The size varies from 6 µ to 32 µ. Ectoplasm is always present; the endoplasm contains numerous food-vacuoles. The nucleus is vesicular, with a greenish tinted membrane which is poor in chromatin. The size of the nucleus is from 1·5 µ to 4·5 µ. A contractile vacuole is not visible. The pseudopodium is broad. It was discovered in the mouths of persons with dental caries at Rovigno and also at Trieste, being most easily found in dense masses of leucocytes, also among leptothrix and spirochæte clusters. It can be easily distinguished from leucocytes by more intense staining with neutral red. Multiplication proceeds by fission. Transmission may take place through the small spherical cysts. This species (fig. 10) has since been observed in Berlin, and is also occasionally found in carcinoma of various regions of the oral cavity. (Leyden and Löwenthal, 1905).
Fig. 10.—Entamœba buccalis, Prow. a-d, the same specimen observed during five minutes. × 1,000. e, amœba fixed and stained with iron-hæmatoxylin. × 1,500. (After Leyden and Löwenthal.)
Entamœba buccalis, Prow., is said to be allied to a protozoön which A. Tietze has found either encysted or free in the lumen of the orifice of the parotid gland of an infant aged 4 months. The gland had undergone pathological change, and had therefore been extirpated. The organisms, which were roundish and three to four times the size of the normal epithelial cells of the gland, were without a membrane and possessed a nucleus in which the chromatic substance appeared to be contained in a karyosome. Bass and John’s30 (Feb. 1915) and Smith, Middleton and Barrett (1914) state that E. buccalis is the cause of pyorrhœa alveolaris.
Entamœba undulans, Aldo Castellani, 1905.
Under this name a protozoön is described which A. Castellani found in addition to Entamœba histolytica and Trichomonas intestinalis in the fæces of an European planter living in Ceylon, who had suffered from amœbic enteritis and liver abscess. The shape of the body was roundish or oval, 25 µ to 30 µ in the greatest diameter. It was without a flagellum, but with an undulating membrane, and capable of protruding a long pseudopodium from different parts of its body at short intervals. The nucleus could not always be recognized in life; it was, however, always demonstrable by staining. One or two contractile vacuoles were present. The protoplasm was finely granular, showing no differentiation into ecto- and endo-plasm. According to Braun, in spite of the author declaring himself expressly against the flagellate nature of the parasite, such a nature may be assumed to be tolerably certain in view of the description and illustration.
It is now considered that Entamœba undulans is a portion of a flagellate, namely, Trichomonas.
Entamœba kartulisi, Doflein, 1901.
Fig. 11.—Entamœba kartulisi, Dofl., from the pus of an abscess in the lower jaw, showing different stages of movement. (After Kartulis.)
Doflein gave this name to amœbæ, from 30 µ to 38 µ in diameter, which Kartulis (1893) found on examining the pus of an abscess in the right lower jaw of an Arab, aged 43, and in a portion of bone that had been extracted. The movements of the amœbæ (fig. 11) were more active than those of “dysenteric amœbæ.” Their coarsely granular cytoplasm contained blood and pus corpuscles, and a nucleus was generally only recognizable after staining. Vacuoles were not seen with certainty. Flexner reported upon a similar case, and Kartulis published five additional cases. As in these cases dental caries was present the infection is likely to have proceeded from the oral cavity as a result of the carious teeth. Craig31 (1911) considers that this parasite is probably identical with Entamœba histolytica.
In the literature the following species have been reported as occurring in the oral cavity of man:—
Amœba gingivalis, Gros, 1849. [? identical with Entamœba buccalis.] Amœba buccalis, Sternberg, 1862. Amœba dentalis, Grassi, 1879.
Far too little, however, is known concerning these to regard them as definite species, that is, independent organisms; Grassi thinks it even possible there may have been a confusion in their case with salivary corpuscles. If they really are amœbæ they are all of them probably identical with Entamœba buccalis.
Genus Paramœba, Schaudinn, 1896.
Schaudinn established the genus Paramœba for a marine rhizopod which multiplied by division, became encysted at the end of its vegetative life and then segmented into swarm bodies with two flagella. These multiplied by longitudinal fission, and finally passed into the condition of Amœbæ. Whether the human parasite described by C. F. Craig (1906) as
Paramœba hominis.
belonged to this genus was for a time uncertain. It is now placed in a new genus Craigia, Calkins, 1912, since it possesses only one flagellum.32
In the amœbic stage it is 15 µ to 25 µ in diameter; ecto- and endo-plasm during rest are indistinguishable. The body substance is granular, with a spherical, sharply contoured nucleus and an accessory nuclear body. No vacuoles are present, but occasionally the endoplasm contains red blood corpuscles. The pseudopodia are hyaline, finger- or lobe-shaped, and are protruded either singly or in twos. Multiplication is by binary fission and by the formation of spherical cysts (15 µ to 20 µ in diameter) in which occurs successive division of the nuclei, ultimately forming ten to twelve roundish bodies each of which soon develops a flagellum. The flagellate stages have similarly a spherical shape and attain a diameter of 10 µ to 15 µ. They also occasionally contain red blood corpuscles and pass either directly or after longitudinal division into the amœboid phase.
Craig found these Amœbæ and the flagellate stage belonging to them in six patients in the military hospital at Manila (Philippine Islands), five of whom were suffering from simple diarrhœa whilst the sixth exhibited an amœbic enteritis and contained also Paramœba hominis, with Entamœba histolytica, Schaudinn. In one of the other cases, Trichomonas intestinalis was present.
B. Amœbæ from other Organs.
Entamœba pulmonalis, Artault, 1898.
Artault33 discovered a few amœboid forms with nucleus and vacuole in the contents of a lung cavity. In the fresh condition they were distinguishable from leucocytes by their remarkable capacity of light refraction. They were also much slower than the latter in staining with methylene blue or fuchsine. Their movements became more lively in a strong light. Water and other reagents killed them, and then, even when stained, they could not be distinguished from leucocytes. They have also been seen by Brumpt. R. Blanchard found amœbæ which may belong here in the lungs of sheep. A. pulmonalis is perhaps the same as Entamœba buccalis. Smith and Weidman34 (1910, 1914) described an entamœba, E. mortinatalium, from the lungs and other organs of infants in America.
Amœba urogenitalis, Baelz, 1883.
This species was found in masses in the sanguineous urine as well as in the vagina of a patient in Japan, aged 23. Shortly before the death of the patient, which was caused by pulmonary tuberculosis, hæmaturia with severe tenesmus of the bladder had set in. The amœba, which showed great motility, and had a diameter of about 50 µ when quiescent, exhibited a granular cytoplasm and a vesicular nucleus. Baelz is of opinion that these parasites were introduced into the vulva with the water used for washing the parts, and thence had penetrated into the bladder and vagina. Doflein places the organism in the genus Entamœba, and it is perhaps identical with E. histolytica.
Similar cases are also reported (1892–3) by other authors: Jürgens, Kartulis, Posner, and Wijnhoff. Jürgens found small mucous cysts, filled with amœboid bodies, in the bladder of an old woman suffering from chronic cystitis; they were also found in the vagina. The amœba observed by Kartulis in the sanguineous urine of a woman, aged 58, suffering from