542 APPLICATION OF METHODS OF BACTERIOLOGY 



whatever to dysentery, but later detailed studies all 

 strengthen the assumption that the Shiga type of the 

 organism is not the only one concerned in causing epidemic 

 dysentery. In a number of cases of dysentery two, and at 

 times three, types of bacillus dysenterise have been encoun- 

 tered. Thus far it has been impossible to differentiate clini- 

 cally between the infections produced by the one or the 

 other type, both severe and mild cases being caused by each. 



The Shiga Type of Organism. The evidence presented 

 by Shiga, who discovered this organism in 1898, in Japan, 

 and the subsequent observations of Flexner upon dysentery 

 in the Philippine Islands, leaves little room for doubt that, 

 in so far as acute epidemic dysentery is concerned, the 

 organism under consideration may reasonably be regarded as 

 the causative factor. By both Shiga and Flexner the 

 organism was almost uniformly encountered in the intestinal 

 contents, the intestinal walls, and the mesenteric glands 

 during the acute stages of the disease. Later it was fre- 

 quently missed, and this became more common as the 

 malady progressed to chronicity or recovery. 



It is a bacillus of medium size, with rounded ends. In 

 general its morphology may properly be likened to that of 

 either the typhoid or colon bacillus. 



It is motile and does not form spores. 



. It can be stained with any of the ordinary aniline dyes. 

 It is decolorized by the method of Gram. It may be cul- 

 tivated on all the ordinary media. It grows at room- 

 temperature, but better at the temperature of the body. 

 It does not liquefy gelatin. 



The colonies upon agar-agar present nothing character- 

 istic; those on gelatin are at first i. e., just after isolation 

 from the body like those of bacillus typhosus; later on, 



