CORNELL UNIVERSITY. 
 
 THE 
 THE GIFT OF 
 
 ROSWELL P. FLOWER 
 
 FOR THE USE OF 
 
 THE N. Y. STATE VETERINARY COLLEGE. 
 
 1897 
 
i 
 
 Cornell University Ubrary 
 QP 42.H8S 
 
 Directions for laboratory JJiJIIllfiilJiffl 
 3 1924 001 040 959 
 
Cornell University 
 Library 
 
 The original of tiiis bool< is in 
 tine Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31 924001 040959 
 

 h^^e^i 
 
 CORNELL UNIVERSITY. 
 
 THE 
 THE GIFT OF 
 
 ROSWELL p. FLOWER 
 
 • FOR THE USE OF 
 THE N. Y. STATE VETERINARY COLLEOB. 
 1897 
 
 *i'- 
 
DIRECTIONS 
 
 llflRITORY WORK IN PHYSIOLOGY 
 
 fO« THE USB OF THE 
 
 MEDICAL CLASSES 
 
 UNIVERSITY.OfJBTHIGAN. 
 
 *^ c 
 
 '■^ 
 
 "f. H. HOWELL, Ph. D., M. D., 
 
 PBOFKSSOK OS^PHYaiOlOGY AND HISTOLOOT. 
 
 GEORGE "WAHB: 
 
 FUBtlSHBB AND BOOKSELLEK, 
 A2fN ASBOB, MICH. 
 
 1831 
 
 G 
 
<f- "2- 
 
 .';f!XL...l3..U.s_l...L«lifc.. 
 
 1891. 
 
 COPYRIGHT BY GEO. WAHB. 
 
 KW3J^ 
 
 Courier office printers. 
 
LESSON I. 
 COAGULATION OF BLOOD. 
 
 1. DEMONSTBATION OF BLOOD PLASMA.— 
 
 Several preparations of cat's blood, in which the cor- 
 puscles have settled, have been prepared for examination. 
 Note the following things: 1st, The mass of red (and 
 white) corpiuscles at the bottom of the vessel; 2d, The 
 more or less colorless plasma; (If the animal was killed 
 while digesting this may contain considerable fat); 3d, 
 Between the corpuscles and plasma a small layer of white, 
 corpuscles. 
 
 The preparation was made in this way. A canula 
 was inserted into the carotid artery and the blood allowed 
 to flow into a cylinder containing a 27 per cent. sol. of 
 Mg SO4 (For cats use, one part Mg SO4 sol. to nine of the 
 ' blood). The Mg 8O4 prevents the blood from clotting and 
 if the preparation is allowed to stand for 24 haurs or \ 
 longer the corpuscles sink to the bottom, showing the 
 clear plasma. 
 
 2. DEMOSSTRATION OF BLOOD SERUM.— 
 
 A specimen of clotted blood showing the serum has 
 been placed on the table for examination. In preparing 
 it the blood is first allowed to clot in the glass ; its edges 
 are then carefully separated from the ^lass with the 
 handle of a scalpel. If allowed to stand the clot eon- 
 tracts, slowly pressing out the serum. 
 
 S. DEMONSTBATIOSr OF THE METHOD OF DEFIBRINATING 
 BLOOD.— 
 
 A dog will be bled by the demonstrator, who will 
 show the method of inserting a canula into a blood vessel. 
 
The blood as it flows fnto a vessel is to be whipped vigor- 
 ously with a bundle of wire for five minutes. Note the 
 mass of stringy fibrin on the whipper. Wash this mass 
 and it will become white as the red corpuscles are washed 
 out. 
 
 4. DEMONSTBATION OF FIBRHf THREADS POBMED IN COAG- 
 ULATION.— 
 
 Take a good-sized drop of your own blood on a glass 
 slide, cover it with a glass slip ; after a few minutes 
 examine under a microscope. If the layer of blood is 
 thick enough, the fibrin network can be seen easily in the 
 6peii spaces among the corpuscles. It appears as a delicate 
 reticulum of colorless threads which must be focussed 
 carefully to be seen. 
 
 6. COAGULATIOIf OF SALTED PLASMA.— 
 
 a. Use first the clear plasma of Exp. 1. You will be 
 given 2cc. Dilute it with water to 15cc., and allow it to 
 stand until it clots. Notice the character of the clot. 
 
 J. Use some of the salted blood of the dog, prepared 
 as in Exp. 1, but in which the corpuscles have not settled. 
 Take 5cc. and dilute with water to 25cc. Put it aside until 
 it clots. 
 6. TO DEMONSTRATE THE ACTION OF FIBRIN FERMENT.— 
 
 There are several "Ways of making solutions of fibrin 
 ferment. The easiest is the following. Take fresh fibrin, 
 wash it under a tap with water (best in a piece of oottoh) 
 until perfectly colorless. Squeeze out the water and cover 
 the fibrin with an 8 per cent. sol. of Na 01. After a few 
 hours, if the solution is filtered it will show the presence 
 of ferment. Prove its existence and property in this way. 
 
 Take some salted blood as in 5 & ; Divide it into two 
 equal portions, add to one double the quantity of water 
 and to the other double its quantity of the ferment s6lu- 
 tion. The latter solution will clot rapidly or slovirly, accord- 
 ing to the strength of the ferment. The former will not 
 clot at all, or will clot much slower. 
 
QUESTIONS TO BE ASSWE^tED IN WREriN€t, 
 
QTJESTIOlifS TO BE ANSWERED IN WRITING. 
 
LESSON II. 
 
 CHEMISTRY OF PROTEIDS OF THE 
 SERUM. 
 
 1. PREPAEATION OF A SOLUTION OP EGG A1BUME5.— 
 
 Catch the. white of an egg in a tumbler, cut it thor- 
 oughly with scissors to loosen the membranes, dilute with 
 20 times its volume of water, shake or stir tBoroughly and 
 filter. Use the cl,ear filtrate, containing egg albumen, to 
 make the following getieral tests for ptoteids. 
 
 2. GENERAL PKECIPITAN^S.— 
 
 Alcohol. — ^To some of the albumen solution in a test 
 tube add an excess of alcohol. The albumen is precipi- 
 tated. /': ^-'f. 
 
 Tannic Acid. — Make the solution of albumen acid 
 with acetic acid and add tannic acjd. /.The albumen is pre- 
 cipitated. This test will detect albumen when it is di- 
 luted to 100,000. - ,;, 
 
 Phospho-tunffstic Acid. — Make the solution of albu- 
 men acid with HCl and add a little of the solution of 
 phospho-tungstic acid. It will also detect the albumen 
 in minute quantities. " • - 
 
 Poidssio-mercuric Iodide.— Make the albumen solu- 
 tion acid with HCl and add some of this solution. It will 
 also detect traces of albumen. 
 
 3. XANTHO-PBOTEIC TEST.— 
 
 This and the subsequent tests should be tried with the 
 sol. prepared as above, and with the same diluted 100 
 times. Use test tubes. i 
 
 Add to the albumen sol. about ^ its volume of strong 
 HNO3 and boil. If there is a perceptible quantity of albu- 
 
— 6 — 
 
 men this will cause a precipitate aiid yellow color. If the 
 albumen is in minute traces no change will be noticed. 
 Allow the solution to cool and then add an excess of 
 NH4OH. Whether the solution is strong or weak in 
 albumen this will give a yellow color, which color consti- 
 tutes the test. 
 
 4. ACETIC ACID AND POTASSIUM FEBROCYANIDE TEST. - 
 
 Add to the albumen solution enough acetic acid to 
 give a strong acid reaction, and then drop in, with a 
 pipette, one or more drops of the potassium ferrocyanide 
 sol. A white flocculent precipitate results. 
 
 5. MILLON'S TEST.— 
 
 Add to some of the albumen sol. a little of Millon.'$ 
 reagent and boil. A precipitate small or large, accpr(|ing. 
 to the quantity of albumen, will forth, which has a charac- 
 teristic pink color. 
 
 e. THE BIURET TEST,-. 
 
 Add to the albumen solution an excess of strong 
 caustic potash or soda- Then drop in carefully one or 
 more drops of a 2 per cent. sol. of Ou SO4 . The solution 
 will give a blqe color. 
 
 7 . COAGULATION OF THE BLOOD ALBUMEN BY HEAT.— 
 
 Heat some serum in a test tube. Unlpss the reaction 
 is strongly alkaline, the albumens (paraglobulin and 
 serum albumen) will be precipitated. If the serum should 
 give no distinct coagulum upon boiling, ^«utralize it with 
 dilute (0.2 % HCl.) acid, and again boiL Filter off the, 
 precipitate and test the filtrate with the biuret and the. 
 potassium ferroyanide tests, to see if any albumen is still 
 in solution. 
 
 8. PRECIPITATION OF PARAGLOBULIN 
 
 Blood serum contains both paroglobulin and serum 
 albumen. To precipitate the former alone, the follQwing 
 method may be used : 
 
Dilute lOcc. of serum with 90cc. of ice cold water and 
 then pass through the solution a stream of COj . A floc- 
 culent precipitate (paraglobulin) will form. Allow the 
 solution to stand until the precipitate settles, decant oif as 
 much of the liquid as possible, anrl throw the balance, 
 with the precipitate, on a small filter. After the filtration 
 is complete, remove the filter, press it well between 
 folds of filter paper until well dried, cut it up into small 
 pieces in a beaker, and add J5cc. of a 3 % solution of Na 
 01, stir, well for several minutes and filter. The solution 
 will contain the paraglobulin. Prove its presence by 
 boiling' and by the potassium ferrocyanide test. 
 
 9. PRECIPITATION OF PARA«LOBUIJN BY DIALYSIS.— 
 
 (demonstkated.) 
 Pour some of the serum into a parchment dialyzing 
 tube which has been previously soaked in distilled water. 
 Swing the tube with its contents in a large vessel of dis- 
 tilled water, which is to be changed at intervals. After 
 24 hours examine the serum in the dialyzing tube, it will 
 contain a flocculent precipitate of paraglobulin. 
 
QUESTIONS TO BE ANSWEBED IS WEITING. 
 
