HOST-PARASITE RELATIONS I INTESTINAL PROTOZOA 



The character of the nuclear division of E. histolytica 

 is of particular importance since the identification of this 

 amoeba in the lesions of arthritis deformans and Hodg- 

 kin's disease (Kofoid, 1923) has been based largely on 

 the mitotic figures found in certain of the cells. Dobell 

 (1919a) has described division in specimens obtained 

 by sectioning tissues from freshly killed cats that had 

 been experimentally infected. He was unable to satisfy 

 himself that chromosomes v^ere present. Kofoid and 

 Swezy (1922a) described mitosis in specimens of E. his- 

 tolytica found in the bone marrow in arthritis deformans 

 and later (1925b) published a detailed account of this 

 process in both trophozoites and cysts from human cases 

 of amcebiasis. They recognize an "interphase with nor- 

 mal resting nucleus, the prophase in which the daughter 

 centrosomes form and the chromosomes emerge and di- 

 vide, the modified amphiaster in which the divided chro- 

 mosomes assemble in the equatorial region of the spindle, 

 the anaphase in which they migrate toward the poles, 

 and the telophase in which the nucleus constricts into 

 two which then return to the interphase" (p. 333). The 

 nuclear membrane remains intact throughout. The num- 

 ber of chromosomes is six ; these divide in the metaphase 

 and migrate to the poles in the anaphase. Then the nu- 

 cleus constricts into two. They claim that mitosis in E. 

 histolytica is in all essential particulars of the type normal 

 to the parasitic Amoebida. 



Multiplication of the nucleus occurs within the cyst; 

 that this leads to an increase in the number of organisms 

 seems probable from the work of Yorke and Adams 

 (1926a; see p. 66). The quadrinucleated cysts no doubt 



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