540 



AMCEBIC DYSENTERY 



usually found in large numbers in the contents of the large 

 intestine, in tropical amoebic dysentery. They also, however, 

 penetrate into the tissues, where they appear to exert a well- 

 marked action. In this disease the lesions are chiefly in the large 

 intestine, especially in the rectum and at the flexures, though 

 they may also be present in the lower part of the ileum. At 

 first there are seen local swellings on the mucous surface, chiefly 

 due to a sort of inflammatory gelatinous oedema with little 

 leucocytic infiltration ; soon, however, the mucous membrane 

 becomes partially ulcerated, more or less extensive necrosis of 



the subjacent tissues oc- 

 curs, and gangrenous 

 sloughs result. The ulcers 

 thus come to have irregular 

 and overhanging margins, 

 and the excavation below 

 is often of wider extent 

 than the aperture in the 

 mucous membrane. The 

 amoebae are found in the 

 mucous membrane when 

 ulcers are being formed, 

 but their most character- 

 istic site is beyond the 

 ulcerated area, where they 

 may be seen penetrating 

 deeply into the submucous, 

 and even into the muscular 

 coats. In these positions 

 they may be unattended 

 by any other organisms, 



and the tissues around them show cedematous swelling and more 

 or less necrotic change without much accompanying cellular 

 reaction, beyond a certain amount of swelling and proliferation 

 of the connective-tissue cells. This action of the amoebae on 

 the tissues explains the character of the ulcers as just de- 

 scribed. These lesions are considered to be characteristic of 

 amoebic dysentery. 



As a complication of this form of dysentery, liver abscesses 

 are of comparatively common occurrence. They are usually 

 single and of large size, sometimes there are more than one, and 

 occasionally numerous small ones may be present. The contents 

 are usually a thick pinkish fluid of somewhat slimy consistence 

 and are largely constituted by necrosed and liquefied tissue with 



FIG. 167. Section of wall of liver abscess, 

 showing an amoeba of spherical form with 

 vacuolated protoplasm. From a case 

 published by Surgeon-Major D. G. 

 Marshall. x 1000. 





