COLUMBIA LIBRARIES OFFSITE HFAI TH RCK NOt S '-.I Af JIlAMt) HX64098788 QP44.H14 A laboratory guide i RECAP A LABORATORY GUIDE N PHYSIOLOGY IHAPTERS I. AND II. ON CIRCULA- TION AND RESPIRATION WiNFIELD S. HALL Columbia ®mtiersfit|> in tfje Citj» of i0eto gorfe COLLEGE OF PHYSICIANS AND SURGEONS Reference Library Given by c5^ce<» ^ Xy"*^ LABORATORY GUIDE PHYSIOLOGY CHAPTERS 1. AND II. ON CIRCULATION AND RESPIRATION. WINFIELD S. HALL, Ph. D., M. D., PROFESSOR OF PHYSIOLOGY, NORTHWESTERN UNIVERSITY MEDICAL SCHOOL CHICAGO. CHICAGO : THE W. T. KEENER CO. iSg6. Copyright, 1896, By Winfield S. Hall. N PREFACE. American laboratories of phjsiolog}' have usually been established in medical schools after these institutions have already associated histology with pathology, and physio- logical chemistry with general chemistry. The problems presented in those American laboratories of physiology wliicli are departments of medical schools are, therefore, essentially the physical problems of physiology. It is, then, quite unnecessary to burden the student with the purchase of a voluminous manual largel}' devoted to mor- phology and to the chemical problems of ph} siology. The student who has but four years to devote to the study of medicine cannot consistently be assigned more than 100 hours to 120 hours of laboratory work in physical physi- olog)'. How to most profitably spend this brief period is a question which has engaged the attention of the writer for a number of years. In the choice of the work to be assigned to the student it has been taken for granted that he has entered upon his study of medicine with a knowl- edge of, at least, the rudiments of phj'sics and of algebra, and that laboratory work in physiology is not begun until the student has made considerable progress in gross and minute anatomy. Courses in anatomy and physiology should be so coordinated as to enable the. student to gain a thorough knowledge of the morphology of an organ be- fore he experiments upon its function. Digitized by the Internet Archive in 2010 with funding from Columbia University Libraries http://www.archive.org/details/laboratoryguidei1896hall INTRODUCTION. THE METHOD OF PRESENTING THE SUUJKCT. IHK (jri-.S'lION OF ILLUSTRATIONS. The profuse illustration of a text-book is in perfect ac- cord with the principles of pedagogy ; that the profuse illustration of a laboratory manual is the reverse is evi- dent from the following considerations: The laboratory student receives from the demonstrator the material with which he is to work. If he receives a piece of apparatus which is new to him, a few questions or hints in his laboratory manual will lead him to discover, from an examination of the apparatus itself, the physical and mechanical principles involved and utilized in it. Most students will spontaneously make drawings showing the essential parts of the instruments ; all students will will- ingly do so if required. This is a most valuable exercise for the pupil, which is likely to be omitted if the manual contains cuts of the apparatus. Nearly every exercise requires the preparation of some simple appliance — e. g., a frog board or a recording lever — whose construction will be much facilitated if the stu- dent is guided by a figure in his manual, but a model which the demonstrator has made will be a better guide. I have often seen students read their text descriptive of some organ — e. g. a frog heart — and verify its state- ments from the accompanying figures, leaving almost un- noticed the object itself, which lay before them. A few brief questions or hints would have led them to discover on the object all of its essential features. Diagrammatic anatomical figures are sometimes useful in a laboratory 6 LABOR A TOR \ " G UIDE IN PHYSIOL O G Y. manual, but true anatomical figures are worse than use- less— they bar the student's independent progress. If his laboratory manual contains illustrations of all apparatus and tissues, and of such experiments as admit of graphic records, the student makes similar drawings in his notes, either unwillingly or dependently — frequently both. The laborator}' work is thus robbed of much of the benefit it is intended to give the student. Independence and origi- nality are completely defeated or aborted, except in the case of the rare student. If the laboratory manual contains graphic records of an experiment,muchof the time of the demonstrator will be con- sumed in explaining to the students individually why the same physiological functions observed with slightly differ- ent apparatus and under slightly different circumstances, may differ in minor detail from the tracings in the book. The energies of the demonstrator will thus be partially di- verted from their legitimate channel. If there is no trac- ing in the text, students will naturally, by comparison of their tracings, discover the essential and the nonessential, and the cause of the essential features of these tracings. After the student has made these independent discoveries he is in a position to gain the maximum profit from the comparison of his own tracings with those which others have taken, and from any explanations which the demon- strator may choose to add. It is evident then, that, from a pedagogical standpoint, the laboratory guide should be very sparsely illustrated, if at all. On the other hand, the student's notes should be profusely illustrated. THE QUESTION OF EXPLANATION. What has been said regarding the illustrations of apparatus and of results applies, in principle, to the ex- LABoKAl OKV iJUJi>E J\ I'JI V SlULUGY. 7 planalioii of physiological observations. As wheat is more valuable than clia'^f, so is the independent discovery of a principle by the student more valuable to him than its explanation b\' a book or instructor. If the facts to be observed and the principle involved be detailed and explained in advance, the student's power of independent observation and investigation remains undeveloped. THE FUNCTION OK THE DEMONSTRATOR. It may be well to introduce this topic by a state- ment of what the function of the demonstrator is not. It certainly is not to rob the student of the pleasure, exhila- ration and benefit of independent investigation of a prob- lem by introducing each laboratory period with an enumeration of the facts and principles which the work of the day is expected to establish. Such an introduction is worse than useless. The desirabilit}' of even asking the attention of the entire class to introductor}' remarks on the general bearing of the problem in hand is to be ques- tioned. If the problem is well chosen and the work in the physiological laboratory properly coordinated with that in the recitation room and lecture room and that in other de- partments, its significance will at once be evident to the intelligent pupil. If the introductory talk is omitted the prompt student may begin at once, upon entering the laboratory, the problem of the day and will have a clear gain of ten to twenty minutes. Any supplementary instruction or hint may most profitably and economically be written upon the blackboard. Most of the experiments given in this book cannot conveniently be performed by one individual working alone. After some experimentation it has been found most advantageous to divide the class into sections not exceed- ing thirty students, and to subdivide these sections into 8 LABORATORY GUIDE IN PHYSIOLOGY. divisions of three students each. Each division is assigned a table. The assistant demonstrator places the material needed for any day's work either upon the tables or where it is readily accessible. Nothing should be done for the student which he can profitably do for himself. A small class with less limited time may easily construct much apparatus in the work- shop. No class is so large as to debar the members from the privilege of constructing frog-boards, tracing levers, etc., (which may be done at the tables) and of setting up, adjusting and readjusting all apparatus. Nothing should be told a student which he can readily find out for himself. The function of the demonstrator is to guide the student by questions and by hints to dis- cover facts and to formulate principles. Extended expla- nations on the part of the demonstrator may instruct the student, but they do not educate him. HINTS TO THE STUDENT. It is a general principle that a student gets out of a course what he puts into it, and with interest. If he in- vests (1) intellectual capacity, (2) the spirit of inquiry and investigation, (3) the power of logical reasoning, and (4) the power to formulate conclusions ; he will promptly receive interest upon the investment. Further, the greater the investment the greater the rate of interest. This may seem inequitable, but it is inevitable. The value of taking full notes of laboratory experi- ments is unquestionable. The following hints regarding note taking may be advantageous : 1. Make a careful description of each new instrument with which you work. 2. Formulate each problem definitely. 