BACILLUS PARATYPHOSUS. 447 



"(a) A distinct species culturally unlike the para- 

 colons. 



"(6) A distinct species culturally resembling the 

 paracolons." 



Buxton and others state that some of those producing 

 typhoidal symptoms cannot be distinguished culturally 

 from some members of the paracolon group. All the 

 organisms of this intermediate group have the morpho- 

 logical characters of the colon-typhoid group of organ- 

 isms, and they cannot, therefore, be distinguished from 

 one another by the form or size. 



The biological differences on agar-agar, blood serum, 

 gelatin, and bouillon, between the members of the inter- 

 mediate group, and between bacillus typhosus and bacil- 

 lus coli are too insignificant and uncertain to be of any 

 assistance in a differentiation between members of the 

 group. In litmus milk certain well-marked differences 

 between different members of the group are noticed. 

 None of the organisms of the intermediate group pro- 

 duce coagulation. Some produce a slight initial acidity, 

 which is later followed by an alkaline reaction. Still 

 other members of the group produce an acidity amount- 

 ing to 1 per cent. 



Buxton states that the intermediates can be distin- 

 guished from bacillus typhosus by their power of fer- 

 menting the disaccharid maltose and all the monosac- 

 charids with gas formation. On the other hand they 

 can be distinguished from bacillus coli by their inability 

 to form acid and gas in lactose media. 



The agglutination reaction of members of the inter- 

 mediate group with the serum of an animal immunized 

 with one of the organisms varies with the different 



