aotOGY 
 
 L13KARY 
 

 
JOHNS HOPKINS UNIVERSITY, 
 
 BALTIMORE. 
 
 INSTRUCTION IN PHYSIOLOGY FOR SCHOOL 
 TEACHERS. 
 
 ANNOUNCEMENT. 
 
 Professor MARTIN will organise, during the present session, a 
 class for the instruction of School Teachers in Physiology. It 
 will be strictly limited to school-teachers, or students of a Normal 
 College, who are engaged in teaching, or who purpose to teach, 
 Physiology. Only eighteen students can be received. 
 
 The class will meet in Hopkins Hall, on Saturday mornings, at 
 10 A. M., commencing on Saturday, October 13 ; and after a lecture, 
 will adjourn to the Biological Laboratory for practical instruction, 
 which will continue until 2 P. M.; those who may be admitted to 
 the course must undertake to give this time uninterruptedly to the 
 work. The class will have twenty meetings, and absence from any 
 one of them, unless for a cause which the authorities of the Univer- 
 sity may deem satisfactory, will be treated as a resignation, and the 
 absentee's place be filled up forthwith. 
 
 Microscopes and other instruments, and the necessary material, 
 will be provided by the University. Students will be required to 
 make good any injury, beyond fair wear and tear, occurring to an 
 instrument while in their charge. 
 
 Candidates for admission to the course are requested to send 
 in applications to the President of the University at once, and those 
 who are accepted will be notified of the fact. 
 
 A registration fee of one dollar will be charged to each accepted 
 student. 
 
 SEPTEMBER, 1877. II. 1. 
 
OBJECT AND PLAN OF THE COURSE. 
 
 The following extract from the first lecture of the course for which 
 the succeeding Laboratory Notes were written, will serve to explain 
 with what object and upon what plan the "Teachers' Class" was 
 organized. 
 
 " It has of late years come to be pretty generally recognized that 
 no scheme of elementary education is complete which does not include 
 instruction in the elements of some of the experimental and observa- 
 tional sciences, so that, side by side with training in the principles of 
 language and of mathematics, training in these other subjects, which 
 are calculated to exercise different powers of the mind, may find a 
 place. Some sort of teaching in them is therefore commonly 
 attempted in schools, and in spite of great difficulties is often excel- 
 lently accomplished ; and there are now, I think, few teachers of 
 experience who do not recognize their value, or who have not (as one 
 advantage at least) found that many children who seemed hopelessly 
 dull and indolent in the study of other subjects have, when brought in 
 contact with these, brightened up and excelled all others in them. 
 
 " These newer school studies, however, labor under some disad- 
 vantage as compared with the older and more time-honored ones. As 
 is to be expected, less perfected methods of teaching them have at 
 present been attained ; the experience of years in such matters cannot 
 compete with the experience of centuries : and there is at present even 
 some danger that through untrained zeal in teaching them much of 
 their value as educational agencies will be overlooked or discredited. 
 So many things are mainly taught by books that it often needs some 
 readjustment of ideas to grasp the conception that there are things in 
 school routine which cannot be properly taught by books ; but none 
 the less it is patent on the least consideration, that if a child be loaded 
 up with the facts of Physics or Chemistry or Physiology out of a book, 
 he will indeed gain a knowledge of facts whose utility and interest is 
 undeniable, but as far as the special educational value of the experi- 
 mental sciences is concerned he may nearly as well, or perhaps better, 
 be learning how to 'orderly decline his noun and his verb,' and how 
 
to add together dollars and cents. The real value of these subjects 
 lies in the fact that while, as a rule, more attractive to children, they 
 admit, with much greater ease and certainty 'than most others, of the 
 systematic training of the faculties of observation and of the powers 
 necessary for drawing correct conclusions from a number of observed 
 facts. A child may be taught that acids neutralise bases verbally or 
 from a book, and may even know by heart all the equivalent portions 
 of acids and bases necessary for neutralisation, but the educational 
 value of Chemistry in school training will be far better utilised 
 if he be made to try with his litmus paper a few acids and a few 
 bases and mixtures of them, and be thus led to draw for himself the 
 conclusion that in certain proportions acids and bases do commonly 
 produce a neutral mixture. 
 
 " The great objection to such teaching is the difficulty of obtaining 
 and using the appliances and material. The difficulty is a real, and in 
 most schools at present a great one, but still much more may be done 
 in simple and easy ways than one who has not tried is commonly dis- 
 posed to believe ; and even in cases where the objects or phenomena 
 concerned cannot be shown themselves, a great step is made if those 
 who teach about them have themselves seen them ; if the teaching is 
 not the mere giving out of an abstract of a teachers' manual, boiled 
 down from some text-book, which in its turn is abstracted from 
 another, so that the facts get chilled and deadened by four or five 
 stages of removal from the actual observation of the phenomena them- 
 selves, but comes with something of a natural glow still on it. 
 
 " It is with the object of helping to make the teaching of Animal 
 Physiology alive and potent as an educational tool that this class has 
 been organized. I shall naturally not try to lead you into the 
 advanced branches of the subject, but shall simply endeavor to give 
 those of you who care for it a real and not a book acquaintance with 
 the fundamental facts of the science, and of so much of anatomy as is 
 necessary for comprehending it. 
 
 " Our general plan will be first to meet here for a lecture ; but that 
 will be the least important part, for I do not suppose I shall tell you 
 anything in it that you have not heard or read of already, and often it 
 
 3 
 
will be a very short one just serving to hold matters together some- 
 what. After the lecture we will adjourn to the Laboratory, and there 
 will study the subjects of the lecture on the things themselves ; and 
 my hope is that in that way you will learn how to set about showing 
 those facts in animal structure and function which are adapted for 
 being shown in a school ; and as to other important facts not so 
 adapted, you will, at least, have seen them for yourselves, and be 
 better able to teach about them than any amount of reading alone will 
 ever qualify you to be. For it may, I think, be laid down, as one more of 
 the rules without exception, that in teaching such subjects as this, 
 the fresher the teacher comes from the observation of the facts the 
 better ; even if he has seen a phenomenon a hundred times before, 
 and feels he knows all about it, there is no preparation for a lesson 
 like looking at it once again " 
 
 ELEMENTARY PHYSIOLOGY. 
 
 Laboratory Directions. 
 I. 
 
 SUPPORTING ORGANS AND TISSUES. 
 
 Paragraphs in brackets are to be omitted until the rest of the section 
 has been worked through ; and are then to be taken up, should time 
 Permit. 
 
 i. Examine and sketch a ''long" bone say humerus or femur. 
 
 -rt. Shaft and extremities', the head of each bone, the neck 
 of the femur : the prominences on the extremities (tuber- 
 osities, trochanters]. 
 
 b. The articular surfaces : their form, smoothness, c. 
 
 c. The rough lines and patches on the bone, marking the 
 
 places where muscles have been attached. 
 
 d. The aperture (foramen] for the entrance of the medullary 
 
 vessels : two such are present in the femur.. 
 4 
 
5 
 
 2. Examine and draw the cut surface of a humerus or femur which 
 
 has been longitudinally divided. 
 Note a. The medullary cavity. 
 
 b. The compact and cancellated bony tissue : the distribution 
 of each. 
 
 3. Examine and draw a vertebra. 
 
 Note a. Its body and arch : the neural canal. 
 
 b. The spinous, transverse and articular processes. 
 
 c. The anterior and posterior (upper and lower) surfaces of 
 
 the body not so smooth as the articular ends of 
 humerus or femur. 
 
 d. Place two consecutive vertebrae together, and note the 
 
 inter-vertebral foramina and the contact of the 
 articular processes. Draw. 
 
 e. Examine an articulated vertebral column. 
 
 4. Examine a calcined bone ; and a bone which has had its earthy 
 
 matter removed by acid. Observe that the earthy matter alone 
 or the animal matter alone retains perfectly the form of the 
 original bone. 
 
 5. Examine with your microscope (Eyepiece 2, Objective A,) one of the 
 
 prepared thin transverse sections of bone : carefully draw a portion. 
 Note a. The Haversian canals. 
 
 b. The lacunce. 
 
 c. The canaliculi. 
 
 d. The general lamellated appearance of the tissue, the 
 
 lamella being for the most part concentric with some 
 Haversian canal. 
 
 6. Examine your section with Eyepiece 2, Obj. D. Note more 
 
 especially the canaliculi, which will not have been well seen with 
 the lower power. Draw a few lacunae with their canaliculi. 
 
 7. Examine microscopically the specimen which has been prepared to 
 
 show the bone corpuscles. 
 
 OP THE 
 
 I5IVBRSIT7 
 
8. Open and examine a fresh joint, observing as you do so, the 
 
 various tough bands and membranes (ligaments,} which hold the 
 bones together. 
 Note a. The glairy synovial fluid moistening it. 
 
 b. The smooth, pale cartilage covering the ends of the 
 
 bones. 
 
 c. The texture and consistency of the cartilage : it cuts 
 
 easily, is flexible and elastic. 
 
 9. With your razor cut off a thin slice of the cartilage, (in a plane 
 
 vertical to that of the head of the bone,) mount it in water, and 
 examine, first, with Oc. 2, Obj. A. and then with Obj. D. Draw 
 carefully. 
 
 Note a. The general ground substance, or matrix, of the car- 
 tilage : homogeneous or slightly granular. 
 
 b. The cartilage corpuscles distributed singly or in groups. 
 
 c. The tendency of the groups to assume the form of rows, 
 
 perpendicular to the bone near the attached surface of 
 the cartilage ; parallel to it near the free surface. 
 
 [10. Examine the forms of the articular surfaces and the movements 
 permitted between the bones in a ball and socket joint (shoulder 
 or hip,) a hinge-joint (elbow), and a pivot joint (atlan to-axial).] 
 
 [u. Examine other forms of articulation. 
 
 a. That between some of the cranial bones (suture}. 
 
 b. That between the vertebral bodies : note the iuterver- 
 
 tebral disc directly uniting the bones, without the 
 intervention of any synovial surfaces.] 
 
 12. Dissect out and examine one of the ligaments of a synovial joint. 
 Note a. Its points of attachment and the mode in which it acts, 
 either to keep the bones in contact, or to check move- 
 ment in some direction. 
 
 b. Its color, flexibility, toughness and inextensibility. 
 6 
 
7 
 
 13. Tear apart with needles a very small bit of ligament, in a drop of 
 water. Examine with Oc. 4, Obj. D. Draw carefully. 
 
 Note in this white fibrous connective tissue 
 
 a. It is mainly composed of very fine fibres. 
 
 b. The fibres run parallel, often in a wavy course. 
 
 c. Having finished your drawing, run a little dilute acetic 
 
 acid in under the cover-slip : the fibres, for the most* 
 part, swell up and disappear for those which remain 
 see 12 b. 
 
 d. Examine and sketch the specimen which the demonstrator 
 
 has prepared to show the connective tissue corpuscles. 
 
 14. Examine, as described in last section, a bit of ligament taken 
 from between the arches of the vertebrae. Draw carefully. 
 
 Note in \\\\s yellow elastic tissue 
 
 a. The fibres, much coarser than those of the white 
 
 fibrous tissue, and often branched ; observe the way 
 the broken ends curl up. 
 
 b. Run in acetic acid : the fibres are unaffected ; those 
 
 fibres which remained unaltered by the acetic acid, 
 (\\^c] in your last specimen, were fibres of this tissue, 
 mixed in the ligament with the white fibrous tissue. 
 
 c. Note the extensibility and elasticity of^this tissue, as 
 
 displayed in a piece of ligamentum nuchce. 
 
 II. 
 
 BLOOD AND LYMPH. 
 
 I. Examine a fresh drop of your own blood with the microscope (Obj. 
 D, Oc. 2 or 4). Run a little oil around the edge of the cover-glass, 
 to prevent evaporation. 
 Note 
 
 a. The solid particles (corpuscles} floating in a fluid (plasma). 
 7 
 
8 
 
 b. The corpuscles are of two kinds : the more numerous 
 
 variety (red corpuscles) are of a pale yellow color, 
 (unless massed together when they appear reddish) 
 and float about freely ; the other variety (white cor- 
 puscles} are much less abundant, and tend to stick to 
 the glass. 
 
 c. As the red corpuscles float about, notice their form : seen 
 
 in full face they are circular, seen edgewise they are 
 somewhat of the shape of a finger-biscuit; careful ex- 
 amination will show that they are biconcave discs. 
 
 d. When a corpuscle is seen in full face, its centre will be 
 
 bright and its edge darker, or vice versa. This 
 depends on the central depression, in consequence of 
 which the corpuscle acts somewhat as a biconcave 
 lens, and rays of light passing through do not all 
 emerge parallel and reach the eyepiece. 
 
 e. Shortly after the blood has been drawn, the majority of the 
 
 red corpuscles adhere by their broad sides and form 
 rows, the so-called rouleaux. 
 
 f. The white corpuscles slowly change their form : sketch the 
 
 outlines of one at intervals of fifteen seconds. If 
 necessary, the demonstrator will heat the specimen on 
 a warm stage so as to promote the movements. 
 
 g. After a time the rouleaux break up and the corpuscles float 
 
 freely again. 
 
 h. Finally, fine threads of fibrin may be seen stretching across 
 the microscopic field. 
 
 i. By this time probably, many of the red corpuscles will have 
 become puckered or crenate. 
 
 Draw red corpuscles as seen in various aspects 
 while floating ; also in rouleaux. Draw several white cor- 
 puscles to illustrate the various shapes they assume. 
 
2. Treat a fresh-drawn drop of blood with a little dilute acetic acid, 
 run in under the cover-slip. The red corpuscles swell up and 
 become spheres instead of discs, and finally the coloured portion 
 (hcE)tio-globin} is discharged into the surrounding fluid, and only the 
 colorless framework (stro/na) of the corpuscles is left ; finally, the 
 stroma also disappears. 
 
 3. Examine blood of frog or newt. Draw. 
 Note as regards the red corpuscles 
 
 a. Their size : they are considerably larger than the human 
 
 red corpuscles. 
 
 b. Their form : seen in front they are oval, and about twice as 
 
 long as broad ; seen edgewise they are linear, with a 
 slight bulging about the centre. Observe the ap- 
 parent form in intermediate positions. 
 
 c. Their structure : at first apparently homogeneous pale 
 
 yellow bodies, a central portion (nucleus), different 
 from the rest, soon becomes visible in them. 
 
 [d. Treat your specimen with magenta ; the nucleus will 
 become deeply stained : no such body can be stained 
 in the mammalian red corpuscle.] 
 
 4. Examine the colorless corpuscles carefully. They exhibit more 
 active movements at the temperature of the room than the corres- 
 ponding human corpuscles usually do. Sketch the outline of one 
 at intervals of fifteen seconds. 
 
 5. Treat a drop of newt's blood with acetic acid : the red corpuscles 
 swell up and lose their coloring matter ; their nuclei and those of 
 the colorless corpuscles become conspicuous. 
 
 [6. Examine specimens of various bloods, as that of rabbit, dog, 
 bird, &c.] 
 
 9 S* 0? THR 
 
 UHI7BRSITY 
 
10 
 
 7. Watch the process of coagulation of fresh-drawn blood : at first 
 perfectly liquid, it gradually becomes viscous, then sets into a jelly 
 adhering to the bottom and sides of the containing vessel ; next 
 follows the pressing out of the first few drops of serum on the top of 
 the gelatinised mass and the "cupping" of the latter; finally, the 
 contraction of the mass in every direction, while more serum passes 
 out, until the clot floats quite free in a considerable quantity of 
 liquid. 
 
 8. Note the " buffy coat" on the clot exhibited by the demonstrator. 
 
 9. Whip some fresh-drawn blood, collect the fibrin, wash and ex- 
 amine it : its color, extensibility and elasticity. 
 
 10. Examine blood kept from coagulating by large quantities of 
 neutral salts. Note that it clots on dilution. 
 
 1 1. Prepare artificial clot by mixing pericardiac fluid and blood-serum. 
 
