690 



PATHOGENIC MICROORGANISMS 



workers, by Smith and Ten Broeck, 24 , by Krumwiedc, Pratt and Kohn, 25 

 and many others. The following fermentation chart indicates briefly 

 a summary of the reactions of the more common members of this group, 

 chiefly constructed according to the work of Krumwiede and his co- 

 workers. 



= acid and gas 



= negative + = acid, no gas. 



This table brings out a very important point namely, that xylose 

 fermentation is one of the sharply differential characteristics between 

 paratyphoid "A" and all the rest of the group. Whether or not it is 

 possible to differentiate by cultural study between the "B" organisms 

 of man and those derived from different animal sources is questionable. 

 We do not believe that it can be done reliably at the present time, 

 though certain studies, by the writers named, on the quantitative rela- 

 tionship between reduction of fuchsin and fermentation of dulcite and 

 arabinose would hold out some hope for future clarification of this 

 difficult problem. These writers, however, also call attention to a fact 

 noted in a less extensive way by us and by many other writers, namely, 

 that agglutination and cultural reactions do not correlate in many 

 instances within this group. This is a thing which Theobald Smith 

 pointed out not only for this group but for other groups of bacteria 

 some time ago, and would lead us to be slow to assume that either 

 agglutination or even cultural similarity are always to be regarded as 

 definitely signifying biological relationship. 



This opinion, too, is confirmed by the extensive and careful investi- 

 gations of Jordan which the reader interested in this subject may find in 

 the series of papers published in the Journal of Infectious Diseases, 

 Volumes 20, 21, 22, 23 and 26. Jordan 26 finds, for instance, that the 



24 Smith and Ten Broeck, Jour. Med. Res., 31, 1915, 503 and 547. 



25 Krumwiede, Parti and Kohn, Jour. Med. Res., 34, 1916, 34 and 355, pp. 55, 357 

 and 443. 



26 Jordan, Jour. Infec. Dis., Vols., 20, 21, 22, 23 and 26. 