3. Describe the means used in the solution of the problem. /..uu>h\rroh-y cuini-: i.\ riiysioi.ocv. 9 4. Enumerate the facts observed throu[^h the help of the means employed. f». Seek for and note causes and inter-relations of the facts as far as possible. G. Differentiate the essential from the incidental. 7. Formulate conclusions from the collected data. 8. Make generalizations as far as they are justifiable. A good notebook should possess the following qualities: (7. It should be complete, containing an account of every problem studied. b. It should be full, containing a sufficient amount to guide another in performing the same experiments and in verifying the facts and conclusions noted. c. It should be logically arranged. d. It should be as neat and artistic as the student can make it in the time which he can devote to it. Such a notebook is a most valuable addition to any library, but the simple making is still more valuable to the one who does it. A. CIRCULATION. I. THE CIRCULATION AND ITS ULTIMATE CAUSE. a. To observe the capillary circulation : 1. Appliances needed. — Cork-board 8 cm. wide by 20 cm. long and about ^ cm. thick; cover glasses, 18 mm. in diameter and 10 mm. in diameter ; normal salt so- lution ; camel's hair brush; pins; compound micro- scope; sealing wax; thread; filter paper; 2 per cent croton oil in olive oil. 2. Preparation. — Pith two frogs the day before the obser- vation is to be made. At the beginning of the labora- tory period when the observation is to be made curar- ize the frog lightly by the hypodermic injection of one drop of a 1 per cent solution of curari. Make a frog- board by cutting a hole 1.5 cm. in diameter near one corner of the cork-board and fasten a large cover glass over the hole with sealing wax. j>. The operation. — After the frog becomes curarized, pin it out ventral surface downward in such a way as to bring one of the hind feet over the hole in the board. Tie thread, not too tightly, to the third and fourth digits, loop the threads over pins and gently separate the digits until the web is quite flat and closely ap- proximated to the surface of the fixed glass which covers the hole. Run a film of normal salt solution under the web; place a drop of the same liquid upon the upper surface of the web; place a small cover glass over it; fix the board upon the microscope stage so as to admit of illumination by transmitted light; illuminate ; focus. LABORATORY GUIDE l\ /'// VS/OLOG V. 11 ^. 0/>S(-r7'(i//(>//s. (1) Is there evidence of matter in motion? Is the moving matter liquid or solid? If the matter is con- fined to particidar channels; are they all alike? If not, describe differences. (2) Observe whether the motion is equal!}' rapid in all channels; if not, observe whether the slower currents are in the larger or the smaller channels. Deter- mine which of the channels are arterioles, which capillaries, and which venules. (3) Have you seen evidence of an intermitt( nt force acting upon the moving bodies? If so, describe its influence and location minuteh'. (4) Do the moving bodies change shape? If so. under what circumstances ? (5) Remove the cover glass, dry the web with filter paper, touch a point with a pin that has been dipped into dilute croton oil. Observe whether the pres- ence of the croton oil effects any change in the diameter of the vessels, or in the rate of the blood flow. If there is a change in both, has one a causa- tive relation to the other ? (6) Note and describe minutely all changes which take place at and near the place touched with the croton oil. If no marked change is produced b}- the croton oil, touch the point with a glass point which has been dipped into HNO.j. (7) Have you noted diapedesis of white or of red cor- puscles; if so, describe the process minutely. 2. />. To obseri'c the action o/ the /roi:;'s heart : I. Appliances. — Dissecting board ; fine scissors ; heavy scissors ; pins ; forceps ; watch glass ; camel's hair brush ; normal salt solution ; fine silk thread ; ice, in a beaker. 12 LABORATORY GUIDE IN PHYSIOLOGY. 2. Preparation. — Pith a frog, lay it with its dorsal surface upon the dissecting board ; stretch out its legs and pin the feet to the board. J. Operation. — Make a median incision through the skin from the pelvis to the mandible ; make transverse in- cisions and pin out the flaps. Raise the tip of the episternum, insert a blade of the fine scissors under it and divide it transversely, about ^ cm. anterior to the tip. Raise the anterior segment of the sternum at the point of the transverse incision \ insert the blade of the strong scissors under it and divide it longitu- dinally in the median line. Withdraw from the board the pins which fix the anterior extremities, make gentle lateral traction upon the fore feet until the split sternum is sufficiently separated to afford a convenient working distance and to plainly expose the whole heart. 4. Observations. (1) Note rate of systole. (2) Note sequence of contraction of auricles, ventri- cle and bulbus. (3) Note change in shape of different parts. (4) Note change in color and the position of this color change in the heart cycle. (5) Carefully excise the heart including the sinus venosus and the bases of the posterior and two an- terior venae cavae, also the bases of the two aortic trunks. Place the excised heart in a watch glass. Observe whether the pulsation continues. If so, what is your conclusion regarding the relation of the heart movements to the central nervous system. (6) If the pulsation continues, note whether the rate of pulsation has been noticeably changed by the excision. LAHOKAIOKY CUIDI: /X PHYSIOLOGY. V<\ (7 ) Bathe the heart with a few drops of NaCl solution, hold the watch glass in the palm of tiie hand and note whether the rate changes. (8) Float the watch glass upon ice water and note the results. (0) If the heart seems vigorous (otherwise procure a fresh one), carefully sever the sinus venosus with the fine scissors. Does the sinus continue to beat ? Does the heart continue to beat ? Interpretation. (10) If the heart beats, sever the auricle from the ven- tricle through the auriculo-ventricular groove. Note results. (11) If the auricles beat, divide them. If they con- tinue to beat, do they follow the same rhythm ? (12) If the ventricle becomes quiescent, stimulate it either mechanically or with n single induction shock. How does it respond to a single stimulus? Con- tinue to subdivide the heart until the parts refuse to respond to stimuli. (13) Repeat the experiment and see if the same results are reached on subsequent trials. Note results and give yonr interpretation. II. THE GRAPHIC RECORD OF THE FROG'S HEART BEAT. 1. Appliances.— Yxog-hozxA\ a straw or strip of bamboo 20 cm. long ; a cork about 2 cm. in diameter and height; pins; needles; sealing wax; parchment paper; a kymograph, stand and lamp. 2. Preparation. — Pith a curarized frog. Make a heart lever after the model shown by the demonstrator. J. Operation. — Open the abdomen of the frog as described under I-b-3 and expose the heart. Open the peri- cardium, place some resistent object — a cover slip, for instance — under the ventricle. So adjust the heart lever that the cork foot of the long arm of the lever will rest upon the juncture of the auricles and ventri- cles. If the weight of the lever seems to be too great for the heart to move easily, the long arm may be made lighter by placing a counterpoise upon the short arm. If the tracing point of the long arm has a sufficient ex- cursion to make a good tracing, bring the kymograph to a position where the point will lightly touch the car- boned surface of the drum. The lever should be nearly tangent to the surface of the drum, and so ar- ranged that the rotating surface of the drum turns away from the tracing point of the lever rather than toward it. 4. Observations. (1) Note whether the curve is a simple one or com- posed of a major wave, with crests superimposed upon it. (2) In either case closely observe the phases of the heart-cycle and determine the relation of each part LAfiOAAro/^y GUIDE /X rilYSIOLOCY. 