 12. Examine the fibrinogen and fibrino-plastin exhibited by the 
 demonstrator, and the clot obtained by mixing solution of the 
 former with serum and of the latter with pericardiac fluid. 
 
 [13. Examine crystals of Hce mo-glob in, the so-called blood crystals.] 
 
 [14. Examine a drop of lymph under the microscope. Note in it the 
 corpuscles floating in a plasma : all like the colorless blood 
 corpuscles.] 
 
 III. 
 
 ANATOMY OF THE SHEEP'S HEART. 
 
 In the following directions " dorsal" means the side of the heart 
 naturally turned towards the vertebral column; "ventral" the side 
 next the breast bone; " right " and " left " refer to the proper right and 
 
 10 
 
II 
 
 left of the heart when in its natural position in the body; "upper" 
 means more towards the head in the natural position of the parts; 
 and "lower" the part turned away from the head. 
 
 1. Take the sheep's heart and /ww^j provided for you; lay them on 
 their dorsal sides with the windpipe turned away from you, and 
 arrange them in their natural relative positions. Note the loose bag 
 {pericardium] in which the heart lies, and the bit of midriff 
 {diaphragm} which has been left attached to it. 
 
 2. Carefully dissecting away adherent fat, &c., trace the vessels 
 named below until they enter the pericardium. Be very careful not 
 to cut the veins, which, being thin, collapse when empty, and may 
 be easily overlooked until injured : as each vein is dissected out, stuff 
 it with cotton wool. When all the vessels have been prepared, 
 draw them. 
 
 a. The vena cava inferior: find it on the under (abdominal) 
 side of the diaphragm ; thence follow it through the tendinous 
 part of that organ until it enters the pericardium, about three 
 inches further up : to follow it in this part of its course, turn the 
 right lung towards your left and the heart towards your right. 
 
 The vein just below the diaphragm will be seen to receive 
 several large vessels, the hepatic veins. 
 
 As it passes through the midriff, two veins from that organ 
 enter it. 
 
 Between diaphragm and pericardium it receives no branch, 
 but lying on its left side will be seen the lower end of the 
 right phrenic nerve, ending below in several branches to the 
 diaphragm. 
 
 b. Superior vena cava : seek its lower end, entering the pericar- 
 dium about one inch above the entry of the inferior cava ; 
 trace it up to the point where it has been cut across, stuff and 
 clean it. 
 
 c. Between the ends of the two venae cavas will be seen the two 
 ; -igli t pulm o nary veins, proceeding from the lung and entering 
 the pericardium ; clean and stuff them. 
 
 ii 
 
12 
 
 3. Turn the right lung and heart back into their natural positions ; 
 clean away the loose fat in front of the pericardium, and seek and 
 clean the following vessels in the mass of tissue lying above the 
 heart, and on the ventral side of the windpipe. 
 
 a. The aorta : immediately on leaving the pericardium, this 
 vessel gives off a large branch ; it then arches back and runs 
 down behind the heart and lungs, giving off numerous 
 branches on its way. 
 
 b. The pulmonary artery : this will be found imbedded in fat 
 on the dorsal side of the aorta. After a course, outside the 
 pericardium, of about an inch, it ends by dividing into two 
 large branches (right and left pulmonary arteries,) which sub- 
 divide into smaller vessels as they enter the lungs. Notice 
 the obliterated vessel (ligamentum arteriosum} passing from 
 the undivided pulmonary trunk to the under side of the aortic 
 arch. 
 
 c. Observe the thickness and firmness of the arterial walls as 
 
 compared with those of the veins ; they stand out without 
 being stuffed. 
 
 4. Notice on the ventral side of the left pulmonary artery, the left 
 
 pulmonary veins passing from the lung into the pericardium. 
 
 5. Clean away fat, &c., from the windpipe (trachea], and make out the 
 
 entrances of its subdivisions (bronchi] into the lungs. 
 
 6. Slit open the pericardiac bag, and note its smooth, moist, glistening 
 
 inner surface, and the similar character of the outer surface 
 of the heart. Cut away the pericardium carefully from the 
 entrances of the various vessels which you have already traced 
 to it. As this is done, you will notice that inside the peri- 
 cardium the pulmonary artery lies on the ventral side of the aorta. 
 
 12 
 
13 
 
 7. Note the general form of the heart that of a cone with its apex 
 
 turned towards the diaphragm. Very carefully dissect out the 
 entry of the pulmonary veins into the heart. It will probably 
 seem as if the right pulmonary veins and the inferior cava opened 
 into the same portion of the organ, but it will be seen subsequently 
 that such is not really the case. Note on the exterior of the 
 organ the following points : 
 
 a. Its upper flabby auricular portion into which the veins open, 
 and its denser lower ventricular part. 
 
 b. Running around the top of the ventricles is a band of fat, an 
 offshoot of which runs obliquely down the front of the heart, 
 passing to the proper right of its apex, and indicating exter- 
 nally the position of the internal partition which separates 
 the right ventricle, which does not reach the apex of the 
 heart, from the left, which does. 
 
 c. Note the fleshy "auricular appendages " one (left] appear- 
 ing below the pulmonary artery ; the other (right} between 
 the aorta and superior cava. 
 
 d. Placing the heart and its vessels as nearly as you can in their 
 natural positions, sketch them as seen from the front. 
 
 8. Dissect away very carefully the collection of fat around the origins 
 
 of the great arterial trunks and that around the base of the 
 ventricles. In the fat will be found 
 
 a. A coronary artery arising from the aorta close to the heart, 
 opposite the right border of the pulmonary artery ; it gives 
 off some branches to the auricles, and then runs down the 
 heart behind the ventricles. 
 
 b. The other coronary artery considerably larger, arises from the 
 aorta behind the pulmonary artery, and is distributed also, 
 to both auricles and ventricles. 
 
 c. The coronary veins and sitius: small coronary veins will be 
 seen accompanying the arteries : for the coronary sinus see 
 hereafter (9. c.} 
 
 13 
 
14 
 
 9. Open the right ventricle by passing the blade of a scalpel through 
 
 the heart about an inch from the upper border of the ventricle 
 and on the right of the band of fat marking externally the limits 
 of the ventricles, and noted above (7. <5), and then cut down 
 towards the apex, keeping on the right of this line : cut off the 
 pulmonary artery about an inch above its origin from the heart, 
 and open the right auricle by cutting a bit out of its wall, to the 
 right of the entrances of the venae cavae. By raising up by its 
 point the wedge-shaped flap cut from the wall of the ventricle, the 
 cavity of -the latter will be exposed. 
 
 a. Pass the handle of a scalpel from the ventricle into the 
 auricle ; and also from the ventricle into the pulmonary artery, 
 and make out thoroughly the relations of these openings. 
 
 b. Slit open the auricular appendage : note the fleshy projections 
 (cohimncE carnece] on its walls, and the smoothness of the rest 
 of the interior of the auricle. Observe the apertures of the 
 vence cavce, and make sure that the pulmonary veins do not 
 open into this auricle. 
 
 c. Behind or below the entrance of the inferior cava, note the 
 entrance of the coronary sinus : pass a probe through the 
 aperture along the sinus and slit it open : notice the muscular 
 layer covering it in. 
 
 10. Raise up by its apex the flap cut out of the ventricular wall, and 
 if necessary prolong the cuts more towards the base of the ven- 
 tricle until the divisions of the tricuspid valve come into view. 
 
 a. Note the columnae carneae on the wall of the ventricle, and 
 the muscular band stretching across its cavity. Also the 
 prolongation (conns arteriosns} of the ventricular cavity 
 towards the aperture of the pulmonary artery. 
 
 b. Cut away the right auricle and examine carefully the tricuspid 
 valve: composed of three membranous flexible flaps, thin- 
 ning away towards their free edges, at present turned towards 
 the ventricle : proceeding from near these edges are strong 
 
tendinous cords (chorda tendinece] which are attached at their 
 other ends to muscular elevations (papillary muscles] of the 
 wall of the ventricle. Draw one of the flaps with its cords 
 and papillary muscle. 
 
 c. Slit up the conus arteriosus until the origin of the pulmonary 
 artery comes into view. Looking carefully for the flaps of 
 the semilunar valves, prolong your cut between two of them 
 so as to open the bit of pulmonary artery still attached to the 
 heart. Spread out the artery and examine the valves. Draw 
 them. 
 
 d. Each flap makes, with the wall of the artery, a pouch, oppo- 
 site which the arterial wall is slightly dilated. The free 
 edge of the valve is turned from the heart, and has in its 
 middle a little nodule (corpus Aurantii.} 
 
 ii. Open the left ventricle in a manner similar to that employed for 
 the right. Then open the left auricle by cutting a bit out of its 
 wall above the appendage. Cut the aorta off about half an inch 
 above its origin from the heart. The aperture between left 
 auricle and left ventricle can now be examined ; also the passage 
 from the ventricle into the aorta, and the entry of the pulmonary 
 veins into the auricle ; and the septuui between the auricles and 
 that between the ventricles. 
 
 a. Pass the handle of a scalpel from the ventricle into the 
 auricle ; another from the ventricle into the aorta : and pass 
 also probes into the points of entrance of the pulmonary 
 veins. Observe that no other veins open into this auricle. 
 
 b. Slit open the auricular appendage : note the fleshy projections 
 
 (columncs carnece] on its interior, and the general smooth- 
 ness of the rest of the inner wall of the auricle. Notice the 
 coluiiDice carnece over the inner surface of the ventricular 
 wall : also the considerable thickness of the latter, as com- 
 pared with that of the right ventricle or of either of the 
 auricles. 
 
 15 
 
i6 
 
 c. Carefully raise the wedge-shaped flap of the ventricle and cut 
 on towards the base of the heart, until the valve (mitral] 
 between auricle and ventricle is brought into view : one of 
 its two flaps will be seen to lie between the auriculo-ventric- 
 ular opening and the origin of the aorta. 
 
 Examine in these flaps their texture, the chordae tendineae, 
 the columnae carneae, &c., as in the case of the right side 
 of the heart (10.) 
 
 d. Examine in situ the semilunar valves at the exit of the aorta ; 
 then cutting up carefully between two of them, examine the 
 bit of aorta still left attached to the heart, and examine the 
 valves more carefully as described in 10. d. Note the origins 
 of the coronary arteries in two of the three dilatations (sinuses 
 of Valsalva] of the aortic wall above the semilunar flaps. 
 
 12. Study, with the assistance of demonstrator, the action of the valves 
 in the dead heart. 
 
 IV. 
 
 STRUCTURE OF BLOOD VESSELS. BEAT OF THE HEART. 
 
 1. Examine the piece of artery provided for you ; note that, although 
 
 empty, it does not collapse ; the thickness of its wall ; its 
 elasticity in all directions. 
 
 2. Examine with your microscope, and sketch 
 
 a. The prepared transverse sections of arterial wall ; note 
 
 the three primary coats entering into its structure. 
 
 b. The specimen prepared to show the epithelial cells 
 
 lining the interior of an artery. 
 
 3. Note in the vein provided for you ; its collapsed state and the 
 
 thinness and flaccidity of its wall compared with the arterial ; 
 its slighter elasticity. Observe, however, that the differences 
 between these smaller arteries and veins are much less marked 
 than those between the great arteries and veins in the neigh- 
 borhood of the heart, which you examined last week. 
 
 16 
 
17 
 
 4. Cut the vein open : examine and sketch its valves. 
 
 5. Examine with your microscope (Oc. 4, Obj. A) the prepared speci- 
 
 men of pia water : note the nuclei of the transverse muscular 
 cells of the arteries (sometimes the outlines of the individual 
 contractile fibre cells can be seen): the capillaries into which the 
 arteries break up ; the thin walls of these capillaries, on which 
 here and there, however, a nucleus may be seen. Draw a bit 
 of one of the arteries and a portion of the capillary network. 
 
 [6. Examine injected specimens showing the arrangement of the 
 capillaries in various tissues.] 
 
 7. Take the frog provided for you : it has, while under the influence 
 of chloroform, had its brain and spinal cord destroyed. Laying 
 the animal on its back, carefully divide with scissors the skin 
 along the middle line of the ventral surface for its whole length. 
 Make cross cuts at each end of this longitudinal one and pin out 
 the flaps of skin. 
 
 Next pick up with your forceps the tissues forming the 
 remainder of the ventral wall near its posterior end. and care- 
 fully divide them longitudinally a little on the left side of the 
 middle line ; being very careful not to injure either the viscera in 
 the cavity beneath or a large vein (anterior abdominal] running 
 along the wall in the middle line. 
 
 About the point where you see this vein turning away from 
 the wall to enter among the viscera in the ventral cavity, you 
 will come to the bony and cartilaginous tissues of the sternal 
 region. Raise the posterior cartilage in your forceps, make a short 
 transverse cut in front of the vein and, looking beneath the 
 sternum, note the pericardium with the heart beating inside it. 
 Divide the fibrous bands which pass from the pericardium to the 
 sternum, and with your larger pair of scissors divide the latter 
 along the median line. 
 
 Commencing at your short transverse cut, make a longitudinal 
 incision extending backwards a little on the right of the middle 
 line, so as to leave the anterior abdominal vein intact with a 
 
 17 
 
i8 
 
 narrow strip of the belly wall over it ; make cross cuts at the 
 ends of the longitudinal ones, and pin out the flaps on each side. 
 Cut away entirely the halves of the sternum, taking great care 
 not to injure the vessels beneath. 
 
 Push a piece of glass tubing down the animal's throat so as 
 to stretch the parts, and picking up the pericardium in your 
 forceps, open it and gently cut it away from about the heart ; 
 push aside any. lobes of the liver which lie on the latter organ. 
 In the heart thus exposed, note 
 
 a. Its beat / a regularly alternating contraction [systole] 
 and dilatation (diastole}. 
 
 b. In consequence of the destruction of the spinal cord 
 comparatively little blood now flows through the heart, 
 but during the contraction you will be able to observe 
 that the ventricular portion, which will be readily 
 recognized, becomes paler; and during diastole again 
 becomes deeply colored, getting more or less filled up 
 with blood which shows through its walls. 
 
 c. Observe that each contraction starts at the auricular end 
 
 and travels towards the ventricular ; this may be more 
 easily seen by-and-bye when the heart begins to beat 
 more slowly. 
 
 The frog's heart differs in certain structural points from that of the 
 sheep. Some of these may be noted as follows : 
 
 a. Passing a blunt hook carefully beneath the ventricle, 
 raise it up. Beneath it will be seen a pulsating por- 
 tion of the heart (sinus venosus}, not separately recog- 
 nizable in the sheep's heart. This cavity receives the 
 venous blood from the systemic circulation and 
 transmits it to the right auricle ; notice opening into it, 
 at its posterior end, the inferior vena cava, and on each 
 side a vein which, roughly speaking, answers to a 
 superior vena cava. 
 18 
 
19 
 
 b. Returning the ventricular portion of the heart to its 
 
 natural position, observe that from it a distinct aorta and 
 pulmonary artery do not arise, but instead a pulsating 
 sac (bulb us arteriosus) which lies in front of the 
 auricles. 
 
 c. A short way from the heart this sac divides into two 
 
 main arterial stems, the right and left aortic arches, 
 each of which soon divides into three vessels. Observe 
 these branches in the prepared specimen, and then 
 carefully clean them in your own. The most anterior 
 (carotid trunk] ends in a small red or black body, from 
 which vessels arise which supply the head. The next 
 (aortic arch proper] after giving off a branch which 
 supplies the fore limb on its own side, runs back to 
 beneath the vertebral column, where it joins its fellow 
 to form the dorsal aorta. The third (pulmono-cutaue- 
 ous] first gives off a branch which runs to the skin of the 
 dorsal region, and then enters the lung on its own side. 
 
 d. Opening into the left auricle is a pulmonary vein, 
 formed by the union of the single pulmonary veins 
 from each lung. 
 
