66 Kansas Academy of Science. 



may be explained by the greater specific gravity of the types 

 of microorganisms found in fresh milk, in the older milk 

 the microbial flora is different and the specific gravity lighter, 

 thus offering better opportunity for the organisms to be carried 

 with the cream upon separation. 



In Table VII are shown the average results of twenty tests 

 which were run to determine the relative distribution of the 

 various groups of organisms present in milk. The plates used 

 were litmus lactose gelatine incubated at room temperature 

 for six days. The colonies found were grouped according to 

 their action upon the litmus and gelatine, as follows : 



(1) Acid liquefiers. 



(2) Acid nonliquefiers. 



(3) Alkaline liquefiers. 



(4) Alkaline nonliquefiers. 



(5) Neutral liquefiers. 



(6) Neutral nonliquefiers. 



(7) Molds. 



As there appeared to be practically no difference in the dis- 

 tribution of the types between a milk having a low bacterial 

 content and one having a high content, the tests were averaged 

 irrespective of numbers. 



Table VII shows that all the types predominate in the cream 

 over the skim milk except the molds, and these are in reversed 

 order. No conclusions could be drawn as to the distribution 

 of the various types. 



The effect of separation upon the keeping quality is roughly 

 shown in Table VIII. The samples were taken as soon after 

 separation as possible and kept in flasks at room temperature 

 until about the time of coagulation, when acid determinations 

 were made as an indication of bacterial activity. 