QUBSTIOIVS TO BE ANSWEEED M WRlTtSQ. i 
 
QUESTIONS TO BE ANSWEEBD IN WlMTIN€f. 
 
LESSON III. 
 
 ACTION OIF NEUTRAL SALTS ON 
 SERUM. 
 
 1. ACTION or (NH4 )a SO4 .— 
 
 Powder some ■(NH4 )2 SO4 a'nd add it to clear serum in 
 a beaker, stirring frequently until the serum is thoroughly 
 saturated. A heavy precipitate will form. Allow it to 
 stand for a while, stirring occasionally, filter and test the 
 filtrate for albuihens with the pbtassiurfa ferrocyanide tfest 
 and by boiling. It will be found free from albumen. 
 Both th6 serum albumen and t;he paraglpbulin have befen 
 completely precipitated. 
 
 2. ACTION OF MG SO4 .— 
 
 Powder some of this salt and saturate the serum with 
 it as in the preceding experiment. Miter and test the 
 filtrate for albumens. By boiling, it will be found to con- 
 tain a quantity of albumen. It is known that the 
 Mg SO4 thi'bwS down only the paraglobulin. The serum 
 albumen is not at ali affected. Save the Mg SO4 precipi- 
 tate on the filter for ^xp. 3. 
 
 3. TEMPEKATURE OF HEAT COAGULATION 
 
 Paraglobulin is precipitated from its solution by boil- 
 ing, but to determine exactly its temperature of heat co- 
 agulation proceed as follows: Take the filter of (2) con- 
 taining the paraglobulin precipitate after the liquid has 
 been filtered off, press it betweeq folds of filter paper to 
 remove the balance of the mother liquor, cut the filter 
 with its precipitate into small pieces in a beaker. Add 
 distilled water (twice the volume of the original serum) 
 allow to stand for some time, filter. With this solution 
 
— 10- 
 
 of nearly pure paraglobulin, determine the temperature 
 of coagulation. Put the solution in a test tube, fit a 
 thermometer in by means of a cork, and swing the tube 
 in a large beaker of water as shown 
 in the illustration. Heat slowly and 
 observe the solution of paraglobulin. 
 At a certain temperature it becomes 
 milky and a little later flocculi can 
 be detected; this latter marks, the 
 temperature of coagulation. Make 
 a report of the temperatures found. 
 
 <^ 
 
 :=? 
 
 4, ACID ALBUMEN (SYNTOSIN) 
 
 Prepare a sol. for yourself as fol- 
 lows : Take a few cc. of egg albumen, 
 and warm for some time with dilute 
 H2 SO4 (2 parts, acid to 100 of Ha 0). 
 Filter the sol. and test for acid albu- 
 men as follows. (Instead of egg albu- 
 men pieces of muscle, if obtainable, 
 will give better results.) 
 
 6. NEUTEAIIZATIOIf PRECIPITATE.— 
 
 Neutralize (it must be done care- 
 fully, using a pipette) some of the solution with 0.5 
 % sol. of Na OH, a precipitate will follow. Add an ex- 
 cess of Na OH, the precipitate will redissolve. Neutralize 
 this solution with weak acid (0.2 % HCl), it will again 
 precipitate. 
 6. EFTECt OF BOIIING.— 
 
 Boil some of the acid albumen sol. It is not coagu- 
 lated. Neutralize with NaOH as before and boil the 
 liquid containing the precipitate. In this form it is coagu- 
 lated and addition of ail excess of NaOH now will not 
 dissolve it 
 
 ALKALI ALBUMEN.— 
 
 Prepare a solution as follows : 
 
 Take a few cc. of egg 
 
—11 — 
 
 albumen add a quantity of 0.2 % Na OH and after a few 
 minutes warm gently. Filter the sol. if necessary, 
 
 8. NEUTRALIZATION PRECIPITATE 
 
 Repeat the experiments described in 5 and 6, neutral ■ 
 iziiig first with weak acid and then adding it to excess, etc. 
 
QUESTIOSfS TO BE ANSWERED Hf WRITIlfG. 
 
LESSON IV. . 
 ESTIMATION OF THE NUMBER OF COR- 
 PUSCLES AND AMOUNT OF H.^EMA- 
 GLOBIN IN HUMAN BLOOD. 
 
 In this lesson the hasmacytometer', to count the num- 
 ber of blood corpuscles, and the haemaglobinoraeter to 
 estimate the amount of haemaglobin in the blood are to be 
 used. Each instrument will be demonstrated to a section 
 of four, each of whom will be expected to use it upon his 
 own blood, and to make a report of the results. 
 
 1. THE HAEMACTTOMETER.— 
 
 Several forms of this instrument are sold. The one to 
 be used is Malassez's latest form, made by Verick. The 
 common principle upon which all such instruments are 
 based is to dilute a known quantity of blood to a 
 known extent with some solution which will prevent 
 coagulation and not injure the corpuscles. The liquid 
 most frequently used is a sol. of IN a^ SOi of a S. G. 1025 
 (about 3%). A drop of this mixture is placed under the 
 microscope in a special chamber of known depth, and with 
 a bottom ruled in sq^aares, each of a known size. The av^ 
 erage number of corpuscles in each square is determined 
 and calculations made from this for the undiluted blood. 
 
 In this particular instrument each square is A- mm. 
 on a side, and is ^ of a mm. deep. Thfe cubic contents of 
 each square will be W x /o x i= nrhn of a cubic mm. 
 Count the number of corpuscles over 10 squares, take the 
 average, multiply this by 2,000, to get the number in a 
 cubic mm. and. finally multiply this last result by the 
 number of times the blood was diluted — (usually 100 
 
_ 14 — 
 
 times) to get the number of corpuscles in a cubic mm. of 
 undiluted blood. 
 
 2. THE HAEMAGLOBEfOMETEB.— 
 
 Several forms of this instrument are in use. Two 
 kinds are in the laboratory — von Fleischl's and Gower's. 
 In each a known quantity of blood, 6.8 cu. mms in von 
 Fleischl's and 20 cu. mms in Gower's, is diluted, and the 
 depth of color compared with that of a standard solution 
 or of a wedge of colored glass. In Gower's instrument 
 the standard solution for comparison is glycerine jelly, 
 colored with picrocarminate of ammonium and intended 
 to represent a IX solution of normal blood ; the quantity 
 of blood taken is to be diluted until it has the same tint. 
 In von Fleischl's instrument the blood taken is diluted a 
 given amount, and the tint is then compared with a wedge 
 of red glass until a thickness is obtained which gives the 
 same color as the diluted blood. 
 
 With each instrument the percentage of hsemaglobin 
 is read off at once upon a scale and requires no calculation. 
 The precautions to be observed in using each instrument 
 will be stated when the demonstration of the method of 
 using it is given. 
 
QUESTIONS TO BE ANSWERED IN WHITING. 
 
QUESTIONS TO BE ANSWEKED IN WEITIHG. 
 
LESSON V. 
 
 THE SPECTROSCOPIC PROPERTIES OF 
 HvEMAGLOBIN, AND THE METHOD 
 OF DETECTING BLOOD. 
 
 1. THE SPECTEOSCOPE.— 
 
 The structure and method of using this instrument 
 will be demonstrated to the class in sections of four. Each 
 student will be expected to mate the following experi- 
 ments, and to submit a report of his work. 
 
 a. The absorption spectrum of oxy-hsemaglobin in 
 diluted blood. 
 
 h. The absorption spectrum of haeraaglbbin in the 
 same solution after reduction by Stoke's liquid. The com- 
 position of Stoke's liquid is as follows : Take 2 parts of 
 ferrous sulphate, grind in mortar and dissolve, and add to 
 this 3 parts of tartaric acid, previously ground. After the 
 tartaric acid is dissolved, add NH4 OH to sti'ong alkaline 
 reaction. Thei'e should be no precipitate. The solution is 
 kept in a well stoppered bottle in the dark, and must be 
 made fresh from time to time. 
 
 c. The absorption spectrum of Carbon-monoxide 
 hsemaglobin. In order to prepare this compound take a 
 solution of diluted blood such as was used in Exp. as., and 
 pass a stream of coal gas through it for several minutes,filter, 
 and notice the difference in color, as compared with some 
 of the original solution of oxy-hsemaglobin. The coal gas 
 contains CO gas, which drives the O out of the oxy-hsema- 
 globin and forins CO-hsemaglobin. 
 
 d. Test the action of Stoke's reducing agent upon the 
 CO-hsemaglobin solution. Eeport the result. 
 
— 16 — 
 
 6. With the aid of the comparison prism at the end 
 the spectroscope (the manner of using it will be demon- 
 strated) superimpose the spectrum of oxy-haemaglobin 
 upon the spectrum of carbon monoxide hsemaglobin. Re- 
 port the result. 
 
 /. The absorption spectrum of acid hEematin and of 
 methaemaglobin will be demonstrated to each section. 
 
 2. THE MICROSCOPIC DETECTION OF BLOOD-COKPUSCLES 
 IN BLOOD STAINS. 
 
 Use two stains, one freshly made, not more than two 
 days old, and one much older. 
 
 {!.) The specimen is on a glazed surface. Scrape 
 off a bit of the material with the scalpel, place it upon a 
 slide, tease or macerate it in each of the following 
 liquids, and examine with a microscope for blood cor- 
 puscles. 
 
 a. SOX caustic potash or soda will in most cases 
 prove the best reagent for swelling out the corpuscles to 
 their normal shape. 
 
 5. Miiller's solution — (Pot. bichromate 2 pts., Naa 
 SO4 Ipt, H2O lOOpts.) 
 
 c. Distilled water. — This reagent will not succeed ex- 
 cept in fresh stains, and even then will dissolve the heema- 
 globin out of the corpuscles, so that only colorless or 
 "shadow" corpuscles will be detected. 
 
 (^.) The specimen is on an absortive surface, such as 
 cotton. Examine with a magnifying glass to get if possible a 
 fragment of the dry blood. With this proceed as above. 
 If this is not possible, cut out a bit of the stained material^ 
 soak and rub it in the liquids mentioned above, and exam- 
 ine the liquids for corpuscles. 
 