 \e. Make a transverse section of the main aortic stem 
 which has been imbedded in paraffin mixture (Paraffin 
 2 parts, Vaseline I part) ; transfer your section to a 
 slide, dissolve away the excess of paraffin with carbolic 
 acid and turpentine, and examine with Oc. 2, Obj. A. 
 Observe that the arch is subdivided by partitions into 
 three channels, answering to the three trunks into 
 which it ultimately divides.] 
 
 <?ote that each beat of the heart commences with a contraction of 
 the sinus venosus, and that this is followed in order by con- 
 traction of the auricles, the ventricle, and the arterial bulb. 
 
 )raw the heart and main vessels as seen from the ventral side. 
 
 19 
 
20 
 
 11. Divide the vessels passing to or from the heart at a short distance 
 from the organ. Take one of the aortic arches in a pair of 
 forceps, and raising the heart, divide any remaining bands 
 which attach it to the rest of the body, and transfer it to a clean 
 microscope slide. Observe that it still continues to beat ; if the 
 beat stop at first, it will be resumed in a few seconds. 
 
 12. With a clean sharp razor divide the heart across the middle of the 
 ventricle and examine the interior of the latter. It is not 
 divided into two distinct chambers, but is spongy, containing 
 numerous intercommunicating cavities. 
 
 [13. Examine the prepared specimen which shows the partition be- 
 tween the two auricles. 
 
 14. With your razor cut the upper portion of the divided heart into 
 a number of pieces. ISfote that many of these still continue to 
 beat, or recommence beating after a short time, and that when 
 the spontaneous beat has ceased, a contraction can be excited in 
 many of them by a gentle prick with a microscope needle. 
 
 [15. Examine the specimen which has been prepared to show the 
 nerve cells in the partition between the auricles.] 
 
 16. Observe, with the assistance of the demonstrator, the beat of the 
 heart in the narcotized rabbit, the chest of which has been 
 opened, and in which artificial respiration is kept up. Note 
 
 a. The rhythmically alternating contractions and dilata- 
 
 tions. 
 
 b. Endeavor to make out that the auricular systole just 
 precedes the ventricular ; this becomes easier to ob- 
 serve as the heart begins to beat slower. 
 
 c. Observe that both sides of the heart work synchronously: 
 
 both auricles contract together and both ventricles 
 together. 
 
 d. Gently take the ventricular portion of the heart between 
 your finger and thumb. Feel how it hardens and 
 forcibly takes its new form during the systole. 
 
 20 
 
21 
 
 V. 
 THE CIRCULATION OF THE BLOOD. 
 
 Take the frog provided for you, which has been narcotized by 
 chloral, and lay it, belly downwards, upon the frog-board. 
 Gently tie strings around the two middle toes, and passing them 
 through the slits in the board, spread out the web between the 
 two toes over the V-shaped notch in the board. Be very 
 careful not to stretch the web. Put a piece of wet blotting 
 paper over the back of the animal, and place the board on the 
 microscope stage so that the spread-out part of the web is over 
 the aperture. Examine with Oc. 2, Obj. A. Notice 
 
 a. The skin with the pigment cells in it these may be 
 contracted into little very l>lack patches or be expanded 
 and less deeplv colored ; then focus through the skin 
 and make out 
 
 b. The arteries, in which the blood flows faster than 
 
 elsewhere, and from larger to smaller vessels, and in 
 which the flow has for the most part a direction 
 towards the free edge of the web. 
 
 c. The capillaries, receiving the blood from the arteries 
 
 and forming a network in which all the vessels are of 
 about the same size, so that there is no alteration in 
 diameter at the points of division, as in the arteries 
 which become smaller as they branch. 
 
 ff. The veins, which arise by the union of cipillaries, and 
 in which the flow is from smaller to larger branches, 
 and on the whole slower than in the arteries but faster 
 than in the capillaries. 
 
 e. In the larger arteries in view the flow may not be quite 
 continuous, but present rhythmic accelerations corres- 
 ponding to the beats of the heart ; but if the web has 
 been properly spread out and the heart is acting 
 21 
 
22 
 
 vigorously, the flow will be quite continuous in the 
 smallest arteries, as also in the capillaries and veins 
 
 2. Put on your Oc. 4, and note 
 
 a. That in the arteries and veins the blood flows faster in 
 the centre of the vessels than towards the sides, and 
 that all the red corpuscles are carried along in this 
 axial stream; while in immediate contact with the 
 vascular wall there is a layer (inert layer] in which the 
 flow is very slow, and where there are no red cor- 
 puscles, but where numerous white corpuscles will be 
 seen, getting along much more slowly than the cor- 
 puscles in the axial stream. 
 
 b. Observe attentively the circulation in the capillaries : 
 you will readily see evidences of the elasticity of the 
 red corpuscles ; they are frequently distorted by 
 mutual pressure ; or you may find one debouching 
 from the end of a capillary whence two others proceed 
 at about equal angles, pulled out to a great length by 
 the diverging currents until one or the other current 
 gets the better, and the corpuscle carried away by it 
 immediately resumes its normal form. 
 
 3. Sketch a portion of the vascular network. 
 
 4. Put on your Oc. 2 and Obj. D, and study more carefully the flow 
 
 in the capillaries. 
 
 5. Observe the circulation in the mesentery of the frog : there being 
 
 here a much smaller quantity of other tissues present to obscure 
 the view, the flow in the capillaries will be much better seen : 
 the axial stream and inert layer will also be more easily seen, 
 especially in the veins. However, inflammatory changes soon 
 supervene and interfere with the natural circulation. Having 
 finished with your frog, destroy its brain and spinal end to 
 prevent its returning to consciousness when the influence of 
 the chloral passes off. 
 
 22 
 
23 
 
 6. Study, with the assistance of the demonstrator, the outflow of 
 
 liquid which is injected intermittently into 
 
 a. A rigid tube with free exit. 
 
 b. A rigid tube with some resistance to the outflow. 
 
 c. An elastic tube with free exit. 
 
 d. An elastic tube with resistance to the outflow. 
 
 The outflow in a, b, c, will be intermittent ; in d, continuous, 
 but with slight accelerations at each stroke of the pump ; there- 
 fore an elastic tube, with resistance to the flow at one end, trans- 
 forms into a constant current an intermittent supply of liquid 
 pumped into its other end fast enough to keep its walls dis- 
 tended. 
 
 7. Study, with the assistance of. the demonstrator, the circulation in 
 
 the larger arterial scheme : observe the general arrangement 
 of the apparatus. 
 
 a. It consists of a pump by which water is intermittently 
 sent into an elastic tube, which with its branches 
 represents the arterial system. The branches end in 
 small tubes, blocked with sponge, which represent the 
 capillaries, and these open into larger tubes which 
 unite and represent the venous system, from which the 
 water finally passes out. There are also connections 
 by which the fluid can pass directly from the arterial 
 to the venous side without experiencing any capillary 
 resistance. 
 
 b. Connected with an arterial and a venous tube are 
 
 mercury pressure gauges which will indicate the pres- 
 sure of the fluid in the vessels connected with them, 
 and any alterations in this pressure. 
 
 c. On an arterial and on a venous tube are levers (pulse 
 
 levers) arranged so as to indicate any changes in the 
 diameters of the tubes. 
 23 
 
 *-*r 
 
 I7ERSITY 
 
24 
 
 $. Observe when the pump begins to work, the direct communica- 
 tions between the arterial and venous sides being open, that 
 with each stroke of the pump there is a sudden and great rise 
 of pressure in both arteries and veins, and that the pulse levers 
 on both are set in movement. Between each stroke of the 
 pump the pressure returns on both sides to its original level, 
 so that there is no steady " arterial pressure/' 
 
 9. When the direct communication is partly closer 1 , observe 
 that the pressure on the arterial side does not sink to zero 
 between each stroke of the pump, but as indicated by the 
 gauge some arterial pressure still remains in the intervals, 
 though greatly increased rhythmically with each stroke. At 
 the same time the pulse on the venous side becomes less 
 marked. 
 
 10. As the resistance to the flow from the arterial to the venous side 
 is increased by shutting off all the direct communications, and 
 making all the water pass through the sponge-blocked tubes, 
 the average arterial pressure rises, and each individual pulse 
 beat in the arteries is less marked. The pressure in the veins 
 does not rise, and the pulse beats there disappear entirely. 
 The state of things in the scheme now approximately repre- 
 sents that in the blood vessels of the body: there is a constant 
 high pressure on the arterial side, slightly increased (and 
 manifesting itself as the pulse) at each stroke of the supplying 
 pump. This pressure is maintained by two factors, the supply 
 from the pump and the resistance to the outflow presented by 
 internal friction in the smaller vessels. The distended elastic 
 tubes exert a continuous pressure on the fluid within them, and 
 drive it steadily through the smaller tubes and the larger ones 
 into which these again open. The intermittent beat is thus 
 transformed into a continuous squeeze, and so arises the steady 
 flow through arteries and veins and the absence of a pulse in 
 them. 
 
 24 
 
11. When the resistance to the flow from the arterial to the venous 
 
 side is still farther increased by completely occluding some of 
 the tubes representing capillaries, observe that the mean arterial 
 pressure rises higher, while the individual pulse beats become 
 still less marked. No change will be observed on the venous 
 side. 
 
 12. The resistance remaining the same, observe that with an increased 
 
 rapidity of the strokes of the pump, the mean arterial pressure 
 rises. 
 
 13. When the narrow mouthed glass tubes connected, one with a 
 
 branch on the arterial side and another with a branch on the 
 venous side, are opened, observe how the water spurts with 
 force out of the tube on the arterial, but flows out gentlv on 
 the venous side. 
 
 14. When colored liquid is introduced into the pump, observe that 
 
 the increase of pressure in the arteries following each stroke of 
 the pump (/. t\ the pulse wave) travels far faster than the 
 liquid ; the pulse lever rises very quickly after the stroke, but 
 it will not be until after several strokes that the colored fluid 
 (as seen in the intercalated piece of glass tubing) will reach the 
 neighborhood of the lever. 
 
 15. Repeat for yourselves the experiments with the arterial scheme. 
 
 VI. 
 
 SOME NERVES REGULATING T ^ E CIRCULATION OF THE BLOOD, EITHER 
 GENERALLY OR LOCALLY. 
 
 i. Spread out, upon its back, the dead rabbit provided for you ; fix 
 it by driving a tack through each paw. 
 
 Make an incision through the skin in the middle line from 
 the front of the lower jaw to the posterior part of the chest ; 
 make a cross cut at each end of this longitudinal one, and 
 reflect the flaps of skin thus marked out. 
 25 
 
26 
 
 2. In the middle line of the neck you can now see and feel, through 
 
 a thin covering, the trachea and larynx. On each side, a short 
 way behind the angle of the lower jaw, you will see the large 
 external jugular vein formed by the union of two veins (anterior 
 and posterior facial] from the head region. 
 
 Between the trachea and the external jugular vein, on each 
 side, you will see a muscle (sterno-mastoid} meeting its fel- 
 low in the middle line near the root of the neck, but diverging 
 from it further forwards. 
 
 3. Clear away carefully, on the left side, the thin muscular and con- 
 
 nective tissue \zyer (platysma myoides} through which the parts 
 above mentioned have hitherto been seen : take special care 
 not to prick the jugular vein and so get blood over your dis- 
 section ; if any small branch of the vein has to be cut, tie it 
 first. On the median border of the sterno-mastoid, opposite the 
 anterior part of the trachea, will now be seen another muscle 
 (sterno-hyoid} appearing between the sterno-mastoid and the 
 trachea. 
 
 4. Carefully separate the sterno-mastoid from the sterno-hyoid, 
 
 pulling the former outwards and tearing through the connective 
 tissue between the two muscles with the back of a scalpel. By 
 this means will be brought into view the common carotid artery 
 and certain nerves. 
 
 5. Divide the sterno-mastoid at its sternal attachment, and turn it 
 
 forward out of the way. Taking hold of the carotid artery in 
 your forceps, gently raise it, and carefully separate it from the 
 nerves and other adjacent tissues, from its entry into the neck 
 until it divides, opposite the angle of the lower jaw, into the 
 internal and external carotid arteries. Notice a small nerve 
 {superficial cervical} which crosses over the artery opposite 
 the posterior border of the larynx. 
 
 6. Trace the external carotid artery forwards : it soon divides into 
 
 several large branches. To see these it will be necessary to 
 26 
 
27 
 
 turn outwards the submaxillary gland, a soft roundish mass 
 about the size of a small hazel nut, lying inside the ramus of 
 the lower jaw near its angle. Especially trace out the branch 
 (external maxillary} of the external carotid which passes on to 
 the face, turning round the jawbone. As it passes the sub- 
 maxillary gland it gives off one or two branches to that organ. 
 Alongside these branches veins pass out of the gland and join 
 a trunk which ultimately opens into the anterior facial vein. 
 The slender duct of the gland will also be seen passing inwards 
 and forwards, and in the present position of the parts (with 
 the gland turned outwards), crossing over the external maxil- 
 lary artery The large hypoglossal nerve will also be seen 
 passing inwards across the divisions of the external carotid ; 
 and running parallel to the nerve, the tendon of the tnandibular 
 muscle, (anterior belly of the digastric of man.) 
 
 7. Trace back the carotid artery to the root of the neck until it 
 passes beneath the external jugular vein, or rather a branch 
 uniting that vein with its fellow across the middle line. 
 
 8. Next follow the pneumogastric nerve, which, taking the same 
 
 course along the neck as the artery did, will be readily recog- 
 nized by its whiteness and considerable size. The smaller, less 
 white nerve lying alongside the pneumogastric is the cervical 
 sympathetic; and running close beside the posterior half of 
 the cervical sympathetic is another still finer nerve, the 
 depressor, 
 
 9. Carefully dissect out the pneumogastric and its branches in the 
 
 neck, taking care not to injure the other nerves. 
 
 Shortly after appearing through an aperture in the base of 
 the skull, the nerve will be seen to be crossed by the hypo- 
 glossal : a little lower down it presents an oval enlargement 
 (ganglion nodosum}. 
 
 From thence the nerve runs down the neck, crossed by the 
 superficial cervical, and sending inwards a branch (superior 
 27 
 
2S 
 
 laryngeal] which arises at about opposite the point of division 
 of the common carotid artery and passes inwards beneath that 
 vessel. Just above this point some $mti\ pharyngeal brandies 
 may be seen to arise, but they are not of importance for our 
 present purpose. On the other hand great care must be taken 
 not to injure a very small branch (cardiac branch] which usually 
 is to be found arising from the nerve, a little farther back in the 
 neck than the superior laryngeal. 
 
 10. A small branch will be found arising from the superior laryngeal 
 nerve, close to the main pneumogastric trunk : it runs back in 
 the neck, and joining the cardiac branch of the pneumogastric 
 (when present), the two form the slender nerve (depressor 
 nerve} which runs down the neck alongside the sympathetic 
 trunk : very carefully separate it from this latter and trace it to 
 the root of the neck. 
 
 n. Taking the cervical sympathetic about the middle of its course 
 in your forceps, gently raise it and follow it forwards : near the 
 skull it will be seen to possess an elongated ganglion (superior 
 cervical ganglion], from which numerous branches are given 
 off. Follow the nerve back along the neck until it passes 
 beneath the external jugular vein. 
 
 12. Appearing in the neck external to the line of the pneumogastric 
 and sympathetic, will be seen the anterior primary branches of 
 the cervical spinal nerves. The superficial cervical nerve arises 
 from one of these. Arising from the hypoglossal trunk near 
 where it crosses the pneumogastric, will be seen the descending 
 branch, which is united by branches with the pneumogastric 
 and the superficial cervical. 
 
 13. Try and find an extremely fine nerve (chorda tympani] which 
 lies alongside the duct of the submaxillary gland. 
 
 14. Cut across the muscles passing from the chest towards the 
 shoulder on both sides, near their thoracic attachments, and 
 
 28 
 
2 9 
 
 turn them outwards. The arteries, veins and nerves passing 
 between the trunk and the fore limbs, will now be exposed ; also 
 the rudimentary collar-bones of the rabbit. Dissect out on the 
 left side the junction of the vein from the arm (subclai'ian} with 
 the external jugular. Pass two ligatures around the external 
 jugular close to its union with the subclavian, divide it between 
 the ligatures, turn it up out of the way, and dissect out a 
 ganglion (ganglion stellatum] which exists on the sympathetic 
 trunk at the bottom of the neck. 
 
