models of the human embryos and the demon- strations. Later the two cavities are together. Study Pigs IV to VI. In Pig VI the palate has formed and the nasal cavities opt:n into the pharynx practically as in the adult. In Pigs IV and V, the the tongue projects up into the nasal cavity. 281. Development of the Turbinated Bones. Study Pig V and the section of the head for the developing teeth. 282. Jacobson's Organ. This is well shown as an invagination of epithelium near the ventral en-d of the nasal septum in Pig V. 283. Development of the Face and Arrests of Development. Recitation on the Organs of Sense 1. What are the organs of sense? 2. What is the optic vesicle? 3. From what is the optic vesicle an outgrowth? 4. Is the optic stalk solid or hollow? 5. How is the optic cup formed? 6. What is formed by the outer layer of the cup? 7. What by the inner layer? 8. How is the lens developed? g. How is the eyeball, including the corniea, developed? 10. What is the choroid fissure, and where is it? 11. What gets into the eye through this fissure? 12. How are the lids of thi e3e formed? How the third lid? 13. How are the 'eyelids sealed. 14. Name an animal in which the lids are sealed at birth. 15.* From what germ layers are derived the following: (a) Retina, (b) Lens, (c) ^'itreus, (d) Cornea, (e) Sclera, (f) the epi- thelium of the conjunctiva? 16. What is the otic vesicle? 17. From what layer is the otic vesicle developed? 18. From what layer is the epithelium lining the labyrinth de- rived? 10. Origin of the epithelium of the middle ear and Eustachian tube? 89 20. Origin of the epitheliurn lining tlie two faces of tlie drum of tbe ear. 21. Are the ear bones originally in the tympanic cavity? 22. From what is thei lining epithelium of the noae derived? 23. What are the nasal pits and where do they open? 24. In the early condition where do the nasal pits join the 'Oral cavity? 25. Name an animal in which the nasal canals open very near the edge of the mouth in the adult. 26. Are there animals in which the nasal canals never open into the oral cavity? 27. Where can one find Jacobson's organ? 28. What is cleft palate? 29. What is hair lip? 30. What are such defects called? Laboratory Report on the Organs of Sense 1. Draw the transection of Pig II showing the optic vesicles and' their connection with the brain. 2. Draw a section showing the otic vesicle. 3. Draw a section of Pig II showing the nasal pits. 4. Draw a section showing the tongue' projecting into the nasal cavity. Name all the parts in the transection: that is, name every structure that appears in the section 90 DIVISION F FETAL MEMBRANES AND PLACENTA; THE GRAVID UTERUS UNIT XXIX Gross Anatomy of Gravid Uterus, Fetal Membranes and Placenta. Laboratory 11 'ork 284. Dissection of the Gravid' Uterus of the Cow. i. Deter- mination of the aspects of the gravid uterus (cephalic, caudal, dor- sal, ventral, right and left). 2. Determination of the various parts: vagina, os uteri, body of the uterus, the uterine 'horns with their fimbriated extremities at the ends of the Fallopian tubes. Note the relation of the ovary to the broad' ligament. 3. Recognition of the ovary. Determine in w'hich one the corpus luteum is situated. 4. Corpus Luteum. Make a section through the ovary contain- ing the cofpus luteum and note how large it is. Section the other ovary and compare with the one containing the corpus luteum. 5. Determine in which horji of the uterus the fetus is situated. Is it the horn on the side where the ovary contains a corpus luteum? 6. See if you can determine the exact position of the fetus by manipulation. This is important to learn. See whether the head is turned toward th^ fundus or toward the os uteri. Remember that, commencing with the outsid'e of the uterus, the fetus in enclosed: (a), in the uterus (muscularis and mucosa); (b), in t'he chorion which lies next the uterus and is connected with the uterine mucosa at the placenta (cotyledons); (c), in the amnion. ,The allantois is within the chorion, but outside the fetus and the amnion. Commencing with the fetus it is first enclosed by (a) the am- nion, (b), the chorion, (c), the uterus. 285. Demonstration of the Membranes and Placenta. Carefully section the muscularis of the uterus and tear away over a con- siderable area. The uterine mucosa will be left. Cut or break this somewhere between the cotyled'ons and the chorion will ap- pear. Between the cotyledons the chorion is not attached to the uterus. 91 2. The Cotyledons. Note the thickenings scattered around the uterus. Separate chorion and mucosa till a cotyledon is reached and tjien pull gently and the chorionic villi can be pulled out of the cotyledon of the mucosa. Note that each cotyledon is a small placenta and that the uterine or maternal part of this placenta is a thickeming of the uterdne mucosa, while the fetal part of the placenta is a thickening of the chorion. 