 (5.) The Hcemin test. The object of this test is to ob- 
 tain the heemin crystals from the.hasmaglobin. Hsemin is 
 hsematin -f HOI, it can always be obtained from blood 
 
— 17 — 
 
 stains in a crystalline form no matter how old the stain is. 
 
 a. To get the crystals from dried clot or fragments of 
 dried Mood.-Seyeral methods may be used. The following is 
 the most certain : Enb up the dried fragments in a mortar to 
 a fine powder, add about an equal amount of crystals of 
 Na 01, powder them together. Take a little of this powder, 
 spread it upon a slide with the blade of a knife, and cover 
 with a cover slip. By means of a pipette run a drop of glacial 
 acetic acid under the cover slip. (Nothing but the glacial 
 acid will suflBce.) Then evaporate to dryness by drawing 
 the slide through a flame rather quickly, and blowing 
 upon it. Next run a drop of distilled water under the slide 
 and examine under the microscope for the htemin crystals. 
 
 b. To get the crystals from blood stains. — Macerate 
 the stain in glacial acetic acid, if possible scrape off" 
 some of the swollen red mass, together with some of the 
 liquid. Place this upon a slide, add a few crystal of 
 Na CI and proceed as in the former experiment. 
 
 3. THE GUAIACUM TEST. 
 
 Use a tincture of Guaiacum (1 pt. guaiacum to 18 pts. 
 alcohol,) add to it an equal bulk of ozonized turpentine,(old 
 turpentine that has been exposed to the air). Layer some of 
 this emulsion over the suspected liquid in a test tube — if 
 any haemaglobin is present a blue color will form at the 
 junction of the two liquids. The color is caused by the 
 oxidation of the guaiacum. 
 
QDESTIONS TO BE ANSWERED IN WRITING. 
 
QUESTIONS TO BE ANSWERED IN WRITING. 
 
QUESTIONS TO BE ANSWERED IN WRITING. 
 
LESSON VI. 
 
 SALIVARY DIGESTION. 
 
 1. SALIVA.— 
 
 Collect a quantity of saliva either by chewing; a piece 
 of rubber or by filling the mouth with ether vapor — filter. 
 With the filtrate proceed as follows: 
 
 a. Reaction for Mucus. — To a small portion (2cc.) 
 add a few drops of strong acetic acid, mucus if present 
 will be precipitated. 
 
 5. Reaction for Proteids. — Filter (a) to remove the 
 mucus, add several drops of potassium ferrocyanide solu- 
 tion. A precipitate of albumen will occur. Test a fresh 
 specimen of saliva for proteids with Millon's reagent also.- 
 Report your results. 
 
 2. PKEPARATION OF STARCH PASTE.— 
 
 Rub up about one gramme Qf raw starch to a thin paste 
 with a little water. Place this paste in a beaker and heat 
 for some time on the water bath over boiling water, then 
 add lOOcc. of boiling water, stir and heat for a while longer. 
 
 3. TESTS FOR STARCH, DEXTRI5 AND SUGAR.— 
 
 a. Starch. — Dilute some of the starch paste with 
 water and add to it some iodine solution, a deep blue color 
 will form. 
 
 h. Dextrin. — Treat a solution of dextrin in the same 
 way with iodine. A brownish red color will form which 
 disappears on heating and reappears on cooling. 
 
 c. Sugar {grape sugar). — Take 5 or lOcc. of the pre- 
 pared Fehling's solution, heat it to boiling, add 1 or 2cc. of 
 the solation of glucose {\%) and continue heating for 
 a while. The CUSO4 in the Fehling sol. will be reduced to 
 
— 20 — 
 
 cuprous oxide which precipitates as a red or yellow 
 powder. Cane sugar will not give this reaction until 
 changed to glucose. 
 
 4. THE DIASTATIC OR AMYLOLYTIC ACTION OF SALIVA.— 
 
 Take some of the filtered saliva (if it filtei's too 
 slowly it may be diluted with an equal bulk of water) 
 place in the warm chamber (40°c.) for five or ten minutes. 
 Place some of the starch paste in the warm chamber alsp 
 for some time, then mix the two (lOcc of starch paste to 
 Sec. of undiluted saliva) and return to the warm chamber. 
 The starch is changed first to dextrin, erythrodextriu, 
 which gives a red reaction with the iodine, and achroo- 
 dextrin which gives no reaction with iodine, and event- 
 ually to sugar and to achroo-dextrin. Prove these changes 
 in this way: Every minute or two take out a drop of the mix- 
 ture with a small pipette (be careful not to allow the 
 door of the warm chamber to remain open longer than 
 necessary) place the drop upon a porcelain plate and add 
 a drop of the iodine solution. It gives first a blue color 
 showing the presence of Btarch ; next a violet color due 
 to the mixture of the blue of the starch reaction with the 
 red caused by the dextrin, next a red brown, proving the 
 presence of dextrin and absence of starch, and finally no 
 color reaction at all, proving the absence of starch and of 
 erythro-dextrin. Meanwhile sugar has appeared, it may 
 be tested for with Fehling's solution at the end of the 
 experiments or within a few minutes after the mixture 
 is placed in the warm chamber. 
 
 5. EFFECT OF LOW TEMPERATURE ON ACTION OF PTYA- 
 
 LINE.— 
 
 Take two test tubes, put some starch paste in one, 
 and saliva in the other, cool down to 0*^0. in a mixture of 
 ice and salt. Mix the two solutions and keep the mixture 
 surrounded by ice. After several minutes test for sugar. 
 None will be found if the temperature is kept low enough, 
 
-21 — 
 
 showing that the ferinent does not act readily at low tem- 
 peratures. 
 
 6. THE EFFECT OF BOILING UPON THE FERMENT.— 
 
 Boil a little of the saliva and then add' some starch 
 paste. Examine the mixture after five minutes for sugar. 
 None will be found. 
 
 7. THE EFFECT OF ACID UPON PTYAXINE.— 
 
 Take 3cc. of the starch paste,_ add 5cc. .of a 0.2X sol. 
 of HCl and then Ice. of saliva, thus making a mixture of 
 about the acidity of the stomach during digestion. Keep 
 the mixture in the warm chamber for about five minutes 
 and then test for sugar. None will be found, because acid 
 of this strength prevents the action of the ferment. 
 
QUESTIONS TO BE ANSWERED IN WRITING. 
 
({UESTIOirS TO BE ANSWEEBD Df WBraiNG. 
 
QUESTIOirS TO BE ASSWEftllD Df TTRITra G. 
 
I ' LESSON VII. 
 
 I 
 
 GASTRIC DIGESTION. 
 
 1. PREPARATION OF AN ARTIFICIAL GASTRIC JUICE AND 
 
 PROOF OF ITS DIGESTIVE ACTION.— , 
 
 The artificial juice is made by adding to some hydro 
 chloric acid (0.2X) a little of a preparation of pepsin. 
 Make some of the dilute acid, say 200cc., by adding to 
 that much distilled water 1.2cc. of commercial H 01. For 
 the pepsin usethe glycerine extract of the raucous mem- 
 brane of the stomach which is prepared by the laboratory,, 
 or which may be obtained from the druggist. To 150cc. 
 of the dilute acid add about lOoc. of the glycerine ex- 
 tract. To make the digestion add tn this artifi(3ial juice, a 
 quantity of boiled fibrin (the fibrin used is in alcohol, it 
 must first be washed well in a stream of water), and put 
 the mixture in the warm chamber. It is to be examined 
 and tested for the products of digestion at the end of 
 the afternoon or later. 
 
 2. THE ACTION OF PEPSIN ALONE.— 
 
 To test this take Ice. of the extract in a test tube, 
 add a shred of fibrin, and lOcc. of water. Place in the 
 warm chamber with preparation (1) and examine at the 
 end of the afternoon to see if the shred of fibrin has been 
 dissolved. 
 
 S. THE ACTION OF 0.2 PER CENT. HCL ALONE.— 
 
 Take lOcc. of the 0.2^ acid in a test tube, add a shred 
 of fibrin and place in the warm chamber. Exanline at the 
 end of the afternoon to see if the shred of fibrin has 
 been dissolved. 
 
-24- 
 
 4, EFFECT OF BOILING UPON THE PEPSIN.— 
 
 I MakelOcc.of an artificial juice as in (1). BoilforafeW 
 minutes, add a shred of fibrin and place iu the warm cham- . 
 her. Examine at the end of the afiernoon to see if the 
 shred of fibrin has been dissolved. 
 
 While tiiese preparations are digesting make the fol- 
 lowing tests for peptones and albnmoses upon a scsrution 
 prepared for the class. The solution contains both albu: 
 moses (hernial bumOse) ajid peptones, and was prepared 
 by digesting fibrin with artificial gastric juice as described 
 in experiment (1.) 
 
 6. HEMIALBUMOSSS.— 
 
 _ a. To some of the solution in a small beaker add Na 
 CI to saturation, and then drop in HNOg ; if a precipitatp 
 forms it proves the presence of hemialbumoses. 
 
 5. Make a similar test but in place of the HNOs use 
 a sol. of 30X acetic acid which has been saturated with 
 NaCl. Take care to saturate the solution also with NaOl. 
 If a precipitate forms it is due to the hemialbumoses. 
 This precipitate disappears upon heating, and reappears 
 when the solution has cooled. 
 
 6. TO SEPARATE THE HEMIALBUMOSES FROM THE PEP- 
 
 TONES.— 
 
 Saturate some of the solution with (Nil4)2S04, the 
 precipitate that form^ consists of hemialbumoses-^filter, 
 (save the precipitate), the filtrate contains the peptones, 
 if any are present. Test for. these peptones by the fol- 
 lowing'slightiy modified biuret reaction: , 
 
 7. TEST FOR PEPTONES. - 
 
 Add to the filtrate from (6) an equal bulkof 70X sol. 
 of Na OH. Stir the precipitate for a while with a rod 
 and filter. To the clear filtrate add one or more drops of 
 dilute CuSOi solntiou. If the red purple color is obtained 
 it pi(;vcs the presence of jjeptones. 
 