 15. Make a diagram of the nerves of the neck; and draw the sub- 
 
 maxillary gland with its vessels, duct, and nerve. 
 
 16. Take hold of the front end of the sternum in your large forceps, 
 
 and raising it, cut through the muscles and rib cartilages on 
 each side of it : turning the breastbone backwards, cut it across 
 with your large scissors, just in front of the posterior boundary 
 of the chest cavity, and remove it entirely. Through the open- 
 ing thus made you will see the diaphragm, convex towards the 
 chest cavity and separating it from the abdomen. Attached to 
 the diaphragm is the pericardium, through which the heart can 
 be seen ; lying at the back of the cavity, on each side, will be 
 found a collapsed lung. Remove the chest wall, on both sides, 
 except about an inch next the vertebral column. The phrenic 
 nerves will now be seen running on each side from the neck to 
 the diaphragm. Pull the heart and left lung over to the right 
 side, and fix them there. Trace the trunk (left superior cava) 
 formed by the union of the left subclavian with the left external 
 jugular vein on toward the heart. Put two ligatures around 
 the subclavian vein near the shoulder, and divide it between 
 them : ligature and divide similarly the left superior cava near 
 the heart, and then cut away both these veins and dissect 
 out the origin of the phrenic nerve from some of the branches 
 of the cervical spinal nerves. Remove the thy mus gland lying 
 at the top of the chest in the middle line, and dissect out 
 29 
 
30 
 
 cautiously the left common carotid artery down to its origin 
 from the aotric arch. 
 
 17. Taking up the vagus (pneumogastric) where you left it at the 
 
 base of the neck, follow it down through the thoracic cavity : 
 opposite the lower border of the arch of the aorta it gives off a 
 branch, the inferiors* recurrent laryngeal nerve, which turns 
 back under the arch of the aorta. The main trunk passes on 
 behind the root of the lung, giving off some small bronchial 
 branches, and finally gets on to the gullet, along with which it 
 passes through the diaphragm. 
 
 1 8. Cut away the ligamentum arteriosiun, and dissect out the recur- 
 
 rent laryngeal nerve near its origin ; from it about that point 
 arise some small cardiac branches, which can be traced into the 
 tissue behind the heart : the farther course of the nerve, which 
 runs back to the larynx, need not now be followed. 
 
 19. Dissect out carefully the inferior cervical ganglion (ganglion 
 
 stellat^un) of the sympathetic : from it numerous branches will 
 be seen to arise, some of which pass in towards the heart; of 
 the others, one branch passes in front of, another behind the 
 subclavian artery, and the two unite beyond it to form the 
 commencement of the thoracic sympathetic cord : cut away 
 the subclavian artery and follow this cord down through the 
 chest, pushing the diaphragm down out of your way. 
 
 20. The thoracic sympathetic trunk, continuous in front with the 
 
 cervical, runs along the chest cavity, outside the pleura, a short 
 way from the bodies of the vertebras, and crossing the ribs near 
 their attachments to the vertebral column. Opposite each rib 
 the cord presents a ganglion : these ganglia are connected by 
 branches with the neighboring intercostal nerves. In the pos- 
 terior part of its course the nerve lies on the median side of the 
 psoas major muscle, which passes into the abdomen behind the 
 diaphragm. 
 
I. From the 8th, 9th, or loth thoracic ganglion, counting from the front, 
 notice that a nerve, the splanchnic, arises : running back, 
 it gets branches from the ganglia posterior to its origin, and 
 then passes into the abdominal cavity through the diaphragm 
 and close to the aorta. 
 
 22 Very carefully trace the depressor nerve into the tissue about 
 the base of the heart. 
 
 23. Having now learnt what to look for, repeat your dissection on 
 
 the right side of the neck and chest. The main difference you 
 will come across will be, that on this side the recurrent nerve 
 curls back around the subclavian artery, and not around the 
 arch of the aorta, and the common carotid and subclavian 
 arteries do not arise directly from the arch of the aorta, but are 
 formed by the bifurcation of a short common trunk, the innomi- 
 ery . 
 
 24. Divide the skin along the middle ventral line of the belly from 
 
 the thorax to the pelvis : make a cross cut at the posterior end 
 of this one, and reflect the flaps of skin. Now divide the 
 muscles of the belly wall similarly, taking care not to injure 
 the viscera in the cavity. Cut through the walls of the belly 
 on each side below the attachment of the diaphragm, from the 
 middle line in front to near the vertebral column, and reflect 
 the flaps thus formed. 
 
 25. Pushing the stomach, intestines and liver over to the left side, 
 
 trace the right splanchnic nerve into the abdomen, tearing 
 through any mesenteric folds which are in the way. The nerve 
 lies a little to right of the aorta and can be traced into a large 
 ganglion (upper cceliac ganglion} which lies in the mesentery : 
 from this ganglion and another (lower cceliac ganglion} near it, 
 numerous branches pass off, which unite the two ganglia and 
 radiate in the neighboring mesentery: most of them pass to 
 the abdominal viscera along the blood-vessels. The left 
 
32 
 
 splanchnic nerve enters the abdomen close on the left side of 
 the aorta ; its final distribution is much like that of the right. 
 
 26. Trace the two pneumogastrics along the gullet on to the 
 
 stomach, and then pass two ligatures around the gullet on the 
 abdominal side of the diaphragm, and divide it between the 
 ligatures. 
 
 27. Find the rectum in the pelvis, pass two ligatures around it and 
 
 divide it similarly. Raise up the liver and find on its under 
 (posterior) side the large portal vein entering it ; put two 
 ligatures around the vein and divide it between them. With 
 
 to 
 
 your scissors divide the thin membrane (mesentery) by which 
 the parts of the alimentary canal are slung, and then remove 
 the stomach and intestines en masse. 
 
 28. The kidneys will now be seen, with the duct (ureter) passing 
 
 back from each to the pelvis. Anterior to the kidneys and 
 nearer the middle line lie two whitish masses, the supra-renal 
 capsules. In the middle line will be seen the abdominal aorta 
 giving oft 1 " among others a branch (renal artery] to each kidney. 
 Alongside the aorta is the inferior vena cava which receives 
 the renal veins. 
 
 29. Tie the inferior vena cava with two ligatures close above the 
 
 diaphragm, and similarly a little way behind the liver. Divide 
 it between each pair of ligatures, and then, cutting through 
 any bands which attach the liver, remove it. Cut away the ring 
 of the body wall to which the diaphragm has been left attached, 
 except its dorsal fourth, and remove also all the diaphragm 
 except the portion of it near the vertebral column. 
 
 30. Now follow the sympathetic trunks down through the abdominal 
 
 cavity. They lie near the middle line at the back of the cavity, 
 and present ganglia at intervals as in the thorax. The two 
 trunks posteriorly become very slender, but by removing the 
 front of the pelvis, the rectum, and the urinary bladder, they 
 32 
 
33 
 
 may, with care, be traced until they unite in a single ganglion 
 in front of the third caudal vertebra. In their course the ganglia 
 on the nerves give off branches which run on the aorta and its 
 branches to the abdominal viscera, being united with numerous 
 accessory ganglia in the mesentery and elsewhere, but the 
 dissection of these fine branches is too difficult to be under- 
 taken in a class. 
 
 nonstration of blood pressure in the carotid artery. 
 
 1. Observe in the narcotized rabbit the pressure in the carotid 
 
 artery, as indicated by the mercury gauge connected with it. 
 
 2. Note the trace marked by the pen on the travelling paper: it in- 
 
 dicates that the pressure is not constant, but presents varia- 
 tions of two kinds : the slower variations agreeing in rhythm 
 with the respiratory movements ; the smaller (pulse waves) 
 and more numerous, with the beats of the heart. Measure the 
 average pressure as indicated by the mercury. 
 
 3. Note the chronograph, which marks seconds on the travelling 
 
 paper. 
 
 4. Note the lower pen which marks the line of no pressure. 
 
 Influence of the pneuinogastric nerve on the hearfs beaiand on the 
 blood pressure. 
 
 1. When both pneuinogastric nerves are divided, notice that the 
 
 pulse waves become more numerous in a given time, indicating 
 that the heart is beating more quickly. 
 
 2. When the distal end of one pneumogastric nerve is stimulated 
 
 feebly, notice that the heart's beats become slower, and the 
 olood pressure falls. 
 
 3. When the nerve is stimulated more strongly, notice that the 
 
 heart's beats, as indicated by the tracing, stop altogether for a 
 time, and the blood pressure falls very greatly and suddenly 
 almost to zero. 
 
 33 
 
34 
 
 4. When the heart begins to beat again, the blood pressure quickly 
 rises to quite, or a little more than, its original level. 
 
 Demonstration of the action of the pneumogastric nerve upon the 
 heart of the frog. 
 
 1. Observe the beat of the heart in the narcotized frog: it is 
 
 regular, and fairly powerful. 
 
 2. When the pneumogastric trunk on one side is directly stimulated, 
 
 observe that the heart ceases to beat for a short time. 
 
 3. When the intestines are smartly tapped in another frog, notice 
 
 that the heart also temporarily ceases to beat. 
 
 4. After the pneumogastric nerves of this second frog have been 
 
 divided, observe that the heart's beat is not affected by a blow- 
 on the intestines. 
 
 5. It can be shown by other experiments that the stimulus pro- 
 
 duced by striking the intestine travels into a part of the 
 sympathetic chain ; from there by some of the communicating 
 branches with the spinal nerves into the spinal cord, and along 
 it to the origin of the pneumogastrics in the brain, where it is 
 reflected down those nerves to the heart. 
 
 Demonstration on blood pressure as affected by the dilatation of the 
 arteries. 
 
 1. When the depressor nerve is divided in the neck of the chlor- 
 
 alized rabbit, notice that the blood pressure (in the great 
 majority of cases) remains unaffected. 
 
 2. When the central end of the nerve is stimulated, notice that 
 
 shortly the average blood pressure begins to fall ; gradually 
 diminishes to a certain level, and there remains constant, except 
 for the respiratory and pulse variations noted above. 
 
 3. When the stimulation of the nerve is stopped, notice that the 
 
 average blood pressure soon begins to rise, and slowly regains 
 
 its former level. 
 
 34 
 
35 
 
 4. It can be shown by other experiments, too complicated for de- 
 monstration here, that the fall of blood pressure on stimulation 
 of the depressor nerve is mainly due to a dilatation of the 
 arteries of the abdominal viscera, brought about through the 
 splanchnic nerves. 
 
 Demonstration on blood pressure as affected by increase of the re- 
 sistance to the flow through the arteries. 
 
 1. When the abdominal aorta of the chloralized rabbit is com- 
 
 pressed, notice that the mean blood pressure in the carotid, as 
 indicated by the arterial gauge, rises. This is due to the 
 greater resistance met with by blood in its flow, it now having 
 fewer arterial paths open to it than before. 
 
 2. As the pressure rises the heart beats slower : this can be shown 
 
 to be mainly a secondary effect, due to irritation of the central 
 ends of the pneumogastrics by the increased blood pressure in 
 the brain. 
 
 3. When the pressure is removed, the mean blood pressure returns 
 
 to its former level. 
 
 Demonstration on the vaso-motor nerves of the skin, 
 
 1. Notice in the narcotized rabbit that both its ears, when looked 
 
 through against the light, are about equally full of blood, and 
 that they both feel about equally warm to the touch. 
 
 2. After the sympathetic nerve has been divided on one side of the 
 
 neck, notice that the vessels of the ear on that side are (usually) 
 dilated and gorged with blood ; the whole ear is redder and feels 
 hotter than the other. 
 
 3. When the cephalic end of the cut sympathetic is stimulated, 
 
 notice that the arteries of the ear gradually contract, until 
 finally they allow little or no blood to pass, and the whole ear 
 becomes cold and very pale. 
 35 
 
36 
 
 4. When the stimulation is stopped, notice that the arteries soon 
 dilate, and the ear becomes again gorged with blood. 
 
 Demonstration on the vaso-motor nerves of a gland. 
 
 1. Notice in the narcotized animal that a glass tube has been passed 
 
 into the duct of the submaxillary gland. The saliva seen at 
 the bottom of the tube is not now rising in it, showing that the 
 gland is not secreting. 
 
 2. Another glass tube has been arranged to collect the blood 
 
 flowing out of the veins of the gland: at present it is small in 
 quantity and dark in color. 
 
 3. When the nerve of the gland is stimulated, notice that it begins 
 
 to secrete rapidly, and that the blood goes to it now in much 
 larger quantity, as indicated by the greater quantity passing 
 out through the vein, and by its brighter color. 
 
 4. The gland nerve contains fibres which excite its secreting cells 
 
 to activity, and also fibres which bring about a relaxation of 
 the walls of the artery supplying it, so that the working cells 
 get a greater blood supply. 
 
 Repetition of some of the above on the arterial schema. 
 
 1. Go to the arterial schema ; connect a mercury gauge, a float and 
 
 a pen, with a tube on the arterial side, and make the pen write 
 on a revolving cylinder. 
 
 2. Having got a regular pump stroke and a constant average 
 
 pressure, imitate (a] the effect of cutting the pneumogastric 
 nerves ; [b] the effect of stimulating the peripheral pneumo- 
 gastric feebly and strongly; (c} the effect of stimulating the 
 central end of the depressor nerve ; (d] the effect of compressing 
 the abdominal aorta. 
 
37 
 VII. 
 
 RESPIRATION. 
 
 1. Examine the prepared skeleton of the human thorax: formed by 
 the twelve dorsal vertebrae behind; the breast bone (sternum] in 
 front : and twelve ribs, with their cartilages, on each side. 
 
 2. The sternum is flattened dorso-ventrally, and consists (in the adult) 
 of three pieces: the upper piece (manubriuni} is wider than the 
 rest, and also thicker : to its sides are attached the cartilages of 
 the first pair of ribs ; above the attachment of each rib is a notch, 
 into which the ventral end of the collar bone of the same side was 
 originally articulated. 
 
 3. The middle segment or body of the sternum presents on its ventral 
 surface three transverse ridges, indicating the points of junction 
 of the separate pieces of which it originally consisted. To its 
 sides are attached the third, fourth, fifth and sixth rib cartilages on 
 each side, and at its point of junction with the manubrium the 
 second rib cartilage. 
 
 The remaining segment of the sternum (ensiform process, 
 xiphoid cartilage] is often incompletely ossified. To it no rib is 
 attached. 
 
 4. Examine the fifth rib : a slender, curved, elastic bone, presenting a 
 dorsal thickened extremity or capitulum, attached to the bodies of 
 the fourth and fifth dorsal vertebrae ; a little way from the head is 
 an enlargement (tubercle) attached to the transverse process of the 
 fifth dorsal vertebra. To the ventral end of the bony rib is at- 
 tached a rib cartilage, which continues the rib forwards, and is 
 fixed to the side of the body of the sternum. From the tubercle 
 the rib curves round to the cartilage ; the part where the curvature 
 is most marked being called the angle of the rib. Note the groove 
 on the under border of the rib, especially marked near the angle j 
 in this the intercostal vessels and nerves formerly lay. 
 
 37 
 
38 
 
 5. Compare the other ribs with the fifth and with one another. The 
 first rib is shorter and broader than the rest, and its head is 
 attached to only one (first dorsal) vertebra. On its upper surface 
 are roughnesses, marking the attachment of certain muscles 
 (middle and anterior sea lent}. From the first the ribs increase in 
 length to the eighth and then diminish again. The cartilages of 
 the sixth and seventh ribs are attached together to the sternum. 
 The eighth, ninth and tenth rib cartilages are not attached directly 
 to the sternum, but each to the rib cartilage above it. The cartilages 
 of the eleventh and twelfth (floating) ribs are not attached directly 
 or indirectly to the sternum. 
 
