352 BACILLARY DYSENTERY. 



large numbers in the dejecta, especially in acute cases, where 

 it may be present in almost pure cultures. The organism does 

 not appear to spread deeply or to invade the general circulation. 

 In the more chronic cases it is difficult to obtain on account of 

 the large number of the bacillus coli and other bacteria pres- 

 ent. 



Pathology. — As already stated, both acute and chronic 

 cases are marked by the presence of this organism. In the 

 former, where death may occur in from one to six days, the 

 chief changes, according to Flexner, are a marked swelling and 

 corrugation of the mucous membrane, with haemorrhage and 

 pseudo-membrane at places. There is extensive coagulation- 

 necrosis with fibrinous exudation and abundance of polymorpho- 

 nuclear leucocytes, and the structure of the mucous membrane, 

 as well as that of the muscularis mucosae, is often lost in the 

 exudation. There is also great thickening of the sub-mucosa, 

 with great infiltration of leucocytes, these being chiefly of the 

 character of "plasma cells." In the more chronic forms the 

 changes correspond, but are more of a proliferative character. 

 The mucous membrane is granular, and superficial areas are 

 devoid of epithelium, whilst ulceration and pseudo-membrane 

 are present in varying degree. 



Agglutination. — All the above-mentioned observers agree 

 regarding the agglutination of this bacillus by the serum — that 

 is, in the cases of dysentery from which the organism can be cul- 

 tivated. The reaction is most marked after from six to seven 

 days in the acute cases, and is usually given in a dilution of from 

 one in twenty to one in fifty within an hour, though sometimes 

 much higher dilutions give a positive result. In the more 

 chronic cases the reaction is less marked, and here the sedi- 

 mentation method is to be preferred. Agglutination of this 

 organism has not been obtained with serum from cases other 

 than those of dysentery, nor has a bacillus been cultivated from 

 other such sources. The reaction is also absent in those cases 

 of dysentery which are manifestly of amoebic nature (p. 529). 



Pathogenic Properties. — Mice and guinea-pigs are especially 

 susceptible both to subcutaneous and intraperitoneal inoculation, 

 dying frequently within 24 to 48 hours. Cats also die from 

 subcutaneous inoculation, but are resistant when fed with the 

 organism, excepting after doses of croton oil, when they fre- 



