COLLECTION, CULTIVATION, OBSERVATION 



S93 



c-h). Aside from certain coprozoic Protozoa (p. 24) which appear in 

 old faeces, Blastocystis hominis (Fig. 375, c-f) occur in almost all 

 faeces. This organism which is considered to be a fungus and harm- 

 less to its host, is usually spherical and measures about 5-25ju in 

 diameter. Within a very thin membrane, there is a narrow peripheral 

 cytoplasmic layer in which 1 or 2 nuclei and several refractile gran- 

 ules are present. The cytoplasmic ring encloses a large homogeneous 

 body which is somewhat eosinophile, but not iodinophile. In some 

 the cytoplasm may be more abundant and the inclusion body smal- 

 ler. Dividing forms appear peanut-shaped. Blastocystis (Grasse, 

 1926; Reyer, 1939). 



Fig. 375. a, Sphaerita in a stained trophozoite of Entamoeba coli; b, 

 Nucleophaga in a stained trophozoite of Iodamoeba butschlii; c, d, Blasto- 

 cystis hominis (in an unstained smear) ; e, f , stained Blastocystis hominis; 

 g, an epithelial cell from a faecal smear; h, a polymorphonuclear leuco- 

 cyte with three ingested erythrocytes. All X1150 (Kudo). 



In a number of parasitic Protozoa, there occur foreign organ- 

 isms which may be mistaken for food inclusions or chromatin. 

 They are vegetable organisms which were named by Dangeard 

 as Sphaerita and Nucleophaga (Fig. 375, a, b). The former occurs 

 in the cytoplasm and the latter in the nucleus of the host protozoan. 

 These parasites are spherical and about 0.5-lju in diameter; they 

 are found most frequently in spherical masses composed of vary- 

 ing numbers of individuals. Nucleophaga appears to destroy the 

 host nucleus. Degenerating epithelial cells or leucocytes (Fig. 375, g, 

 h) may simulate parasitic amoebae. Fishes and birds are often in- 

 fected by Coccidia and when they are consumed as food, the oocysts 

 pass the alimentary canal unchanged and appear in the stools. 

 Sphaerita (Chatton and Brodsky, 1909; Mattes, 1924; Becker, 1926; 



