Walker,[23] Darling,[24] Wenyon[25] and others believe that _Entamœba histolytica_, which was only seen by Schaudinn in a single case, that of a Chinaman, is really _E. tetragena_. Darling states that if the published illustrations of _E. histolytica_ and of _E. tetragena_ are collected from the literature and compared, it will be seen that the writers have been calling _E. histolytica_ the large trophozoites seen in dysenteric stools. These large trophozoites frequently display no karyosome, but they can be demonstrated as _E. tetragena_ by animal inoculation, or by the history of the case. On the other hand, the illustrations of _E. tetragena_ show that the authors have been dealing with the small generation or reduced forms (“_E. minuta_”), which are the direct descendants of the large trophozoites. If kittens are inoculated rectally with dysenteric material containing large trophozoites, the strain may be carried in successive kittens for four to six transfers. If, on the other hand, kittens are inoculated rectally with small trophozoites of the pre-cyst generation, the transmission cannot be carried through more than one or two kittens. Wenyon has succeeded in maintaining _E. tetragena_ in kittens for several generations. [23] _Philip. Journ. Sc._ (1911), B, vi, p. 259. [24] _Annals Trop. Med. and Parasitol._ (1913), vii, p. 321. [25] _Brit. Med. Journ._, Nov. 15, 1913, p. 1287, and _Journ. Lond. School Trop. Med._, ii, p. 27. In some of the preparations from the last remove, pathological forms of the trophozoites may be seen. These show abnormal forms of budding, especially peripherally, such as have been described by Schaudinn and by Craig as characteristic of _E. histolytica_. Schaudinn’s small peripheral, exogenous buds and cysts are thus explained. Craig has latterly changed his views. Further, Darling states that _tetragena_ cysts fed by the mouth to kittens produce bowel lesions in which trophozoites having the characters of _E. tetragena_, _E. histolytica_ and _E. nipponica_ (Koidzumi) occur.