 6. The thorax as a whole is somewhat conical in form, being wider 
 below than above, and also from side to side than dorso-ventrally. 
 The ribs as a rule do not lie in a horizontal plane, but the middle 
 portion of each is at a lower level than a straight line joining the 
 two ends, and the ventral end is lower than the dorsal. 
 
 7. Observe that, by reason of the elasticity of the ribs, their mode of 
 articulation to the vertebral column, and the pliability of the rib 
 cartilages, a certain amount of movement is possible to each of 
 them, so that they (with the sternum) can be raised or lowered a 
 little on the vertebral column, and can rotate to a certain extent 
 around an axis joining their dorsal and ventral attachments. 
 
 8. Take the rabbit provided for you (from which the abdominal 
 viscera, except the liver and kidneys, have been removed), and 
 dissect away the skin from the front and sides of the neck and 
 chest; remove the platysma (VI. 3), and also a fibrous membrane 
 which covers the chest under the skin. 
 
 9. Divide at their sternal attachments and turn outwards, the muscles 
 now seen passing from the chest to the shoulder. The larger of 
 these, fan-shaped, is the pectoralis major ; the smaller (pectoralis 
 tennis], a ribband-like muscle lying along the anterior edge of 
 the great pectoral, is not a distinct muscle in man. The vessels 
 and nerves of the fore limb will now be seen passing outwards over 
 
 the border of the first rib. 
 
 38 
 
39 
 
 10. There will now be exposed on the chest- wall anteriorly the pectoralis 
 minor, like the great pectoral in shape but smaller : behind this is 
 seen another muscle (serratus anticus major), which arises by zig-zag 
 processes attached to the ribs, from the third to the ninth, at the 
 junction of the bones with the rib cartilage. I nterdigi taring with the 
 processes of the serratus, thoracic attachments of the descending 
 oblique muscle will be seen : divide all these muscles and turn them 
 out of the way. The external intercostal muscles will then be ex- 
 posed for the greater part of their course: but near the spinal 
 column they will be covered by another muscle, the longissimus 
 dorsi; in part also by the rhomboideus passing from the neck to 
 the scapula : also in front by the scalenus inedius. 
 
 1 1 . Divide and remove the sterno-mastoid and sterno-hyoid muscles 
 (VI. 3): also the sterno-thyroid. which arises on each side from the 
 back of the manubrium of the sternum along with the sterno-hyoid, 
 and passes thence forwards along the side of the trachea, to be 
 inserted into the thyroid cartilage. 
 
 12. Dissect out the muscles passing from the neck to the ribs: they 
 will be seen easiest first at their rib attachments ; the scalenus an- 
 ticus arises from the transverse processes of the cervical vertebrae 
 from the fourth to the seventh, and is inserted into the first rib, 
 near its cartilage ; the scalenus medius arises by a tendon from 
 the transverse process of the fifth cervical vertebra, and spreading 
 out below, is inserted into the third, fourth and fifth ribs; the 
 scalenus posticus, arising from the transverse processes of the 
 fourth, fifth and sixth cervical vertebrae, is inserted into the first rib. 
 
 13. Separate, in front of the larynx, the muscles and other organs 
 which occupy the space between the rami of the lower jaw. The hyoid 
 bone, to which the larynx is attached, will be thus brought into view. 
 
 14. Note the thyroid body lying on the sides of the trachea close to 
 the larynx : cut the wind-pipe across just beyond the thyroid body ; 
 and divide similarly the gullet, a muscular tube which will be found 
 lying immediately on the dorsal side of the wind-pipe. 
 
 39 
 
40 
 
 15. Open the rabbit's mouth as widely as possible, cutting through any 
 muscles, &c., which interfere with the separation of the jaws, and 
 then disarticulate or break the lower jaw, so as to get a good look 
 into the pharynx. 
 
 1 6. Pull the tongue forwards; at its root will be seen the tip of the 
 whitish epiglottis ; taking hold of it with your forceps, raise it and 
 pull it forwards ; the aperture of the glottis will then be seen ; a 
 probe passed down it comes out of the divided trachea lower down. 
 Pass another probe down the throat behind the glottis : it appears 
 through the divided gullet. 
 
 17. Examine the diaphragm from its exposed abdominal side: it is 
 concave towards the abdomen; tendinous and transparent in the 
 centre, allowing the lungs to be seen through it, but muscular and 
 somewhat less transparent on the sides, but still allowing the lungs 
 to be seen through it. Pull it down by taking hold of the suspen- 
 sory ligament of the liver, which is still attached to it ; as it moves, 
 observe that the lungs follow it closely, providing it has not been 
 injured. 
 
 1 8. Tie a piece of glass rod air-tight into the windpipe (to prevent 
 
 the lungs collapsing when the chest cavity is opened), and 
 examine more closely the external intercostal muscle in some 
 one of the intercostal spaces. Its fibres have a direction from 
 the posterior border of the rib which bounds the intercostal space 
 in front, backwards and ventrally to the anterior border of the 
 next rib ; it is absent between the rib cartilages. 
 
 19. The internal intercostal muscle, the fibres of which run from 
 
 each rib backwards and dorsally to the anterior border of the 
 next rib, is uncovered by the external between the rib car- 
 tilages ; farther back it may be exposed by carefully dissecting 
 away the external intercostal muscle ; at the same time the 
 intercostal nerve and vessels will be brought into view running 
 along the posterior border of the rib bounding the space in 
 
 front. 
 
 40 
 
41 
 
 20. If the internal intercostal muscle be very carefully dissected 
 
 away, the parietal layer of the pleura will be exposed with the 
 pink lung seen through it. 
 
 21. Now open the chest and cut away the ribs as directed in VI. 16. 
 
 On account of the stoppage of the windpipe the lungs cannot 
 collapse. Note again the phrenic nerve, and finally remove 
 together from the chest, the lungs, trachea and heart. 
 
 22. Remove the pleura near the spinal column on each side, and note 
 
 that the internal intercostal muscles are wanting there : by 
 careful removal of the dorsal portions of the external intercostal 
 muscles, the "elevators of the ribs " (levatores costarum) can 
 be brought into view : each is a small muscle arising from the 
 transverse process of a vertebra, and inserted upon the outer 
 surface of the rib belonging to the next vertebra, near its angle. 
 To see these muscles satisfactorily, they must, however, be 
 dissected out from the dorsal side- 
 
 23. Examine the trachea : note the horse-shoe shaped cartilages in 
 
 its walls, all arranged so that its posterior wall possesses no 
 cartilage. Cut it open below the glass rod ; observe that the 
 lungs immediately collapse ; note the moist, soft mucous 
 membrane lining it. 
 
 24. Posteriorly the trachea divides into the two bronchial which one 
 
 enters the root of each lung ; trace one as far as you can into 
 the lung, cutting away the soft parts. It divides into numerous 
 bronchial tubes (the cartilages in whose walls are so arranged 
 as to leave no side without any), which branch until the 
 branches become too fine to dissect out farther. 
 
 Draw the trachea, bronchi, the uninjured lung, and the bron- 
 chial tubes on the other side so far as you have dissected 
 them out. 
 
 25. Cut with your razor a thin section of the bronchial tube (of the 
 
 sheep) which has been imbedded for you in paraffin mixture ; 
 mount in glycerine and examine with Oc. 4, Obj. A. 
 
 IUJTIVBESITY: 
 
 * 
 
42 
 
 You will easily make out in it several layers : inside an epi- 
 thelial coat composed of elongated cells ; next a dense con- 
 nective tissue layer, the cutis of the mucous membrane ; then 
 a loose connective tissue layer, the submucous coat ; outside 
 this may be seen a denser layer which contains transversely 
 arranged plain muscular fibres ; and then another connective 
 tissue coat in which the cartilages are imbedded. - 
 
 26. Scrape off a few of the superficial cells from the inside of the 
 
 bronchial tube which has been preserved in osmic acid. 
 Mount in water and examine with Oc. 2, Obj. D. Observe the 
 elongated (columnar) cells, with a distinct oval nucleus : and a 
 number of fine processes (cilia] on the broader end of each cell. 
 
 27. Snip off a bit of fresh mucous membrane from inside the trachea 
 
 of a terrapin. Mount it in 0.75 per cent, salt solution, and 
 examine its edges with Oc. 2, Obj. D., until you see cilia in 
 movement. While they move fast only a shimmering border 
 will be seen, along which a current is kept up in a definite 
 direction in the neighboring fluid, as indicated by the blood 
 corpuscles, &c., swept along. As the cilia die and their move- 
 ments become slower individual cilia can be seen, and their 
 movement can be studied more closely. 
 
 28. Cut a thin section of the prepared lung which has been imbedded 
 
 for you. Mount in glycerine and examine with Oc. 2, Obj. A. 
 Note the smaller bronchial tubes, and between them, making 
 up the great bulk of the lung, the thin-walled polygonal cavities 
 or air cells. 
 
 29. Observe, with the assistance of the demonstrator, the circulation 
 
 of the blood in the lung of the frog. Note especially the 
 extremely close capillary network, far closer than that in the 
 web or mesentery. 
 
 30. Study with the assistance of the demonstrator the model illus- 
 
 trating the pressure relationships of the lungs and heart in the 
 chest cavity. 
 
 42 
 
43 
 
 A bell-jar has its bottom closed with a sheet of india rubber. 
 In its cavity lie two elastic bags, of which one is smaller than 
 the other, and has a somewhat thicker wall. 
 
 From the smaller bag a tube passes out air-tight through a 
 lateral opening in the bell-jar and dips under water. The bag 
 is also filled with water. 
 
 The larger bag has connected with it a tube which passes 
 air-tight through a hole in the cork which closes the neck of 
 the bell-jar, and by which the cavity of the bag communicates 
 freely with the external air. Through the cork passes another 
 tube (tube A), open at present, but which can be closed at 
 pleasure. 
 
 At present then the air presses directly through the tube A 
 on the outside of both bags ; it also presses directly on the 
 inside of the larger bag, and indirectly through the water on 
 the inside of the smaller bag. These pressures balancing one 
 another, both bags are now collapsed on account of their 
 elasticity. 
 
 As air is drawn out of A both bags dilate ; but the larger one 
 being more extensible, dilates more than the smaller. The 
 cause of the dilatation is that now the air is rarefied in the bell 
 jar, and so presses less on the outsides of the bags ; conse- 
 quently, the internal pressure is no longer balanced and dilates 
 the bags, air entering the larger and water the smaller. If the 
 tube A be now closed both bags remain dilated. 
 
 If now the india-rubber bottom of the bell-jar be pulled down 
 so as to enlarge its cavity, the air in it will be still more rarefied 
 and its pressure diminished, and both bags will again dilate, 
 air entering one and water the other; but, as before, the more 
 extensible bag dilates most. This represents an inspiration. If 
 the india-rubber be let go it returns to its former place and 
 both bags contract, driving out some of their contents ; this 
 represents an expiration. 
 
 43 
 
44 
 
 In the chest at rest the state of things in fact answers to 
 that in the bell-jar when the tube A was first closed, the lungs 
 answering to the more extensible bag, the heart to the less ex- 
 tensible, and the heart and lungs being in that state of exten- 
 sion at which equilibrium is produced between the pressure of 
 the air or blood in their cavities on the one hand, and the elas- 
 ticity of their walls and the pressure outside them on the 
 other ; but in the chest this outside pressure is not exerted, 
 as in the model, by remaining air, but by the walls of the 
 chest and the other organs with which the heart and lungs are in 
 contact. When the walls of the chest move so as to enlarge the 
 thoracic cavity, their pressure is removed or diminished, and 
 then lungs and heart are dilated by the pressure of the air 
 and blood in their cavities : but the lungs being far more 
 extensible than the heart, dilate much more ; as they dilate, 
 the air inside them is rarefied, and external air rushes in 
 through the trachea until equilibrium of pressure is produced 
 between the external air and that in the lungs, and so an in- 
 spiration is brought about : in expiration exactly the reverse 
 phenomena take place. 
 
 31. Examine fresh-drawn venous and arterial blood : observe the 
 
 dark purple red color of the former, and the bright scarlet red 
 color of the latter. Whip both specimens and set them aside : 
 notice that as the venous blood is whipped in contact with the 
 air it becomes brighter : but if left at rest for a time both 
 specimens become somewhat venous. 
 
 32. Pass a stream of carbonic anhydride through some whipped 
 
 blood which has been rendered arterial by shaking with air. 
 The bubbling of the carbonic anhydride through the blood 
 will (like the shaking) bring new portions of it constantly in 
 contact with the air, and the blood, though perhaps somewhat 
 changed, will still remain arterial in character. 
 
 44 
 
45 
 
 33- Add a small quantity of a reducing substance (Stokes' solution) 
 to arterialized blood, and mix with a gentle shake. Observe 
 that the blood very rapidly becomes venous in character ; 
 much more rapidly than when it was let stand without any 
 addition. Shake the mixture up briskly with air, it again is 
 arterialized ; let it stand at rest for a brief time, it again be- 
 comes venous. 
 
 34. Observe that all the above results can be obtained when 
 
 oxygen is substituted for air. 
 
 From the above we may conclude that contact with oxygen 
 converts venous blood into arterial : that contact with carbonic 
 anhydride will not convert arterial blood into venous : that 
 reducing agents will convert arterial blood into venous : that 
 blood removed from the body develops reducing substances. 
 The change of venous blood in the lung capillaries into arterial 
 depends then on the access of oxygen ; the change from arterial 
 to venous, in the systemic capillaries, upon the access of re- 
 ducing matters. 
 
 35. Observe, with the assistance of the demonstrator, that whipped 
 
 arterialized blood exposed in an air-pump to a gradually in- 
 creased vacuum at first gives off comparatively little gas, as in- 
 dicated by the bubbles arising from it, but that finally as the 
 vacuum approaches perfection it froths up and gives off a 
 large quantity. Notice that blood-serum under these circum- 
 stances gives off much less gas. We may conclude, there- 
 fore, that a large portion of the gas which can be obtained 
 from the blood by exposure to a vacuum is held by the red 
 corpuscles. 
 
 36. Examine with your microscope crystals of the coloring matter 
 
 (haemoglobin) of the red corpuscles. 
 
 37. Examine a watery solution of haemoglobin which has been 
 
 exposed to the air ; it is red, but not of so bright a tint as arterial 
 blood ; this depends on the fact that haemoglobin in solution 
 45 
 
4 6 
 
 reflects less light than when contained in the solid corpuscles. 
 Shake up some of your reducing solution ; it assumes a 
 darker color : shake it up again briskly with air ; it 
 again becomes bright in color. We may assume then that 
 the color of arterial blood depends on the fact that the haemo- 
 globin of its red corpuscles is combined with oxygen (forming 
 oxyhaemoglobin), while the color of venous blood depends on 
 the fact that more or less of the haemoglobin of the red 
 corpuscles has been deprived of its oxygen. 
 
 38. [Examine, with the assistance of the demonstrator, solution 
 
 of oxyhaemoglobin with the spectroscope or micro-spectroscope. 
 First notice the complete or continuous spectrum when 
 nothing is interposed between the source of light and the 
 instrument. Next introduce between the light and the lens of 
 the instrument a solution of oxyhaemoglobin : when this has a 
 certain concentration you will see all the original spectrum 
 except a portion of the blue end, and two bands near 
 one another about the green area of the spectrum, which are 
 dark and so make the series of colors discontinuous. The oxy- 
 haemoglobin therefore blocks or cuts off the rays of light which 
 formerly reached this part of the spectrum.] 
 
 39. [Examine similarly solution of reduced haemoglobin. Instead 
 
 of the two dark bands now is seen one rather broader and 
 with less denned margins, in a position about between that of 
 the oxyhaemoglobin bands.] 
 
