EFFECT OF TEMPERATURE ON BACTERIA. SI 
abundant as in previous tests. [he whole experiment is quite 
anomalous, and suggests a condition of things that may, per- 
haps, explain cases of ice cream poisoning. Experiments are 
being carried on at the present time to determine whether the 
species 249 (as well as others that grow at 10°) produces any 
toxic products when growing in milk at low temperatures. 
The report upon these experiments will appear later. 
This experiment of Dec. 4 was a very long one, requiring 
two months or more for its completion, and involving the mak- 
ing and the studying of several hundreds of cultures. 
EXPERIMENT NO. 9. JANUARY 29. 
This experiment was a repetition of the last. The sample of 
milk at 20° curdled in about 4o hours (in the night), showing 
no signs of gas. The sample at 10° curdled in about 180 hours, 
and began to digest rapidly. The sample at 1° was tested at 
intervals for’ 4o days. It never curdled, although it became 
somewhat acid, and it thickened. 
The details of the analyses are given in the Tables 25, 26, 
and 27, and the growth of the chief types of bacteria are shown 
graphically in Plate 5. It should be remarked that all of the 
plates made in the analyses in this experiment proved satisfac- 
tory except a single series of the 1° sample, and the whole 
represents one of the most satisfactory series of analyses that 
we have made. 
Milk kept at 1°—1. This temperature held the growth of bac- 
teria in check for about 8 days, after which all types except the 
Groups V. and No. 225 began to multiply. The development 
was slow, however, veguiring 33 days to equal the number found 
in the 20° sample in 36 hours. 
‘5, All of the chief types of bacteria developed abundantly, 
and were present in high percentage at the close of the experi- 
ment. ‘The contrast between this result and that obtained at 
20° is very strikingly shown by Plate 5. 
3. ‘The lactic bacteria of Group I. developed constantly 
and became very abundant after 30 days, but later they declined 
in numbers. 
