APPLICATION OF EEFEIGEKATION TO HANDLING OF MILK. 13 
According to Park, 1 two samples of milk maintained at different 
temperatures for 24, 48, 96, and 168 hours, respectively, showed the 
development of bacteria as indicated in Table VI. The first sample 
was obtained under the best possible conditions, while the second 
sample was obtained in the usual way. (The figures of the second 
sample are heavy face m the table.) When received the first sample 
contained 3,000 bacteria and the second 30,000 per cubic centimeter. 
Table VI. — Effect of lime and temperature on the growth of bacteria in milk. 
Temperature. 
24 hours. 
48 hours. 
96 hours. 
168 hours. 
32° F. (0°C.).. 
39° F. (4°C). 
42°F.(5°C.). 
46° F. (6°C.). 
50° F. (10° C.) 
55° F. (13° C.) 
60° F. (16° C.) 
68° F. (20° C.) 
86° F. (30° C.) 
94° F. (35° C.) 
2,400 
30, 000 
2,500 
38, 000 
2,600 
43, 000 
3,100 
42, 000 
11,600 
89, 000 
18, 800 
187, 000 
180, 000 
900, 000 
450, 000 
4,000,000 
1,400,000,000 
14,000,000,000 
25,000,000,000 
25, 000, 000, 000 
2,100 
27, 000 
3,600 
56, 000 
3,600 
210, 000 
12, 000 
360, 000 
540, 000 
1, 940, 000 
3,400,000 
38,000,000 
28,000 000 
168,000,000 
25, 000, 000, 000 
25, 000, 000, 000 
1,850 
24, 000 
218,000 
4,300,000 
400, 000 
5,760,000 
1,480,000 
12, 200, 000 
1,400 
19, 000 
4, 200, 000 
38,000,000 
In Table VI it will be noted that at 32° F. there is an actual 
decrease in the number of bacteria in both samples of milk during 
the 168 hours, while at all other temperatures there is an increase 
in the number of bacteria. Ordinarily the consumer receives milk 
when it is from 24 to 48 hours old ; hence it becomes an easy matter 
to deliver the milk in good condition, providing the milk is produced 
under sanitar}^ conditions and is properly cooled and held at a tem- 
perature of 50° F. or below. An examination of the tables and fig- 
ure will show how intimately the two influences of time and tem- 
perature act and interact in relation to the multiplication of bacteria 
in milk. Figure 2 is a graphical representation of the relation of 
temperature to bacterial growth in milk, taken from Bulletin 26 of the 
Storrs (Conn.) Agricultural Experiment Station. 2 
At a is represented a single bacterium; at b is shown the progeny 
resulting from the growth of a single bacterium in 24 hours in milk 
kept at a temperature of 50° F.; at c is represented the progeny 
from a single bacterium in 24 hours in milk kept at 70° F. At 50° 
the multiplication was fivefold, at 70° the multiplication was seven 
i Park, William Hallock. The great bacterial contamination of the milk of cities. Can it be lessened 
by the action of health authorities? Journal of Hygiene, vol. 1, no. 3, pp. 391-406. Cambridge, July, 
1901. 
2 Conn, Herbert William. The relation of temperature to the keeping property of milk. Connecticut 
(Storrs) Agricultural Experiment Station Bui. 26. Storrs, 1903. 
