CHAPTER XXI. 



BACILLUS DYSENTERIC. 



The group of bacilli found in cases of epidemic, endemic, and sporadic 

 dysentery The morphological, biological, and pathogen ical char- 

 acters of the several members of the group The differentiation 

 of the different types of bacilli. 



THE investigations of epidemic dysentery by Shiga, 

 Flexner, Kruse, Vedder, Duval, Basset, Park, and 

 many others, have demonstrated that this disease is 

 caused by an organism that varies somewhat in its char- 

 acters as encountered in different cases. So far at least 

 four distinct types of the organism have been found that 

 differ in minor particulars, though not sufficiently to war- 

 rant their separation from each other into distinct species. 

 The type of organism first encountered by Shiga in 

 Japan is the one that is probably very widely distrib- 

 uted because it has been found in practically every place 

 where investigations have been made. The type of 

 organism encountered by Flexner in his investigations 

 in the Philippine Islands, Has also been found very gen- 

 erally in the United States, especially in dysentery 

 occurring in infants. The tyj>e of organism isolated by 

 Hiss and Russell, and later by Park and his associates, 

 has most of the characteristics of the Flexner type of 

 organism, though the agglutination reaction shows that 

 it is not identical with it. 



At first the German investigators were inclined to 

 regard the Flexner type of organism as having no caus- 

 ative relation whatever to dysentery, but the later de- 



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