ENTAMCEBA HISTOLYTICA 



35 



even in repose, although the former is not equally thick at all parts of 

 the periphery. In the endoplasm generally there are numerous foreign 

 bodies (bacteria, epithelial cells, colourless and red blood corpuscles 

 (fig. 6), and occasionally living flagellates of the intestine). The 

 nucleus is 4 yii to 6 yu, in diameter, and may be difficult to recognize 

 because it is sometimes weakly refractile and poor in chromatin. Its 

 shape is slightly variable ; it is usually excentric, sometimes wholly 

 peripheral at the limit of the two parts of the body. Vacuoles are not 

 present in quite fresh specimens, but appear later. In the study of 

 E. histolytica, the morphological characters of the trophozoite or 

 vegetative stage of the organism formerly separated as E. tetragena 

 (figs. 5, 6, 8a) must be considered (see p. 38). 



FIG. 5. Entamceba histolyiica (tetragena form), showing three successive changes of form 

 due to movement. X iioo. (After Hartmann.) 



The history of the development ot these species, which give rise to amoebic 

 enteritis as distinguished from bacillary dysentery, was formerly not so well known 

 .as that of E. coli. Upon being introduced into cats (per anum] dysenteric amoebae 

 provoke symptoms similar to those in man. In the 

 latter, besides metastatic liver abscesses, abscesses 

 of the lungs, and, according to Kartulis, cerebral 

 abscesses are occasionally produced, Marchoux 

 (1899) states that when the disease has lasted for 

 some time liver abscesses are produced in cats also. 



In the large intestine of infected cats the 

 amoebae creep over the epithelium, and here and 

 there they force the epithelial cells apart, as well 

 as removing them or pushing them in front of 

 them ; the amcebae thus insert themselves into the 

 narrowest fissures. They penetrate also into the 

 glands through the epithelium, and thence into 

 the connective tissue of the mucosa. Intestinal 

 and glandular epithelia perish under the influence 

 of these parasites : the cells are pushed aside, 

 fall to pieces or are absorbed by the amoebae, 

 mucosa the amoebae migrate further, and often accumulate above the muscles. 

 Finally they rupture this and force their way into the submucosa. In cats, 



FlG. 6. Entamceba histolytica 

 which has ingested many red blood' 

 corpuscles. x iioo. (After Hart- 



In the connective tissue of the 