— 25 — 
 
 8. BIURET BEACTION OF HEMIALBUMOSES.— 
 
 ■ Eedis&olvelhe precipitated albumoses of (6) in water 
 and test a portion of, it with NaOH and CuS04as in (7.) 
 What results? 
 
 9. EEACTION OF HEMIALBUMOSES WITH THE POTASSIUM 
 
 FEKBOCYASIBE TEST.— 
 
 Test tiie remainder of the solution with potassium 
 ferrocj-anide and acetic acid as directed in the paper upon 
 proteid reactions. What result is obtained? 
 
 10. EXAMINE PKEPAKATION (1) AS FOLLOWS.— 
 
 Note the disaijpearance of the fibrin and the frag- 
 ments of undigested material —filter. JSIeutralize the 
 filtrate with 6% NaOE. The precipitate that occurs, 
 if any, is syntonin (piopeptones,) the first stage in gastric 
 digestion. Boil and filter. The filtrate contains the hemi- 
 albumoses and the peptones, though possibly the diges- 
 tion has not gone far enough to form the latter. Test for 
 these two substances by the test, given in 5b, and in 6 
 and 7. 
 
 11. PROOF OF THE EXISTENCE OF THE RENNIN FERMENT. 
 
 Use a good glycerine extract of the mucus membrane 
 of the stomach (the commercial preparation sold as gly- 
 cerol pepsin answers very well.) Heat 20cc. of mitk in 
 the warm chamber to 40°c, add one drop of the glycerine 
 extract, stir thoroughly and put back in the-warm chamber. 
 In a short time, usually within five minutes, the milk will 
 set owing to the coagulation of the casein by the ferment 
 rennin. 
 
 12. TO DETECT THE FREE HCL IN GASTRIC JUICE.— 
 
 The fonowing;tests are usually employed to detect the 
 presence of a free mineral acid in gastric juice in vomit. 
 
 a. Congo Red. — Place a drop of the suspected liquid 
 upon a piece of Congo red paper. If a free mineral acid 
 is present, the color changes to a deep blue or greenish 
 
— 36 — 
 
 blue. Organic acids may also cause a change in color but 
 less intense. 
 
 i. .Methyl Violet — To a dilute solution of methyl 
 violet add an equal volume of the suspected liquid. If 
 the color changes to blue, free mineral acid is present. 
 
 c. TropceoUn 000. — To a solution of tropseolin 
 add an equal volume of the suspected liquid. If the 
 solution takes on a reddish color, free mineral acid is pres- 
 ent. 
 
 Three solutions. A, B, C are given' to the class to test 
 according to the directions above. A report of the results 
 is to be made. 
 
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QUESTIONS TO BE ANSWEKED IN WBITIIfG. 
 
QUESTIONS TO BE ANSWERED Mf WEITISG. 
 
QUESTIONS TO BE ANSWERED IN WEITING. 
 
LESSON VIII. 
 
 PANCREATIC DIGESTION. 
 
 Extracts of pancreas containing one or all of its diges- 
 tive ferments may be made in various ways. By extract- 
 ing the fresh minced gland with water; by making a 
 glycerine extract of the gland, etc. 
 
 One of the best methods of making such extracts is as 
 follows : Use ox's pancreas, dissect off the fat as com- 
 pletely as possible, let it stand for 24 hours, mince it very 
 finely with a meat chopper, cover with a large bulk of 
 strong alcohol and allow it to stand for 24 hours, pour off 
 the alcohol and extract a second time with a new lot oi 
 alcohol. Pour this off, dry the mass at the room tempera- 
 ture, and then extract with ethei". Pour off the ether, dry 
 thoroughly at the room temperature, and keep the dry 
 powder in a well stoppered flask. To use this powder 
 take a small portion, extract with water at the tempera- 
 ture of the room for one or several hours, filter and 
 neutralize the feebly acid filtrate with Na^COsSol. -J %. 
 This sol. is to be used for digesting. 
 
 In the class work commercial preparations of the 
 pancreas are used, (Parke, Davis &.Co.'s Liquid Pancre- 
 atin is recommended. 
 
 1. THE TRTPTIC (OE PROTEOLYTIC) ACTION OF THE PAN- 
 CEEATIC JUICE.— 
 
 Make an artificial pancreatic juice as follows : Add to 
 50cc. of a ^ ^ solution of Nag COs , 5cc. of the liquid pan- 
 creatin. To prove the tryptic action of this mixture, add 
 to it a number of shreds of boiled fibrin and place the 
 preparation in the warm chamber for at least two hours. 
 At the end of that time notice the more or less complete 
 
— 30- 
 
 » 
 disappearance of the fibrin (some remnants are always 
 left undissolved). Filter the solution and test the filtrate 
 for the following products: neutralization precipitate, 
 hemialbumoses, and peptones as follows : 
 
 a. Neutralization Precipitate. — Neutralize the liquid 
 with 0.2 % sol. of Ha SO4 . The amount of neutralization 
 precipitate will depend upon the strength of the trypsin 
 and the duration of the digestion. It is the first stage of 
 the transition to peptones, and if the digestion has been 
 in progress sufficiently long, this stage will have been 
 completed, and no neutralization precipitate will be 
 obtained. Filter, if necessary, and test the filtrate for 
 hemialbumoses as in the next paragraph. 
 
 S; Hemialbumoses. — Saturate the liquid with am- 
 monium sulphate. If a precipitate occurs it is a hemial- 
 bumose, the second intermediate stage in the formation of 
 peptones. The amount of the proteid in this stage of 
 conversion will also depend naturally on the duration of 
 digestion and the strength of the ferment. Filter off the 
 precipitate of hemialbumoses, and test the clear liquid for 
 peptones according to the next paragraph, 
 
 0. Peptones. — Add to the filtrate an equal bulk of 70 
 % caustic soda, filter ofi" the precipitate of salts, and to 
 the clear filtrate add a drop or two of a dilute solution 
 (2 %) of Cu SO4J if a red color forms (biuret reaction), 
 it proves the presence of peptones. Whether peptones 
 are or are not present depends upon the duration of the 
 digestion. 
 
 2. THE FORMATION OP LEUCIN AND TYBOSIN PROM PEP- 
 TONES BY THE ACTION OP TRYPSIN— 
 
 The prolonged action of trypsin will break up some of 
 the peptones into simpler bodies, leucin, tyrosin, etc. 
 Demonstrate this as follows : Make an artificial pancreatic 
 juice as above,' add fibrin to it and a few drops of an alco- 
 holic sol. of thymol (to prevent putrefaction). Place the 
 preparation, corked, in a warm chamber until the next 
 
— 31 — 
 
 week and then examine as follows : Filter, neutralize and 
 boil, evaporate to a small bulk, and add an eicess of 
 alcohol. This will throw down the peptones and albu- 
 moses. Filter oiF the precipitate, evaporate the filtrate 
 fo a small bulk, and set aside to crystallize.. Leucin and 
 lyrosin crystals will separate out, the former as brownish 
 balls with rfedia:ting lines, the latter as long needles. 
 
 3. THE AMTLOL¥TIC FEBMEIfT OF PANCKEAS.— 
 
 Uj.e the liquid pancreatin preparation. Add 2cc. of it 
 to 15cc. of water. To this mixture add some starch paste; 
 place the mixture in the warm chamber for 10 minutes, 
 and then test the solution for the presence of sugar by 
 means of the Fehling's solution. 
 
 4. THE FATTY ACID FERMENT OF PANCBEAS.— 
 
 Use the same preparation of liquid pancreatin. Neu- 
 tralize it very carefully with Naa CO3 (^ %). Add Ice. of 
 this preparation to 5cc. of specially prepared neutral olive 
 oil. Shake well and put in the warm chamber for 15 min- 
 utes. At the end of that time test its reaction with litmus 
 paper, it will be found acid owing to the splitting up of 
 some of the tats with formation of free fatty acids. 
 
 5. EMUISIFTING POWER OF THE PANCREAS PREPARA- 
 
 TION.— 
 
 a. Use the liquid preparation of pancreatin. Add 
 Ice. to 5cc. of olive oil, shake thoroughly for several 
 minutes, and place in the warm chamber. 
 
 J. Make a similar preparation, using olive oil and 
 water without the pancreatin solution. Treat in the same 
 way as a. Examine the two at the end of 15 minutes, 
 anfi also make a mount for microscopic examination. 
 Report what you see in the two cases. 
 
QlflESTIONS TO BE ANSWERED IN WBITING. 
 
QUESTIONS TO BE AUSWBBED IN WRITING. 
 
(JUESTIONS TO BE ANSWEEED W WEITISG. 
 
LESSON IX. 
 
 BILE AND GLYCOGEN. 
 
 1. BILE.— 
 
 Note the difference in color between the dog bile 
 and ox bile. , 
 
 2. MUCIN.— 
 
 Prove the presence of muciir in bile- by the acetic acid 
 test That is, dilute a specimen of the bile with several 
 times its bulk of water and add one or several drops of 
 acetic acid. (Save for next test.) 
 
 3. AlBUMEN.— 
 
 Filter from precipitate of (2) and add to the filtrate a 
 drop or two of potassium ferrocyanide. Report.the result. 
 In another specimen of the bile test for proteid with the 
 Milioii's reagent. What is the result ? 
 
 4. THE BILE SALTS*- 
 
 Sodium OlyeocJiolate \ To delect these substances in 
 Sodium Taurocholate) the bile use Pettenkofer's 
 
 test, as follows : Put some of the bile diluted with an 
 
 equal bulk of 'water, in a test tube, add a few drops of a 
 
 solution (10 %) of cane sugar, and then inclining the test 
 
 tube pour carefully strong Hj SO4 down the side of the 
 
 tube so as to fornl a layer at the bottom. Shake the tube 
 
 gently from side to side, so as to gradually mix the two 
 
 liquids, a red purple color will be developed. 
 
 5. TO EXTRACT THE BILE SALTS.— 
 
 Rub up some ox bile (lOcc.) with animal charcoal to a 
 thick paste. Evaporate to comple.te dryness over the 
 water bath. Extract this dried residue with absolute 
 4 
 
— 34 — 
 
 alcohol, and filter. You will get an alcoholic solution of 
 the two bile salts. To precipitate them add a large excess 
 of ether, in which they are insoluble. The bile salts will 
 come down ap a white precipitate. This may be filtered off, 
 a little of it dissolved in water, and Pettenkofer's test 
 used to prove its nature. 
 