3. Extent of the Chorion. Separate the fetal and maternal part of the placenta at the cotyledotis and follow out the chorion. It will be seen to pass from the fetus to the tip of the horn in w'hich the fetus is, an3'from the fetus to the common part of the uterus, then up to the tip of the other horn. That is the entire cavity of the uterus is occupied by the chorion. 4. Open the vagina and .note the external os uteri and note the plug of tenacious mucus. Make a longisection of the neck of the uterus to the opening into the common part — the internal os uteri. Note that the passage is very tortuous in the meek. S. Allantois. Tear away the chorion in one of the horns, and the sac of the allantois will be found. Make a small hole in it and inflate. Note on which side of the fetus it lies. Remember that the allantois in the cow exteinds as far as the chorion, but that it does not inclose the fetus. It is a Y-shaped sac extending from the fetus, the stem of the Y being in the umbilical cord. 6. Amnion. Remove the chorion over the fetus and a sac with some blood vessels will be seen enclosing the fetus. Make a very small hole in it and inflate. Reinflate the allantois and note the relation of the two sacs. The allantois and amnion may be separated and' if they are, the common stalk of the allantois will be seen to pass to the umbilical cord. 286. Umbilical Cord, and the Umiilical Vessels, i. The um- bilical cord arises from the abdomen of the fetus. Note whether it is twisted or not. Make a slit in the amnion to expose it. The villous appearance of the surface is due to the epithelial outgrowths from the amnion covering it. See the section of the umbilicus for the proof of this. Make a section about half way through the umbilicus and the two veins, tWo arteries and the duct of the allantois (the urac'hus) may be seen. By blowing into this the allantois can be inflated, and in fresh specimens the bladder may be filled and the air forced out through the urethra. Vessels of the umbilical cord: Follow the cord to the chorionic attachments and' note how the great vessels spread out upon iL. 02 2. Cut through the chorion leaving the beginnings of the um- bilicus attached and put the fetus on a tray for dissection. Count the cotyledons on the uterus. This is most accurately done by cutting them off or by cutting the uterus up into pieces of moderate size. Keep a note of the number. This is especially important for veterinary students. 3. Dissection of the Umbilicus. Trace the various vessels from the chorion to the fetus, also the urachus or duct of the al- lantois. See if th&re is any twist in the cord. Note that all the bl'Ood vessels, arteries as well as veins, have very thick walls. 4. The umbilical ring. This is at the junction of the umbilicus and the body. It might contain: (a), the stalk of the yolk sac and the vitellime vessels; (b), the urachus or tube of the ailantois; (c), the umbilical vessels. Trace the umbilical vessels carefully and note that the arteries, always two of them, pass caudad and dorsad along the sides of the urinary bladder to the iliac arteries. The umbilical veins join the single umbilical vein as they enter the body. Note carefully that the veins in the umbilicus are thick-walled' almost like the arteries, but the single umbilical vein inside the body is thin-walled and capacious. Remember that in many animals the umbilical veins of the chorion unite into one at the peripheral end of the umbilicus instead of at the proximal end as with the cow. 5. Cut away the abdominal wall and note the mesentery con- necting the umbilical vein to the abdomen. Follow the umbilical vein to the liver, remove the liver substance and follow the vein. It will be seen to branch out in the liver. One large branch, the ductus venosus arantii, goes directly to the postcava. The branches of the umbilical vein join the portal vessels and thus pass through the liver capillaries. In the Pig and the Horse there is no ductus venosus arantii, therefore all the blood from the um- bilical vein passes through the liver capillaries before reaching the heart. As will be seen later there are originally two umbilica. veins passing along the somatopleure and joining the heart independ- ently. 2S7. Examination of the Fetus. I. Examine the outside of the body for beginning hair, horns, hoofs, etc. Remember that the hairs do not appear all over the body at the same time. The large hairs about the muzzle and the eyes appear very early. 