64 STORRS AGRICULTURAL EXPERIMENT STATION. 
Milk kept at 37°.—'This sample showed the most interesting 
result of any of our experiments; for at 16 hours and 18 hours, 
the time of curdling, the only bacteria present were those of 
Group III., 2. aerogenes. ‘These developed to the extent of 
470,000,000 per cubic centimeter, and all other species had dis- 
appeared except a very small number of Group IV., too small 
to be indicated in percentage. 
Plate 4 shows in an exceptionally striking way the contrast 
between the growth of bacteria in the three samples. 
EXPERIMENT NO. 6. JUNE I0. 
A repetition of the other experiments, except that the milk 
was slightly fresher when first plated—about one hour after 
milking. The milk at 37° curdled in 11 hours, that kept at 20° 
in 4o hours, and that at 10° in 270 hours. ‘The weather was 
warmanddamp. ‘The study of the milk at 20° and 10° showed 
nothing peculiar, but the 37° sample was very exceptional in 
curdling in 11 hours and in containing few bacteria. ‘Tables 
16, 17, and 18 show the details of analysis. 
Milk kept at ro°.—’The only points especially to be noticed 
are the following. ‘There was a general growth of all species 
except Groups V. and VIII. Groups I. and IV. constituted 98 
per cent. of all at the time of curdling, Group I. being about 
twice as abundant as Group IV., but Group IV. showed 1,200,- 
000,000 per cubic centimeter. ‘The total number of bacteria 
was very high, and, as a consequence, the last three tests are not 
very reliable. 
Milk kept at 20°.—As usual, Group I. grew rapidly, and at’ 
36 hours there were 1,870,000,000 per cubic centimeter. Group 
IV. developed also, not being so completely checked as usual. 
No other bacteria developed. 
Milk kept at 37°.— This showed a very meertiae result. The 
milk curdled in 11 hours, but at that time contained only 
8,000,000 of bacteria, only 5 per cent. of which were acid 
bacteria, Group III., and none of which belonged to Groups I. 
and II. Of the bacteria 63 per cent. were liquefiers, although 
these were only about 5,000,000 per cubic centimeter. ‘The 
milk was certainly not curdled by lactic bacteria, and doubtless 
the rennet enzymes produced by the liquefiers curdled the milk. 
This is the only example we have ever had the opportunity to 
study where normal milk was curdled by liquefiers rather than 
by lactic bacteria. 