15 of the cycle with each part of the tracing. If the tracing has a single crest, more delicately counter- poise the lever and more carefully adjust the nar- row foot of the lever to the auriculo-ventricular groove and repeat the experiment. (3) Take tracings of the auricle alone. Compare these with those of the auriculo-ventricular notch and determine the causes of variation. (4) Without altering the counterpoise take a tracing of the ventricle and compare it with the two preced- ing curves and account for all the differences. (5) Try to take a double tracing with one lever foot resting upon the auricle and the foot of the second lever resting upon the ventricle. The tracing points must touch the drum in a vertical line. Are the crests synchronous? If not, why ? (tj) If a time tracing be added one may determine the time relations of the different phases of the heart cycle. III. THE APEX BEAT. THE HEART SOUNDS. 1. Appliances. — A cardiograph and a transmitting tambour (Marey) or materials for constructing them. A stethoscope; a stand and support; clamps; a kymo- graph; two tambour pans Nos. 1 and 2 thin; sheets of rubber; thread; corks; sealing wax; tambour holder; straws; needles; parchment paper. 2. Preparation. — Any laboratory will have different forms of cardiographs for demonstration purposes, but not every laboratory is able to afford numerous dupli- cates. An expert tinsmith will make the tambour pans at very moderate cost, and the student can do all the rest. Pans may be made of two sizes No. 1, diameter 5 cm., depth 4 mm., outside diameter of tube 3 to 4 mm., length of tube 3 to 4 cm. No. 2, diameter 4 cm., depth 3 mm., tube as in No. 1, see Fig. 1. To make the cardiograph : Take a tambour pan No. 1, stretch the sheet rubber across the pan and tie in place with thread. A few drops of sealing wax will keep the thread in place after it is tied. Mount the tambour as follows : From any well seasoned, close- grained hard wood in boards, about 1 cm. thick, cut small triangular pieces about 10 cm. on a side. In the center of each triangle bore a hole to receive a medium sized cork (about 1.5 cm. in diameter) the upper edges of the triangle may be beveled and each corner may be furnished with a leg by screwing into each corner from the lower surface, a round headed LASOKA/OK) CUmi: IX rilYSIOLOGY. screw, leaving; about 1 cm. of tlie screw out to serve as the leg. If the class is large, the (knionstrators should prepare these tambour boards in advance. The tambour is mounted by fitting a cork to the hole in the tambour board, boring the cork and pressing the tambour tube through the hole from below upward. Fix a button of cork to the membrane with sealing wax. The completed car- diograph will present in section the relations shown in Fig. 2. As will be seen from the cut, the position of the button may be varied by varying its shape or b}- changing the adjust- ment of the tambour tube in the cork. To construct a transmitting or recording tambour use a No. 2 tambour pan, stretch the rubber less tightly than for the receiving tambour and mount similarly in a triangular tambour board, omitting the screw legs. Make a recording needle like the frog's heart lever, except that the foot, which rests upon the middle of the tambour membrane, may pre- sent a larger surface. The cork which forms the ful- crum of the lever should be fixed to the tambour board in such a position that the long arm of the lever is vertically above a diameter of the tambour. Any change of pressure upon the air in the tambour will cause the membrane to rise or fall, thus producing in the tracing point of the lever a corresponding rise or fall differing from those of the membrane only in their greater extent. It is evident that if the tube of the receiving tambour be joined to the tube of the trans- mitting tambour through a thick rubber tube any movements which affect the button of the first will be 18 LABORATORY GUIDE IN PHYSIOLOGY. manifested by a rise or fall of the lever which rests upon the second. J. Ope7'ation. — Let a student remove the clothing from the region of the apex beat of the heart and take, upon the table, a recumbent dorso-sinister position. Place the button of the receiving tambour upon that point of the thorax most affected by the apex beat of the heart. The movements of the chest wall will be faithfully transmitted and magnified by the two tam- bours. Fix the recording tambour with clamp, and support and bring into the above described relation to the kjmiograph. (See section II.) 4. Observations. (1) Note the exact point upon the chest where the apex. beat is most distinctly marked. Is it the same for different members of the class? (2) Take several cardiograms from the same individ- ual, being careful so to adjust the apparatus as to gain the maximum excursion of the lever. What features have all of these tracings in common? What features seem to be accidental and nones- sential? What is the cause of the essential feat- ures ? What are the sources of the nonessential features ? (3) Take cardiograms of several individuals. Do all of them possess the features which seemed essential in the first series, taken from one individual. If not, how would you account for the difference ? (4) With a stethoscope, whose construction you have carefully described in your notes, listen to the heart sounds while the cardiograph is tracing the record of the heart movements. Note that two sounds are audible and that there is a noticeable pause follow- LAnONA TORY GUIDE J\ /'//VS/O/.OG V. 19 iii^' tlie shorter, sharper soniul; let us call the sound which succeeds the pause the first sound. (5) With what part of the cardiof^rani does the first sound seem to correspond? With what part of the cardio<;ram does the second sound seem to corre- spond? (live reasons for this correspondence. (6) As far as the data will admit, enumerate causes for the first sound ; for the second sound ; for the es- sential features of tlie cardiogram. IV. THE FLOW OF LIQUIDS THROUGH TUBES. LATERAL PRESSURE. /. Appliances. — Reservoir with short discharge nozzle whose lumen is 6 mm. in diameter ; 5 pieces of glass tubing whose lumen is about 6 mm. in diameter and whose length shall be 60 cm. ; two lengths of glass tubing whose lumen is about 3 mm. in diameter and whose length shall be 60 cm. ; rubber tubing for joining up the apparatus ; 3 T tubes of 6 mm. tubing ; short tube with capillary point from each size of tubing ; 2 one liter flasks ; 2 supports; a light pine stick about 6 feet long ; stopcocks. 2. Preparation. — A resourceful demonstrator will have no difificulty in contriving reservoirs, [t is sometimes not easy to provide a large class with suitable and conven- ient reservoirs. The following form has proven very satisfactory : A glass tube about 3 cm. in diameter may be readily furnished with a glass nozzle of the required size by any glass blower. The nozzle should be about 3 cm. from one end of the tube. That end may be closed with plaster of Paris and filled with hard paraffine to the lower margin of the nozzle opening. This reservoir may be held ^^"l__ upright by a support. When com- plete it presents the appearance in- ^e-^ dicated in Fig. 3. 4— 4ii LAnORATORV GVIPF. /X PZ/VS/o/AX, ) . 21 Operation. — Mark upon the side of the reservoir a point 3G cm. above the center of the nozzle, also a point 04 cm. above the nozzle. While the reservoir is filled from one flask the water may be caught in the other. As- sume some convenient unit of time, as ten or fifteen seconds. Observations. — Fill the reservoir to the height of 04 cm. Allow the water to flow from the nozzle freely into the flasks. Note the distance to which the jet is thrown when the water begins to flow. Note distance when the upper level of the water passes the 30 cm. mark ; the 4 cm. mark. What are your conclusions? {ci) Velocity. — How does the velocity of the discharge vary with the varying height of the column of water? Why does it so vary? Does it verify the law of Torricilli ? The rate at which a fluid is discharged through an orifice [better a nozzle] /'// a reservoir is equal to the velocity which would be acquired by a body falling freely through a height equal to the distance be- tween the orifice and the surface of the fluid. Recall the law of falling bodies : Let g equal the distance through which a body will fall in one second under the influence of gravitation alone, h the total height fallen through, t the time in seconds and V the velocity; derive from the facts the follow- ing equations : (1) v = gt. (2) h=^. From these equations derive (3) v = \2gh ; (ap- proximately =4.429^ h.) Expressed as a variation the constant may be discarded and the variable would read (4) v :x^h. Verify the truth of this mathematically derived law. *g=9,80J) meters. 