BACILLUS PARATYPHOSUS 539 



toms in man. A group containing numerous different 

 members, but culturally alike. 



" Paratyphoids : those which cause typhoidal symptoms. 



" (a) A distinct species culturally unlike the paracolons. 



"(6) A distinct species culturally resembling the para- 

 colons." 



Buxton and others state that some of those producing 

 typhoidal symptoms cannot be distinguished culturally 

 from some members of the paracolon group. All the organ- 

 isms of this intermediate group have* the morphological 

 characters of the colon-typhoid group of organisms, 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 bacillus 

 coli are too insignificant and uncertain to be of any assist- 

 ance 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 produce coagulation. 

 Some produce a slight initial acidity, which is later followed 

 by an alkaline reaction. Still other members of the group 

 produce an acidity amounting to 1 per cent. 



Buxton states that the intermediates can be distinguished 

 from bacillus typhosus by their power of fermenting the 

 disaccharid maltose and all the monosaccharids 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 intermediate 

 group with the serum of an animal immunized with one of 



