42 THE ANIMAL PARASITES OF MAN 



non-pathogenic, and to occur in the intestine of man in the tropics. 

 It has a general resemblance to E. coll, but forms small cysts (6 a to 

 10 fju in diameter). The nucleus of the cyst is said to break up into a 

 variable number of daughter nuclei, from three to thirteen having 

 been noted. Lesage states that it is culturable in symbiosis with 

 bacteria. It is probably a variety of E. coli, if not a cultural amosba. 



Entamceba hominis (Walker, 1908) has a diameter of 6 fj, to 15 //,. A 

 contractile vacuole is present. Encystment is total, and small cysts are 

 formed. It is culturable. The original strain, now lost, was obtained 

 from an autopsy in Boston Hospital. This organism is probably 

 a cultural amoeba. 



Entamceba phagocytoides (Gauducheau, 1908). This parasite was 

 discovered in a case of dysentery at Hanoi, Indo-China. The amoeba 

 is small, 2 //- to 15/4 in diameter. It is active. It ingests bacteria and 

 red blood corpuscles, while peculiar spirilla-like bodies are found in 

 its cytoplasm. It multiplies by binary and multiple fission. It can 

 be cultivated. More recently (1912) the author appears to consider 

 the amoeba to be a stage of a Trichomonas, but abandons the view 

 later (1914). Further researches on this organism are needed. 



Entamceba minuta (Elmassian, I9O9) 1 was found, in association 

 with E. coli, in a case of chronic dysentery in Paraguay. It resembles 

 E. tetragena but is smaller, rarely exceeding 14 //, in diameter. Schizo- 

 gony occurs, four merozoites being produced. The encystment is 

 total and endogenous, giving rise to cysts containing four nuclei. 

 This amoeba is considered by Darling and others to be the pre-cyst 

 trophozoite stage of E. histolytica (tetragena). 



Entamceba nipponica (Koidzumi, 1909) was found in the motions 

 of Japanese suffering from dysentery or from diarrhoea, in the former 

 case in corhpany with Entamceba histolytica. Its diameter is 15 //, to 

 30 fji. The endoplasm is phagocytic for red blood corpuscles. The 

 nucleus is well defined, resembling that of E. coli and of E. tetragena. 

 Multiplication occurs by binary fission and by schizogony. Encyst- 

 ment is total, but has not been completely followed. Darling and 

 others consider that this is an abnormal form of E. histolytica, 

 while Akashi (1913) doubts if it is an amoeba at all, but rather is 

 to be regarded as shed epithelial cells. 



GENERAL REMARK. It is now considered by some workers that 

 true Entamcebae cannot be cultivated on artificial media. Quite 

 recently Williams and Calkins (i9i3) 2 have somewhat doubted this 

 opinion, and state that certain cultural amoebae, originally obtained 

 from Musgrave in Manila, exhibit the various morphological variations 

 associated with true entamcebae of the human digestive tract. 



1 Centralbl.f. Bakter., Orig., lii, p. 335. 

 - Journ. of Med. Research, xxix, p. 43. 