 6. GMELEf'S TEST FOR THE BIIE PIGMENTS.— 
 
 Put a drop of the bile upon a porcelain, surface, place 
 next to it a drop of fuming HNOs and run the two drops 
 together. The pigment shows a play of colors, which 
 in ox bile ruijs through green, blue, violet, reddish yellow 
 and finally a light yellow. The colors are due to succes- 
 sive oxidations of the pigment by the HNO3 . 
 
 7. GlYCOGEN.— 
 
 Preparation of from liver: Use a rabbit or dog sev- 
 eral hours alter a hearty meal. Take out the liver as 
 quickly as possible after killing the animal, chop it into 
 small pieces, and throw into a bulk of water while actively 
 boiling. After boiling for some time, remove from the 
 water and. grind in a mortar to a fine pulp, using clean 
 sand or glass powder to aid in the trituration. Eeturn to 
 the boiling water, add acetic acid to feeble acid reaction 
 and boil for some time longer. Filter the solution while 
 hot. The filtrate will contain glycogen, which will be 
 indicated to the eye by the.opalescent appearance. Instead 
 of using a rabbit or dog, oysters, if the season permits, will 
 be given to the class. Each member of the class will be 
 expected to prepare from the oysters by the method given 
 an impure solution of glycogen with which the tests below 
 are to be made. 
 
 8. IODINE TEST.— 
 
 Add some iodine sol. to the. liquid. It will take a 
 dark red color. This color disappears upon heating and 
 reappears upon cooling.' 
 
— 35 — 
 
 9. ACTION OP AM¥LOL¥TIC FERMENTS.— 
 
 Add some filtered saliva to some of the liquid after 
 neutralization in a test tube, and place the mixture in the 
 warm chamber for 10 or 15 rainutef. Remove, divide into 
 two portions, test one with iodine for glycogen, the other 
 with Fehling's sol. for sugar. Report your results. 
 
QUESTTONS TO BE AN SWEKED IN WKITIN G. 
 
QUESTIONS TO BE ANSWERED IS WBITING. 
 
QUESTIONS TO BE ANSWEBBD IN WRITING- 
 
LESSON X. 
 
 EXPERIMENTS UPON MtJSCLE AND 
 NERVE. 
 
 1. THE CUEVE OF elasticity!— 
 
 Before preparing the muscle for this experiment get 
 ready a drum kymograph with its smoked paper, upon 
 which the experiment is to be recorded. The method of 
 smoking the paper and placing it upon the drum will be 
 demonstrated to the class. These, records are to be shel- 
 laced and handed in at the end of the day for examina- 
 tion. 
 
 First. — Destroy the brain and spinal cord of the frog. 
 To do this cut through the skin at the junction of the skull 
 and spinal column (on aline joining the posterior margins 
 of the ear capsules) and introduce a pithing rod, first into' 
 the brain and then down the spin'al cord, destroying each. 
 Take oiit the gastrocnemius muscle on one side with its 
 skin around it as follows: Make a circular .slit at the 
 tarsus, extending around the leg. Seizing the edge of the 
 cut skin with the forceps pull it up toward the knee 
 exposing the gastrocnemius. Cut through the "tendo 
 Achillis" and free the gastrocnemius from the leg bone 
 up to the knee. Cut across the leg bone juat below the 
 knee and remove it; then pull back the bag of skin over 
 the gastrocnemius. Cut away the thigh muscles so as to 
 expose the femur and cut through this. Suspend the 
 muscle by clamping the piece of femoral bone. Fasten a 
 hook to the tendon and connect this by a wire to the 
 
•38 — 
 
 muscle lever, 
 ment. 
 
 The muscle is then ready for the experi- 
 
 Experiment. — Add a 10 grra. weight 
 to the lever just under the muscle ^nd 
 record the extension of the muscle by 
 'allowing the end of thie lever to write ■ 
 on a recording surface. Remove the 
 \veight an(l notice that the muscle re- 
 turns to nearly its former length. If the ■ 
 conditions were normal as in the living 
 animal the elasticity of- the muscle 
 would be perfect, it would come, back 
 completely to its normal length. Now 
 add in succession 20 grm., 30 grin., 50 
 grm., 60 grm., recording the extension 
 caused by each weight and moving the 
 recording surface an equal distance af 
 ter each experiment. The specimen 
 curve given will indicate the method of 
 making the experiment. 
 
 In order to make the conditions as 
 constant as possible let each extension 
 last the same time and give the muscle an eqoal interval 
 of rest after each observation. By joining the ends of the 
 lines marking the extensions as shown in the figure, the 
 curve of elasticity or extensibility is obtained.- It makes 
 an hyperbola. • e 
 
 2 . BEPEAT EXP. 1, USING A RUBBER BAND.— 
 
 The curve of elasticity with dead elastic substances is 
 
 a straight line. 
 
 * 
 
 3. SIMPLE MUSCLE CONTRACTION.— 
 
 In this and most of the succeeding experiments the 
 induction coil will be used to stimulate the muscle. The 
 principle upon which the instrument works will be 
 explained and the way in which it is connected with a 
 
- —39 — 
 
 baltery and wilh the muscle will be demonstrated. Each 
 student will be expected to set up his own appnvat'us. 
 
 Dissect out the gastrocnemius muscle of the other leg 
 in the way described. Alter attaching the muscle to the 
 lever, place a 10 grm. weight upon the latter to keep the 
 muscle properly extended. Prepare a Du Bois Reymond 
 induction coil wilh a simple niake and break key in the 
 primary circuit, and a short circuitinic key in tiie secondary 
 circuit. Carry wires from the shoi't oircuiting key to the 
 two ends of the muscle. With thi.s latter key open, record 
 the contractions of the n)uscle made by making and 
 breaking the battery current. Usually the contraction 
 caused by the breaking shock is the stronger, team how 
 to use the keys so as to stimulate the muscle either by tiie 
 breaking shock alone or the reveive. For breaking shocks 
 the procedure is as follows: 1st, close the short circuit 
 key; 2nd, clo>e the key of the primary current; 3id, open 
 the short circuit key ; 4lh, break the current through the 
 primary coil. Using the keys in this sequence no making 
 shocks can reach the mufecle. 
 
 i. RELATION BETWEEIf STRENGTH OF STIMULUS AND 
 HEIGHT or CONTRACTION.— 
 
 Use the same muscle as in (2) and stimulate only with 
 breaking shocks. Si art hrst willi the secondary coil so far 
 frOm the primary that no contraction's obtained; then 
 gradually bring it nearer to the primary coil moving it a 
 mm. each time and obtaining a contraction at each inter- 
 val. Notice tiiatfor a time the contractions increase wilh 
 the streiigtii of the stimulus. After reaching a certain 
 height the contractions become maximal and increase of 
 .stimulus beyond this point causes no further increase of 
 the contraction. 
 
qOESTIOSS TO BE ANSWERED IN WRITING. 
 
QUESTIONS TO BE AUSWEBED JS WEETUfG. 
 
QUESTIONS TO BE ANSWERED IN WEITING. 
 
LESSON XI. 
 
 EXPERIMENTS UPON MUSCLE AND 
 NERVE. 
 
 1. THE EFFECT OF THE LOAD UPON THE HEIGHT OF THE 
 
 CONTRACTION AND THE WORK DONE — 
 
 Make a muscle preparation as in Exp. 1, Leswri X. 
 Arrange the apparatus so as to use only the breaking 
 shocks. Determine the height of contraction with no load 
 but the lever and the pan for receiving the weights, then 
 increase the load by successive additions of 10 grm. 
 weights and determine the height of contraction for each 
 load. Always allow an equal interval of rest between 
 each experiment, and if possible, arrange the apparatus so 
 as to "after load " the muscle, i. e. place a support under 
 the lever so that the weight will not pull on the muscle 
 till it begins to shorten. Cartry the experiments up to a 
 load of 50 grms. or more and from the data obtained, con- 
 struct a curve of work as follows. Make a base line and 
 on it lay oiF equal distances to represent the different 
 loads used. Over the number marking each load erect an 
 ordinate representing the work done in gramme milli- 
 meters, i. e., the load raised multiplied by the height to 
 which it was raised. Each gramme millimeter may be 
 represented by an ordinate i millimeter in length. Pre- 
 serve the record. 
 
 2. MUSCLE FATIGUE WITH SUCCESSIVE STIMULI.— 
 
 With the same or a similar preparatioil of the gastro- 
 enemius of a frog and using only breaking shocks stimulate 
 the muscle once every second, recording the contractions. 
 Notice that the contractions gradually become smaller, 
 until finally the muscle is .so fatigued, that it will not con- 
 
— 43 — 
 
 i" 
 tract at all. Give the muscle 5 minutes rest and repeat 
 
 the series of experiments ; the muscle again gives contrac- 
 tions, but fatigue developes more quickly than in the first 
 aeries. Preserve the record. 
 
 3. SUMMATION OF CONTRACTIONS AND TETANUS.— 
 
 With a new preparation get the summation of rapidly 
 following contractions into a tetanus, by rapidly making 
 and breaking the primary current with the simple kej"^. 
 Then attach the wires from the battery to the lower screws 
 of the , primary coil of the induction apparatils, so as to 
 send into the muscle a number of rapidly repeated stimuli. 
 The tetanus curve in this case will be complete, showing 
 no indication of the separate contractions. Compare the 
 height of the contraction in this case with that caused by 
 single maximal stimuli. Preserve the record. 
 
 4. THE CUKTE OF FATIGUE FROM CONTINUOUS STIMULA- 
 
 TION.— 
 
 With the same preparation tetanize the muscle con- 
 tinuously for several minutes, recording the contractions 
 upon a slowly revolving drum. The writing point of the 
 lever will gradually come back to the b:ise line, the curve 
 descending uniformly if the strength of the current is con- 
 stant. Give the muscle several mi-nutes rest and repeat 
 the experiment. Preserve the record. 
 
