50 STORRS AGRICUI.TURAL EXPERIMENT STATION. 



It will be noticed that these experiments were continued over 

 a longer period than those already described. The purpose of 

 this was to determine whether in milk that was more than 

 twent3'-four hours old the development of the bacteria was 

 similar to that which has been described in the report upon 

 ripening cream previously' referred to (p. 26). It will be 

 noticed from the tables given in the preceding pages of this 

 article, that although there is considerable increase in the 

 number of lactic bacteria in the first twenty-four hours, there 

 is nothing that compares with the development of this class of 

 organisms in ripening cream. In the present experiments the 

 tests were continued until the milk was thoroughly sour or 

 curdled, and the results are, therefore, parallel to those ob- 

 tained in the stud}' of ripened cream. As was to be expected, 

 the milk that had not been iced soured and curdled quicker 

 than the milk that had been kept for fourteen hours upon 

 ice, the difference in the time of curdling being about fifteen 

 hours. Thus the curdling was delayed about the length of 

 time the milk was kept on ice. The first experiment was per- 

 formed in the month of October, at a time when the weather 

 was tolerably warm. The tables above give the results of 

 the analyses. Tables 15 and 16 repre.senting the milk which 

 was placed immediately at 20° without icing, and Tables 17 

 and 18 those that were first iced for fourteen hours. It will of 

 course be evident that the first of each pair of tables in this 

 experiment, and, indeed, in all the subsequent experiments in 

 this paper, are strictly parallel with those given in the first 

 section, z. e., a stud}- of milk at 20°. They thus give addi- 

 tional evidence in regard to the development of bacteria in 

 milk during the first few hours, when the milk is kept at a 

 temperature of 20° C. 



From the four tables above the following facts may be noted : 



1. The multiplication of bacteria was much more rapid in 

 the milk that had not been iced. This of course was to have 

 been expected. 



2. The number of bacteria which developed in the iced 

 milk was far less than that in the non-iced milk, even at the 

 time when the milk was curdled. As will be noticed in this 

 experiment the iced milk at the time of curdling contained 

 only about 300,000,000 per cubic centimeter, while the milk 



