SPECIAL MORPHOLOGY AND TAXONOMY OF SPOROZOA 449 



between tissue cells where they may fill up cavities without doing 

 much or any harm to the host. (3) Intracellular parasites whereby 

 the usually minute organisms live at the expense of the cell host. 

 The life histories of different types will be gWen in connection with 

 the different groups as no general account will suffice for all. 



Fig. 187. — Types of Cnidosporidian spores. A, Nosc7na apis. After Fantham 

 and Porter; B, same, after Kudo; C, D, E, different Haplosporidia spores, after 

 Swellengrebel, Perrin, and Swarczewsky; F, PUstophora macrospora, after Leger 

 and Hesse; G, PUstophora longifilis, after Schuberg; H, Myxobolus toyamai, after 

 Kudo; /, StempelUa magna, after Kudo; K, Mrazekia argoisi, after Leger and Hesse; 

 L, Nosema bombyces, after Stempel; M, Thelohania giardi, after Mercier. (From 

 Kudo.) 



Order 1. Myxosporidia, BIjtschli. 



The Myxosporidia are the best Ivno^ni of the Neosporidia both 

 as to number of species and life histories. Of the 249 species listed 

 by Kudo (1919) all but 11 are parasitic in fi.shes, 5 have been found 

 in amphibia, 4 in reptiles, 1 in an insect and 1 in an annelid. They 

 therefore, characteristic fish parasites, where they occur both 



are 



as coelozoic and as histozoic forms, never, according to Davis (1917), 

 29 