32 LABOR A TOR Y G UIDE IN PH YSIOL OGY. b. Discharge. — If we let D equal the quantity dis- charged from the nozzle in a unit of time, will D var}' with the velocity? If so, it varies with the h. Does D vary as the velocity. If so, we may write D a)y'h. Verify as follows : During a unit of time allow the water to flow from the 6 mm. nozzle, meantime maintaining a fixed level — e. g., at 64 cm. — by pour- ing water into the reservoir from a flask. Note the amount of discharge (D). Repeat the experiment after having fixed to the nozzle a VQ.xy short piece of 3 mm. tubing. Note that the height (h) remains the same. Is D the same ? Does the formula D xy/h express the facts ? If not, make a formula that will bear verification. Derive the formulae (5) D = 4.429 - rVh,(6)D xr^h when r= the radius of the discharging tube. x'Vt- tach to the nozzle one length of 6 mm. tubing. Note the discharge in the unit of time. Attach a second length of the 6 mm. tubing, taking care that the tubing is approximately horizontal, note the discharge in a unit of time. What is your conclu- sion ? Why does the discharge increase when the length is increased ? If R equals resistance, and L length of tubing, does the following expression represent the facts : (7) Ro) L? Join two lengths of 3 mm. tubing and note dis- charge in a unit of time. What is the variable fac- tor in this experiment ? Does a tube of small radius afford more resistance than one of large radius ? If not, the discharge, all other things being equal, will vary as the square of the radius. D soi*^, i. e., the 3 mm. tube would discharge one-fourth as much in fifteen seconds as would the 6 mm. tube. /..i/WK.rroKV GUJP/-: /x riiysn)i.oGY. '23 Is the relation of discliarge to resistance direct or reciprocal ? X'crify the following formula: (S) I) :r, -. Now we already have found the formula I) yr'sh. Verify the formula (0) D >::'",'/'• c. Pressure; Disjoin all tubes from the reservoir. Join a Tluhe to the nozzle in this position j^ ; join a segment of large glass tubing to the perpendic- ular arm of the T-tube and support it in an upright position. (1) Fill the reservoir to the 30 cm. mark, allow the water to escape from the distal end of the Ttube during a unit of time, meantime maintaining the height of the water in the reservoir. Carefully note the height at which the water stands in the upright tube — the piezometer. (•2) Repeat with water maintained at G4 cm. height in the reservoir. (3) Join a length of large tubing to the distal end of the T-tube ; repeat the experiment using only the 64 cm. height. (4) Join a T-tube to the distal end of the segment of tubing just added and repeat the experiment. Does the addition of the last Ttube make any essential change in the height, at which the water stands in piezoixeter No. 1? Does the reading of piezometer No. 2 agree with the read- ing of piezometer No. 1 in experiment (2). (5) Add a second segment of large tubing. Repeat the experiment. Does reading of piezometer No. 2 correspond with reading of piezometer No. 1 in experimerit (3 ) ? (G) Add piezometer No. 3. (Note : The piezometers 24 LABORATORY GUJDE IN PHYSIOLOGY. may be held in position by using the two supports and the pine stick.) Repeat the experiment. Does reading of piezometer No. 3 correspond with that of No. 2 in experiment (4) and with No. 1 in experiment (2)? Does reading of piezometer No. 2 correspond with that of No. 1 in experi- ment (4). (7) Attach a large capillary, repeat observations. (8) Attach a fine capillary and repeat observations. What is the relation of pressure to height of column ? Does pressure vary as height or as the square root of height; i. e., which of the following formulae represents the facts? (10) P 3oh. (10') P DO^h. What is the relation of pressure to the central re- sistance (Re) ? What is the relation of pressure to distal resistance. (Rd)? Which of the following formulae represents the facts: (11) P :oRc. (11') P DoRd. V. THE FLOW OF LIQUIDS THROUGH TUBES, UNDER THE INFLUENCE OF INTERMIT- TENT PRESSURE. THE IM- PULSE WAVE. /. Appliances. — Two glass tubes of about 6 mm. lumen and about 75 mm. long ; a thin elastic tube, — thin walled black rubber — of about the same lumen as the glass tube and about 150 cm. long ; a double valved strong rubber bulb (about 7.5 cm. long) ; elastic tub- ing, large size ; very thick walled rubber tubing for joining up the apparatus ; Y-tube ; two flasks, or water receptacles ; heavy linen thread ; a wide capillary and a fine capillary ; a piece of glass tubing 10 cm. long ; 500 cc. graduated C3'linder. 2. Preparation. — Join the large elastic tube to the entrance valve of the bulb. Couple the two glass tubes closely and join one end to the exit valve of the bulb. Make all joints as close as possible and tie tightly with thread. Draw a coarse and a fine capillary tube from the 10 cm. piece of glass tubing. J. Operation. ■- Clasp the bulb in the hand and make rhyth- matical contractions at the rate of about fifteen in ten seconds. The process will, of course, pump the water from one flask into the other. 4. Obseri'ations. a. Intermittent force and inelastic tubes. (1) Does the stream of water which is ejected from the exit tube flow in a constant or in an intermittent jet ? (•2) Attach a wide capillary and repeat. What is the character of the stream ? 25 26 LABORATORY GUIDE IN PHYSIOLOGY. (3) Attach a fine capillary and repeat. Note the results. b. Intei-mittent Jorce and elastic tubes. (4) Disjoin the glass tubing from the bulb and join the elastic tube. Work the bulb as directed above, and observe the character of the fiow. (5) Join on the coarse capillary and repeat, noting the change. (6) Replace the coarse capillary by the fine capil- lar)- and repeat. Sum up the results and formulate conclusions. c. Quantitative tests. ("7) How much water will be ejected through a fine capillar}' tube in ten seconds in experiment (3)? (8) How much through a fine capillary in the same time in experiment (6). Note : In performing experiments (Y) and (8) great care should be used to exert exactly the same force upon the bulb. The same capillar}' should be used in the two experiments. What is the significance of these two experiments? d. The impulse ivave. Graphic tests. Appliances. — Support; cork-board (about 8 by 10 cm.); small glass rod about 20 cm. long ; corks ; needles ; kymograph ; piece of sheet lead 1 cm. wide and 5 cm. long ; copper wire No. 16. Make a tracing lever from the glass rod by drawing out one end to a rather fine point and drawing the other to about one-half its original diameter and bending it to make an angle of 135. Bend up 1.5 cm. of each end of the sheet lead so that it will stand at right angles to the middle two cm., bore the cork and pass the larger end of the trac- ing lever through it. Fix the cork-board to a ring of the support with copper wire ; fix the sheet lead to LABOKATOKY GUIDE IN PHYSIOLOGY 27 one end of upper surface of the cork-board with copper wire and pass a needle tlirough the limbs of the lead bearings and the lever-cork in such a way as to bring the lever over the middle of the board. The com- pleted apparatus will have the relations indicated in the accompanying cut. [See Fig. 4.] ^ tA (9) If the finger be held upon the elastic tube while the bulb is being rhythmatically squeezed, a series of impulses or pulsations will be felt by the finger. Place one finger upon the elastic tube near the bulb, and another three or four feet from the bulb. Let the bulb be pumped with sudden, but infrequent contractions. Do you note a dif- ference in the time of pulsation felt b}' the two fingers? It so, which is felt first? Why? What is the cause of the pulsation ? (10) To get a tracing of this pulse, pass the rubber tube across the cork board under the tracing lever [See Fig. 4] ; adjust to kymograph and take tracing. Vary the character of the bulb contrac- tions as follows: Taking one complete rotation of the drum for each variation : (I) Slow initial contraction of bulb and slow re- laxation. 28 LABOR A TOR Y G UID E IN PHYSIOl. OGY. (II) Slow initial contraction of bulb and quick relaxation. (III) Quick initial contraction of bulb and slow relaxation. (IV) Quick initial contraction of bulb and quick relaxation. (V) Same as IV with slow rhythm. (VI) Same as IV with rapid rhythm. Make a careful. study of these tracings and deter- mine : First, the characteristic and essential features. Second, the accidental and nonessential features. Third, what is the cause of the essential. Fourth, what is the cause of the nonessential features. VI THE LAWS OF BLOON PRESSURE DETERMINED FROn AN ARTIRICIAL CIRCULATORY SYSTEH. / Ap/>/ia>ues.