738 OKDER: MICROSPORIDIIDA 



there is some doubt as to the exact method of spore formation in the Poly- 

 sporogenea, which in many cases give rise to tumour-like structures in 

 fish, in which the parasites and the host tissues are so closely intermingled 

 (diffuse infiltration) that the details of development are difficult to follow. 

 The Oligosporogenea are more readily studied, as the small uninucleate 

 parasites are scattered through the cytoplasm of cells. 



The following classification of the order Microsporidiida is based on 

 that suggested by Leger and Hesse: 



1. Suh-Onler: Monocnidea Leger and Hesse, 1922. 

 The spore, which varies in shape, has only a single polar capsule. 



(1) Family: GLUGEID^ Gurley, 1893. 

 The spores, ovoid or pyriform in shape, are developed from pansporo- 

 blasts formed in vacuolic spaces in the cytoplasm of the parasite, which 

 continues to grow and produce more nuclei as spore formation is pro- 

 ceeding. Each pansporoblast gives rise to two sporoblasts, and finally to 

 two spores. 



Genus: Glugea Thelohan, 1891. 



(2) Famihj : NOSEMATlDyE Labbe, 1899. 

 The spores, which are ovoid or pyriform in shape, are developed from 

 uninucleate rounded bodies which are the products of multiple or binary 

 fission of the vegetative forms. Each uninucleate body, which is a 

 pansporoblast, gives rise to a varying number of spores, which may or 

 may not be enclosed in a capsule. 



Genus: Nosema Niigeli, 1857. 

 Each pansporoblast gives rise to a single spore. 



Genus : Perezia Leger and Duboscq, 1909. 

 Each pansporoblast gives rise to two spores. 



Gemis: Gurleya Doflein, 1898. 

 The spores are elongated, being broad at one end and somewhat 

 tapering at the other. Each pansporoblast gives rise to four spores. 



Genus: Thelohania Henneguy, 1892. 

 Each pansporoblast typically gives rise to eight spores, but sometimes 

 only four or as many as sixteen are formed. 



