86 STORRS AGRICULTURAL EXPERIMENT STATION. 
Milk kept at 20°.—This followed the general course of milk 
at this temperature. The lactic Group I. developed very rapidly, 
and largely checked the growth of the other types. The lique- 
fiers proved themselves rather more persistent than usual in 
milk at this temperature, and were quite evident at the time of 
curdling. Their percentage, however, was small, about 2 per 
cent., and they clearly had no appreciable action on the milk. 
GHNERAL SUMMARY. 
From the experiments here recorded, together with those 
published in the Annual Report of 1902-3, the following gen- 
eral summary may be given of the effect of different tempera- 
tures upon the development of the types of bacteria in ordinary 
market milk. 
1. The effect of variations in temperature upon the develop- 
ment of the different species of bacteria in milk is not always 
the same under apparently identical conditions. Such varia- 
tions are to be expected when we bear in mind that different 
samples of milk vary so widely in their bacterial content at the 
outset. The presence of an especially persistent species in any 
lot of milk may, at any time, be expected to interfere with the 
normal course of events and to produce unusual results. But 
in spite of these variations there appears to be clearly discern- 
ible a normal development of bacteria associated with different 
temperatures. 
2. There is, in all cases, a certain period at the beginning 
when there is no increase in total numbers of bacteria. During 
this period some species are multiplying, while others are appar- 
ently dying. The length of this period depends upon tempera- 
‘ture. At 37°C. it is very short, while at 1°C, it ‘may lastirom 
6 to 8 days, since, at this temperature, milk may, in 6 days, 
actually contain fewer bacteria than when fresh. 
3. After this preliminary period there always follows a 
multiplication of bacteria; but the types that develop differ so 
markedly that samples of the same milk kept at different tem-_ 
peratures are, at later periods, very different in their bacterial 
content, even though they contain the same number of bacteria. 
— 