--i:x^o large Y tubes of about « mm. lumen; four medium Y tubes, lumen about 4 mm.; eight small Y tubes, lumen about 2 mm.; six thick walled capil- lary tubes, about 3 mm. outside measurement, and lumen not to exceed 1 mm. These capillary tubes should be about 15 cm. long. Two T-tubes of me- dium lumen ; two medium ^ized glass tubes about 75 5.J— ^ 'fo :^^ /y^ cm. long. All rubber tubing should be thin walled and very elastic, and should be in three sizes, corre- sponding to the glass tubes. Two pieces of large size, 75 cm. long, and two pieces about half that length ; four pieces of medium size, about 40 cm. long ; ten pieces of small size ; bulb, thread, heavy linen, mer- cury, large glass receptacle for water, two medium sized rubber couplings. 30 LAB OR A TOR Y G UIDE IN PHYSIOLOG Y. 2. Preparation. — First, make two manometers whose distal limb shall be 40 cm. long, and proximal limb 30 cm., with a horizontal shoulder 5 cm. long. Second, draw out the two limbs of the medium Y tube until they are about the same in size as the small tubing (see Fig. 6). Third, construct the artificial cir- culatory system according to Fig. 5. J. Operation. — First, supply the monometers with mercury so that there shall be 12 to 15 cm. in each limb of the arterial manometer, and 5 to 10 cm. in each limb of the venous manometer. If the class is not familiar with the use and interpretation of the manometer, the demonstrator should lead them to discover all of its essential features. Second, the whole system should be filled with water and freed from air before the ob- servations begin. Third, care should be taken that no stoppage in the system occurs ; otherwise the mercury may be thrown out of the manometers and lost. 4.. Obse7-vatio7is. a. The manometer (mercurial). (1) Find the actual pressure when the mercury in the distal column stands 6 cm. higher than that in the proximal column. (2) Find the pressure per square cm. where the observation is the same. (3) Which of these data would be the more valua- ble to record ? (4) After the arterial circulatory system has been freed from air and is at rest, do the proximal and distal columns of mercury stand at the same level ? If not, why? What allowance, if any, should be made for this ? b. Arterial pressjire. LABORATORY CUIDE JX I'llVSIOlAHiY. 31 (5) With capillaries 1 to 6 open and tubes 7 and 8 closed, let one member of the division make strong rhythmatical contractions of the bulb at the rate of about 20 per second. Note effect on man- ometer. Account for all of the plienomena. c. Venous /pressure. (ti) Note the effect of the contraction upon the venous manometer. If there is any change in the manometer, compare in rhythm and in extent with the changes in the arterial manometer. (/. Relation of arterial to venous pressure. (7) Make ver}' slow contractions. Note results. (^8) Make rapid, strong contractions. Note re- sults. (9) Make rapid, weak contractions. Note results: (10) Remove the clamps from vessels V and 8 (local dilation of arterioles) and repeat experiments 7, 8 and 9, noting and interpreting results. What effect does a dilatation of arterioles have upon venous pressure? What effect does it have upon arterial pressure ? e. Pressure forniulce. Let: P =pressure, Rd=:distal resistance, Pa = arterial pressure, v = velocity, Pv = venous pressure, r = radius of vessel, Hd = strength of contractions, will 3our observations justify the following formulae? 1 2 3 4 Pa xH. 7. Pa DcHxRd. Pv DOH. 8. Pa X r-. Pa xRd. 9. Pa xHxRdxr. Pv 3cRd. 10. Pa XV. Pa>Pv. 11. P DcHxRdxr'x V PaxPv. 32 LABORATORY GUIDE IN PHYSIOLOGY. Does V depend upon H, do Rd and r^ have any rela- tion either incidental or essential ? Would Pa x HxRd practically mean as much as formula 11? f. Graphic record of pulse tracing from the arterial cir- culatory system. With the recording apparatus used in Chapter V. or with a sphygmograph, or better, with both pieces of apparatus, make tracings of the pulsations of the arterial tubes "a" and "b." (See Fig. 5.) Compare all tracings carefully and interpret all the features of the record, differentiating the es- sential from the nonessential, as before. Vn. THE PULSE, SPHYGMOGRAPHS AND SPHYG- MOGRAHS. 1. Appliances.— \ sphygmosraph; tracing slips; a fish tail gas jet, or kerosene lamp ; a fixing fluid of 2 per cent gum damar in benzole. If each division has a wide mouthed bottle of this solution the tracing may be quickly dipped, drained and dried upon a piece of fil- ter paper, or newspaper. (A fixing fluid after this formula is excellent for the kymograph tracings.) It may be kept in a large museum jar and the tracings dipped into it whole, or in sections. 2. Preparation. — Smoke about two dozen tracing slips. J. Operation. — The adjustment of the sphygmograph. That the sphygmograph is so little used by the general practitioner may be attributed to the fact that hurry of business, or some other cause, has hindered him from making himself thoroughl}' conversant with the adjustment and use of the instrument, with its limita- tions and with the interpretation of the tracings. First. Let the observer stand with his right foot on a chair. This brings his thigh into a horizontal posi- tion. Second. Let the subject stand at the right of the observer, resting the dorsal surface of the left forearm upon the observer's knee. Third. Let the observer with pencil or pen mark the location of the radial artery. Fourth. Let the observer wind the clockwork which drives the tracing paper; adjust the latter in readiness for tracing ; rest the instrument upon the 34 LABORATORY GUIDE IN PHYSIOLOGY. subject's arm with its foot upon the radial artery and adjust the position, tension and pressure, in such a manner as to obtain the maximum amplitude of swing of the tracing needle. Take the tracing. Study. 4. Observations. a. The location, etc., of the radial artery. (1) What are the relations of the radial artery at the distal end of the radius? (2) How may the relations vary? (3) Is there any variation, among the members of the division, in the location of the radial artery? (4) May excessive muscular development effect the ease with which the artery may be located and its pulsations studied ? (5) May excessive deposit of adipose hinder the observations of the pulse ? (6) May faulty position of subject or of his cloth- ing effect the pulse ? b. The observation of the radial pulse. (7) Feel the pulse with the side or back of the finger ; then with volar surface and tip of each finger of each hand and note the finger or fingers with which the feeling is most acute. It will be wise to always use these fingers in all tactile ex- aminations. Their acuteness will increase with practice. One may thus acquire the educated touch TACTUS ERUDITUS. (8) How much may be learned of the pulse by means of the touch alone. Observe and note {a) frequency ; (b) character ; i^c') rhythm ; (d) size ; (^,) compressibility. (/) What else may be de- termined by this method ? (9) Take at least three pulse tracings of each indi- vidual in the division, (a) Compare the trac- LABORATORY GUI PI': IX Rf/VS/OLOGV. 35 ings taken from one individual ; if they differ, determine the cause of the difference. {l>) Com- pare tracings of different members of the division. Determine, if possible, tlie causes of differences. (10) Does location or relations of the artery effect the sphygmogram ? Does the adjustment of the instrument effect the sphygmogram? Does the elasticity of the artery effect the tracing ? How does strength or rate of heart beat effect it? Make a list of the facts regarding the condition of the circulatory system which may be determined with the help of the sphygmograph. Make a list of the precautions necessar}- to observe in the use of the sphygmograph. VIII. TO DETERHINE THE GENERAL INFLUENCE OF THE VAGUS NERVE UPON THE CIRCULATION. (Let six students work together.) 1. Appliances. — Student operating case containing scissors, scalpel, artery forceps, 3 serre-fines, silver probe; and a pair of barber's clippers; a rabbit board; large sheet of heavy paper; sealing wax; cotton; ether; thread; 1 Daniel cell; inductorium; vagus electrode; 2 Du Bois keys; V wires; stethoscope; a strong, adult rabbit. 2. Preparatio7is. — Let the six students be subdivided into three groups of two students each. Let group "a" be responsible for the anaesthesia. Use the sheet of heavy paper to make a conical hood, whose spiral turns may be held in place with sealing wax. Place a wad of cotton loosely in the mouth of the cone. Let group " b " perform the operation. Fix the rab- bit, back downward, upon the holder; fix the nose in special holder (see Fig. 1); with the barber's clippers remove the hair from ventral side of thorax and neck; make hands and instruments clean, place instruments in a shallow basin of warm, 1 per cent carbolic acid solution ; cut two or three ligatures of thread and place them in the instrument-basin. 