Dec. 27, 1915 
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 1 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 hydroxid and then acidified 
by the addition, drop by drop, of a 10 per cent solution of monobasic 
potassium phosphate (KH 2 P 0 4 ). After incubation for two hours at 
41 0 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 
Date. 
Urea 
given. 
Nitrogen 
as NHs 
and urea 
per 100 
c. c. of 
milk. 
Urine. 
Milk. 
Date. 
Urea 
given. 
Nitrogen 
as NHs 
and urea 
per 100 
c. c. of 
milk. 
Urine. 
Milk. 
Gm. 
Mgm. 
C. c. 
C. c. 
Gm. 
Mgm . 
C.c. 
C. c. 
1 
H 
O 
0 
13. 2 
190 
500 
July 1 6 . .. 
20 
11.3 
580 
445 
II. . . 
0 
10. 5 
210 
5 10 
17... 
20 
7.5 
360 
420 
12 . . . 
0 
* 3 -° 
80 
480 
18... 
20 
10.2 
390 
415 
13 ... 
0 
9.0 
3 T 5 
435 
19. . * 
0 
7 - 7 
190 
410 
14... 
0 
9. I 
200 
480 
20. . . 
O 
11. 4 
155 
390 
15 ... 
20 
11. 1 
345 
375 
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 
(1) 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 
