328 HANDBOOK OF PROTOZOOLOGY 



when injected is highly toxic to other animals. The order is 

 represented by one genus. 



Genus Sarcocystis Lankester. Numerous species have been 

 described from various mammals on the basis of difference in 

 host species and slight difference in the dimensions of the spore. 

 They are, however, morphologically indistinguishable from one 

 another. 



Sarcocystis lindemanni (Rivolta). In man. 



Sarcocystis tenella Railliet (Figs. 140, a; 141). In sheep. 



Sarcocystis miescheriana Kiihn (Fig. 140, b). In pigs. 



Sarcocystis muris Blanchard. In rats and mice. 



Sarcocystis bertrami Doflein. In horses. 



Sarcocystis cimiculi Brumpt. In rabbits. 



Sarcocystis rileyi Stiles. In ducks. 



ORDER 2 HAPLOSPORIDIA LUHE 



This order includes those sporozoans which produce simple 

 spores. In some species the spores may resemble superficially 

 those of the Microsporidia, but do not possess the polar capsule 

 or the filament. The boundaries and affinities of this order to 

 other groups are indistinctly known. 



The Haplosporidia are cytozoic, histozoic, or coelozoic para- 

 sites of invertebrates and lower vertebrates. The spore is spheri- 

 cal or ellipsoidal in form and covered by a resistant membrane 

 which may possess ridges or may be prolonged into a more or less 

 long tail-like projection. In a few species the spore membrane 

 possesses a lid which, when opened, will enable the sporoplasm 

 to emerge as an amoebula. The sporoplasm is uninucleate and 

 fills the intrasporal cavity. 



The development of a haplosporidian, Ichthyosporidium 

 giganteum, as worked out by Swarzcewsky, is as follows (Fig. 

 142) : The spores germinate in the alimentary canal of the 

 host fish and the sporoplasms make their way to the connective 

 tissue of various organs (a). These amoebulae grow and their 

 nuclei multiply in number, thus forming plasmodia. The Plas- 

 modia divide into smaller bodies, while the nuclei continue to 

 divide (b-e). Presently the nuclei become paired (/, g) and the 

 nuclear membranes disappear (h). The plasmodia now break up 