 At the end of this experiment cut across the belly of 
 the muscle and test the reaction with litmus paper, it will 
 be found acid owing to the sarco lactic acid formed during 
 contraction. 
 
QUESTIONS TO BE ANSWEKEI) IN WRITING. 
 
QUESTIONS TO BE ANSWEKEl) IS WRITISG. 
 
LESSON XII. 
 
 EXPERIMENTS UPON MUSCLE AND 
 NERVE. 
 
 1. KIGOE MORTIS. 
 
 , Rigor mortis will be demonstrated to the class upon a" 
 dead animal. The followinj!! points of difference between 
 the living muscle and the muscle in rigor are to be noted ; 
 loss of irritability, rigidity, contracted condition, opacity, 
 acid reaction due to formation of sarcolactic acid. 
 
 2. STIMriATION OP A MUSCLE BY THE GALTANIC CUE- 
 
 BENT.— 
 
 The gastrocnemius muscle of a frog is to be removed 
 and attached to a lever as in the former experiments. Carry 
 the' wires from the galvanic battery directly to the two 
 ends of the muscle, interposing a key upon the course of 
 the wires. Observe that the muscle contracts when the 
 current is made and when it is broken, but that it remains. 
 quietiWhile the current is flowing throughit. The making 
 stimulus is the stronger and if a single battery is used may 
 be the only one which is effective in causing a contraction, 
 in that case use more cells until a breaking contraction i^ 
 also obtained. (Under certain abnormal conditions the 
 frogs muscle will remain in a condition of partial (tonic) 
 contraction during the passage of the current). 
 
 3. THE LATENT FEEIOB OF A MUSCLE CONTEACTION 
 
 The method of demonstrating this period and of meas- 
 uring its duration will be shown and explained to the class. 
 
 4. STIMULATION OF NEETES.— 
 
 In these experiments the gastrocnmius muscle is to be 
 isolated together with the sciatic nerve. The frog must 
 first be skinned and the sciatic nerve then dissected out 
 S 
 
— 44 — 
 
 from its origin down to the muscle. The method of isolat- 
 ing the nerve and the precautions to be observed, espec- 
 ially with reference to the care of the nerve after its 
 isolation, will be dem'onstrated to the class. The muscle is 
 to be attached to the. lever and tracings obtained by the 
 following methods of stimulation, all of which, if care is 
 taken, may be used upon a single preparation.^ Preserve 
 the records of the experiments. 
 
 a. Stimulate the nerve with a single induction cur- 
 rent, using catheter electrodes. 
 
 5. Stimulate the nerve witti tetanic induction shocks. 
 
 c. Stimulate the nerve with the galvanic curreint. 
 Prove that it is stimulated by the making of the current 
 and by the breaking, but not during the passage of the 
 current. 
 
 5. BLOCKING THE NERTE IMPULSE.— 
 
 a. Use the same preparation as in (4) or a similar 
 one, if necessary. Tie a string around the nerve near the 
 muscle so as to kill a narrow portion of it. Now stimulate 
 to the distal side of the ligature. No contraction will be 
 obtained. The impulse' is aroused by the stimulus but 
 cannot pass to the muscle over the narrow portion de- 
 stroyed by the ligature. 
 
 5.. A similar but more satisfactory method is as fol- 
 lows : Freeze a small portion of the nerve with the 
 apparatus provided. Stimulation on the distal side has no 
 effect. Now gently thaw out the frozen portion, stimula- 
 tion on the distal side will give a contraction. Freezing " 
 a nerve suspends, its conductivity but does not destroy it 
 unless prolonged. 
 
 6. MECHANICAL STIMULATION OF THE NEKVE.— 
 
 With the same or a new preparation try tlie effect of 
 mechanical stimulation of the nerve. Rest' the nerve upon 
 a pad of filter paper moistened with salt solution, and tap 
 it gently with the handle of a scalpel. With a little skill, 
 
— 45 — 
 
 one can get tetanic as well as single contractions ot the 
 muscle by this method. 
 
 7. CHEMICAL STmUlATION.-- 
 
 The effect of chemical stimuli may be illustrated by 
 the' action of sodium chloride. Cut off the portion of nerve 
 used in the experiment just given and touch a crystal of 
 NaOl to the cut end of the nerve, the muscle will 
 contract. Preserve a record of the experiments. 
 
 8. ELECTROTONUS.— 
 
 The effect of a galvanic current in throwing the nerve 
 into an electronic condition, and the consequent variations 
 in irritability around tlie uatliode and- anode will be dem- 
 onstrated to the class. 
 
 9. NATURAL CURRENT 0^ MUSCLE AND NERVE AND ITS NEG- 
 
 ATIVE VARIATION.— 
 
 The natural current and its negative variation (action 
 current) will be demonstrated to the class by means of the. 
 galvanometer, the capillary electrometer, and the rheos- 
 copic frog preparations. 
 
 10. GALVANI'S EXPERIMENT.^ 
 
 Solder together a slip of zinc and copper. Prepare a 
 frog, the method will be demonstrated, so that the two 
 legs are connected with the lower portion ot the spinal 
 column only by means of the lower spinal nerves. Sus- 
 pend the frog from a hook passing through the spinal 
 column. Touch one end of the soldered slips to the mus- 
 cle of one leg and the other to the exposed spinal nerves. 
 At each contact the legs will give violent contractions 
 owing to the stimulation of the nerves by the electrical 
 current produced. 
 
 11. STIMULATION OF HUMAN MUSCLES.— 
 
 (a.) With induction currents. Two electrodes are 
 used in this experiment and are to be connected with the 
 secondary coil of the induction apparatus. Their ends are 
 
— 46 — 
 
 covered with sponge or flannel. One electrode is large 
 (the indifferent electrode). Moisten this with warm normal 
 saline or slightly acidulated water and press it firmly upon 
 the skin of the chest or the forearm of the other side. The 
 smaller electrode (active electrode) is applied to the motor 
 points of the muscles of the forearm. The motor points 
 are the points where the nerve enters the muscle. Con- 
 tractions of the flexor muscles of the forearm can readily 
 be obtained in this way. 
 
 (5.) With galvanic currents. Connect the electrodes 
 directly with a battery of ten or twelve elements and 
 use them as before, making and breaking the current 
 with a key interposed on one wire. Contractions of the 
 muscles are readily obtained in this way, especially when 
 the active electrode forms the cathode,. the contractions 
 being manifested by flexion of the fin-gers. 
 
 12. DEMOUSTBATIONS OF CILIAEY MOYEMEIfTS UNDEK THE 
 
 MICBOSCOPE.— 
 
 With a pair of flne scissors snip ofi" a small bit of the 
 mucous membrane of the throat of a frog near" the oesopha- 
 gus. Tease it into small pieces in normal saline. Cover with 
 a slip and examine under the microscope. Note the rapid 
 running movement, in good places where the cilia are 
 moving somewhat normally. Places may be found also 
 where the cilia are dying, and therefore moving with suffi- 
 cient slowness for the individual cilia and the character of 
 their contractions to be made out. 
 
 13. DESaySTRlTIOSS OF CILIAKF MOVEMENTS TO A 
 
 CLASS.— 
 
 Dissect out in a frog the oesophagus and the mucous 
 membrane of the mouth cavity. Pin it out upon an in- 
 clined plane of cork so that the ciliated surface is upward. 
 Place a small bit of muscle or cork upon the membrane 
 at the mouth end, and observe that it is carried along with 
 some rapidity toward the stomach end, by the combined 
 co-ordinated contractions of the cilia. 
 
QUESTIONS TO BE ANSWERED IN WBITING, 
 
QUESTIONS TO BE AN SWEEEB IN WBITING. 
 
LESSON XIII. 
 
 REFLEX ACTION. SPINAL CORD. 
 
 Cut the medulla of a frog some hours before the experi- 
 ments are made. In cutting the medulla be sure that it is 
 completely divided from the cord, and lose as little blood 
 as possible. The cut is to b& made,_as in pithing a frog', on 
 the line joining the posterior margins of the ear capsules. 
 1. 
 
 a. Notice the position taken by the reiiex frog as 
 compared with the normal frog. 
 
 J. When placed on the back it' makes no effort to 
 gain its equilibrium. 
 
 e. When thrown into a basin of water it does not 
 swim. 
 
 d. When irritated it does not jump. The power of 
 the animal to make spontaneous or voluntary movements 
 seems to have been destro3'ed. 
 2. 
 
 Suspend the frog by one of the frog hooks and 
 demonstrate the following reflexes : 
 
 a. With the point of a needle irritate the flank gently. 
 Notice the twitching of the muscles in that locality. (Sim- 
 ple reflex). 
 
 , h. Irritate the same point more strongly, the reflex 
 moveijaents spread to the limbs. 
 
 c. Gently pinch the toe of each leg, the leg will be 
 withdrawn. 
 
 3. PURPOSEFUL CHAEACTER OF THE REFLEX MOYE- 
 
 MENTS.— 
 After each of the following experiments immerse the 
 frog in a large bulk of distilled water: 
 
 a. Place a bit of filter paper 1 mm. square, moist-. 
 
_48— , 
 
 ened with. acetic acid (10%) on the right flank, the right leg 
 will be brought forward and the irritating body swept off. 
 
 h. Repeat the experiment on the left flank, the left leg ' 
 will be used. 
 
 c. Place a bit of the filter paper across the dorsal mid- 
 line, coordinated movements on both sides will follow, 
 both legs, being used to remove the paper. 
 
 d. Tie the right leg rather, loosely so that it cannot be 
 drawn forward. Then place a bit of the filter paper on the 
 right thigh; After ineflectnal attempts to remove the 
 paper with the right leg, the left leg will be used, owing 
 to the radiation of th-e impulse in the cord. Hand in a 
 report of these experiments with the results obtained. 
 