36 LAh'Oh'ATOA'V GUIDE /-V PHYSIOLOGY. 37 Let group " r " arrange the electrical apparatus for stimulation of the nerves. Fill the cell ; join up with ke)' in the priniar}- circuit, and a short circuiting key in the secondary circuit. Test the apparatus to see if everything is in order. J. Operation. — Group "^/." (1) Pour 2 cc. or 3 cc. of sulphuric ether upon the cotton in the cone ; place the cone over the rabbit's nose ; observe, and note carefidly every step in the anaesthesia. (2) Carefully note the rate of the heart beat before beginning anaesthesia. (3) Keep the cotton moist with ether; watch the respiration and pulse, and be careful not to give the animal too much and interrupt the experiment. Group "^." Wash the clipped surface of the throat. After the rabbit is completely ana?sthetized, make with scissors a median incision through the skin, beginning at the apex of the sternum and cutting anteriorly for about 5 or (_> cm., divide the subcutane- ous connective tissue over the middle of the trachea. Carefully separate from the median line on either side laterally the subcutaneous connective tissue with the associated adipose tissue. How many pairs of muscles come into view? What two muscles approach the median line to form the- apex of a triangle at the anterior end of the sternum ? Observe a pair of thin muscles lying dorsal to the muscles just mentioned and joining in the median line to form a thin muscle sheet covering the trachea on its ventral side? Wliat muscles are these ? Carefully lift up the median edge of the sterno- mastoid muscle and separate with the handle of a 38 LAB OR A TOR Y G UIDE IN PH YSIOL O G V. scalpel or a seeker the delicate intermuscular con- nective tissue. A blood vessel and several nerves come into view. Is the blood vessel an artery or a vein ? How many large nerves accompany the blood vessel ? Take hold of the sheath of the vessel, lift it up and note in the connective tissue accompanying the blood vessels two nerves, one large and one small. When the artery is in its normal position, what relation do these two nerves sustain to it? Which of the two nerves is external and which is dorsal to the blood vessel? Which is in close relation to the artery? What is the name of each of the nerves ? In preparing the nerve for stimulation one should neither grasp it with the forceps nor with the fingers. It may be separated from the delicate connective tis- sue in which it lies by use of a blunt seeker. Far better than any metallic instrument is a small glass rod drawn to a point, curved and rounded in the Bun- sen lamp. Prevent the tissues drying up by occasion- ally pressing them lightly with pledgets of cotton moistened in salt solution (0.6 per cent). Adjust the electrode carefully upon the vagus and see that no unnecessary tension is allowed to be ex- erted upon the nerve. It is usually necessary to hold the electrode in place during the observation. Group 'V." The preparatory step in making stimula- tion is the closure of the primary circuit. Why? The next step is to ascertain for certain that there is an in- ductive current. How? Now with the induction cur- rent, short circuited, how may you stimulate? Will it probably be better to stimulate with a strong or with a weak current at first ? If with a weak current first, give reason. How would you verify your posi- L.inoK'.rroA'Y guide lv rnvs/oi.oGY. 39 tion bj' experiment ? If you adopt a weak stimulation at first, liow will j'ou arrange the apparatus to obtain it? Ohservatiotis. — a. AncBst/iesia. (1) Are you able to make out different stages in anaesthesia ? (2) How many stages did your animal manifest ? (3) Give the characteristics of each stage. (4) What effect did the ether have upon the rate of heart beat. (5) What effect did the ether have upon the respi- ration ? b. The stimulation of the vagus. (6) Stimulate one vagus. Note with a stethoscope whether the rate of the heart is increased. (7) Cut both vagi high up in the neck. Note the rate of heart beat at intervals of five minutes for fifteen minutes. (8) Stimulate one vagus. Compare the result with that obtained under experiment 0. (9) Will very strong stimulation bring the heart to a standstill ? (10) If the heart was brought to a complete stand- still by the stimulation, will it start up again spontaneous!}' when the stimulus is removed ? • Will the rate reach the degree of acceleration observed in experiment V ? (11) Sum up the observations into a concise state- ment as to the influence of the vagus upon the heart. (NoTF. : Dispatch the rabbit with chloroform.") B. RESPIRATION. IX. EXTERNAL RESPIRATORY MOVEMENTS— INTRA=THORACIC PRESSURE. /. Appliances. — Operating case; clippers; rabbit board; rab- bit ; cone for anaesthesia ; ether ; kymograph ; cardio- graph, which may, in this case, be called a rabbit stethograph ; two recording tambours ; 10 cm. of glass tubing, 3 mm. lumen; rubber tubing to match. 2. Preparation. — (1) Fix and anaesthetize rabbit. (2) Clip and shave ventral aspect of rabbit's thorax. (3) Make thorax of rabbit, instruments and hands clean. (4) Prepare a thoracic cannula by drawing the glass tube slightly in the center, cutting diagonally at the middle, smoothing diagonally on an emery stone. (5) Join a 30 cm. piece of rubber tubing to the can- nula at the larger end, and clamp it near the can- nula. (6) Cleanse cannula thoroughly. J. Operation. — a. External respiratory movements. Place the button of the rabbit stethograph upon the ventral surface of the rabbit as near as possible over the junction of the diaphragm with the body wall, and a little to the right or left of the median line. So ad- just the stethograph as to obtain the maximum excur- sion of the recording lever. The stethograph maybe held in position through the agency of a clamp and support; sometimes, however, better results may be /..l/iOA-.l /'(Un- Gi'ini: /X rHYSlOI.OGY. 41 secured h\ luildiiif,' tlie stethograph in the hands, sup- porting tlie wrists on the edge of the rabbit board. b. Intra thoracic pressure. Locate an intercostal s|)ace' to the left of the ster- num and opposite its middle point. Make an in- cision 0.5 cm. long, parallel with the intercostal space and 1 cm. from the sternum. Dissect through the intercostal muscles, taking care not to cut the pleura. Insert the point of the glass cannula into the wound, press it carefully through the pleura into the left pleural cavit}' or mediastinum as may fre- quently chance, turn the distal end of the cannula sharply outward until the instrument has a nearly horizontal position. Pass the cannula through the intervening pleural membranes into the right pleural cavity. Join the rubber tube to a recording tambour and unclamp. Slowly and gently manipulate the cannula until there is evident communication through the lumen of the cannula and tube from the pleural cavity to the tambour. So adjust the cannula that the recording lever makes the maximum excursion. Bring the levers into such a relation to the kymograph that the tracing point of the stethograph lever shall be vertically over that of the lever which is to record intra-tlioracic pressure, and about two centimeters from it. At the end of the observations close the wounds and dress it aseptically. Observations. — a. External respiratory movements. (1) During one revolution of the drum — 5 minutes — note the rate and rhythm of the respiratory movements as recorded by the stethograph. (2) Does the stethogram show anything more than rate and rhythm ? 