EXPERIMENT STATION BULLETINS. 



233 



In this work 10 cultures of the suddenly cooled exceeded the time of 

 development of the non-cooled; 12 cultures of the non-cooled or cooled 

 gradually, exceeded the time of development of the cooled; 6 cultures of 

 the suddenly cooled developed in the same time as the non-cooled. Sud- 

 den cooling seems to have no effect on the time of development. 



6. The Restraining Influence of Coli> Upon the Species 



Isolated. 



Gold always retards the development of bacteria. This is clearly shown 

 upon the species in question by the table below: 



* Cultures— age of cultures when Pasteurized. 

 " t Controls— cultures made at the same time as those Pasteurized, but placed at room temperature 

 instead of refrigerator temperature. 



i Cooled— cultures Pasteurized, suddenly cooled and placed in the refrigerator at 15° C. 



ll Non-cooled — cultures Pasteurized, gradually cooled and placed in the refrigerator at 15° C. 



The blank spaces indicate no growth after 45 days. 



Sudden cooling apparently had no effect in the case of refrigerator 

 temperature 15° C. [59° F.],*but the constant cool temperature retarded 

 greatly the growth of these micro-organisms. 



To make this thoroughly applicable, six miscellaneous micro-organisms 

 were treated in the same way as the previous set but were not subjected 

 to Pasteurization. Here it will be noticed that the time of development 

 is much less, but the refrigerator temperature retarded the growth by 

 several days. The table will explain itself. 



* Controls kept at temperature of room . 



^Refrigerator cultures— thoss inoculated then placed in refrigerator. 



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