93 2. Dissections of the whole body. Dissect as much as possible. LO'ok into the various stomachs and see how the different ones appear. Make longisections of some of the bones and note the position where the centers of ossification are. 3. Dissection of the Fetal Heart. Make a careful study of the heart, 'whic'h has been dissected and all the parts labeled. Then try to find the parts in. the fetus that you dissect. Compare the great arteries arising from the aorta with those in man. Note the Thymus. This is partly m the neck and partly betwieen the lungs and on the base of the heart. The butchers call this the "neck sweet bread." The pancreas is often called the "belly sweet bread." When through with the fetus do not throw it away, but put it in a jar. We may need to imake further use of some part. Note that the lungs are solid organs like the pancreas or sal- ivary gland. If they never have been inflated a piece of lung would sink as readily as a piece of liver. This method is used to aid in determining whether a dead fetus was born alive. If it ever breathed the air remaining in the lungs prevents sinking. 288. Forms of Placenta in Various Mammals. These are ail represented in the gross preparations of gravid uteri in the lab- oratory. They are: (i) The diffuse placenta (Pig, 'horse, camel, hippopotamus and whale). The pig's placenta is exhibited. 2. Cotyledonary or polycotyledonary Placenta. The cow's pla- centa is an example. This form is especially characteristic of ruminants. Carefully distinguish between the maternal cotyle- dons of the cow and sheep. Remember that the maternal coty- ledons appear in t'he uterus even, before birth. The sheep's are often pigmented. 3. The Zonary or Belt Placenta. This is illustrated by the cat and dog. It is present in carnivora generally. It is also present in the elephant. 4. Discoid Placenta. This is represented by the huiman speci- mens and by the rat and the mouse. This form is found in H'o.mo, primates (apes and monkeys), in rodents represented by the rat and mouse. For a. further discussion of the' form of placenta found in diff- erent animals see Turner, Comparative Anatomy of the Placenta; Wiedersheim's Comparative Anatomy; M'ilne-Edwards, Lecons sur la physiologie et I'anat. t. ix, p. 533, et sq. 289. Period of Iwcubation' with various Birds, and Period of Gestation in some Mammals. Hen, 21 days; Turkey, 27 days; 94 Peacock, 31 days; Duck, 25 days; Goose, 29 days. The period of gestation: Mouse, 21 days; Rabbit 28 days; Rat 35 days; Dog, 58-62 days; Cat, 56 days; Pig, 112 days; Sheep and Goat, 140 days; Homo, 280 days; Cow. 280 days; Horse, 336 days. The elephant has a period of almost two years, (20-21 months). Recitation on the Gross Structure of the Membranes and Placenta 1. What is the gravid uterus? 2. How can one determine whether the ovum giving rise to the embrj'o came from the right or from the left ovary? 3. How many corpora lutea would you expect to find in a pig? 4. In a oow or sheep with twins? 5. In what part of the uterus is the embryo developed in cow, pig. etc.? 6. In what part in Homo? In Anthropoids? 7. In the cow or sheep suppose there is but one embryo, are the fetal membranes in both horns of the uterus? 8. In passing from the outside of a gravid uterus to the em- bryo what structures would be met? 9. In passing from the embryo to the outside of the uterus what structures would be imet? 10. What other animals have a free^allantois like the cow? (See Minot, p. 103). 11. How is it in man? 12. Where is the amnion: (a), in the cow and kitten; (b), in man? 13. What is a maternal and what a fetal placenta? 14. When can one find the maternal cotyledons in cow and sheep? 15. How could you distinguish the cotyledons of a cow and of a sheep (a) during gestation, (b) before gestation? 16. What animals have a diffuse placenta? What is meant by it? 17. What animals have a cotyledonary placenta? 18. W^hat is a zonary or belt placenta? Give examples in which it is found. 19. What is a discoid placenta? Examples. 20. What is the umbilical cord?* 21. How many arteries and' how many veins in it (a) in cow? (b) in Homo? 22. Where does the allantois come from originally? 23. What does the allantois communicate with in the large em- bryos like those dissected? 24. What part of the allantois persists in the adult? 95 25. What is the urachus? 26. What is the umbilical ring, and what does the umbilicus contain at this level? 27. Do the intestines extend into the umbilicus? 28. What is the amnion covered with next the fetus? 29. What is the outside of the amnion derived from? 30. What is the umbilical cord covered with? 31. Give periods of incubation, and of gestation. Laboratory Report Draw a section near the middle of the set in either of the pigs (Pig II, III, IV, V or VI). Name all the tissues present and the germ layer from which they originated. Name all the organs and structures and' state whether they originated from the somato- pleure, splanchnopleure, from the medullary plate or the primitive segments. State whic'h set, slide and section was drawn. 96 UNIT XXX. Development and Structure of the Fetal Membranes and Placenta. Laboratory Work. 2go. Fold's of thei Amnion'. For the growing folds of the am- nion!, study the entire 36-'hour or younger chick. The head fold will be most proiminemt. 