42 LAB OKA TOR V G UID E IN PHYSIOL OGY. (3) What phase of a respiratory cycle does a rise of the lever indicate ? (4) What is the relative duration of inspiration and expiration as indicated by the stethogram. (5) Does the stethogram indicate any variation in different parts of the inspiratory act? Of the ex- piratory act ? (6) Differentiate the essential from the nonessen- tial in the stethogram and determine as far as may be, the cause of each. b. Inlra-thoracic pressure. (7) Does the rhythm of varying pressure corre- spond to the rhythm of the respiratory movements? (8) If so, does that necessarily establish the rela- tion of cause and effect between them? (9) What change of pressure is indicated by the rise of the pressure lever ? (10) What movement of the pressure lever corre- sponds to a rise of the stethograph lever? (11) What is the condition of intrathoracic pressure during inspiration? During expira- tion ? (12) Stop the entrance of air into the respiratory passage by closing the rabbit's nostrils. What effect does this have upon the respiratory move- ments ? (13) Is the intra-thoracic pressure affected by the experiment? If so, explain the effect. (14) If two phenomena involving the same matter, correspond perfectly in their cycles, and if a variation of one is always accompanied by a variation in the other, can there be any reason- able doubt that they sustain to each other the relation of cause and effect ? LAliOKA TORY GUIDE JX J'/J ) S/o/.UuV, 43 (15) Which of the phenomena studied is the cause and which the effect? Demonstrate. To measure intra-thoracic pressure. (16) Clamp tlie rubber tube of the pressure ap- paratus. Replace the recording tambour with a water manometer. Unclamp. Is the pressure during inspiration positive or nega- tive, and how much ? (17) Is the pressure during expiration positive or negative, and how much ? (18) If the whole apparatus were filled wiih water instead of air and water, would it make any essen- tial difference in the result ? What effect do the variations of tlie intra-thoracic pressure have upon the circulation ? Upon the respiration ? X. RESPIRATORY MOVEMENTS IN MAN. Appliances. — K3^mograph ; stethograph ; spirometer; tape measure ; wooden and steel calipers. A simple but efficient stethograph may be made as follows : Materials: support, three large clamp holders, iron rod, 8 or 10 mm. in diameter and 50 cm. long, two wooden rods, 1 cm. in diameter and 40 c. long, a re- ceiving tambour, a transmitting tambour with support. 2. Preparation. — To make a stethograph : Clamp the center of the iron rod to a heavy-base support. Clamp the wooden rods to the iron rod so that they will extend out to one side of the iron rod in a horizontal plane. (See Fig. 8.) A receiving tambour may be constructed especially for this purpose as follows : Let a tinsmith construct, from small brass wire, (^ — ^ mm. in diameter), spiral springs which shall present the outline of truncated cones (See Fig. 8 a.^, and fit inside the larger tam- bour pans. i.A/ioh'.r/'oh'v iiuini-: /x riivsioi.oGY. 4.'5 If the student be supplied with tambour pans, spring, sheet rubber, thread, sealing wax and cork, he may construct his receiving tambour by placing the spring in the tambour pans, stretching the sheet rubber over the spring, tying and sealing. The now conical dia- phragm of the recording tambour should be provided with a cork but- ton, and adjusted by passing its tube through a horizontal hole near the end of one of the wooden rods (see Fig. 8), and con- necting to the transmitting tambour through a small rubber tube. J. Operation. — Each member of the division should in turn remove all clothing above the waist and be the sub- ject of observation for the other members. In making observations with the stethcgraph the subject should sit with his back or side to the table. The observer may readily adjust the stethograph to record the changes of any lateral or dorso-ventral diameter of the thorax. For all observations, whether with the stethograph, calipers or tape, the subject should keep the parts of the body symmetrically disposed. 4.. Ohservations. — a. Inspection. (1) How much may be learned of man's respiratory movements by simple inspection? INIake a care- ful enumeration and record. /'. The stethographic ohservations. (2) Adjust the stethograph and make a record — a stethogram — of the changes of the lateral diame- ter of the thorax at the ninth rib. Does the stethograph show more than could be learned from inspection? If so, what? 46 LABORATORY GUIDE IN PHYSIOLOGY. (3) Take a stethogram of the lateral diameter at the sixth rib. How does it differ from the ninth rib stethogram? Why? (4) Take a stethogram of the dorso-ventral diame- ter of the thorax over the lower end of the glad- iolus. Compare. (5) Take these typical stethograms while the sub- ject reads a paragraph, sighs, coughs, and laughs. Account for the peculiarities. (6) Take the three stethograms after the subject has taken vigorous exercise. What changes are to be noted ? (7) After a similar series of stethograms have been taken for others, compare; determine the essen- tial features; give causes of these. (8) Seek the causes of the differences which exist between stethograms of different individuals. May they be accounted for by stature, condition, occupation or habit? c. The spirometer. (9) Test the lung capacity of each member of the division. May differences in lung capacity be ac- counted for by difference in stature, condition, oc- cupation or habit? d. The girth of the chest. (10) Take the girth of chest in a horizontal plane over the nipple. {a.') With chest in normal repose. (p.) At the end of forced expiration. (<:.) At the end of forced inspiration. (11) Take the girth of chest in a horizontal plane over the juncture of the ninth rib with its cartilage with the chest normal, empty and full. (12) With calipers measure (a) horizontal dorso- LABORATORY GUll'iE I.\ I'll VSIOI.OGV. 47 ventral diameter in plane of nipples, normal, empty and full. {b') Lateral diameter; normal, empty, and full. (f) Lateral diameter over ninth rib; normal, empty and full. (13) Tabulate results for the whole class including name, age, height, weight, condition (fat, medi- um or lean), previous occupation, home, (whether in a hilly or flat country), habit, (whether inactive or active); if the latter, what sort of activity (tennis, bicycle, etc.) Make a careful study of this table and state your conclusions. XI. THE ACTION OF THE DIAPHRAGM. 1. Appliances. — Operating case; clippers; rabbit board, or dog board; rabbit or dog; ether; ether cone; absorbent cotton ; kymograph ; recording tambour ; beaker with warm water ; medicine dropper or bulb. (If a dog be used, the medicine dropper will not be large enough, its place may be taken by a soft spherical rubber bulb about 2 cm. in diameter.) Inductorium, 1 cell, 2 ke3's, vagus electrode, 5 common wires and 2 fine wires. 2. Preparation. — Fix the animal to the board, anaesthetize, clip anterior median region of abdomen. Put the bulb into the warm water, join the glass tube of the bulb to the recording tambour through a rubber tube. This apparatus thus joined may be called a phrenograph and its record a phrenogram. Set up electrical apparatus with short circuiting key in secondary coil. J. Operatioti. — From the posterior extremity of thexyphoid appendix make a median incision through the abdomi nal walls from 3 cm. to 5 cm. according to the size of the animal. Clamp with your serre-fines any small vessels which may be oozing. After having clamped the rubber tube, which connects the bulb to the tam- bour, carefully insert the warm, wet bulb between the diaphragm and the liver. The liver will usually afford sufficient resistance to cause alternate compression and relaxation of the bulb and a consequent rise and fall of the recording lever; if such be not the case, the liver may be held in place by two fingers inserted into LABORATORY GUIDE /X PHYSIOLOGY 19 the wound. In the meantime let another member of the division dissect out the left phrenic nerve. Fig. 9 shows the relation of the phrenic at the base of the neck, in the rabbit. ./, Observations. — a. Tactile observation of the diaphragm, (1) In what condition is the diaphragm during in- spiration ? Expiration ? (2) In what position is the diaphragm during these two phases of respiration? (3) What parts of the diaphragm make the great- est change of position during inspiration? (4) What causes the diaphragm to arch anteriorly during normal expiration ? During the present observations? 50 LAB OR A TOR \ " G UIDE IN PH YSIOL O G Y. (5) Are the diaphragmatic movements synchronous with the costal movements? b. The normal phreno gram. (6) Take a phrenogram. What may be learned from it? (7) Without varying the adjustment of the phreno- graph bulb, take a tracing while repeatedly inter- rupting the respiration by holding the nostrils. What does the phrenogram show? What is the interpretation ? If you had taken a tracing of intra-thoracic pres- sure, what would it have shown? c. The phre7iic fierve a?id its functtoft. (8) Describe minutel}' the relations of the nervus phrenicus in the neck. (9) Cut the nerve while tracing a phrenogram from the left side of the diaphragm. Note the result. (10) Take a phrenogram from the right side of the diaphragm. Does it differ essentially from the normal? (11) While taking a left phrenogram stimulate the distal end of the left phrenic nerve. Interpret the result. (12) While taking a right phrenogram stimulate the distal end of the left phrenic nerve. Interpret the result. (13) Dissect out and cut the right phrenic nerve. Does the diaphragm cease to move ? If it moves, is its movement active or passive ? Account for the phenomena. Kill animal with chloroform. XII. a. RESPIRATORY PRESSURE. B. STinULATION OF PUL/VIONARY VAQU5 THROUGH INCREASE OF INTRA=PUL- MONARY PRESSURE. /. Appliances. — Operating case ; clippers ; rabbit board ; ether ; ether cone ; absorbent cotton ; rabbit stetho- graph ; kymograph ; a small mercury manometer, to the proximal limb of which is attached a thick walled rubber tube, a piece of glass tubing for a mouthpiece; a screw clamp. 