746 ORDEK: MICEOSPORIDIIDA 



by 0-8 micron in breadth. There is a short hyaline prolongation 1-2 microns 

 long at one end of the spore. The pansporoblast gives rise to four 

 spores. 



M. niphargi Poisson, 1924. — This is a parasite of the amphipod^ 

 Niphargus stygius. The spores measure 8 to 9 by 2 microns. The 

 pansporoblast gives rise to eight or sixteen spores. 



M. piscicola Cepede, 1924.— This is the first species of the genus to 

 be described from a vertebrate. It occurs in the pyloric coeca of the 

 whiting, Gadus merlangus. 



A closely allied, if not identical, genus is Myxocystis Mrazek, 1897. 

 These Microsporidiida give rise to white spheres, often ciliated externally^ 

 which float about in the body-cavity spaces of aquatic worms {LimModrihis), 

 Mrazek (1897), who first described these forms, later (1910) demonstrated 

 that the white spheres were agglomerations of wandering cells, the cyto- 

 plasm of which was infected with uninucleate Microsporidiida, which 

 multiplied by binary fission. Each uninucleate pansporoblast gave rise 

 to a single spore. The spores are ovoid, the narrow end being drawn 

 out into a kind of neck. The spores of M. mrazehi Hesse, 1905, parasitic 

 in Limnodrilus hoff^neisteri, measure 9 to 10 microns by 1 to 2 microns. 



Genus: Octosporea Flu, 1911. 



This genus was created by Flu (1911) for a parasite of the intestinal 

 epithelium of the house fly. He thought it was a schizogregarine, but 

 Chatton and Krempf (1911) proved that it belonged to the Microsporidiida. 

 The spores are bacillary and slightly curved. No details of their structure 

 could be made out in the fresh condition, and there was no indication of 

 a manubrium. The pansporoblast gives rise to eight or exceptionally 

 sixteen spores. 



Octosporea muscae domesticae Flu, 1911. — This parasite was first seen 

 by Flu (1911) in various tissues of the house fly. Chatton and Krempf 

 (1911) saw it in Drosophila confusa and D. plurilineata, and first realized 

 that it was a microsporidian. The young forms, 3 microns in diameter, 

 occur in the epithelial cells of the intestine. Reproduction takes place 

 by schizogony, forms with as many as thirty-two nuclei occurring. The 

 spores are 5 to 6 microns in length by 1 micron in breadth. The only other 

 species is 0. ^nonospora Chatton and Krempf, 1911, parasitic in the same 

 species of Drosophila and Homalomyia scalaris. The spores are 4 to 5 

 microns in length. 



(ze»)»s; Toxonema Leger and Hesse, 1922. 

 Toxonema vibrio Leger and Hesse, 1922. — This parasite is the only 

 member of the genus (Fig. 318). The total length of the spore is 3-5 



