Amebic Dysentery 697 



mals with Emtamoeba coli, was successful with the pathogenic 

 varieties, and succeeded in infecting 50 per cent, of the kittens 

 he experimented upon by injecting the amebas into the 

 rectum. 



Lesions. The gross morbid appearances of the intestinal 

 lesions in both forms of dysentery are sufficiently distinct in 

 typical cases to enable an experienced pathologist to differ- 

 entiate them, yet not sufficiently distinct to make them easy 

 of description. The one great characteristic feature of the 

 amebic dysentery is abscess of the liver which occurs in 

 nearly 25 per cent, of the cases, but which never occurs in 

 bacillary dysentery. 



The distinct and somewhat rigid ectoplasm of the Enta- 

 moeba histolytica is supposed to make it easy for the organism, 

 which it will be remembered are actively motile, to penetrate 

 between the epithelial cells of the intestinal mucosa to the 

 lymph-spaces of the submucosa below. Here the amebas 

 multiply in large numbers, and by the enzymic action of their 

 metabolic products produce necrosis of the suprajacent tis- 

 sues with resulting exfoliation and the production of round, 

 oval, or ragged ulcerations with markedly infiltrated and un- 

 dermined edges. As the amebas continue to increase and 

 fill up the lymphatics, and as bacteria add their effects to 

 those occasioned by the amebas, the ulcers increase in extent 

 and depth until the mucosa and submucosa may be almost 

 entirely destroyed, leaving the entire large intestine denuded, 

 except for occasional islands of much congested, inflamed, and 

 partly necrotic mucous membrane. The diseased wall is the 

 seat of much congestion and is much thickened. The 

 amebas not only occur in great numbers in the interstices 

 of the tissues about the base of the ulcers and in the lym- 

 phatics, but also enter the capillaries, through which they are 

 carried to the larger vessels, and eventually to the liver, where 

 their activities continue and give rise to the amebic abscess. 

 The first expression of their injury to the liver parenchyma 

 is shown by focal necroses. In each of these the organisms 

 multiply and the lesion extends until neighboring necroses are 

 brought into union, and eventuate in great collections of 

 colliquated necrotic material which may be so extensive as 

 to involve the entire thickness of the organ. There is usually 

 one large abscess, but there may be several small ones, or 

 the liver may be riddled with minute lesions. The contents 

 of the abscess is pinkish necrotic material in which amebas are 

 few. The walls are of semi- necrotic material, in which great 



