I.—NOTES ON RECENT RESEARCHES.
Since the foregoing section on Protozoology was sent to press, certain interesting observations and results have been published. Brief notes on such, and some references thereto, are now added.
It is necessary, however, to remark that sometimes it is impossible to give a precise or rigid definition to a genus of Protozoa, owing to differences of opinion, to differences regarding nomenclature or to incompleteness of knowledge. Such a lack of definition, while inconvenient for the time being, is not unhopeful, as it directs attention to the necessity for further work, which is inevitable in such a relatively new and wide subject as protozoology. Thus, it may be noted in illustration that Minchin, in 1912, in his text-book regarding the genus Entamœba writes: “The entozoic amœbæ are commonly placed in a distinct genus, Entamœba, distinguished from the free-living forms by little, however, except their habitat and the general (but not invariable) absence of a contractile vacuole.”
Differences between Entamœba histolytica and E. coli.—In continuation of the remarks on pp. [34] and [40], it may be added that Lugol’s solution (iodine in aqueous potassium iodide solution) in fresh specimens shows by brownish staining the presence of glycogen in the vacuoles of Entamœba coli. Such a reaction is rarely or never given by E. histolytica.
Phagedænic Amœbæ.—Carini and others record cases in which the skin around an operation wound in connection with liver abscess became gangrenous. Amœbæ, possibly Entamœba histolytica, were found therein and may have been responsible for the gangreno-phagedænic action.
Endamœba gingivalis (see pp. [43], 44).—Smith and Barrett,[1248] after analysing the early literature, state (June, 1915) that Endamœba gingivalis, Gros, 1849, is the correct name for the following organisms: E. buccalis, Prowazek, 1904 (see p. [43]); Amœba gingivalis, Gros, 1849; Amœba buccalis, Steinberg, 1862, and Amœba dentalis, Grassi, 1879. They conclude that E. gingivalis is the causal agent of pyorrhœa alveolaris, and that this disease responds to treatment with emetine.
Entamœba kartulisi (see p. [44]), synonym E. maxillaris, Kartulis, is considered to be E. gingivalis.
Smith and Barrett adopt the generic name Endamœba, Leidy, 1879 (see footnote on p. [31], also p. [34]). Leidy worked on Endamœba blattæ.
Craigia and Craigiasis (see p. [45]).—Barlow[1249] (May, 1915) found Craigia (Paramœba) hominis in cases of chronic diarrhœa and mild dysentery in Honduras. He also described a new species of Craigia under the name of C. migrans. Fifty-six cases were studied, five of which were due to Craigia hominis, the remainder to C. migrans. In C. migrans, each flagellate, on attaining full development, becomes an amœba without dividing. Each amœba encysts and produces a number of flagellates which are somewhat like cercomonads. On the other hand, in C. hominis the flagellate form produces, by longitudinal fission, several generations of flagellates before entering upon the amœbic stage. The cysts of C. migrans contain fewer “swarmers” (flagellulæ) than those of C. hominis, but the “swarmers” are somewhat larger, namely, 5 µ instead of 3 µ in diameter. Further, there is no accessory nuclear body in C. migrans, but its flagellum stains more deeply than that of C. hominis and has a peculiar banded appearance.