PRACTICAL EXERCISES 691 



quantity of sugar in successive specimens may be estimated and com- 

 pared. The rate of flow of the urine as measured by the number of 

 drops falling from the catheter may also be estimated from time to time 

 in order to determine whether diuresis is taking place. 



If a rabbit is used for this experiment, the sugar solution may be 

 injected into the ear vein. The vein is caused to swell up by pressing 

 on it with the finger and thumb, and the hypodermic needle is then 

 inserted towards the heart. 



(b) Instead of collecting the urine by a catheter in the bladder, the 

 abdomen of the dog may be opened, and a cannula tied into each ureter. 

 The two cannulae are then connected by short rubber tubes with a 

 glass Y-piece, on the stem of which a test-tube is tied for collecting the 

 urine. Replace the test-tube by a fresh one from time to time. The 

 urine already in the bladder is removed by pressure or by a trocar, and 

 tested for sugar, since the anaesthetic itself may cause a certain amount 

 of glycosuria. Test the samples of urine obtained from the ureters 

 for sugar, and in those in which it is present estimate its amount. Note 

 also any changes in the rate of secretion of urine, and any abnormal 

 constituents, as albumin. 



(2) Phlorhizin Glycosuria. Dissolve grm. of phlorhizin in warm 

 water, and inject it subcutaneously into a rabbit. Obtain a sample of 

 the urine at the end of two hours, by pressure on the abdomen with 

 the thumb or by passing a catheter, and test for sugar. If none is 

 present, wait some time longer,* and again test the urine. 



This experiment can also be performed without risk on man. One 

 grm. of phlorhizin has been injected twice a day without disturbing the 

 individual. Much sugar is found in the urine, but it disappears the 

 day after the administration of phlorhizin is stopped. The phlorhizin 

 may also be given by the mouth, but more is required, and it is not 

 very easily absorbed, and often causes diarrhoea (v. Mering). 



(3) Alimentary Glycosuria. The urine having been tested for sugar 

 for two successive days, and none being found 



(a) A large quantity of dextrose is to be taken in the form which is 

 most agreeable to the student some hours after a meal. The urine of 

 the next twenty-four hours is to be collected and measured. A sample 

 of it is then to be tested for reducing sugar by Trommer's and the 

 phenyl-hydrazine test. If any sugar is found, the reducing power of a 

 definite quantity of the urine is to be determined by titration with 

 Fehling's solution (p. 518). 



(b} Instead of dextrose use cane-sugar and proceed as in (a). But 

 estimate the reducing power of the urine () before and (/3) after boiling 

 with hydrochloric acid (p. 459). 



(c) A large meal of rice and arrowroot, sweetened with as much dex- 

 trose as the observer can induce himself to swallow, is to be taken, and 

 the urine treated as in (a). 



(a) A large number of sweet oranges may be eaten.* 

 4. Milk. (i) Examine a drop of fresh cow's milk with the micro- 

 scope. Note the fat globules of various sizes. 



(2) Determine the specific gravity of the milk with a hydrometer 

 (lactometer). Then centrifugalize some of the milk to separate the 

 cream, which rises to the top of the tubes. Remove the cream and 

 determine the specific gravity of the skimmed milk. It will be found 

 to have increased, since the fat is of lower specific gravity than the rest 

 of the milk. Normal cow's milk has a specific gravity of 1,028 to 

 1,034, skimmed milk 1,033 to 1,037. 



* These experiments may be distributed among the class so that each 

 student does one 



