88 STORRS AGRICULTURAL EXPERIMENT STATION. 
7. In milk kept at 10° neither of the types of lactic bacteria 
seems to be favored. ‘The delay in growth lasts 2 or 3 days, 
after which all types of bacteria appear to develop some- 
what uniformly. Sometimes the lactic bacteria develop abund- 
antly, sometimes only slightly. The neutral bacteria almost 
always grow rapidly, and the liquefiers, in many cases, become 
abundant. In time the milk is apt to curdle, commonly with 
an acid reaction, but it never shows the predominance of 4act. 
lactts actdi found at 20°. At 10°, therefore, the lactic bacteria 
are not so favorably influenced as at 20°, and they exert no 
check upon the growth of other bacteria. The milk, therefore, 
in time becomes more decidedly affected by bacteria than at 
20°, and its wholesomeness more under suspicion. 
8. From our experiments there seems to be no difference 
between the effect of 10° and 1° upon the bacteria, except 
upon the rapidity of growth. 1° very markedly checks the 
growth of bacteria; but later they grow to great numbers. As 
at 10°, the lactic bacteria fail to outweigh the other species, so 
that all types develop abundantly. A fewspecies appear to be 
particularly well adapted to this low temperature, and are es- 
pecially abundant at the end of the experiments. 
9. ‘The curdling point appears to be quite independent of the 
number of bacteria present. In one sample, at 37°, the milk 
curdled with only 8,000,000 per cubic centimeter, while in 
others there have been found 4,000,000,000 per cubic centi- 
meter without any curdling. These differences are due partly 
to the development of enzyms, and partly to the products of 
some species neutralizing the actions of others. The amount 
of acid present at the time of ordinary acid curdling does not 
widely vary. ; : 
10. Milk is not necessarily wholesome because it is sweet, 
especially if it has been kept at low temperatures. At the tem- 
perature of an ice chest milk may remain sweet for a long time, 
and yet contain enormous numbers of bacteria, among which 
are species more likely to be unwholesome than those that 
develop at 20°. From this standpoint the suggestion arises that 
instances of ice cream poisoning are perhaps due to the preserva- 
tion of cream for several days at a low temperature, such treat- 
ment keeping the milk sweet, but favoring the development of 
species of bacteria that are, at higher temperatures, checked by 
the lactic organisins. 
