X] BACILLI : SPECIAL 197 



water is of even greater importance than that of the bacillus 

 coli. For it must be obvious that, since bacillus coli is 

 often present in many materials besides sewage, its presence 

 alone in water, particularly in limited numbers, does not 

 justify the conclusion that such water had been directly 

 polluted with sewage. If, however, bacillus coli and proteus 

 vulgaris should be present in considerable numbers, such 

 a conclusion as to probable sewage pollution would be most 

 probably a correct one. The bacillus which I am about to 

 describe being of rarer distribution outside sewage, and 

 being present in sewage, it is clear that for diagnostic 

 purposes it is of importance. Now, this bacillus has certain 

 characters in cultivation in common with bacillus coli, and 

 from the aspect of its colonies in gelatine and in streak 

 cultures on gelatine might be mistaken for- it : it grows as 

 rapidly as, if not more so than, bacillus coli, and forms the 

 same kind of flat, dry, translucent, angular, patch-like colonies ; 

 in gelatine streak it forms the same kind of translucent band 

 with filmy, irregular, or crenate and knobbed margin. Like 

 bacillus coli, it grows well in phenolated gelatine a7id ifi 

 phenolated broth, it differs, however, from bacillus coli in the 

 following respects ; — 



It grows quicker in plates and in streak culture in 

 gelatine ; its colonies are flatter and show, when examined 

 with a magnifying glass, already after twenty-four hours, 

 better after forty-eight hours, in reflected light very charac- 

 teristic white granules scattered through the middle part of 

 the patch ; the same white granules are noticed along the 

 middle of the band in streak culture ; later, say after three 

 days, the number of the granules increase considerably and 

 extend from the middle to near the margin both in the 

 colonies of the plate as also in the band of the streak, so 

 that thereby the growth becomes whitish in reflected, opaque 



