460 
Table Xo. 2 . — Milk from a healthy cotv (Xo. 1). 
[Immediately after milking contained 500 bacteria per cubic centimeter.] 
Bacteria per cubic centimeter at different 
temperatures. 
Time after milking. 
Boom temper- 
ature, 26° to ! 
29° C. 
15° C. 
37° C. 
2 hours . 
1,800 ! 
700 
400 ; 
7,800 ! 
29, 000 
340, 000, 000 
Innumerable. 
Sour. 
4 hours 
6 hours : 
8 hours 
10 hours 
24 hours 
48 hours 
900 
500 
600 
1, 200 
80,000 
1,380,000 
89,000, 000 
Sour. 
11,300 
38,000 
342,000 
50,000,000 
Sour. 
72 hours 
96 hours 
Table Xo 3 . — Milk from a healthy cow (Xo. 1 ) . 
[Immediately after milking contained 8,300 bacteria per cubic centimeter.] 
Time after milking. 
Bacteria per cubic centimeter at various 
temperatures. 
Room, 26° to 
29° C. 
15° C. 
37° C. 
2 hours 
8,000 
3 hours 
2,000 
2,000 
2,000 
4 hours 
6,000 
5 hours 
2,000 
6 hours 
2,000 
1,000 
6,000 
7 hours 
1,000 
20,000 
8 hours 
1,000 
5,000 
166,000 
THE EFFECT OF TEMPERATURE. 
Temperature has a decided influence upon this phenomenon. 
When the milk is kept warm (37° C.) the decrease in the number 
of colonies is striking, but of short duration. When the milk is kept 
cool (15° C.) the decrease is less marked, but more prolonged. This 
is well illustrated by the curves, Figs. 9 to 14. 
These curves were plotted from the following tables, which show 
the germicidal properties of milk for individual species of bacteria. 
The experiments were conducted as follows : 
Milk was obtained from a healthy cow, using particular care to 
prevent outside contamination. F or this milk we are greatty indebted 
to Doctor Schroeder and Mr. Cotton, of the Experiment Station, 
Department of Agriculture, Bethesda, Md. 
In addition to the usual precautions, a cloth wet with bichloride 
solution Avas placed under the cow, permitting only the teats to pro- 
