1048 PARASITES OF PROTOZOA 



in free-living amoebae in cultures may develop a high incidence in a 

 short time. Dangeard (1886b) found 5". endogena in great abundance 

 in cultures of its two rhizopod hosts; and Ivanic (1925) stated that 

 cultures often perish from severe infection. A host may be parasitized 

 by two or more species (Mattes, 1924; Yuan-Po, 1928) , but usually only 

 one species has been distinguished. 



Brumpt and Lavier (1935b) described two different sphaeritas in 

 two amoebae on the same smears: 5". parvula from Hyaloliinax cerco- 

 pitheci, and one with larger spores in an Entamoeba of the m'muta type. 

 This indicates host-specificity; but various amoebae of man, it appears, 

 contain a common species (p. 1042), and Lwoff (1925) stated that the 

 chytrids do not seem to manifest a narrow host-specificity. 



The earliest stage in the cytoplasm of the host is a small, amoeboid, 

 uninucleate thallus. Dangeard (1895) described the parasite in Euglena 

 as at first smaller than the flagellate's nucleus, with a dense, homoge- 

 neous cytoplasm and a vesicular nucleus with a large nucleolus. Mitchell 

 (1928) found the earliest stages to be from 2.5 to 3.5 p in diameter, with 

 a vesicular nucleus from 1.3 to 1.5 \x in diameter. Early stages of the 

 parasites in amoebae have been found as small as 1.5 \i (Chatton and 

 Brodsky, 1909) and 2 |j (Mattes, 1924); the latter observer failed to 

 find a distinct nucleus. Sphaerita endamoehae , according to Becker 

 (1926), is from 1.9 to 2.5 |a in its early intracytoplasmic stage, with a 

 fine cell membrane and a relatively large, solid nucleus. 



Most accounts describe increase in the size of the cytosome and the 

 nucleus before the nucleus begins to divide. In Eugle?ia viridis (Dan- 

 geard, 1895; Mitchell, 1928) the uninucleate thallus may become 

 larger than the host nucleus, and its nucleus becomes correspondingly 

 large. Its shape is spheroidal, ellipsoidal, or elongated. The shape in 

 this phase, together with its size and the presence of vacuoles, is re- 

 garded as of taxonomic significance by Jahn (1933), who distinguished 

 E. phacl on such grounds. Other sphaeritas appear to attain no such size 

 before nuclear multiplication sets in. Sphaerita in Vahlkampfia Umax 

 attains only about triple its diameter before nuclear divisions begin 

 (Chatton and Brodsky, 1909). In 5". endamoehae, according to Becker 

 (1926), nuclear multiplication keeps pace with growth, and there are 

 binucleate stages no larger than uninucleate ones. Similar development 

 has been noted by the writer in Sphaerita (Fig. 217A) in several 



