84 FEED W. TANNER 



coagulation in two days. Strains 1, 5, 13, 16, 17, 18, 23, 24, 

 30, 31, 39, 57, and 60, coagulated the milk in this time. The 

 curd formed was solid in consistency and in many cases settled 

 to the bottom of the flask. When peptonization took place 

 this curd was decomposed until the whole flask had assumed a 

 golden color. 



Another group produced clearing without coagulation. The 

 rapidity of this action varied. With some of the strains it was 

 evident after twenty-four hours' incubation at 37°. Clearing 

 usually started at the surface— a dark transparent layer being 

 formed which rapidly extended downward. With a few of the 

 strains, however, the entire contents of the flask seemed to 

 change to a thinner consistency. The final product was of a 

 golden color. The green pigment which was often produced in 

 large amounts in this medium, combined with this golden color, 

 to give the solution a striking appearance. 



The third type was made up of those strains which seemed to 

 have no effect on the milk in twenty days. It is possible that 

 some change might have been secured, had these cultures been 

 held longer. 



The fourth group consisted of those strains which rendered 

 the medium slimy. This was very apparent after twenty days. 

 The strains which possessed capsules always produced a slimy 

 growth in broth and milk. 



The Society's chart calls for the determination of the reaction 

 at the end of one, two, four, ten, and twenty days. This was 

 attempted, but erratic results were obtained, since the medium 

 was so highly colored that it was impossible to determine 

 the real end point with phenolphthalein. The green pigment 

 seemed to be the greatest factor in masking the neutral point. 

 Another possible reason why varying results were obtained is 

 that phenolphthalein is not sensitive in solutions which contain 

 ammonia; and much ammonia is formed in the splitting of 

 casein. Were the solutions boiled to remove carbon dioxide, 

 some of the volatile compounds might be driven off and cause a 

 greater error than the carbon dioxide itself. For determining 

 the group number the reaction at the end of the tenth day 