291. Amnion aind Ohorion. Study sections of the 70- 7S-hour chick for the folds of the somatopleure rising up over the embryo to enclose it in a tent-like covering, the amnioin, at the same time to form the serosa or chordon. The folding is not equally ad- vanced throughout the entire length of the embryo, hence section® at different levels will' slboiw different steps im development. 292. Oo'mposition of Amnion and Chorion; Extra Embryonic Coelom. Study the chick sections and Pig I to determine the con stitution of the amraioim and chorion. Note particularly in which direction each layer of somatopleure faces in the 'amnion; in the chorion. As the coelom is- the space formed by the separatioin of tihe soim'atopleure and splanchnopleure it is easy to find it. The part beyond the embryo is said to be extra-embryonic. 293. AUantois. For an example of a free allantois in the extra- embryonic coelom study a chick of about 90 hours. The allantois of the cow is also- free as was found in dissecting the gravid uterus. In man and many other animals the allantois is not thus free. Consult Minot, p. 103. In all forms the allantois is an outgrowth from the cloaca and hence is lined by entoderm. See Pigs III and VI for the uracShus and its connections with the genito-urinary sinus. 294. Diffuse Placenta. For an example of this study sections of the gravid' uterus of a pig with the chorion in position.Obseirve carefully the epithelial covering of the chorionic villi and of the crypts of the uterus into which the villi extend. 295. Cotyledohary Placenta. Sectioms of thei maternal and fetal cotyledons of the cow will illustrate this. If some of the chorionic villi are pulled out before the organ is fixed it will make the structural relation's plainer. 296. Zonary Placenta. For the zonary or belt placenta study a longisection of the uterus and enitiire chorion of cat or dog. In this section will appear a cross section of the placenta and show itS' edges as well as the middle. The edges in the fresh state ap- 97 pear deep red or sometimes greenish. Note especially how spongy the uterine mucosa is. It is also to be noticed that the space containing the embryo is relatively very large. This is true of all animals in the early stages. Later thei space is relatively much smaller. 297. Discoid Placenta. This type of placenta is well shoiwn in a section' of the gravid uterus of a ,somiewhat advanced mouse em- bryo. Thei placenta will be fouind on the meso-metrial aspect of the uterus. 298. Decidua Capsularis or Reflexa. In some animals (appar- eimtly 'fflan and many rod'ents), the ovum in its early development melts its way through the uterine epithelium and becoimes im- bedded in the mucosa. The :miUco.sa .then grows up over the em- bryo aind completely encloses it sO' that it is now not directly in the cavity of tlhe uterus but in a special siac of uterine mucosa. (See Minot, p. 118). For this condition .study a section of the gravid uterus of a mouae with a very young embryo. In the later stages, as seen in the previous preparation, the decidua capsularis disappears or fuses with the rest of the uterine mucosa and then the embryo appears to be in. the uterine cavity surrounded, of course, by the ohorioin and amnion. 299. Indeciduata. For an example of the indeciduate placenta that of the cow (285) is good. Here at birth the chorionic villi pull out of the maternal cotyledons without tearing the maternal tissue away, hence a sectiom of the fetal part of the placenta would show no part of the uterus or only a few cells. Animals with dif- fuse or cotyledonary placenta are indeciduates. 300. Deciduata. If at birth the fetal placenta carries^ with it much of the maternal placenta the animal is said to be a deciduate. Animals with zonary or discoid placenta are deciduates. As an example study a sectiomi of the human placenta. It will show the fetal tissues and also the deciduate cells from^ the maternal pla- centa. 301. Umbilical Cord of Homo and Bos. Study and compare (a) as to blood vessels (b) and' other structures. In a section of a youin.g embryO', besides the umbilical vessels and the allantois one would find the vitelline duct and the omphalo-'mesaraic blood ves- sels (vitelline artery and veins). If the sections were made near the body ome would also find sections of the intestines. Pig VI shows especially well the presence of the intestines in the coelom of the umbilical co'rd. Such an umbilical hernia has been found in all mammals investigated. Normally it disappears long before birth. 98 Recitation on the Development and Structure of the Fetal Membranes and Placenta. How is the amnion formed in tihe cliick? From what is the amnion derived'? How do its two layers I 2, face? 3 4 How is the serosa or chorion formed'? Do the amnion and chorion form twO' enclosing sacs for the emibryo? Which is next the embryo? 