GENUS BACILLUS 315 



taken from a perfectly normal one. This species is now con- 

 sidered important etiologically although there is no distinct 

 disease for which it seems to be entirely responsible. 



Identification of B. coli. Considerable difficulty is often 

 experienced in positively identifying this species. According 

 to Smith, 15 "a type-species of B. coli includes those forms 

 which grow on gelatin in the form of delicate bluish or more 

 opaque whitish expansions with irregular margin, (2) which 

 are actively motile when examined in the hanging drop from 

 young surface-colonies taken from gelatin plates, (3) which 

 coagulate milk within a few days, (4) grow upon potato 

 either as a rich-pale or brownish-yellow deposit, or merely as 

 a glistening, barely recognizable layer, (5) and which give a 

 distinct indol-reaction. Their behavior in the fermenta- 

 tion tube must conform to the following scheme : 

 "Variety A. One per cent dextrose-bouillon (at 37 C.). 



"Total gas, approximately % ; H/C0 2 approximately 2/1; 

 reaction strongly acid. 



' ' One per cent lactose bouillon : 



"As in dextrose-bouillon (with slight variation). 



' ' One per cent saccharose-bouillon : 



"Gas-production slower than in the preceding, lasting 

 from seven to fourteen days. Total gas finally about 2/3 

 H/C0 2 nearly 3/2. The final reaction in the -bulb may be 

 slightly acid or alkaline, according to the rate of gas-produc- 

 tion. Variety B. The same in all respects excepting as to its 

 behavior in saccharose bouillon. Neither gas nor acids are 

 formed in it."* 



BACILLUS SUIPESTIFER KBUSE. 



Synonyms. Bacillus of hog cholera Salmon- Smith; 

 bacillus of swine plague Billings; bacillus of swine pest 

 Selander; Bacillus cholerae suis; Bacillus cholerae suum 



13 Smith, loc. cit. 



*Dunham has designated this variety of B. coli, B. coli communior 

 because he believes it to be more common in the intestine than va- 

 riety A or the colon bacillus as he designates it. 



