62 STORRS AGRICULTURAL EXPERIMENT STATION. 



5. It will be noticed that the higher temperature appar- 

 ently favored the development of liquefiers, which rose from 

 10 per cent, to 51 per cent, in twent3'-one hours at 20°, but at 

 13° reached only 15 per cent., even at the highest point of 

 development. 



6. One especially striking effect of the low temperature is 

 the increase in the variety of bacteria. In all the experiments 

 described on preceding pages, as well as in those on later 

 pages, it will be seen that at a temperature of 20° there is 

 commonly a decline in the number of varieties of bacteria 

 found in the milk, so that in the later hours the number is less 

 than at first, and in the milk which is forty to sixty hours old 

 the number of species has commonly become reduced to two or 

 three. In the milk kept at 13°, however, the reverse is the 

 case. As can be seen by Table 25 the milk at fifty-two hours 

 has a greater variety of species than the fresh milk and these 

 species are present in considerable numbers even at the end. 

 In other words, this experiment would seem to indicate that 

 whereas at the temperature of 20° the development of the 

 acid organisms is stimulated to such an extent that they event- 

 ually take the place of most other species of bacteria in the 

 milk, at a temperature of 13° the acid organisms are so held 

 in check that the miscellaneous species of bacteria which are 

 present in small numbers have an abundant chance to develop. 



Experiment No. 11. January 24.. — In this experiment the 

 tests of the sample of milk which was kept at 20"^ were not 

 satisfactory because in one test the set of plates developed 

 numerous liquefiers, and in another test the set was broken. 

 The only reliable test was that made of the fresh milk. The 

 sample of milk which was kept at 13°, however, was carried 

 through a series of tests, all of which were satisfactory. The 

 results given in Tables 27 and 28 are of interest, even though 

 it is not possible to compare them with results for the same 

 sample of milk kept at 20°. 



From the tables on page 63 the following facts may be noted: 



I. Here, as in the previous experiment, the extremely slow 



development of the total number of bacteria is very striking, 



at the end of fifty- two hours there being in all only 67,000. 



From the time of the first test to that made at the end of forty 