 4. REFLEX TIME.— 
 
 Immerse the tip of the longest toe in dilute Ha SO4 
 (0. 1%) up to a determined mark. Measure with a nietro- 
 nome, or watch, the time which elapses between the im- 
 mersion and the withdrawal of the foot. Make half a 
 dozen such attempts on each foot, (washing the foot after 
 each experiment) and notice for each foot the time re- 
 quired. The reflex time is constant, provided the depth 
 of the immersion is always exactly the same and the 
 strength of the acid is not changed. Determine that the 
 deeper the immersion of the foot, (the greater the area of 
 skin stimulated) the shorter is the time of the reflex. 
 
QUESTIONS TO BE ANSWERED IN WEITING. 
 
QUESTIONS TO BE ANSWERED IN WRITING. 
 
LESSON XIV. 
 
 EXPERIMENTS ON THE FROG'S 
 HEART. 
 
 1. TO EXPOSE THE HEART.— 
 
 Pith the frog and lay it on .its back on a plate of glass. 
 With the scissors open the skin along the ventral mid line 
 and reflect it to eaeh side. Raise the lower cartilaginous 
 end of the sternum with a pair of forceps, insert the blade 
 of the scissors under the muscular wall at this^point, avoid- 
 ing the anterior abdominal vein, and cut through the ster- 
 num along the mid line. The h^art will be exposed, lying 
 in the body cavity and enclosed in the pericardium. Open 
 it fully to View by cutting through the bony scapulae on 
 ,each side and removing the entire anterior wall; catch the 
 pericardium with a pair of tine forceps and slit it open 
 with the scissors. Lifting the apex of the ventricle gently 
 a fine thread of connective tissue, the fraenum, containing 
 a small blood vessel will be seen running from the dorsal 
 surface of the ventricle to the pericardium. Tie the 
 fraenum with a fine silk thread and cut it loose from the 
 pericardium on the other side of the ligature. The fraenum 
 with its attached thread forms a convenient means of turn- ■ 
 ing back the ventricle to expose the parts beneath. 
 
 2. AN ATOMT OFJTHE FROG'S HEABT.— Ty 
 Make out the following points in the supei-ficial 
 
 anatomy of the heart. The single conical ventricle ; the 
 two auricles; the bulbus arteriosus springing from the 
 ventricle and lying upon the auricles as it passes forward; 
 the two arterial or aortic arches arising from the anterior' 
 end of the bulbus and curving to each side. Each arch i 
 soon splits into three vessels, the carotid, for the head, the I 
 pulmo-cutaneous, carrying the venous blood to the skin ( 
 
-50 — 
 
 'and lungs to be arterialized, and the aorta which carves 
 around to the back to meet its fellow with which it unites 
 to form the descending aorta. By means of the thread 
 attached to the fraenum lift up the ventricle. Make out 
 the following structures. The right and the left superior 
 vena cava, bringing back blood from the head and upper 
 extremities; the inferior vena cava appearing just above 
 the liver ; the sinus venosus, the chamber into which the 
 three cavae open. The sinus in turn communicates with 
 the right auricle. 
 
 ■ ^ 3. SEQUENCE OF THE HEABT BEAT.— 
 
 "With a little, care it will be easy to see that the heart 
 beat begins with a contraction of the sinus venosus and 
 the mouths of t-lie veins opening into it. This is quickly 
 followed by the systole of the two auricles, this by the 
 systole of the ventricle, and this by the systole of the 
 bulbus arteriosus. The wave of contraction sweeps over 
 the heprt from the venous to the arterial end, "with just 
 perceptible interruptions as it passes from one chamber 
 to another. 
 
 4. AUTOMATICITY OF THE HEABT BEAT.— 
 
 r Eemove the heart without injuring it by cutting 
 
 through the venae cavae and aortic arches. Place it in a 
 watch crystal in a little pool of the blood or of normal 
 • saline^ and cover with another crystal. The heart con- 
 tinues to beat with its normal rhythm. 
 
 / 5. EFFECT OF TEMPEBATUBE OS THE BATE OF HEABT 
 BEAT 
 
 Place the watch crystal containing the heart on a 
 piece of ice. Note the rapidity of beat and observe that 
 as the heat cools down the beat becomes much slower. 
 Next place the crystal on a water bath containing hot 
 water and observe that as the temperature rises the rate of 
 heart beat is increased. If the temperature rises to about 
 40°c the heart muscle will go into heat rigor. 
 
— 51 — 
 
 6. INHIBITION OP THE HEABT BEAT.— 
 
 Have ready an induction cpil and stimulating elec- 
 trodes prepared for use. Expose the heart of a frog as 
 before, taking care to do no dissecting at the base of the 
 heart. Dissect out the vagosympathetic nerve in the 
 neck close to the skull. (The method of making this dis- 
 section will be demonstrated). Ligate the nerve near the 
 skull, cut it between the ligature and the skull and lay 
 the nerve upon the electrodes taking particular care 
 to handle it as gently as possible. Stimulate with 
 induction shocks, and if the experiment is successful the 
 heart will stop beating with the ventricle.in wide diastole. 
 If not successful on one side try the other. After the 
 stimulation has ceased the heart begins to beat again, at , 
 first feebly or irregularly, but soon becoming normal. 
 The vago-sympathetic nerve contaius both inhibitory fibres 
 of the vagus and accelerator fibres of the sympathetic. In 
 stimulating the combined trunk the inhibitory effect 
 usu'ally predominates. 
 
 7.- STIMULATION OF THE CABDIO-INHIBITORT CENTRE — 
 
 The heart m-ay be inhibited easily, by direct stimula- 
 tion of the intra-cardiac inhibitory centre, the group of 
 nerve cells in whicii the vagus* fibres end before distribu- 
 tion to the heart muscle cells. To do this raise the ven- 
 tricle by means of the thread attached to the fraenum. 
 At the junction of sinus venosus and auricle a whitish 
 crescentic line or patch will be seen, touch this with the 
 ends of the electrode and stimulate. The heart will stop 
 beating. 
 
 8. LIGATURES OF STJJfNIUS.— 
 
 First Ligature. — Lift the apex of the ventricle and 
 with the aid of an aneurism needle pass a thread round 
 it so as to lie in the groove between sinus venosus and 
 auricle. Tie this ligature in the groove; auricles and, 
 ventricle will stop beating, while the sinus keeps on with 
 its normal rhythm. If the relaxed auricles are pricked 
 
— 62 — 
 
 gently with a pia they will give a single beat followed by 
 a contraction of the ventricle. If the ventricle is pricked 
 it will give a beat followed by a contraction of the auri- 
 cles. The wave of contraction may be made to pass in 
 either direction according to which chamber is first stimu- 
 lated. The, experiment shows that normally the contrac- 
 tions of the auricles and ventricle are started by and 
 depend upon the contractions of -the sinus. If the 
 heart is left in this condition for some time auricles and 
 ventricles may begin to beat again, but with a rhythm 
 independent of that of the sinus. ' 
 
 Second Ligature. — While auricles and ventricle are 
 still at rest tie a secon i ligature in the auriculo ventricular 
 groove. The ventricle will begin to beat again, apparently 
 because of the mechanical stimulation of the ligature. 
 
 9. TO RECOBB THE HEART BEAT.— 
 
 Have prepared a drum kymograph and a counter- 
 poised lever with a vertical arm of wire, tippsd with a 
 small block of cork. The end of the lever is to bs pro- 
 vided with a writing point. (The method of preparing 
 this lever will be demonstrated). Expose the heart of a frog 
 as before. Place the frog upon a convenient support and 
 let the cork end of the vertical arm of the lever rest as 
 gently as possible upon the surface of the ventricle. Bring 
 the drum up to the writing point of the lever and obtain a 
 record of the ventricular contractions. Th^ record is to 
 be preserved and handed in for examination. 
 
 10. TO KECOED THE INHIBITION OF THE HEART BEAT.— 
 
 In addition to the druin kymograph and lever get 
 ready an induction coil, stimulating electrodes, and time 
 marker. This last instrument is a small electro magnet 
 with a writing point. It is to be interposed in the primary 
 curi'ent of the induction coil so as to record the moment 
 of stimulation. (The method of arranging this will be 
 demonstrated). Upon the same frog used in Exp. 9, 
 
— 53 — 
 
 dissect out the vago-sympathetic nerve. Arrange 
 your frog so that the recording lever writes against the 
 drum. Place the stimulating electrodes under the vago- 
 sympathetic nerve and have them supported in that posi- 
 tion by a clamp. Bring the writing point of the time 
 marker against the drum' so as to be in a vertical line with 
 the point of the heart lever. Stai't the drum and alter a 
 number of normal heart beats are recorded stimulate the 
 nerve. Notice that the inhibitory effect upon the heart is 
 not immediate. There will be one or two beats after Xhe 
 time marker has made its record of the time of stimula- 
 tion. Preserve the record. 
 
 11. ACTION OF MUSCABIN AND ATEOPIN 03f THE HEART 
 
 Using the same or a new frog, paint the surface of the 
 heart with a camel's hair brush dipped in a dilute solution 
 of muscarin. The heart soon stops beating. Paint the 
 same heart with the prepared solution of atJ-opin. The 
 heart begins to beat again. JJow attempt to inhibit the 
 heart by stimulating the vago> sympathetic nerve or the 
 intra-cardiac centre. The stimulation will have no effect. 
 
QUESTIONS TO BE ANSWERED IN TVEITING. 
 
QUESTItHfS TO BE ANSWERED IN WEITING 
 
QUESTIOITS TO BE ANSWEEEB IS WBJTISG. 
 
LESSON XV. 
 
 SPHYGMOGRAPH. — EXPERIMENTS IN 
 CIRCULATION UPON THE RABBIT. 
 
 1. USE OP THE SPHYGMOGRAPH.— 
 
 Several forms of sphygrhograph possessed by the 
 laboratory will be exhibited and explained (Marey, Pond, 
 Petzold, Willilams). Using some one of these instruments 
 each student will be expected to obtain a sphygmogram, 
 shellac it, if necessary, and hand it in with a written 
 description of what it shows. 
 
