1040 PARASITES OF PROTOZOA 



somes, or volutin; and he concluded that they were bacterial parasites, 

 which do not occur in all ciliates. Similar groups of granules were re- 

 ported by Kirby (1932b) in Nyctotherus silvestrtanus. 



Bacteria were found by Hesse (1909) in monocystid gregarines from 

 the seminal vesicles of oligochetes. Each of the species Monocystis lum 

 hricuU, M. agilh, M. striata, Khynchocysth pilosa, and Stomatophora 

 coronata had its own peculiar parasite which was unlike those of the 

 others. Their forms varied, in different species, from ovoid to filamen- 

 tous. Hesse remarked that the bacterial parasites were uncommon, but 

 when present attacked most individuals of a species, and often led to the 

 destruction of the invaded gregarines. 



Sphaerita and Nucleophaga 

 historical account and distribution 



In Free-living Protozoa. — Most of the fungi of the order Chytridiales 

 are parasitic in plants or animals ( Fitzpatrick, 1930; Minden, 1915). In 

 the lower plants they occur mainly on or in algae; and a considerable num- 

 ber have been found in Phytomastigophora. Though most abundant in 

 this group of Protozoa, they attack also other free-living forms, especially 

 Sarcodina and cysts of cihates (Biitschli, 1889; see also p. 1059), and 

 many have been encountered in parasitic Protozoa. The chytrids that are 

 known to be hyperparasitic in Protozoa all belong to the genera Sphaerita 

 and Nucleophaga. These are the chytrids, also, that have most often been 

 found in free-living species, except for euglenid flagellates. 



Carter (1856) described "irregular, botryoidal masses, dividing up 

 into spherical cells" in "Astasia" (=iPeranema) . It is likely that he was 

 observing Sphaerita, and that the enlarged granular nuclei described in 

 Amoeba radiosa (?) were parasitized by Nucleophaga. The specimens 

 of A. verrucosa, "partly filled with spherical ovules in the granuliferous 

 stage of development," were probably heavily parasitized by chytrids. 

 Wallich (1863a) found that a large subspherical, granular mass ap- 

 peared in each of the specimens of A. villosa in a saucer; and later from 

 five to a dozen of these masses developed in individual specimens. He 

 observed extrusion and rupture of these, which he regarded as of the 

 nature of nuclei. He evidently was describing an increasingly heavy 

 infestation of a culture of amoebae by Sphaerita. The granulation of the 

 nucleus described by Carter (1863) in A. princips, accompanied by 