5. What is the cboriomi ini contact with in the bird and in the mammal? 6. W'hat is the position of the amnion? 7. What is the space between the chorion and amnion? 8. Compare the supposed formation of the amnion in man with its formation in the chick. (See Minot, p. 116). 9. What is the allantois and from, what does it arise? 10. With what germ layer is it lined. With what germ layer is it covered. 11. Where is the allantois in embryos with a free allantois? 12. Where is it in animals with a body stalk? Example. 13. Wliat are the structural relations in animals 'with a d'iflfuse placenta? Examples. 14. Compare the gravid uterus of a mouse and man, (a) im an early stage, (b) in a ■later stage of embryonic development. 15. What is a decidua? Decidua serotina? Decidua vera? Decidua reflexa? Decidua capsularis? Examples. 16. Compare a section of the gravid uterus of Bos and Homo. 17. Compare a section of the gravid' uterus of horse and cat. 18. What is a body or belly stalk? Is it an umbilical cord? 19. Do the chorionic villi enter the uterine glands? 20. What deitermines the position of the maternal placenta in cow, cat, mouse, Hioimo? 21. What determines the position of the human placenta and what is the normal place for the maternal placenta. (See Minot, pp. 119-121). Laboratory Report on the Membranes and Placenta. j^. Draw a chick to show the 'formation of the amnion and chorion. 2. Draw a section of the gravid uterus of the mouse, (a) show- ing the decidua capsularis; (b) showing discoid placenta. 3. Draw and compare the umbilical cord of Bos and Homo. 99 DIVISION G FETAL CIRCULATION AND PLACENTAL BLOOD. UNIT XXXL Maternal and Fetal Blood. Laboratory Work 302. Primary Umbilical Veins. — For the primary condition when the umbilical veins are paired and extend along the somatopleure to the heart, study very young embryos. Pig VIL 303. Umbilical Vessels in Later Embryos. — These may be well seen in Pigs II to VI. Trace the vein to the liver. Trace the arteries and urachus. For the vessels in section and' also the um- bilical cord with the intestinal coils, Pig IV is especially good. 304. Umbilical Vesicle and Vessels. — These show well in Pig II. The vesicle shows especially well in the young embryos of ■kittens. 305. Relation of Maternal and Fetal Blood. — For the relation of the blood of mother and embryo in the placenta, study the tran- section of the gravid uterus -of the mouse (297). Use a high power and it will be very easy to distinguish the vessels, as those of the fetus contain nucleated corpuscles. It is of fundamental importance to determine once for all whether the blood 'mingles in the placenta. If so, then the blood of the mother would truly be found in the veins of the embryo. Remembering the wandering power of leucocytes, does it riot seem possible that they could pass over fro'm the maternal tissues to the embryo even though there are no direct channels between the two. Recitation on the Fetal Circulation and Placental Blood 1. What are the first embryonic blood vessels? Where d'o they originate and where do they extend? 2. How many vitelline veins are there; how many arteries? ^ 3. How many umbilical veins are there originally ? 4. How do the umbilical veins reach the heart (a) in the early embryo? (b) in later embryos? 5. In late embryos which umbilical vein persists as an umbil- ical vein? What becomes of the other one? 6. How many umbilical arteries ar? there and what is their course? 7- Into what adult structures do the vitelline arteries develop? 8. Into what do the vitelline veins develop? 9. Do the vitelline and the umbilical veins ever join the heart? 10. Discuss the formation of the portal vessels. 11. How does the blood from the placenta get to the heart in late embryos (a) Homo, (b) Sus or Equus? 12. What is the ductus venosus Arantii? In what animals is it absent. Examples where it is present. Is it early or late in devel- opment? 13. What are the cardinal veins and' where are they? 14. What are the ducts of Cuvier, from what are they formed and where do they terminate? 15. Are there any structures in the adult representing them? 16. How many precavae are there in man, cat, rabbit, horse? 17. How is a single precava formed from the original paired vessels? 18. How many postcavae are there? 19. From what is the postcava derived? Give all the constituent."!, 20. What is the difference between the ductus venoms as used by Minot and ^Mc^Murrich, and the ductus venosus Arantii? 21. What is the ductus arteriosus? 22. What is the ductus BotalH? Where is it, and what does it connect? 23. How are the fetal and the maternal blood related in the placenta? 24. Is there a direct communication between the fetal and the maternal blood channels? 25. Do the red blood corpuscles of the mother pass into the fetal vessels? Give the proof. 26. Discuss the passage of leucocytes from the maternal to the fetal tissues. 