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.

Shiga distinguished two species; a larger pathogenic species with a somewhat active movement, and a small harmless species with a somewhat sluggish movement. Bowman mentions two varieties, Strong and Musgrave (1900) two species—the pathogenic Amœba dysenteriæ and the non-pathogenic Amœba coli; Jäger (1902) and Jürgens (1902) mention at least two species. In the following year (1903) a work by Schaudinn was published which marked a real advance. This, in conjunction with the establishing of a special genus (Endamœba or Entamœba) for human intestinal amœbæ first by Leidy[11] and then by Casagrandi and Barbagallo,[12] for the time cleared up the confused nomenclature, the old name Amœba coli being retained for the harmless intestinal amœbæ of man, whereas the pathogenic species was designated Entamœba histolytica. The history of more recent work is incorporated in the accounts of the entamœbæ given below.

Entamœba coli, Lösch, 1875, emend. Schaudinn, 1903.