ENTAMOEBA HYSTOLYTICA 



547 



dysentery. It penetrates into the intestinal mucosa and submucosa, 

 and in this manner produces ulceration. It can even be carried to 

 the liver and there produce abscess. Amebic dysentery is most 

 prevalent in the tropics, but it is also found in the United States, 

 particularly in the Southern States. The organism consists of a mass 

 of protoplasm, contains a nucleus, and generally several non-contractile 

 vacuoles. It is round when at rest. It is generally larger than 

 Entamoeba coli. Craig gives its average diameter as 35 micra, and 

 says that he has seen individuals as large as 60 to 70 micra. In 

 full-grown individuals the differentiation into a granular entoplasm 

 and a hyaline ectoplasm is very marked. The latter forms a consider- 



FIG. 186 



Entamoeba hystolytica. (After Craig.) A, organism showing rods and granules of chro- 

 matin in the nucleus, vacuole with some stained substance, and dense ectoplasm; B, the chro- 

 matin of the nucleus passing into the cell plasm, where it is distributed as chromidia, shown 

 in C; D, aggregation of chromidia to form secondary nuclei; E, "spore formation" by budding; 

 F, spores of Entamceba histolytica as seen in feces. 



able portion of the entire cytoplasm; it is highly refractive and glass- 

 like in appearance. It can generally be seen at its best when the 

 organisms are examined in a warm, fresh stool. Here it is generally 

 very lively motile, much more so than Entamoeba coli. When pseudo- 

 podia are formed a rapid or also more slow outflow of the hyaline ecto- 

 plasm takes place, and the pseudopodium is first formed of it alone, 

 later the granular entoplasm also flows in. Schaudinn and Juergens 

 believe that the power of the Entamreba hystolytica to penetrate into 

 tissues depends primarily upon the evidently very firm tenacious 

 ectoplasm. The nucleus is not easily distinguishable in the live 

 unstained condition, and it contains a small amount of chromatin 

 only. The pathogenic entameba when found in bloody stools often 



