210 SAMUEL C. PRESCOTT 



in 1894, when the organisms were first reported by Laws and 

 Andrewes. 16 Their sanitary importance was not emphasized until 

 1899 an d 1900, when Houston 17 laid special stress upon the fact 

 that streptococci and staphylococci seem to be characteristic of sewage 

 and animal waste. Horrocks 18 found them in great abundance 

 in sewage and in polluted waters, and showed by experiment that 

 they outlived the colon bacilli in samples of sewage, a subject later 

 explained 19 in 1902, and further discussed by S. K. Baker and one 

 of the writers 20 the following year. LeGros 21 in a monogroph pub- 

 lished in 1902 described many streptococci, all derived from the 

 body or from sewage. 



The first investigators in this country to call attention to these 

 streptococci were Winslow and Miss Hunnewell 22 in 1901. During 

 the same year they were reported by Gage 23 in the sewage of Lawrence. 



The evidence hitherto presented seems to show the streptococci 

 to be associated with animal bodies, occurring either on the surface 

 or within the intestinal tract. The work here described tends to 

 show that these organisms are found in abundance, as is the colon 

 bacillus, on certain substances, at least, outside the body. That 

 they have not been earlier reported is possibly due to a confusion 

 of these organisms and certain bacterium forms, as is suggested by 

 recent work by Heinemann, 27 but more probably because no system- 

 atic search for them has been made. 



The methods of isolation and investigation, and the comparison 

 of the characteristics of the organisms derived from grain with those 

 of the same species from intestinal sources, may now be most con- 

 veniently considered separately. 



COMPARISON OF COLON BACILLI FROM THE DIFFERENT SOURCES. 



Before making a detailed comparison of the organisms from 

 the two sources, it is necessary to define the characteristics which 

 we have regarded as typical of B. coll. These may be expressed 

 as follows: 



Form. Bacillus, 2-3 /x long by 0.5 it- wide, with rounded ends. 



Grouping. Occurs singly, or in short chains or masses. 



Motility. Actively motile; cilia present. 



Spore formation. None. 



Staining reactions. Stains with usual reagents and by Gram's method. 



