256 HOG CHOLERA 



larger areas of blood clots. In some cases the small intestine 

 has submucous ecchymoses throughout its entire length. In 

 the large intestines these may be so numerous as to give the 

 membrane a dark red appearance. The intestinal contents are 

 now and then incased in a layer of blood clot. 



The chronic form is perhaps the most common, at least in 

 those epizootics which have been reported. The acute hemor- 

 rhagic cases usually die in the beginning of the outbreak and 

 are apt to be overlooked. Following these are the more pro- 

 tracted ones. In these animals the disease may be limited in 

 its manifestations to the large intestine, although the other 

 organs are not exempt from degenerative changes. These are 

 due in part to the impairment of the functions of the large 

 intestine, consequent fermentations and the absorption of the 

 poisonous products elaborated by the specific bacilli in the 

 spleen and other organs. 



The lesions of the large intestines are necrotic and ulcera- 

 tive in character. The ulcers may be isolated and appear as 

 circular, slightly projecting masses, stained yellowish or 

 blackish or both in alternate rings, or they may be .slightly 

 deprc.s.sed and somewhat ragged in outline. When the super- 

 ficial .slough is scraped away many ulcers show a grayish or 

 white base. A vertical section reveals a rather firm neoplastic 

 growth, extending usually to the inner muscular coat. When 

 sections of such an ulcer are stained with aniline dyes and ex- 

 amined under the microscope, the submucous tissue is very 

 much thickened, infiltrated with rounds cells and containing a 

 large number of dilated vessels. Resting upon this thickened 

 submucosa, is a line of very deeply stained amorphous matter 

 and upon this is situated the necrotic mass which fails to retain 

 the coloring matter and which is permeated by a very large 

 number of bacteria of various kinds. Frequently the eggs of 

 trichocephalus are imbedded in the slough. 



The extent of the submucous infiltration depends upon 

 the age of the ulcer. ^ In old ulcers it contains many newly- 

 formed capillaries, and evidences of the formation of connective 

 tissue are present. The capillaries may extend to the very 