2. Preparation. — Fix and anaesthetize the rabbit, and clip the ventral surface of the neck. Join up the manometer as shown in Fig. 10. 2- Operation. — Make a longitudinal incision over the trachea. Carefully pass a strong linen ligature under the trachea. Make a median ventral slit in the trachea anterior to the ligature. Pass through the slit, the limb of the Y-tube marked 1. (Fig. 10.) Ligate. -/. Observations. a. Respiratory pressure. (1) After the ligature is tied how does the rabbit breathe ? Are tlie thoracic and abdominal move- ments of respiration accompanied by other res- piratory movements ? (2) Witli tube "n " (see Fig. 10) open is there any variation of the mercur\' during respiration? (3) With a screw clamp slowly close tube " n." As the resistance to the tiow of air increases what change is noted in the manometer ? 52 LABORATORY GUIDE IN PHYSIOLOGY. (4) Quickly clamp tube "n " at end of expiration and carefully note the manometer reading. Is it positive or negative ? (5) Clamp tube " n " at the end of inspiration. Is the pressure positive or negative ? (6) You have been determining certain facts regard- ing RS3PIRAT0RY PRESSURE. Are the causes of the changes of respiratory pressure the same as the causes of the changes of intra-thoracic pressure? (7) In what way does respiratory pressure differ from intra-thoracic pressure ? Stiviulation of the pulmonary vagus. nj.io » u Centimeter Scale (8) Count the pulse. Adjust the stethograph, and mouth over the glass mouthpiece; quickly blow in- to the tube " n " until the manometer indicates two during the tracing of a stethogram place the centimeters of intra-pulmonary pressure ; clamp, count the pulse. After a few seconds release the clamp and let the rabbit breathe normally for a few minutes. Repeat the experiment. Vary by producing in turn 3 cm., then 4 cm. and finally 6 cm. of intra-pul- monary pressure. Fix the stethogram and com- pare. (9) Compare your results with those obtained from other rabbits. What are the essential features of LAJWK.-nOKY CUIDI-: AV Pin SIOLOGV. 5)} the modified stethogram ? Formulate the results. (10) What effect has a sudden increase of intra- pulnionar}' pressure upon the rate of the heart's action. (11) What nerve is tlistrihuted to both lun^s and heart? Admitting that it is possible for the ob- served effects to be produced through the agency of the nerves just named, state how this action may be accomplished. (12) Could the effects be produced in any other way than in that which you have given ? (13) Is the demonstration unassailable, if not, what experiments would lead to results conclusive for or against the theory ? (14) Is the minimum intra- pulmonary pressure, which typically modified the stethogram, greater or less than the respirator}' pressure of forced expiration ? (15) What effect upon intrathoracic pressure would the induction of high intra-pulmonary pressure have ? (IG) What effect upon blood flow would high intra- pulmonary pressure accompanied by repeated acts of forced expiration have ? WHiat incident effect upon the rate of heart beat ? XIII. RESPIRATION UNDER ABNORMAL CON= DITIONS. 1. Appliances. — Three small animals, e. g., mice, rats, guinea pigs or squirrels. Two wide-mouthed bottles or jars which may be sealed; scales or large balances; CO3 generator; water bath; operating case; dissect- ing boards. 2. Preparation. — Determine the weight of each animal. Choose a receptacle whose cubic contents is about three to five times as many c. c. as the weight of animal "a" in grams. Choose second and third re- ceptacles whose contents represent about 15 to 18 c. c. to one gram of animals "b" and "c," respectively. J . Operation. — I. Preliminary. b. Put animal "b" into jar "b." Before closing count respirations ; close air-tight. c. Fill jar "c" one-third full of water and displace the water with COg. Put animal "c" into the jar, taking care to allow as little loss of CO3 as possible ; close ; count respirations. a. Put animal "a" into the small jar "a"; count respirations; close the jar. II. Post-mortem examination. After an animal dies fix it to the dissecting board and open the abdominal and thoracic cavities; take great care not>tocut a large blood vessel; pin the flaps out so that all of the organs will be exposed and in place. 4. Observations. — a. Respiration in small closed space. 54 LABOKATORY GUIDE IX /•// VS/OLOGY. 55 (1) Make careful record of number of respirations and general condition of animal "a" in the nor- mal state, and at the end of every five minutes after the closure of the jar. What changes in rate or depth of respiration have been noted ? (2) Note all abnormal signs and symptoms. (3) On post-mortem examination record condition of heart, large blood vessels, lungs, liver, kidneys and of the general appearance of the tissues. (4) Compare the conditions with those found in a normal animal, prepared bj' the demonstrator. d. Respiration in a larger closed spact. (5) Note all symptoms of animal "b" every five minutes after confinement in the jar. (6) Make a post-mortem examination ; record in detail the condition of the organs as in the case of animal " a." (^7) Compare animal "b" with the normal animal. (8) Compare animal " b " with animal " a. " c. Respiration in an atmosphere of one-third CO.^. (9) Note all symptoms at intervals of five minutes. (10) Compare these observations with correspond- ing ones from animal "a" and animal "b." Wliat are your conclusions? (11) Make a post-mortem examination; make a record as before. (12) Compare appearances in animal "c" with those in the normal animal ; with those of animal "a ; " with those of animal " b." (13) Make a generalized statement of the facts discovered in the experiments. (14) What is the cause of death when an animal is inclosed in a small space? 56 LABORATORY GUIDE IX PHYSIOLOGY. (15) What is the cause of death when an animal is inclosed in a large space ? (16) Have the relations which you have discovered any bearing upon the future development of animal life upon the earth? XIV. RESPIRATION IN ABNORMAL MEDIA. /. App/iancfs.— Three, small animals ; three jars ; water bath; hydrogen generator; large test tube of hard glass; support with tube clamp; Bunsen burner; delivery tube; bichromate of potassium; ammonium chloride; operating case; dissecting boards. 2. Preparation. — Construct a nitrogen generator as indi- cated in Fig. 11. ^^ Ti$.tl ?. Operation. — I. Preliminary. a. Fill a jar full of water; displace the water with nitrogen, generated from 0 gms. of powdered KgCrgO, + 3 gms. of NH^Cl in the apparatus shown in Fig. 11. Put animal "a" into the atmosphere of nitrogen; close the jar. b. Fill a jar full of water, displace it with hydrogen gas. Put animal " b " into the jar and close it. c. Fill a jar one-third full of water; displace the water with illuminating gas. Put animal "c" into the jar and close it. 57 58 LABORATORY GUIDE IN PHYSIOLOGY. II. Post-mortem examination — See XIII. 3 II. 4. Observaiiofis. — a. Respiration in afi atmosphere of nitrogen. (1) Note all symptoms. (2) How do these compare with those of death by oxygen starvation ? (3) Record post-mortem appearances. (4) Compare with previous cases. b. Respiration in an atmosphere oj hydrogen. (5) Note carefully every abnormal appearance and symptom. (6) Make a record of the post-mortem appearances. (7) Compare these with the appearances after death by oxygen starvation; by CO., narcosis. c. Respiration in an atmosphere of one -third illuminating gas (C6'+). (8) Record all symptoms. (9) Record post-mortem appearances. (10) How does death in an atmosphere of CO compare, as to symptoms, with death in an at- mosphere of nitrogen ? (11) Compare it in turn with other forms of death as induced in XIII. and XIV. (12) Compare the post-mortem appearances in this case with those in preceding cases. QP44 II14 Hall A laboratory guide in physiology Chap. I- II. On circulation and respira+ion. \ rt.VHfc'i'TlTi-, ..am'" ^