BACILLUS PARATYPHOSUS. 461 



agglutination reaction with the typhoid bacillus was 

 absent, has revealed a group of bacilli which differ from 

 bacillus typhosus in certain important particulars. These 

 bacteria possess characters which are intermediate be- 

 tween those of bacillus typhosus and bacillus coli, some 

 resembling more closely bacillus typhosus, and others 

 bacillus coli, and for these reasons they have sometimes 

 been classed as the intermediate group. Some of the 

 organisms isolated from such cases of continued fever 

 resemble very closely bacillus enteriditis, which Gaertner 

 found in cases of meat poisoning. 



The general opinion to-day is that these organisms 

 produce a form of infection sometimes resembling in 

 many of its characters that produced by bacillus ty- 

 phosus. The infection, however, is usually of a milder 

 type and only a comparatively small number* of cases 

 have terminated fatally, so that the pathology of the 

 disease is not well known. Moreover, the biological char- 

 acters of the different organisms isolated from cases of 

 paratyphoid fever show such wide variations that it is 

 probable that the pathology of different cases also 

 varies with the particular type of organism causing the 

 infection. 



Buxton l was one of the first to make a careful com- 

 parative study of the morphology and biology of this 

 group of organisms. He classifies the intermediary 

 group of organisms in the following manner: 



" Paracolons : those which do not cause typhoidal 

 symptoms in man. A group containing numerous dif- 

 ferent members, but culturally alike. 



" Paratyphoids : those which cause typhoidal symp- 

 toms. 



1 Buxton: Journal of Medical Research, 1902, vol. viii., p. 201. 