27. How do the blood vessels of the embryo get to the chorion in animals with a free allantois? Examples. 28. How does the chorion become vascularized in animals with a body stalk? Give examples. 29. Trace the blood from the placenta through the fetus and back to the placenta in very early human embryos. Same for late human embryos. 30. Trace the blood from the placenta through the fetus and back to the placenta in early pig embryos and in late pig embryos. Diflference between man and pig. 31. What is the foramen ovale, and its purpose in the fetal cir- culation? When does it appear? 101 32. When does the ductus arteriosus appear and what is its pur- pose? 33. How does the red tlood get into the vessels of the mam- malian embryo? The hird embryo? 34. How can an apparently double postcava be explained? In case the postcava is double a part of the way what is the position of the ureters? 35- What vestiges of the fetal circulatory system, persist in the adult? (See Keith's Embryology). Laboratory Report on the Vascular System and Blood I. Draw a part of the placenta of the mouse showing the mater- nal and fetal vessels with their contained corpuscles. 2. Draw the section of the gravid uterus of the mouse' and com- pare the discoid placenta of mouse and man. 102 DIVISION H DETERMINATION OF SEX AND MATERNAI, IMPRESSIONS UNIT XXXII The laboratory work of this unit will consist of a critical exam- ination, with the student, of his personal specimens. Determination of Sex 1. Stage of development in an embryo when the sex is deter- mined. All the organs of one sex are found in the other and all the organs develop equally for a considerable time. It is only after the generative organs especially characteristic of the adult condition have begun to preponderate to a considerable extent that it is possible to distinguish the sex of an embryo. 2. From the fact that the genital and all the other organs of the body appear identical in structure and rate of development for a considerable time in the two sexes, it has been inferred that some external influence may determine the final prepon_derating growth and differentiation which shall make of the apparently indiflferent or hermaphroditic embryo a male or a female. 3. Over 500 different hypotheses for the causes determining sex have been advanced, and an almost endless number of experiments have been tried to find' out, if possible, the secret of sex production so that it might be controlled at will. 4. Statistics show that in nature, when no special experimenis are being conducted to modify the normal course of events, more males begin to develop than females. It is apparently equally cer- tain in the higher forms at least, that females are more tenacious of life than males, as more males die before birth and during child- hood than females. (For human beings, in miscarriages, 160 male embryos are lost to 100 females; of still births 131 are male to 100 female; of living births 105 are males and 100 females). 5. Feeding and other experiments 'to determine sex have given such varying and contradictory results that no general conclusions can be drawn. 6. Influence of the Parents. Does the male or the female de- termine the sex of the offspring? If one looks into the cases of animals in which the eggs are sometimes fertilized and sometimes not there would seem to be some' hope of an answer. If the male determined the sex then one would expect that ifertili'zed eggs would 103 always be of a given sex. This is apparently the case in the boney bee where the unfertilized eggs' are males (drones) while the fertilized eggs give rise to females (queens .and workers). In Plant Lice, fertilized eggs produce females and' unfertilized eggs both males and females. In a moth (Psyche), the fertilized eggs produce imales and fe- males while the unfertilized eggs are females. 7. Germinal Cells. In some quite widely separated forms two kind's of zoosperms are found in the males; only one kind is known to be functional, however. Likewise, in some unrelated animals the eggs which are to give rise to the different sexes are strikingly unlike. For example, in Dinophilus, a worm, and in the grape Phylloxera, the eggs giving rise to males are much smaller than those producing females. General Conclusions. (1) Apparently the male parent has no in- fluence in determining the sex. (2) The female parent produces eggs which are either male or female, (3) The sex of the eggs is determined before the female animal containing them is born, there- fore she can not change the sex in any way during the development of the offspring. The direct control or regulation of the sex for men or animals during the development of the embryo is impossible because the sex is determined long before the fertilization of the ovum. For books and papers upon the determination of sex the student is referred to the Index