 40. [Examine similarly the spectrum of the solution obtained by 
 
 diluting venous blood with water. It gives the spectrum of 
 oxyhasmoglobin, so that ordinary venous blood still contains a 
 considerable quantity of that substance ; enough in fact for its 
 two well denned absorption bands to conceal the presence of 
 the less marked absorption band of the reduced haemoglobin, 
 which lies on and near them.] 
 46 
 
47 
 
 41. [Examine similarly the absorption spectrum of the blood of 
 
 an asphyxiated animal : notice that it gives the absorption 
 bands of reduced haemoglobin. Under ordinary circumstances, 
 therefore, by no means all of the oxygen is removed from the 
 oxyhaemoglobin as the blood flows through the systemic 
 capillaries, but in death from suffocation all this oxygen is 
 used up.] 
 
 42. Draw air for a short time through some lime water: no notice- 
 
 able turbidity will be produced. Now blow air from your lungs 
 through the lime water for an equal time ; the lime water will 
 become distinctly turbid from a precipitate of calcic carbonate. 
 The air of the room then contains comparatively little carbonic 
 anhydride ; but that expired from the lungs contains a con- 
 siderable quantity. 
 
 43. Observe that a breathing animal gives off a considerable quantity 
 
 of carbonic anhydride and aqueous vapor from its lungs. 
 
 Notice the arrangement of the apparatus : at one end is a 
 water aspirator which draws air through the whole ; at the 
 opposite is a tube through which the air enters, and from 
 which it bubbles through bulbs containing solution of caustic 
 potash which takes all carbonic anhydride out of it ; it then 
 passes over bits of pumice stone wet with sulphuric acid, 
 which takes all water vapor out of it ; next it goes through 
 the bell-jar, connected air-tight with the trachea of the chloral- 
 ized rabbit, so that the animal breathes out of and into this jar. 
 The air from the bell-jar passes into a bulb surrounded by ice, 
 and then through bulbs containing baryta water, and so to the 
 aspirator. 
 
 When the apparatus has been at work some time, notice that 
 a considerable quantity of water has been condensed in the 
 cooled bulb, and that the baryta water has become turbid from 
 the precipitation of barytic carbonate. The animal then 
 breathing-in air containing neither water vapor nor carbonic 
 47 
 
4 8 
 
 anhydride, has imparted a considerable quantity of both these 
 substances to the air it expires. 
 
 44. Observe, with the assistance of the demonstrator, the chloral- 
 
 ized rabbit whose chest has been opened while artificial respira- 
 tion is kept up. Notice that the blood on the right side of the 
 heart, as seen through the thin-walled auricular appendage, is 
 venous ; while on the left side, as seen in the same way, it is 
 arterial. 
 
 When the artificial respiration is carried on very vigorously, 
 observe that the blood on both sides of the heart becomes 
 arterial in color. If the artificial respiration be now stopped, 
 observe that for a short time the animal makes no respiratory 
 movements, as seen on either nostrils, ribs or diaphragm. The 
 blood now contains so much oxygen that it does not stimulate 
 the respiratory centre from which the impulses proceed along 
 the various nerve-paths to excite contraction of the respiratory 
 muscles. 
 
 After a time, however, the oxygen in the blood getting partly 
 used up, the respiratory centre is again excited, and the 
 animal makes respiratory movements, though of course, its 
 thorax being open, these bring no air into its lungs. Soon, the 
 artificial respiration being still discontinued, the respiratory 
 movements become more and more violent, and at last general 
 convulsions supervene. Meanwhile the blood on the left side 
 of the heart becomes more and more venous ; the heart's beats 
 become feebler and finally irregular, and the right side of the 
 organ becomes gorged with blood. If the artificial respiration 
 be now resumed, before the heart has quite stopped beating* 
 things come back gradually to their original condition. 
 
 45. When the phrenic nerves are divided and the artificial res- 
 
 piration stopped until the animal becomes dyspnceic, observe 
 that the diaphragm no longer contracts when the ribs ascend ; it 
 may be pulled up and down a little by the movements of the 
 ribs, but its own muscular fibres do not contract. 
 48 
 
49 
 
 When either phrenic nerve is stimulated, observe that the 
 diaphragm contracts on that side ; when both are stimulated 
 the diaphragm contracts on both sides, becomes flatter towards 
 the chest, and pushes down the abdominal viscera : when the 
 stimulation is discontinued, observe that the latter push the 
 diaphragm up again. The diaphragm by its contractions, 
 therefore, enlarges the chest cavity, and its motor nerves are 
 the two phrenics. 
 
 VIII. 
 
 ALIMENTARY CANAL AND DIGESTION. 
 
 1. Lay the dead rat on its back, and fix it, if necessary, by driving 
 tacks through the paws. Remove the skin from the ventral sur- 
 face and sides of neck, chest and abdomen. 
 
 2. Note in the neck region the large salivary glands which meet in the 
 middle line : the posterior gland, close to the middle line, rounded 
 and compact, is the submaxillary : on raising it, its duct will be 
 seen passing forwards to the mouth, into which it may be followed 
 by separating the halves of the lower jaw. 
 
 3. The large gland, composed of several loosely united lobes, and 
 reaching from the neighborhood of the ear to the submaxillary, 
 is \\\t parotid. Its duct will be found passing forwards over the 
 face to the mouth, near the angle of which it passes in througli 
 the cheek muscles. 
 
 4. In front of the submaxillary will be found a small gland, the 
 sublingual. 
 
 5. Remove the muscles, &c., covering the larynx and trachea : cut 
 away the front and side walls of the chest and abdomen : remove 
 larynx, trachea, lungs and heart. 
 
 49 
 
50 
 
 6. The gullet, a slender muscular tube, will now be exposed in the 
 neck ; trace it through the chest : make a diagram of the 
 abdominal viscera as now exposed before displacing any of them ; 
 then turning the liver up out of the way, follow the gullet in 
 the abdomen until it ends in the stomach. 
 
 7. Note the form of the latter organ : its projection (fundus] to the 
 left of the entry of the gullet: \\sgreat and small curvatures: 
 its narrower pyloric portion on the right, from which the small 
 intestine proceeds. Attached to the stomach, and hanging down 
 over the other abdominal viscera, notice a thin membrane, the 
 omentum. 
 
 8. Follow on and unravel the coils of the small intestine, spreading 
 out as far as possible the delicate membrane (mesentery] which 
 slings it. In the mesentery are numerous bands of fat, running in 
 which will be seen blood-vessels and lacteals. 
 
 9. The small intestine ends by opening into the side of the large. 
 Observe the ccecum or blind end of the latter, projecting on one 
 side of the point of entry of the small intestine ; on the other 
 side follow the large intestine until it ends at the anal aperture, 
 cutting away the front of the pelvis to follow its terminal portion 
 (rectum}. The portion between the caecum and the rectum is the 
 colon. 
 
 lo. Spread out the portion of the mesentery lying in the concavity of 
 the first coil (duodenum] of the small intestine : lying in this 
 portion of mesentery will be seen a thin branched glandular mass, 
 the pancreas. 
 
 n. Observe the portal vein entering the under side of the liver by 
 several branches. Alongside it will be seen the gall duct, formed 
 by the union of two main branches, and proceeding, as a slender 
 tube, through the pancreas, to open into the duodenum about an 
 inch and a half from the pyloric orifice of the stomach. 
 
 12. Note the spleen: an elongated red body lying in the mesentery 
 behind and to the left of the stomach. 
 
 50 
 
13- Divide the gullet at the top of the neck, and the rectum close to 
 the anus, and dividing mesenteric bands, &c., by which inter- 
 mediate portions of the alimentary canal are fixed, remove the 
 whole tube ; then cutting away the mesentery, spread it out at full 
 length, and note the relative length and diameter of its various 
 parts. The whole is seven or eight times as long as the head 
 and trunk of the animal, and the small intestine forms by far the 
 greater part of it. 
 
 Make a diagram of the whole. 
 
 14. Open the stomach : note that the mucous membrane lining the 
 fundus is thin and smooth, and is sharply marked off from the 
 thick corrugated mucous membrane lining the rest of the organ. 
 Pass probes through the cardiac orifice into the gullet and 
 through the pyloric orifice into the duodenum. 
 
 15. Cut out a small portion of 'the preserved small intestine of the 
 dog, carefully open it in a little water in a watch-glass, and 
 examine its inner surface : observe the closely set projections 
 (villi} of the mucous membrane. 
 
 16. Open the large intestine opposite the point of entry of the small, 
 and examine the ileo-colic valve formed by folds of the mucous 
 membrane. Cut out a small bit of the preserved large intestine and 
 examine as above ; there are no villi, but the mucous membrane 
 presents numerous folds. 
 
 17. Remove the liver: note its general form; convex towards the 
 chest and concave or flattened posteriorly ; its lobes ; its dorsal 
 border rather thicker than the ventral. 
 
 1 8. Cut sections from the stomach which has been imbedded for you ; 
 mount in glycerine and examine with a low power. Note in it 
 four distinct layers : externally a thin connective tissue peritoneal 
 coat ; then a much thicker muscular coat arranged in two or more 
 layers : inside this a loose connective tissue submucous coat con- 
 taining numerous blood-vessels : inside, the folded mucous mem- 
 brane almost entirely composed of closely set tubular glands. 
 Draw your section. 
 
52 
 
 19 Prepare and examine similarly sections of small intestine. The 
 same four coats will be seen, but the mucous membrane is raised 
 up into numerous villi, between the bases of which lie the 
 mouths of the glands. Draw. 
 
 20. Examine prepared specimens of small intestine in which the 
 
 lacteals and blood-vessels have been injected with different 
 colors. 
 
 21. Prepare and examine sections of large intestine : the villi are 
 absent. 
 
 Put on your objective D and examine the epithelial cells lining 
 the glands and the membrane between their orifices : they are 
 elongated (columnar] and nucleated, and arranged in a single 
 layer. Draw. 
 
 22. Scrape gently the surface of the piece of liver which has been 
 preserved in bichromate of potash. Mount your scrapings in a 
 little water and examine with Oc. 2, Obj. D. Note the poly- 
 hedral granular nucleated hepatic cells. They are not flat like 
 the blood corpuscles, for as they float about no edge is exposed. 
 Draw. 
 
 23. Cut and mount in glycerine sections of the imbedded liver ; 
 
 examine with Oc. 2, Obj. A. Note that the hepatic cells are 
 collected into masses or lobules, separated more or less distinctly 
 from neighboring lobules by connective tissue and vessels. In 
 each lobule the cells have an imperfect radial arrangement. Draw. 
 
 24. Examine the prepared specimens of injected liver. Note the in- 
 terlobular vessels ; the capillary lobular plexus, the vessels of 
 which converge to a vessel, the intralobular vein, in the centre : 
 also the hepatic cells indistinctly seen lying in the meshes of the 
 lobular plexus. 
 
 25. Observe that solution of grape-sugar warmed with Fehling's 
 solution (cupric oxide dissolved in excess of caustic potash in 
 the presence of a tartrate) causes a reddish or yellow precipitate of 
 
 cuprous oxide or its hydrate. 
 
 52 
 

 53 
 
 26. Observe that fresh starch emulsion, warmed with Fehling's 
 solution, gives no precipitate, nor does filtered saliva. 
 
 27. Add a little saliva to some of the starch emulsion and place in 
 the warm chamber for a few minutes : now test with the Feh- 
 ling's solution: an abundant precipitate of cuprous oxide will be 
 formed. 
 
 28. Observe that solution of any proteid. as egg albumen or serum 
 albumen, boiled with Millon's reagent, gives a pink precipitate. 
 Also, that boiled with excess of strong nitric acid it forms a 
 yellow solution, which becomes orange on the addition of am- 
 monia (xantho-proteic reaction}. 
 
 29. Observe that these proteids do not dialyse : after two or three 
 hours the distilled water outside the dialyser (which contains the 
 proteid solution) gives no trace of either of the above (28) 
 reactions. 
 
 30. Examine the prepared peptone : a whitish amorphous substance 
 readily soluble in water. Note that its solution gives the above 
 (28) proteid reactions. Observe that it dialyses readily: when 
 some of its solution is placed in a dialyser, the distilled water 
 outside, after an hour or two, gives distinctly those proteid 
 reactions. 
 
 31. Examine the artificial gastric digestions which are going on in 
 the warm chamber. 
 
 32. Shake up some olive oil with some fresh ox bile : observe that the 
 oil is broken up into a creamy emulsion and 'remains so for some 
 time. 
 
 33. Observe that olive oil will pass through a paper filter moistened 
 with bile better than through one moistened with water ; also that 
 oil rises much higher in a capillary tube moistened with bile, than 
 in one moistened with water. 
 
 34. Shake up olive oil with infusion of pancreas : observe that this 
 emulsifies it even better than the bile. 
 
 53 
 
54 
 
 35- Treat starch emulsion with pancreatic infusion, and test for 
 grape-sugar : observe that the pancreatic infusion transforms the 
 starch as well as or better than the saliva. 
 
 36. Observe the digestion of proteids with pancreatic extract, which 
 is going on in the warm chamber. 
 
 37. Observe in the animal which has been killed during digestion the 
 lacteals in the mesentery and on the intestines filled with milk- 
 white chyle ; and the peristaltic movements of the intestines. 
 
 38. Take a little of the chyle from an opened lacteal, and examine 
 with your microscope, Oc. 4, Obj. D. 
 
 IX. 
 
 MUSCLE AND NERVE. 
 
 1. Remove the skin from a hind limb of the dead frog provided for 
 you. For the most part it will pull off easily, but about the hip and 
 knee-joints you will meet with tough bands fixing it: carefully 
 divide these without injuring the muscles beneath. 
 
 2. Of the muscles now exposed select that of the calf of the leg 
 (%astrocnemius muscle] for closer examination : note its belly and 
 tendons : dissect out carefully its origin and insertion. Draw. 
 
 3. Divide its lower tendon (tendo Achillis) and turn the muscle up 
 gently towards the knee, so as to expose its deeper surface. Ob- 
 serve the nerve entering this, and trace it back to its origin from a 
 larger trunk behind the knee. 
 
 4. Cut out, in the manner shown by the demonstrator, the nrostyle of 
 the frog and the tissues immediately around it. The abdominal 
 cavity will thus be opened, and in it will easily be found the sciatic 
 plexus on each side of the middle line. 
 
 5+ 
 
55 
 
 5. Follow down the plexus on one side : the nerves forming it will be 
 found ultimately to give rise to a single trunk, the sciatic nerve : 
 follow this nerve down the thigh, pushing aside muscles, &c., which 
 come in the way. Note the various branches given off by the 
 nerve in its course. 
 
 6. Just above the knee the sciatic nerve divides into two main trunks : 
 follow these down the leg, noting their branches : from one of them 
 arises the branch which supplies the gastrocnemius muscle. 
 
 7. Tear apart with your needles a small bit of one of the muscles : 
 mount in water and examine with Oc. 2, Obj. D. Note \hzfibres 
 of which the muscle is composed, and the alternating light and 
 dark stripes across them. Look for fibres showing the sarcolemma. 
 Draw. 
 
 [8. Examine with your low power the specimen prepared to show 
 muscular fibres isolated in their whole length : note their elongated 
 form, and the way they taper towards each end.] 
 
 9. Tear apart with your needles, in 0.5$ common salt solution, a 
 fragment of fresh nerve. Examine with Oc. 2, Obj. D. Note the 
 nerve fibres mixed with connective tissue : observe the double 
 contour of the former. Draw. 
 
 10. Examine the specimens which have been prepared to show the 
 axis cylinder of the nerve fibres. 
 
 [11. Examine the specimen which has been prepared to* show the con- 
 nection of the nerve fibre with the muscular fibre.] 
 
 12. Dissect out very carefully, in a recently killed frog, the sciatic 
 nerve on one side : it is essential that you do not drag or squeeze 
 the nerve. 
 
 13. Pinch the top end of the nerve with your forceps: observe that 
 the muscles connected with it contract. 
 
 14. Cut off the part of the nerve that you have pinched, and lay a drop 
 of strong salt solution on the cut end of the remainder: the 
 muscles will again be thrown into contraction. 
 
 55 
 
56 
 
 r5- Stimulate the nerve, below where the salt solution has injured it, 
 with induced electrical currents in the manner shown by the 
 demonstrator : the muscles will again contract. 
 
