548 CLASSIFICATION AND MORPHOLOGY OF AMEBA 



contains several and sometimes many red blood corpuscles. These 

 are digested in the interior of the parasite, and its protoplasm and 

 the fluid in the vacuoles frequently show a slight greenish tinge. If 

 stained with Wright's stain the ectoplasm stains very intensely, while 

 the entoplasm stains lightly. Entamoeba coli behaves in exactly an 

 opposite manner. The nucleus of Entamoeba hystolytica stains poorly 

 on account of the scanty amount of chromatin. Reproduction occurs 

 by division and budding with spore formation. The latter appears 

 to occur in the intestines of man when conditions become unfavorable 

 to the organism and when it becomes advantageous for it to assume 

 the more resistant spore form. Then the nucleus expels and dis- 

 tributes most of its chromatin into the cytoplasm, the expelled chrom- 

 atin collects into small masses, and these reach the ectoplasm, where 

 they become protruded with some cytoplasm, beyond the periphery 

 of the main body, and are finally cut off from the mother cell entirely. 



Human feces containing Entamoeba hystolytica, when injected 

 into the rectum of kittens, produce typical, generally fatal attacks of 

 amebic dysentery. Upon postmortem examination the character- 

 istic ulcerative changes of the disease are found in the intestines. 



From a study of various cultures of amebse, Walker came to the 

 conclusion that Schaudinn's observation on the differences between 

 Entamoeba coli and Entamoeba hystolytica were incorrect; but, as 

 Craig properly remarks, Walker studied only a very few cases of 

 human dysentery, and confined his observations to a few cultures of 

 intestinal amebse from human sources. The characteristic re- 

 production by budding in Entamoeba hystolytica, however, cannot 

 be observed in artificial cultures, but must be studied under the natural 

 conditions in which this pathogenic organism it found in the intestines 

 and discharges of man. 



New Species of Pathogenic Amebse. -Several new species of amebse 

 pathogenic to man have recently been described by observers working 

 on cases of chronic tropical dysentery in different parts of the world. 



Viereck studied the stools of 62 cases of dysentery from Africa, 

 Europe, and South America. He found living amebse Jn 37 cases, 

 and bodies which he thought were amebse in 17 cases. In 2 cases 

 he encountered an ameba which resembled Entamoeba coli more 

 than it did Entamoeba hystolytica, but it formed four cysts instead 

 of eight. It produced dysentery in cats. Viereck also found this 

 ameba in non-dysenteric stools, and suggested that it might be a 

 variety of Entamoeba coli. He called it Entawceba tetragena. 



Hartmann, almost simultaneously with Viereck, described an 

 ameba which was found to be identical with Entamoeba tetragena. 

 This organism was found only in cases of dysentery, and it produced 

 typical ulcerating dysentery in cats. As a rule, it is not as pathogenic 

 for cats as the Entamoeba histolytica. In all cases from Africa and 

 South America which Hartmann examined he found Entamoeba 

 tetragena, 