Catalog of the Library of the Surgeon- General's Office under Sex. Dr. Johra Beard, The determination of Sex in Animal Develop- ment. Separately printed', and also in Zool. Jahrb,, anat. Abth. V. 16, pp. 703-764. Jena 1902. Dr. M. V. Lenhossek. Das Problem der geschlechtsbestimimen- den Ursachen. Jena, 1903. In these two papers is an excellent discussion of the whole sub- ject from the standpoint of the latest biological knowledge. Many references are given to other authors. Blaternal hnpressions I. Literature. During the last three thousand years there has been a great deal of professional and' popular literature upon the ■effects of the impressions of the mother upon the bodily organiza- tion of the unborn young. It is necessary for the student to distinguish clearly between the belief in maternal impressions and in the doctrine of Heredity.. If anything is certain in biology it is that the mental and' bodily or- 104 ganization of human beings and animals is absolutely dependent upon and determined by ancestors. But the question under discus- sion is not one of heredity, but whether during gestation the mother can by her mental impressions modify the organization of her unborn young. 2. Supposed' Effects. The extent of bodily change produced by mental impresionsi varies from a mere strawberry mark tO' a great red blotch on the face or neck (nevus arteriosus), a club foot or 'hand and indeed all the horrors of teratology. 3. Age when the Effects are Produced. If one consults the lit- erature he will find that the body of the unborn young may be thus profoundly altered at almost any time during gestation, that is at a period so early that one could not determine the presence of an embryo, until a period so late that the young, if born, would be capable of an independent existence outside of the mother's body. 4. Investigation of Pathologic Embryos. This 'has been prose- cuted' with great assiduity during the last ten years. Fortunately most defective embryos die and are expelled. It is known that the defects appear very early in some cases. They have fceen seen in a human embryo not over 12 days old, and a single blastoderm with two primitive streaks has been found in the chick. 5. Defective and Normal Young in the same Uterus. It occa- sionally happens with human beings that one twin is defective and the other perfect. It is common with animals as the sheep. It is very common among animals with multiple birth like cats, rabbits and^pigs. 6. Defective Embryos with Egg Laying Animals. Practically all the defects found in mammals are found in the young of egg laying animals. Conclusions: (a) Heredity is a fixed law of Nature. (b) A developing embryo of a mammal is an independent organ- ism from the beginning of its development. Its relation with the mother is one of contact only. It gains its nourishment by absorp- tion. (c) As the mother cannot change her own organization by mental impressions, i. e., cannot produce a strawberry mark on her own face, cut off an arm or leg, or produce a club hand or foot in herself by her imagination, how can she perform such wonders on an independent organism merely in contact with her? (d) How can maternal impressions affect one of a pair of itwins and not the other, or in case of multiple births, oae of 7 or 8 or more ? 105 (e) The defects in the embryos of egg-laying animals are so like those in mammals that one must believe that their cause is fun- damentally the same. No one would attribute these defects to the imagination of the parents. The eggs may be hatched in an incu- bator with birds, or with fishes and amphibia they may be left by the parents. Indeed in many cases the parents die before the eggs are hatched. For literature upon Maternal Impressions consult the Index Cat- alog of the Surgeon-Generars Office, under Foetus, Maternal Im- pressions or Influence. Gould' and Pyle, Anomalies and Curiosities of Medicine. Works on General Pathology. Ew.art, the Penycuik experiments and his later papers in the Highland and Agricultural Society's Transactions Dr. F. P. Mall on Pathologic Human Embryos in the Welch Book and in the Festchrift for Dt. Vaughan. Dareste ,Monstruos- ities. In literature read Dr. Oliver W. Holmies' Elsie Venner. Read Chapter 30 of Genesis, commencing with the 2Sth verse. This gives an account of the severe selection Jacob practiced (42nd verse), and the method he adopted to secure ringstreaked spotted, and speckled young in his flocks. The student should note carefully in reading this account that the stock from which the flocks of Jacob were selected contained many ringstreaked and spotted ani- mals, hence, with the knowledge of heredity we now have, we would expect that many of the young would be ringstreaked, speckled and spotted although the immediate parents were unmarked. This is familiarly expressed at the present day by saying, "it was in the blood." 106