216 SAMUEL C. PRESCOTT 



EXAMINATION OF GRAINS FOR STREPTOCOCCUS PYOGENES. 



The investigations hitherto described have aimed to point out 

 the common occurrence of B. coli on the Gramineae. 



To give greater interest and value to this work, it was deemed 

 desirable to extend its scope by an inquiry into the character and 

 constancy of occurrence of streptococci. 



To put the problem in more concrete form: Are the two classes 

 of organisms, colon bacilli and streptococci, of constant occurrence, 

 and if so, do they present any biological relation to each other simi- 

 lar to that existing in sewage or polluted water? 



ISOLATION OF BOTH B. COLI AND STREPTOCOCCUS 



It has been shown by one of us that when B. coli and Strept. 

 pyo genes are both present in a sample of water or sewage, inocu- 

 lation from the sample into dextrose broth and incubation at 37 

 gives a development of B. coli in the first few (six to twelve) hours, 

 while at the end of 36 to 48 hours the streptococci are predominant. 

 Applying this procedure to grain, we have found that of a very 

 large number of experiments nearly all have shown the occurrence 

 of both organisms. 



Thirteen cultures of the colon bacillus isolated from the following 

 sources proved to be identical: 



Seven cultures from wheat. 

 Two " buckwheat. 



Two " rye. 



One culture from barley. 

 One " " oats. 



The purpose of the colon isolations was to confirm earlier results 

 and determine if both kinds develop true to the type. 



Plating from the dextrose broth culture on litmus lactose agar 

 as soon as gas formation was well begun gave a predominance of 

 the colon- type organisms, while after 24 hours the streptococci 

 were present in abundance. We have, therefore, not only constant 

 occurrence of both types, but the same course of development in 

 dextrose broth cultures with grains and with sewage a fact which 

 may have great practical significance in sanitary work. 



Comparison of this last series of cultures with the first series will 

 show the constancy in biochemical reactions and morphological 

 features of the colon bacilli from all sources. 



