Dec. 27, 191S 



Diuresis and Milk Flow 



567 



The constancy of the nitrogen content of the milk made it impossible 

 that any of the administered urea found its way into the milk, which 

 hypothesis was borne out by direct determination of urea in the milk. 



One hundred c. c. of milk were measured off into a 250 c. c. volumetric 

 flask, diluted with 100 c. c. of water, and the proteins removed at boiling 

 temperature by the cautious addition of a 10 per cent solution of acetic 

 acid. Generally about i c. c. was required. After cooling, the contents 

 were made up to volume, set aside for 10 minutes, and then filtered 

 through a dry folded filter. One hundred c. c. of the filtrate were 

 pipetted off into an aeration bottle made slightly alkaline to phenol- 

 phthalein with a 10 per cent solution of sodium hydro xid and then acidified 

 by the addition, drop by drop, of a 10 per cent solution of monobasic 

 potassium phosphate (KHjPOJ. After incubation for two hours at 

 41° C. with 2 c. c. of a 10 per cent solution of urease in the presence of 

 toluol, the ammonia was aspirated into N/28 hydrochloric acid. Fusel 

 oil was used to prevent foaming. The air current was broken up into 

 fine bubbles in the acid by firmly inserting a small plug of glass wool into 

 the end of the tube dipping into the acid. Later, it was found feasible 

 to make the urea determination without the previous removal of the 

 milk proteins, as the fusel oil was sufficiently active in preventing foam- 

 ing. A small amount of ammonia was found to be present in milk, but 

 as this is practically negligible, the results are expressed as total 

 ammonia in terms of milligrams of nitrogen per 100 c. c. of milk. (See 

 Table VIII.) 



Table VIII. — Effect of the administration of urea to goat 2 on the urea content of milk 



The independence of the urea excreted and the urea put out in the 

 mammary secretion strongly suggests that the urea in milk in large part 

 is the result of mammary activity and not the result of a mere diffusion 

 from the circulation. 



CONCLUSIONS 



(i) Urea administered in a diuretic dose is able to decrease temporarily 

 the' flow of milk. Upon repeated administration the increased intake 

 of water which follows the impoverishment of the tissues with respect to 



