PATHOGENIC PROTOZOA OF THE CLASS SARCODINA 421 



glasslike, and refractive, much firmer than the comparatively 

 delicate membrane of E. coli, and the two are relatively easily 

 distinguishable by this means. The ectoplasm apparently com- 

 prises about one-third of the protoplasm. One or more vacu- 

 oles are always present, as many as ten sometimes being found. 

 The nucleus is faint and difficult to distinguish in the un- 

 stained mount. It is about 5 to 6 ft in diameter. The chro- 

 matin is relatively sparse. With Wright's stain the ectoplasm 

 stains more deeply than the endoplasm, the opposite of what is 

 true in E. coli. 



Reproduction is accomplished in two ways. The first consists 

 of a division of the nucleus, followed by a constriction of the cell 

 to form two individuals. This process is essentially the same as 

 that in E. coli. The method of spore formation, gemmation, or 

 budding, is quite different. When conditions arise unfavorable 

 to continued vegetative existence, spores are produced. The 

 nucleus, by a process of fragmentation, throws out chromatin 

 granules or chromidia, which gradually collect under the ecto- 

 plasm, form new nuclei, and are finally thrown off from the ex- 

 terior, together with some of the protoplasm, as a spore or bud. 

 These spores are round or oval, have a yellowish membrane, and 

 measure 3 to 6 fi t usually about 4 fi t in diameter. The membrane 

 which forms about these spores is resistant to the penetration and 

 action of stains. 



Pathogenesis. Experimental Evidence. Schaudinn dried feces 

 of dysentery patients after demonstrating that they contained 

 E. histolytica, in the form of spores in large numbers, and that they 

 were free from E. coli. These were fed to a kitten, and death 

 resulted in fourteen days, with characteristic ulceration of the 

 intestinal wall. Similar experiments have since been repeated 

 many times. There is little or no doubt of the pathogenicity of 

 the organism, and the disease produced may be considered as a 

 clinical entity. 



Character of Disease and Lesions. The disease produced is a 

 chronic dysentery, marked by intestinal ulceration, and frequently 

 by abscesses in the liver. The presence of the relatively firm 

 ectoplasm is believed to account for the ability of the organism 

 to force its way into the tissues between the cells. 



