716 METABOLISM AND ANIMAL HEAT 



when the solution has been neutralized with sodium hydroxide it gives 

 Trommer's test, owing to the hydrolysis of the glycogen into dextrose. 

 (2) Deeply etherize a dog or rabbit five hours after a meal rich in 

 carbo-hydrates e.g., rice and potatoes in the case of the dog, carrots 

 in the case of the rabbit. Fasten it on a holder. Clip off the hair 

 over the abdomen in the middle line. Make a mesial incision through 

 the skin and abdominal wall from the ensiform cartilage to the pubis. 

 The liver will now be rapidly cut out (by the demonstrator) and divided 

 into two portions, one of which will be (distributed among the class 

 and) treated as in (a) or (b) ; the other will be kept for an hour at a 

 temperature of 40 C., and then subjected to process (a) or (b). Little, 

 if any, sugar and much glycogen will be found in the portion which 

 was boiled immediately after excision. Abundance of sugar will be 

 found in the portion kept at 40 C. ; it may or may not contain glycogen. 



2. Catheterism. In many physiological experiments it is necessary 

 to obtain urine from the bladder by means of a catheter. It is possible 

 to pass a fine rubber catheter into the bladder of a male dog. A 

 larger one is easily passed in a male rabbit, and a still larger in a bitch, 

 which is often used for experiments on metabolism. Even in the bitch 

 the opening of the urethra lies entirely concealed within the vagina, 

 much deeper than the cul-de-sac in the mucous membrane, into which 

 the beginner usually tries to force the catheter. For a first attempt 

 the animal should be etherized and fastened on a holder. The little 

 or index finger of the left hand is passed into the vagina till the sym- 

 physis pubis can be felt. A little below this is the opening of the 

 urethra. With the right hand the point of a catheter of suitable 

 calibre is directed along the finger, and after a little ' guess and trial ' 

 it slips into the bladder, its entrance being announced by the escape of 

 urine. A glass tube drawn out to a sufficiently small calibre and bent 

 near the point is the easiest form of catheter to pass in a bitch. The 

 point must, of course, be rounded in the flame. The insertion of the 

 catheter is much facilitated by the use of a speculum. 



When the bitch is to be used in a long series of experiments an 

 operation is sometimes performed first of all to render the urethral 

 orifice more accessible. 



3. Glycosuria. (i) (a) Weigh a dog (female by preference) or rabbit. 

 Fasten on a holder, and etherize. Insert a glass cannula into the 

 femoral or saphena vein of the dog, or into the jugular of the rabbit 

 (p. 214). Fill a burette with a 2 per cent, solution of dextrose in 

 physiological salt solution, connect it with the cannula by means of an 

 indiarubber tube, taking care that there are no air-bubbles in the tube, 

 and slowly inject as much of the solution as will amount to or f- grm. 

 of sugar per kilo of body- weight. Tie the vein, remove the cannula, and 

 in half an hour evacuate the bladder by passing a catheter, by pressure 

 on the abdomen, or, if both of these methods fail, by tapping the bladder 

 with a trocar pushed through the linea alba (supra pubic puncture). 

 In an hour again draw off the urine. Test both specimens for sugar. 



In this experiment the opportunity may also be taken to demon- 

 strate that egg-albumin, when injected into the blood, is excreted by 

 the kidneys, a filtered solution containing the albumin of one egg and 

 sugar in the quantity mentioned being injected. 



The catheter may be inserted before the injection is begun, and the 

 bladder evacuated. After the injection the urine that drops from the 

 catheter may be collected in test-tubes, first every two minutes, and 

 then, as soon as sugar is found, every ten minutes. Determine the 

 interval between injection and the appearance of the first trace of 

 sugar and albumin. If a sufficient amount of urine is obtained, the 



