56 STORKS AGRICULTURAL EXPERIMENT STATION. 



does not necessarily mean that they were absent, but that the>^ 

 had not increased sufficiently to make themselves evident in 

 the plates. 



8. As concerns actual numbers there was an increase in 

 nearly all species of bacteria. In the non-iced milk, however, 

 the actual numbers of the Streptococcus group increased for 

 a while and then decreased; whereas in the iced milk the abso- 

 lute number continued to increase to the end. In regard to 

 the liquefiers the actual numbers also increased in the iced 

 milk and the non-iced milk, but the increase after the first 

 hours was very slight. In actual numbers, then, the liquefiers 

 simply held their own, although decreasing in proportion. 



From these two experiments the following general conclu- 

 sions may be drawn: 



1. In milk, as previously shown in cream, there is in later 

 hours marked increase of lactic organisms which become so 

 numerous as greatly to reduce the percentage of all other bac- 

 teria and apparently to cause some species actually to disap- 

 pear. The percentage of lactic bacteria in these experiments 

 was, however, not cjuite so high as in many samples of ripened 

 cream previously described.* 



2. The effect of a preliminary icing of about fourteen 

 hours is greatly to reduce the number of bacteria which is 

 to be found at any sub.sequent period. Although the milk 

 eventually becomes acid and curdles, even at the time of 

 curdling the number of bacteria is much reduced by the 

 preliminary icing. 



3. The effect of icing is to increase the probability of a de- 

 velopment of the miscellaneous types of bacteria, whereas in 

 milk that has not been iced these miscellaneous forms disap- 

 pear more rapidly. 



4. The icing of the milk appears to delay the period of 

 decline of the Streptococcus group, and thus to increase the 

 number of this species present at the end. 



5. In regard to the other species the effect of the icing is 

 only to delay the development, but not proportionately to- 

 modify it. 



*Storrs Experinieiit Station Rept. 1900, pp. 13-33. 



