452 
Table No. 2. — Milk, from a healthy cow (No. 1). 
[Immediately after milking contained 500 bacteria per cubic centimeter.] 
Time after milking. 
Bacteria per cubic centimeter at different 
temperatures. 
Room temper- 
ature, 26°'to 
29° C. 
15° C. 
37° C. 
2 hours. 
1,300 
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. 
1 
11.300 
38,000 
342,000 
50,000,000 
Sour. 
72 hours . 
96 hours 
Table No. 3. — Milk from a healthy cow (No. 1). 
[Immediately after milking contained 8,300 bacteria per cubic centimeter.] 
Bacteria per cubic centimeter at various 
temperatures. 
1 ime after milking. 
! 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 1 ’ 
2.000 
6 hours 
2,000 
1,000 
6.000 
7 hours . . _ 
1.000 
20.000 
8 hours 
i 1,000 
i 
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 nos. 8 to 13. 
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 precau- 
tions to prevent outside contamination. For this milk we are 
greatly indebted to Doctor Schroeder and Mr. Cotton, of the Ex- 
periment Station, Department of Agriculture, Bethesda, Md. 
In addition to the usual precautions, a cloth wet with bichloride 
solution was placed under the cow, permitting only the teats to pro- 
ject through. The foremilk was discarded and about 10 to 15 cubic- 
