endemic, or else they were much rarer than was expected. Further, amœbæ were present in the most varied kinds of intestinal diseases, both of infective and non-infective characters. Also they were present in quite healthy persons. Moreover, for various reasons, infection experiments on animals failed to supply proof, and finally a bacterium was discovered (Shiga, 1898) to be the excitant of one form of dysentery. Agglutination attested the specific part played by this organism, as it was produced by the blood serum of a person suffering from or recovered from dysentery, but not by the serum of one who was uninfected. Bacillary dysentery consequently was a distinct entity. The final step to be taken was to decide whether there was a specific amœbic enteritis (amœbic dysentery or amœbiasis, according to Musgrave). [Illustration: FIG. 2.--Encysted intestinal amœbæ showing nuclear multiplication. (After B. Grassi.)] This question should decidedly be regarded from the positive point of view. It is intimately connected with another, namely, whether there are not several species of intestinal amœbæ. The possibility of this had already been recognized. In addition to the _Amœba coli_ Lösch, R. Blanchard distinguished yet another, _Amœba intestinalis_, and designated thereby the large amœbæ described in the first communication made by Kartulis; later on he stated the distinction between the species. Councilman and Lafleur[10] (1891) considered the amœba of dysentery to be _Amœba coli_ Lösch and so re-named the species _Amœba dysenteriæ_. Kruse and Pasquale (1893) employed the same nomenclature, but retained the old name _Amœba coli_ Lösch for the non-infectious species. Quincke and Roos (1893) set forth three species: a smaller species (25 µ) finely granular, pathogenic for men and cats (_Amœba coli_ Lösch); a larger species (40 µ) coarsely granular, pathogenic for men but not for cats (_A. coli mitis_); and a similar species non-pathogenic either for man or cat (_A. intestini vulgaris_). Celli and Fiocca (1894–6) went still further, they distinguished: (1) _Amœba lobosa_ variety _guttula_ (= _A. guttula_ Duj), variety _oblonga_ (= _A. oblonga_ Schm.) and variety _coli_ (= _A. coli_ Lösch). (2) _Amœba spinosa_ n. sp. occurring in the vagina as well as in the intestine of human patients suffering from diarrhœa and dysentery. (3) _Amœba diaphana_ n. sp. found in the human intestine in cases of dysentery. (4) _Amœba vermicularis_ Weisse, present in the vagina and in dysentery; and (5) _Amœba reticularis_ n. sp. in dysentery. [10] “Amœbic Dysentery,” _Johns Hopkins Hosp. Repts._, ii, pp. 395–548, 7 plates.