 2. SECTION AND STIMIIIAITON OF THE CERVICAL SYMPA- 
 
 THETIC— 
 
 This and other experiments on the rabbit are to be 
 done under the immediate direction of an instructor by one 
 or two members of the class, who will demonstrate their 
 results, if successful, to the entire class. The rabbit 
 is to be narcotized half an hour or more before the 
 experiment begins by injecting into the abdominal' cavity, 
 with an hypodermic syringe, 1 grm. of chloral dissolved 
 in as little water as possible, (| grm. chloral and 5ct grm. 
 of morphia sulphate dissolved together often acts better). 
 Have prepared an induction coil and stimulating elec- 
 trodes. When the rabbit is thoroughly under the chloral 
 tie it out on the board, and clip the hair of the neck close 
 to the skin. With the aid of an instructor dissect out the 
 cervical sympathetic, pass a ligature round it, raise it 
 gently. Hold the ear of the same side by the tip so as to 
 get the best view of the pirculation, then cut the sympa- 
 thetic with a pair of sCissors. The ear quickly becomes 
 flushed with blood. Seek out the peripheral jend (end 
 towards the head) of the divided nerve and stimulate it 
 
V 
 
 with induction shocks. The ear becomes blanched in a 
 most striking way.. After the stimulation is slopped llie 
 ear slowly becomes 'flushed again. ■ This part of .the 
 experiment may be repeated a number of times. Write 
 out a' report of ' your experiment with an explanation of 
 the results. 
 
 3. TAKING BLOOD PRESSrKE IS A MAMMAL— 
 
 The experiment is to be performed on a, rabbit which 
 should be narcotized as described in Exp. 2. In additior , 
 be|pre the animal is narcotized, the following apparatus 
 must be prepared. An induction coil and stimulating 
 electrodes; a drum kymograph with smoked paper; a 
 glass canula; a mercury manometer with attachments. 
 This last'is troublesome to prepare. It is to be made of 
 glass, and a sample mounted for use will he given as a 
 , patferoQ to imitate. When the apparatus is ready and in 
 position for use, narcotize the animal, tie it to the boaid. 
 Dissect out the carotid cleanly,'place two ligatures round 
 it, tie the one toward the head, and plaice a serrefine upon 
 the artery distal to the other. Open the artery close to 
 the ligature whiqh is tied, making an oblique cut with 
 the scissors. Insert the canula and fasten it in with the' 
 second ligature. Before opening the clamps between the 
 artery and manometer see that the pressure in the latter 
 is about equal to the ordinary pressure in the carotid ftf a 
 rabbit (70 mm. mercury). When everything is ready 
 open the connections between the artery and manometer 
 and take a'tracing, with the drum revolving at its slowest 
 rate, for one i-evolution of the drum. Stop the drum and 
 proceed with the next experiment. The record is to be 
 preserved; see No. 5. 
 
 4. TO EECORD THE INHIBITION OF THE HEART.— 
 
 Dissect out the yagus, tie a ligature round it, cut the 
 nerve on the head side of the ligature. Start the drum at 
 a new level, and after taking a tracing of normal blood 
 pressure for a short distance stimulate the peripheral end 
 
— 57 — 
 
 of the vagus with induction shocks. The stoppage of the 
 heart and the consequent fall of blood pressure will be 
 recorded on, the drum. If possible get several records of 
 the inhibition. 
 
 5. TO ESTIMATE THE BLOOD PEESSUBE.— 
 
 With everything kept in the same position as in Exp. 
 4, kill the rabbit with chloroform. Clamp the tube con- 
 nected with the canula,"" remove the canula from, the 
 carotid and immerse it in a beaker of water so placed that 
 the surface of the water is on a level with the carotid. 
 Now open the connection with the manometer, the pen 
 in the latter will drop to- the point of no pressure. Let 
 the drum revolve and take a base line of no pressure. 
 The arterial pressure will be given by measuring the 
 vertical distance from this line to the line of blood pres- 
 sure and multiplying by two. (Provided the level of the 
 drum has not been 'changed meantime). Shellac the 
 records of Exp. 4 and 5 and make a written report 
 explaining what the records show. 
 
QUESTIONS TO BE AHSWEEED IN WRITING. 
 
QUESTIONS XO BE ANSWESEP IN WBITING. 
 
jUESTIOSS Td BE A3fSWE»ED IN WBETING. 
 
LESSON XVI. 
 
 RESPIRATION. 
 
 1. PROOF OF THE PRESENCE OF CO2 IN THE EXPIRED 
 AIR.— 
 
 Arrange a flask as shown in the illustration. Partially 
 fill it with clear lime water. Blow the expired air through 
 
 the tube a for several min- 
 utes. The CO2 combines with 
 the calcium to form an insol- 
 ublecalcium carbonate which 
 comes down as a precipitate. 
 
 2. PROOF OF THE PRESENCE 
 OF ORGANIC MATTER IN 
 THE EXPIRED AIR.— 
 
 Arrange a large test tiibe 
 like the flask in Exp. 1. Par- 
 tially fill the tube with a \% 
 sol. of silver nitrate to which 
 some formic acid has been 
 added. Blow through the so- 
 lution for five minutes, andthen place the tube in the 
 sunlight. The liquid quickly turns to dark brown or 
 black owing, to' the rapid reduction of the silver in tlie 
 presence of organic matter. If a similar tube is prepared, 
 but not blown through, and placed in the sunlight it will 
 also darken but very much more slowly than the first. 
 
 3. MEASUREMENT OF THE RESPIRATORY VOLUMES-- 
 
 By means of the Hutchinson's spirometer make de- 
 terminations of the following respiratory volumes, the 
 vital capacity ; the tidal air ; the complemental air ; the 
 
-60 — 
 
 supplemental air. The method of using the spirometer 
 will be demonstrated. 
 
 4. XQ RECORD THE RESPIRATORY MOTEMENTS IN MAN. 
 
 Have ready a drum kymograph with blackened paper ; 
 a tambour mounted pn an upright so as to write against 
 the drum, and lead or glass tubing connecting this with a 
 second tambour (Marey's pneumQgraph)which is to be fast- 
 ened to the body. Tie this latter to the body so that the 
 metal plate lies upon the abdominal or chest wall. Make 
 connections between the two tambours. Start the drum 
 and take records of the breathing movements, first, when 
 breathing, quietly, ^ and next, when breathing forcibly. 
 Preserve the records and make a report upon them. 
 
 5. TO RECORD THE RESPIRATORY MOVEMENTS IN A RAB- 
 
 BIT. 
 
 The same method may be used as in 4, or better pro- 
 ceed as follows : Draw out a glass T piece, as shown in 
 ^ the illustration, so as to fit the rabbit's tra- 
 chea. Narcotize the rabbit as described in 
 \ Lesson XV. Tie it to the board; clip the 
 hair from the neck. Dissect down to the 
 trachea in the mid line (the method will 
 be demonstrated) pass a stout ligature round 
 ,the trachea by means of an aneurism needle, 
 avoiding the nerves. Open the trachea above 
 the ligature, insert one end of the straight 
 limb of the T piece and tie it firmly in. 
 Connect the side piece to a tambour ar- 
 
 H ranged as in 4. Attach a short piece of rub- 
 ber tubing to the other end of the straight 
 limb. By partially clamping this tube the 
 respiratory movements may be registered without seri- 
 ously interfering with the respirations of the animal. 
 Take a series of quiet normal respiratory movements, 
 and then proceed with Exp. 6 and 7 on the same animal. 
 
 (L 
 
— 61 — 
 
 6. DYSPNOEA A5D APNOEA. 
 
 Occlude the respiratory passages by pinching 
 trachea below the tracheal canula. The respirations 
 coaie more and more forced. When the dyspncea is ' 
 developed open the trachea and record the raovem( 
 upon the drum. Apnoea; connect a hand bHlows with 
 side piece of the tracheal canula Hnd vigorously venti 
 the lungs for several minutes. Then make the com 
 tionsLwith the tambour as quickly as possible. After 
 ventilation the respiratory movements will either C( 
 altogether for a short while or will be very shallow. T 
 quickly increase to normal. /To obtain a good resu' 
 maybe necessary to repeat the ventilation two or n 
 times. Preserve the records for examination. One i 
 make himself partially or completely apnoeic by i 
 rapid and long continued voluntary breathing. 
 
 7. SECTION AND STIMULATION OF THE VAGUS. 
 
 Upon this same animal exjjose the vagus nerve 
 each side. Start the drum and while taking a tracin. 
 the normal respiratory movements cut both vagi, 
 respirations wiil become deeper and slower. Takearec 
 Next lift the central end of one of the vagi from 
 wound and stimulate it with weak induction .shocks, 
 of two effects will be obtained, either a slowing or c 
 plete cessation of the respiratory movements, which is 
 usual result, or a i quickening. Try different strengtl: 
 stimulation ; with the weakest stimulation one is n 
 likely to get the quickening effect. Preserve and 1; 
 in these records with a written explanation of the'res' 
 Kill the animal with chloroform for the next experim 
 
 8. TO MEASURE THE NEGATIVE PRESSURE IN 
 ' THORAX. 
 
 Connect a glass manometer, containins water in 
 two limbs, with the side piece of the tracheal can 
 The connection must be made by rigid tubing and 
 joints must be perfectly tight. Close tightly the en 
 
— 62 — 
 
 the straight limb of the canula. Mark the level of the 
 water in the distal limb of the manoiiieter. Then as 
 gently as possible open the chest cavity on the two sides, 
 without, of course, puncturing the lungs. The lungs will 
 collapse by their elasticity and force up the water in the 
 distal, limlj of the manometer for a few mms. The, 
 height to which the water is forced up will measure, in 
 water pressure, the negative pressure existing in the 
 thorax of the animal when the chest is in its normal posi- 
 tiouij Give a written explanation of the connection of 
 the elasticity of the liings with the negative pressure io 
 the thorax. 
 
 9. RESPIRATORY MOTEMENTS OP THE VOCAL CORDS. 
 
 With a laryngoscope, the method of using which 
 will be demonstrated, examine on a person the opening o^ 
 the glottis and the movements made by the vocal cords 
 when the respirations are somewhat forced. 
 
QUESTIONS TO BE ANSWERED IN WRITING. 
 
loss TO BE ANSWERED IN WRITING. 
 
WmS TO BE ANSWIEED IN WBETIKG. 
 
QUESTIONS TO BE AITSWBKED IN WHITING.