 1 6. Tie a bit of thread tightly around the nerve low down in the thigh : 
 none of the above stimuli applied above the ligature will now cause 
 the muscles of the leg to contract : applied below the ligature they 
 are still efficacious. 
 
 17. Observe, with the assistance of the demonstrator, that when the 
 nerve of the gastrocnemius is stimulated the muscle will lift a 
 considerable weight by its contraction. 
 
 1 8. Obtain and analyse, with the assistance of the demonstrator, the 
 curve of a simple muscular contraction. 
 
 19. Tear apart a bit of plain muscular tissue from the wall of the intes- 
 tine : note the elongated, nucleated unstriped cells of which it is 
 made up. Draw. 
 
 X. 
 
 THE ANATOMY OF THE CEREBRO-SP1NAL CENTRE. 
 
 1 . Taking the rat provided, remove the skin from its back and skull, 
 and dissect away the muscles from about the arches of the vertebrae 
 and the occipital region. 
 
 2. Insert carefully the point of one blade of your large scissors through 
 the thin roof of the cranium, and raise up and remove a bit of the 
 bone. Working from the opening thus made, cut away piecemeal 
 the roof and upper portion of the sides of the skull, taking care, 
 of course, not to insert the scissors into the brain. Then remove 
 similarly the roof of the spinal canal for its whole extent. 
 
 3. Separate the muscles at the back of the hip-joint and find the sciatic 
 plexus; trace its constituent nerves forward until they enter the 
 neural canal. 
 
 56 
 
57 
 
 4. Gently pushing the spinal cord to one side, note the origin of the 
 nerves from it; notice the ganglion on each posterior root: the 
 direction and relative length of the roots in different regions ; the 
 cauda equina ; trace up the roots of the sciatic plexus until they 
 join the spinal cord. 
 
 5. Remove the membranes from the parts of the cerebro-spinal centre 
 now exposed : noting the olfactory lobes, the cerebral hemispheres, 
 the corpora quadrigemina, the cerebellum, medulla oblongata, the 
 cervical and lumbar enlargements of the cord. Trace the latter as 
 the filiun terminate down to its ending in the tail. 
 
 6. Divide the spinal cord opposite the third vertebra. Remove care- 
 fully the bony ingrowth from the skull between the cerebrum and 
 cerebellum, and cut away the bone from around \\\zjlocculi of the 
 latter; then raise the olfactory lobes from the pits in which they 
 lie, and gradually remove the brain from the base of the skull, turn- 
 ing it backwards. As this is done, various nerves passing through 
 foramina in the base of the skull will come into view. Keep a 
 sharp look-out for them, as some are very small : and as each comes 
 into view, divide it so as to leave as much as possible attached to 
 the brain. Having in this way removed the fyrain and the bit of 
 spinal cord attached to it, place them in a dish containing dilute 
 alcohol. 
 
 7. Next remove the spinal cord in the same way, cutting the nerve 
 roots beyond their point of junction ; and place it aside in alcohol 
 to harden for future examination. 
 
 8. Draw the brain as seen from the dorsal aspect ; note olfactory lobes, 
 cerebral hemispheres, corpora quadrigemina, the cerebellum and its 
 flocculi, the medulla oblongata ; the smoothness of the cerebrum, and 
 the folded surface of the cerebellum. Raise the cerebellum and, 
 removing the thin membrane which covers it, note the fourtJi 
 ventricle on the dorsal side of the medulla. Push the cerebral 
 hemispheres apart on each side of the median fissure, and notice 
 the corpus callosum. 
 
 57 
 
58 
 
 9- Turn the brain over, and carefully remove the pia mater, &c., 
 under dilute alcohol, without injuring the various nerves. From 
 before back note 
 
 a. The olfactory lobes. 
 
 b. The cerebral hemispheres, with a white streak on their under 
 surface continuous in front with the olfactory lobes. 
 
 c. The optic commissure, lying in the space left by the posterior 
 divergence of the cerebral hemispheres. 
 
 d. The optic nerves proceeding from it in front and the optic tracts 
 behind. 
 
 e. Immediately between the optic commissure you may find a 
 remnant of the infundibulum and pituitary body, and behind 
 that the mammillary body. 
 
 f. Behind these organs is the pons Varolii, and passing forwards 
 and outwards from it to the cerebral hemispheres are 
 
 g. The crura cerebri. 
 
 h. The pons behind passes without any very marked line of division 
 into the medulla oblongata. 
 
 10. Look for the cranial nerves carefully: according to the care with 
 which you have removed the brain and dissected away the pia 
 mater from its base you will find more or fewer of the following : 
 
 a. The olfactory nerves : proceeding from the ventral side of the 
 olfactory lobes. 
 
 b. The optic nerves, proceeding from the optic commissure. 
 
 c. The oculo-motors (third pair), proceeding from the crura cerebri. 
 
 d. The fourth pair (pathetici} appearing round the outer sides of 
 the crura cerebri. 
 
 e. The large fifth pair (trigeminales) on the sides of the pons 
 Varolii. 
 
 /. The sixth pair (abducentes] arising on the ventral surface of the 
 
 medulla where it meets the pons. 
 g. The seventh pair (facials] arise from the side of the medulla 
 
 close to its anterior end. 
 
 58 
 
59 
 
 h. The eighth pair (auditories) arise close behind the seventh, than 
 
 which they are considerably larger. 
 /'. The ninth (glossopharyngeals] and tenth (pneumogastrics') 
 
 pairs arise by several roots from the side of the medulla farther 
 
 back. 
 j. The eleventh pair (spinal accessories'] arise from the upper part 
 
 of the spinal cord between the spinal nerve roots, and run 
 
 forwards to the point of origin of the pneumogastrics, and then 
 
 turn outwards. 
 k. The twelfth pair (hypoglossals] arise by several roots from the 
 
 medulla, nearer the middle ventral line than the glossopharyngeals 
 
 and pneumogastrics. 
 
 11. Make a careful drawing of the base of the brain with its nerves, as 
 seen in your dissection. 
 
 12. Examine the prepared cat's brain: make out on it the cranial 
 nerves which you failed to see on your own specimen. Notice the 
 greater proportionate size of its cerebral hemispheres; and the 
 convolutions on their surfaces. 
 
 13. Arrange with your neighbor that one brain be divided carefully in 
 the median vertical line from before back: while the other is 
 kept for dissection another way. 
 
 14. In the surface exposed by the section notice the, relation of the 
 cerebral hemisphere to the corpora quadrigemina and the cere- 
 bellum, and the relative size of these parts. The narrow third 
 ventricle just above the space bounded, on the base of the brain, 
 by the optic commissure in front and the crura cerebri behind : 
 and the passage from it to the fourth : the optic thalamus forming the 
 side of the third ventricle : the corpus callosnm and the plane in 
 which it lies : the choroid plexus passing in between corpora quad- 
 rigemina and cerebral hemispheres : the arbor vita in the cere- 
 bellum. The septum, liicidum with the fifth ventricle will probably 
 have been torn away in making the section. Draw your section. 
 
 59 
 
6o 
 
 15. Make transverse sections of a cerebral hemisphere at various points : 
 note the external grey layer ; the lateral ventricle ; the grey masses 
 beneath the floor of the latter. Draw : indicating white and grey 
 portions by different shading. 
 
 1 6. In the other brain carefully remove the substance of the cerebral 
 hemispheres and corpus callosum from above until the lateral 
 ventricles are exposed in all their extent : note the grey projections 
 in the floor of each: an anterior (corpus striatuni] and a much 
 larger posterior (optic thalamus}. Draw. 
 
 17. Expose the corpora quadrigemina from above and draw them. 
 
 1 8. Place the spinal cord in a dish containing water or dilute alcohol. 
 Spread out its roots and observe their attachment to the cord more 
 carefully than was possible before removal : note the ganglion of 
 the posterior root. Observe that most of the roots arise by several 
 bundles from the cord. 
 
 19. Notice the form of the cord and of its cross section: the cervical 
 and lumbar enlargements : \hsfiluin terminate. Draw carefully. 
 
 20. Cut the cord across and observe the arrangements of the grey and 
 white portions. 
 
 XI. 
 
 HlSTOLOGICAL STRUCTURE OF NERVE CENTRES. 
 REFLEX ACTIONS. 
 
 Examine with Oc. 2, Obj. A, the prepared stained transverse 
 sections of spinal cord. Note the anterior and posterior 
 fissures ; the pia mater and the processes from it which run into 
 the cord, one entirely filling up the posterior fissure ; the more 
 stained grey and the less stained white substance ; the central 
 canal ; the nerve cells in the grey matter. Draw carefully. 
 
 60 
 
6i 
 
 2. Put on your Obj. D and examine the cells more closely : observe 
 their nuclei and branches. Draw several carefully. Observe 
 the axis cylinders, seen as red dots in the centre of the cross 
 sections of the meclullated nerve fibres of the white substance. 
 
 3. Examine the specimens prepared to show isolated nerve cells 
 from the spinal cord of the ox : note the nuclei and nucleoli 
 of the cells ; the granular cell body ; the numerous branched 
 processes : some of the cells show also one long unbranched 
 process. 
 
 4. Cut sections of the spinal ganglia which have been imbedded for 
 you : mount in glycerine and examine with your low power : 
 note the connective tissue and the nerve fibres in the ganglion ; 
 and their arrangement : the numerous ganglion cells, with con- 
 spicuous nuclei and nucleoli. Draw. 
 
 5. Tease out in glycerine a bit of a sympathetic ganglion : study 
 and draw the ganglion cells. 
 
 6. Examine and sketch the prepared stained sections of cerebrum : 
 note the numerous nerve cells in the grey matter. 
 
 7. Examine the prepared sections of cerebellum : observe and draw 
 the pear-shaped nerve cells with their processes, seen in the 
 deeper layer of the grey matter. 
 
 8. Learn, with the assistance of the demonstrator, how to destroy a 
 frog's brain : this operation leaves the animal devoid of consci- 
 ousness and of the power of spontaneous movement. Once it 
 has recovered from the shock of the operation and drawn its hind 
 limbs up into their natural position, observe that the animal 
 makes no further attempt at movement except in response to ex- 
 ternal changes ; and that its movements then are not only often 
 different in themselves from those executed under similar condi- 
 tions by a frog with its brain, but differ also in the fact that they 
 are invariable and can be predicted. 
 
 61 
 
 fc^ 0? HDT**^ 
 
62 
 
 9. Gently stroke one flank with the point of a needle : a twitching of 
 the muscles immediately under the point irritated will follow. 
 
 10. On increasing the stimulus the consequent contractions will 
 spread to other muscles on the same side, and finally to muscles 
 on the other side of the body ; and movements of the limbs tend- 
 ing to push the point away will occur. 
 
 11. Hang up the frog by its lower jaw, so that the rest of its body is 
 not in contact with any support. Observe the results 
 
 a. Of pinching one toe gently. 
 
 b. Of pinching the skin about the anus. 
 
 c. Of pinching the skin on the back. 
 
 d. Of prolonged pinching in spite of efforts to pull the 
 
 toe away or to push the forceps away. 
 
 12. Instead of pinching, let one toe dip into very dilute sulphuric 
 acid (just strong enough to be tasted): as soon as the toe is 
 pulled out, immerse the leg in a beaker of clean water to wash 
 away the acid. 
 
 13. Lay bits of paper, moistened with acetic acid, on various parts 
 of the frog's skin : observe that the movements excited in most 
 cases are such as tend to remove the irritant : wash carefully after 
 each experiment. 
 
 14. Having found a place from which the acidulated paper is wiped 
 off always by one leg, tie a weight to that limb so that it cannot 
 be used ; then put on the stimulant : observe that after vain 
 attempts to use the usual leg, the other is employed to wipe the 
 paper away. 
 
 15. Observe the brainless frog which has been poisoned with strych- 
 nia : powerful reflex movements are very easily excited in it, but 
 they have lost their co-ordination to an end their purposive 
 character. 
 
 16. Destroy the spinal cord in both the above frogs : it will be no 
 longer possible to excite any reflex movements. 
 
 62 
 
6 3 
 XII. 
 
 THE LARYNX. 
 
 1. Examine the cartilages of the sheep's larynx and draw them 
 from different sides. The thyroid cartilage', its form, size, &c. ; 
 upper and lower cornua ; the articular surfaces on the latter. 
 The cricoid cartilage : its form, &c. ; the articular surfaces on it 
 for the lower cornua of the thyroid and for the arytenoids. The 
 arytenoid cartilages : the cornicula laryngis (cartilages of San- 
 torini) composed of yellow elastic cartilage, continuous with 
 the upper ends of the arytenoid cartilages. 
 
 2. Place the cartilages together in their natural positions, fixing 
 them with pins. 
 
 3. Dissect away the various extrinsic muscles, remnants of the 
 gullet, pharynx, &c., attached to the sheep's larynx provided for 
 you. Observe the epiglottis overhanging its upper aperture, which 
 is bounded on the sides and behind by folds of mucous membrane 
 and the cornicula laryngis. Looking into the larynx through 
 the opening, observe the projections formed by the vocal cords ; 
 and the V-shaped passage between them (glottis}. 
 
 4. Clean the membrane between the hyoid bone and the thyroid 
 cartilage: make out the connection between the upper cornua of 
 the cartilage and the great cornua of the hyoid. 
 
 5. Clean the crico-thyroid membrane in front where uncovered by 
 the crico-thyroid muscles : dissect out these muscles very carefully : 
 clean the rest of the outer surface of the thyroid cartilage, 
 and draw the parts then exposed so as to show the position, 
 form, &c., of the crico-thyroid muscle. 
 
 6. Proceeding then to the back of the larynx, remove the mucous 
 membrane covering the posterior surfaces of the cricoid and 
 arytenoid cartilages. Clean carefully the arytenoid Z.K& posterior 
 crico-arytenoid muscles thus exposed. Draw. 
 
 63 
 
6 4 
 
 7. P"ixing the larynx so that it is turned over a little on one side, divide 
 the crico-thyroid muscle on the opposite side, and carefully turn 
 outwards that half of the thyroid cartilage, detaching the tissues 
 adherent to its inner side. 
 
 8. Now dissect out the insertion of the posterior crico-arytenoid 
 muscle on the side from which the thyroid cartilage has been 
 raised, and clean the lateral crico-arytenoid. 
 
 9. Carefully clean the paler thyro-arytenoid muscle, which is 
 largely developed in the sheep, its fibres forming a broad sheet 
 passing from the arytenoid cartilage to the re-entering angle of 
 the thyroid cartilage for nearly its whole length. 
 
 Draw the muscles, &c., now exposed. 
 
 10. Observing carefully the origins and insertions of the various 
 muscles, make out what movements they will produce in the 
 cartilages to which they are attached. 
 
 ir. Carefully divide the cricoid cartilage in the middle dorsal line: 
 turn then the halves outwards and examine the interior of the 
 larynx. 
 
 12. Examine specially the boundaries of the glottis : for its posterior 
 half or more it will be seen that the wall of the aperture is 
 bounded by the arytenoid cartilages covered with mucous mem- 
 brane ; and it is only its anterior portion that has the vocal cords 
 on its sides. Putting the halves of the cricoid cartilage together 
 again, observe the wider opening at the posterior part of the 
 glottis (glottis respiratoria) as compared with its anterior narrow 
 portion (glottis vocalis] between the vocal cords. Notice how 
 this anterior portion will be more or less opened or shut by rota- 
 tion of the arytenoid cartilages. 
 
 13. Dissect away the muscles, mucous membrane, &c., of the larynx 
 and make out its ligaments and the articulations of its cartilages. 
 Note the attachment of the cartilage of the epiglottis to the 
 upper part of the thyroid cartilage : the movements permitted at 
 the cricoid-thyroid and crico-arytenoid articulations and the 
 
 64 
 
65 
 
 bundles of elastic fibres just beneath the mucous membrane, 
 which form the vocal cords. 
 
 14. Examine the prepared cartilages and dissections of the human 
 larynx and compare them with those of the sheep. In the former 
 note especially the ventricle of the larynx and the false vocal 
 cords. 
 
