220 SAMUEL C. PRESCOTT 



ting the possibility of this view, it seems to us unlikely. The other 

 alternative is that these organisms are constantly associated with, 

 and of normal occurrence upon, the grain heads ; that they find suf- 

 ficient sustenance to support life, or even to increase in numbers; 

 in other words, that they show a mild form of association or semi- 

 parasitic relation with the plants on which they develop. It seems 

 unreasonable that organisms exhibiting such marked identity in all 

 details of growth and cultural behavior should be regarded as of 

 different species. More likely these organisms bear much the same 

 relation to the sugary heads that B. subtilis does to the stalks of hay, 

 or Strept. hollandicus to Pinguicula, or the nitrogen- fixing bacteria to 

 the legumes. With this view, it is easy to see how the organisms 

 could find their way to the animal intestine where the temperature 

 and food conditions for rapid development are ideal. Nor is it sur- 

 prising, in view of the careful and exhaustive search for bacterial 

 proofs of contamination, that the organisms in the intestine should 

 first be sought, and, because of their abundance, regarded as origi- 

 nating in this habitat. The explanation made possible by regarding 

 these species of bacteria as constantly associated with the starch-pro- 

 ducing grains is not only simpler, but in our opinion fits in more 

 readily with all the observed facts. Probably many more such asso- 

 ciations of certain species of bacteria with plants which can supply 

 their food requirements will be observed in the future, and here is 

 certainly an interesting field for research. 



While thus of interest from the general biological standpoint, 

 it is in their bearing on the questions relating to sanitary bacterio- 

 logical practice that our observations have the utmost importance. 

 Whatever may be the origin of the individuals whence these organisms 

 have been developed, their presence on the grains suggests sources 

 of the colon bacilli and streptococci in water other than direct sewage 

 pollution. Whether the organisms find their way from grain to 

 natural waters can be determined only by an exhaustive study of 

 the bacteriology of unpolluted streams in a new grain-producing 

 region such as western Canada. 



Certainly the presence of small numbers of these organisms 

 must be interpreted with the utmost discretion. As a result of 

 careful study, we are not inclined to believe that our results invali- 