 15. Analyse some of the vowel sounds with the help of Helmholtz's 
 
 resonators. 
 
 1 6. Study the form of your mouth cavity during the production of 
 the various vowel sounds, and the movements of its walls in pro- 
 ducing the different consonants. 
 
 XIII. 
 
 THE KIDNEYS. 
 
 1. Remove the alimentary canal from the abdominal cavity of the 
 dead rat : with your stronger scissors carefully remove the front 
 of the bony pelvic ring. The kidneys will easily be recognized, 
 one on each side of the back part of the abdominal cavity, the 
 right farther forward than the left. 
 
 2. Dissect away neatly the connective tissue, &c., in fr-snt of the ver- 
 tebral column, so as to clean the inferior vena cava and the 
 abdominal aorta. Trace out the renal arteries and veins. 
 
 3. Find the ureter, a slender tube passing back from the kidney 
 towards the pelvis : it leaves the inner border of the kidney behind 
 the vein and artery : and lying at first at some distance from the 
 middle line, converges towards its fellow as it passes back. 
 
 4. Follow the ureters back until they reach the urinary bladder; 
 dissect away the tissues around the latter and note its form, &c. 
 
 5. Make a drawing of the renal organs as now exposed. 
 
 65 
 
66 
 
 6. Open the bladder : look for the apertures of entry of the ureters, 
 and pass bristles through them into those tubes. Note the mucous 
 membrane lining the bladder. 
 
 7. Remove one kidney from the body and divide it from its outer to 
 its inner border: turn the two halves apart, still leaving them 
 connected by the tissues at the inner border, so as to see the cut 
 surfaces. 
 
 8. Note at the inner border (hilus] the dilatation (pelvis) of the 
 ureter : the outer, darker, granular cortical portion of the kidney, 
 and the inner, paler, smoother medullary portion : the papilla 
 formed by the projections of the medullary substance at the hilus, 
 each contained in a subdivision (calyx] of the pelvis of the ureter. 
 
 9. Examine and draw carefully a similar section of a sheep's kidney 
 in which the above parts will be more easily seen. Note also in 
 it t\\t pyramids of Malpighi (one corresponding to each papilla) and 
 the strata of cortical substance extending some way between them. 
 
 10. Cut a section of the prepared kidney so as to include both cortical 
 and medullary parts : mount in glycerine and examine with your 
 low power. Note the arrangement of straight and contorted 
 tubules, and the distribution of glomeruli. Draw. 
 
 11. Cut a thinner section of the medullary part of the hardened 
 kidney: mount in glycerine, examine with your higher power. 
 Note the tubuli recti, which, according to the plane of your 
 section, will be cut in different ways ; observe their distinct, often 
 cuboidal, nucleated lining epithelium. Draw. 
 
 12. Cut and treat similarly a section from the cortical portion. Note 
 the tubuli contorti, and their indistinct granular epithelium : they 
 will be found cut in all directions ; some across, some longitudi- 
 nally, some obliquely. Here and there will be found round empty 
 spaces, which are cavities from which glomeruli have fallen out : 
 in other places granular balls, representing shrivelled glomeruli, 
 will be seen occupying these cavities. Draw. 
 
 66 
 
67 
 
 13. Cut a thin transverse section of the papilla of the hardened 
 kidney; mount in glycerine; examine with low, then with high 
 power. Note the transverse sections of the large excretory 
 tubules, and among them a certain number of sections of the 
 smaller tubes forming the loops of Henle. 
 
 14. Examine the prepared specimens of injected kidney with your low 
 power. Note the blood-vessels, sparse in the medullary part, bui 
 forming a close capillary network in the cortical : the little tufts of 
 vessels forming the glomeruli : and the afferent and efferent vessels 
 of the glomeruli. Select a good bit of the specimen and draw. 
 
 15. Tease apart with your needles in water a bit of the preserved mus- 
 cular coat of the bladder. Examine with Oc. 2, Obj. D. Note and 
 draw the contractile fibre-cells. 
 
 1 6. Cut sections of the preserved and imbedded mucous membrane of 
 the bladder: note its stratified epithelium: the superficial cells 
 flattened, the deeper elongated. Draw. 
 
 XIV. 
 
 THE SKIN AND ITS APPENDAGES. 
 
 I. Examine with your low power and draw the prepared sections of 
 skin. Note 
 
 a. The epidermis (cuticle} ; its superficial horny layer, and 
 deeper, less transparent mucous layer (rete mucosum, 
 Malpighian layer}. According to the mode of prepara- 
 tion the horny layer may be more or less deeply stained 
 than the rete mucosum. 
 
 b. The dermis [corium] : deeply stained and with numerous 
 projections (papilla) on its surface, which fit into hol- 
 lows on the deeper side of the epidermis. Note the 
 numerous blood vessels cut across in the dermis. 
 
 67 
 
68 
 
 c. The subcutaneous areolar tissue, into which the dermis 
 gradually passes on its deeper side. Composed mainly of 
 a loose network of bundles of tissue like that of the 
 dermis, the meshes of the network being filled up with 
 fat cells and the deep ends of sweat glands. 
 
 2. Examine with Oc. 2, Obj. D. Picking out the thinnest part of 
 the specimen, note the columnar cells forming the deepest layer 
 of the epidermis : superficial to these, the numerous strata of 
 roundish cells, then strata in which the cells begin to get somewhat 
 flattened parallel to the surface. In the deeper part of the horny 
 layer individual cells can still be recognized ; but not in its super- 
 ficial layers. Draw carefully. 
 
 3. Tease apart with needles in water a small bit of dermis from afresh 
 piece of skin. Examine, Oc. 2, Obj. D. Note the connective 
 tissue fibres of which it is mainly composed. Treat with dilute 
 acetic acid : note that most of the fibres swell up and disappear ; 
 the majority are therefore white fibrous tissue, (p. 7, Obs. 13). 
 
 4. Examine and draw specimens prepared to show the sweat glands. 
 
 Note- 
 
 a. The contorted portion of the duct in places where it can be 
 seen passing through the horny layer of the cuticle. 
 
 b. The slightly waved or straight part of the duct passing 
 
 through the dermis, and recognisable by being its epithe- 
 lium, stained similarly to the rete mucosum of the epidermis. 
 
 c. The coiled mass formed in the subcutaneous tissue by the 
 
 secreting part of the tube which will be cut across in 
 various planes : note in the transverse sections the epi- 
 thelium lining it, and its central lumen. 
 
 5. Pull out one of your eyelashes ; wash in dilute potash solu- 
 tion and mount in the same. Examine with your low power. 
 Note the bulbous enlargement or root of the hair : its shaft, in. 
 which more or less of a darker central medulla can be seen : and 
 the tapering point where the medulla is absent. Draw. 
 
 68 
 
69 
 
 6. Examine with Oc. 2, Obj. D. Bring the upper surface of the shaft 
 into focus : note on it the fine markings caused by the cells of 
 the hair cuticle. Draw. Focus deeper and examine the medulla, 
 and note the fibrous part (cortical substance) '.ying between cuticle 
 and medulla, and in most hairs containing collections of pigment 
 granules. 
 
 7. Examine with your low power the prepared specimens which show 
 the hair follicles and the hair roots in situ. Note the epidermic 
 and dermic layers in the follicles ; in some places the small der- 
 mic papilla at its base, on which the hair sits, can also be seen. 
 Note also the sebaceous glands on the sides of the hair follicles : 
 in some places their openings into the latter will be seen. Draw. 
 
 S. Picking out a good part of the specimen, put on your Obj D, and 
 trace out the continuity of the hair with the epidermic lining of the 
 follicle. 
 
 9. Examine the prepared stained sections of nail with your low power. 
 
 Note the deeply colored deeper layer (rete mucositm) produced 
 into numerous little clubbed processes (which originally fitted 
 into the hollows between the rows of papillae on the dermis of 
 the bed of the nail) and the less stained outer horny layer. 
 Draw. 
 
 10. Examine with your high power : make out the form, &c., of the 
 cells in the various layers. 
 
 11. Examine the prepared specimens showing tactile corpuscles in the 
 papillae of the dermis. Draw. 
 
 12. Take the fresh Pacinian body provided by the demonstrator: lay 
 in I per cent, acetic acid on a slide and examine with the unas- 
 sisted eye : note its central opacity, then put on a cover, press 
 gently and examine with Oc. 4, Obj. A. Note 
 
 a. The numerous concentric nucleated capsules forming 
 most of its mass. 
 
 b. The way in which the inner capsules are more closely 
 
 packed. 
 
 69 
 
;o 
 
 c. The central non-laminated " colloid mass" or "core" 
 
 d. The nerve fibre, entering at one end and passing on 
 through the capsules into the central mass. Draw. 
 
 13. Use Oc. 2, Obj. D, and try and find the swollen termination of 
 the axis cylinder of the nerve fibre. 
 
 14. Cut thin sections from the imbedded bits of mucous membrane 
 of the tongue. Mount in glycerine and examine, first with a low, 
 then with a higher power. Compare its epithelium and corium 
 with the epidermis and corium of the skin. 
 
 XV. 
 
 THE EYE. 
 
 
 
 1. Place the bullock's eye in water, and remove from around it the 
 loose fat and connective tissue. As this is done, the tendons of 
 the straight and oblique muscles will be seen ; do not detach 
 them. Clean carefully also the attachment of the large retractor 
 of the bulb muscle all round the equatorial region of the eyeball. 
 
 2. Note now carefully the sclerotic and cornea ; the conjunctiva cover- 
 ing the anterior part of the sclerotic : the entry of the optic nerve : 
 the form of the eyeball as a whole : the curvature of the cornea. 
 Through the cornea examine the iris and pupil, 
 
 3. Remove the eye from the water and carefully cut away the 
 cornea along its junction with the sclerotic. As the first incision 
 is made, note the escape of the aqueous humor. 
 
 4. Replace the eye in water and fix it with pins to the wax, pupil 
 uppermost. Examine the iris more closely : raise the inner 
 edge so as to see the so-called posterior chamber of the aqueous 
 humor. Feel the convex anterior surface of the lens projecting 
 in the aperture of the pupil. 
 
5. Make an incision in the sclerotic at one point, extending back 
 for about one-quarter of an inch from the attachment of the 
 iris. Raise the edges of this cut, and find in them the canal of 
 Schlemm cut across. Follow this canal all round along the outer 
 edge of the iris, cutting it open as you proceed. 
 
 6. Make four radial equidistant incisions through the sclerotic from 
 its anterior edge to near the point of entry of the optic nerve. 
 Taking the greatest care not to injure parts beneath the sclerotic, 
 raise the four flaps thus marked out and pin them back. The 
 pigmented choroid coat will thus be exposed. Just outside the 
 canal of Schlemm, some fibres will have to be torn through, in 
 order to reflect the sclerotic ; they pass from the sclerotic back- 
 wards and inwards to the choroid. 
 
 7. At the front part of the choroid and just outside the ring formed 
 by the canal of Schlemm, it will be seen to be unpigmented. If 
 a sm ill strip of this unpigmented portion be raised in the forceps, 
 it will be found to tear off readily in a radial direction : it is the 
 radial portion of the ciliary muscle, the sclerotic attachment of 
 which has been just torn through. 
 
 2. Make radial incisions in the iris and reflect it. The whole front of 
 the lens and, outside its edge, part of the front of the vitreous 
 humor enclosed in its hyaloid membrane, will be now exposed. 
 On the inner surface of the reflected flaps of iris will be seen the 
 folds of the front part of the choroid, forming the ciliary processes. 
 
 9. Gently raise the ciliary processes and push them outwards : as this 
 is done, the inner attachment of the folded suspensory ligament of 
 the lens will be seen. 
 
 10. Now very carefully reflect the whole choroid: as this is done, 
 notice the bright iridescent patch (tapetuni) on its inner surface. 
 
 11. The retina will now be exposed as a pink membrane lying on the 
 hyaloid membrane. Examine its inner surface from the front 
 through the transparent vitreous humor. Observe the place 
 where the optic nerve enters, marked out by the vessels 
 radiating from that point. 
 
72 
 
 12. Remove the lens, examine its form, &c., squeeze it and note the 
 greater density of its inner layers. 
 
 13. Cut the hyaloid membrane, and press out and examine the trans- 
 parent jelly-like vitreous humor. 
 
 14. Examine first with low then with high power the prepared sec- 
 tions of retina Draw. Note 
 
 [a. The internal limiting membrane.] 
 
 b. The nerve fibre layer. 
 
 c. The nerve cell layer. 
 
 d. The molecular layer. 
 
 e. The inner granular layer. 
 
 f. The intergranular (fenestrated) layer. 
 
 g. The outer granular layer. 
 
 h. The external limiting membrane. 
 
 t. The rod and cone layer. 
 
 j. The pigmentary layer. 
 
 k. The radial fibres of Miiller. 
 
 15. Examine the specimen prepared to show a bird's-eye-view of a 
 retina from the outer side. Notice the cones scattered here and 
 there among the rods. 
 
 16. Tease out a bit of fresh frog's retina in a drop of osmic acid so- 
 lution. Examine with your high power. Observe the gigantic 
 rods and the tendency of their outer segments to split up into 
 discs. Draw. 
 
 [17. Examine the prepared sections of cornea and conjunctiva.] 
 
 18. Notice in the freshly extracted eye of an albino rabbit the small 
 inverted image, formed on the back of the eyeball, of objects held 
 in front of the eye. 
 
 19 Study, with the assistance of the demonstrator, the path of the 
 light rays through the artificial eye, and the necessity for accom- 
 modation in order to obtain clear images of objects at different 
 distances. 
 
 72 
 
73 
 
 20. Observe that your own eye is not accommodated for distinct 
 vision at different distances at one time. 
 
 21. Perform Scheiner's experiment with the assistance of the demon- 
 strator. Determine your near limit of accommodation. 
 
 [22. Observe the changes of the front surface of the lens during 
 movements of accommodation, by means of Helmholtz's phako- 
 scope.] 
 
 23. Determine the position of your " blind spot" 
 
 24. Study Purkinje's figures. 
 
 25. Observe that in vision with two eyes, objects out of the horopter 
 are seen double. 
 
 XVI. 
 
 AUDITORY, GUSTATORY AND OLFACTORY ORGANS. 
 
 1. Examine and draw the bones of the tympanic cavity. 
 
 2. Examine the specimens prepared to show the tympanic membrane 
 and Eustachian tube, and the tympanic bones in situ. 
 
 3. Examine and draw the preparation showing the bony semicircular 
 canals. 
 
 4. Examine and draw the preparation showing the membranous 
 semicircular canals and the vestibule. 
 
 5. Examine with Oc. 2, Obj. A., the prepared sectrons of cochloa. 
 "Draw. Note carefully 
 
 a. The modiolus. 
 
 b. The lamina spiralis. 
 
 c. The basilar membrane. 
 
 d. The membrane of Reissner. 
 
 e. Scala media, scala vestibuli and scala tympani. 
 
 f. The rods of Corti. 
 
 g. The hair cells. 
 
 h. The membrana tec tor ia. 
 73 
 
74 
 
 6. Examine with a higher power the structures on the basilar mem- 
 brane. 
 
 [7 Examine with Oc. 2, Obj. D., the specimens prepared to show 
 the epithelium and hairs in the ampulla of the semicircular 
 canals.] 
 
 8. Examine the specimen prepared to show the turbiuate bones, and 
 the cribriform plate of the ethmoid bone. 
 
 9. Examine the preparation showing the yellow mucous membrane 
 covering the olfactory region of the nasal chamber. 
 
 10. Examine with Oc. 2, Obj. D , the prepared sections of the Schnei- 
 derian membrane. Draw. 
 
 11. Tease out in water a small portion of the prepared olfactory 
 epithelium ; mount and examine with Oc. 2, Obj. D. Draw the two 
 kinds of cells. 
 
 12. Examine (Oc. 2, Obj. D.) and draw the specimens prepared to 
 show the so-called taste-buds in the epithelium of parts of tongue. 
 
 USI7EBSIT7 
 
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