SPECIAL MORPHOLOGY AND TAXONOMY OF SPOROZOA 461 



outside of it and peripherally in the pansporoblast. It divides 

 repeatedly until 8, 32, or many sporozoites result (Fig. 192). 



The Actinomyxida are parasites of annelids and sipunculids and 

 the spores are invariably triradiate. The anchor or star-form 

 processes of the capsule are regarded by Doflein as supports in 

 floating, evidence for which is given by Kofoid's observation of 

 these spores in plankton. 



Ikeda (1912) divides the five known genera into two groups which 

 he designates Simplicia, with one genus Tetractinoviyxon, Ikeda, 

 and Multiplicia with the other four genera. 



1. Genus Tetradinomyxon, Ikeda (1912). Parasite of the sipunculid 



Petalostoma minutimi, Kef. Pyramidal spores with two mem- 

 branes ecto- and endospores. Three ectospore nuclei at the angles 

 of the base of the pyramid, three polar capsules at the apex. 



2. Genus Hexactinomyxon Stolg (1899). Spores with six anchor-like 



processes; parasite of the intestinal epithelium of Psammorydes 

 barbatus. 



3. Genus Triadinomyxon, Stolg (1899). Spore with three anchor-like 



processes parasite of intestine of Tubifex tubifex. 



4. Genus Synadinomyxon, Stol? (1899). Spores with two long and one 



short, sharp-pointed processes; parasites of the intestine of Tubifex 

 rivulorum. 



5. Genus Sphceradinomyxon, CauU. and Mesnil (1905). Spores _ spherical 



and without pointed processes, parasites in the body cavity of the 

 marine ohgochete Clitellis arenarius 0. F M 



Sub-class II. SARCOSPORIDIA. 



The Sarcosporidia are parasites of vertebrates, particularly mam- 

 mals in which the ultimate seat of parasitism is the muscular tissue. 

 There is but one genus— *Sa/'coc7/.s'^i*— with several species in pigs 

 {S. miescheriana, Kiihn, 1865, forming "miescher's tubules"), in 

 sheep {S. tenella, Railliet, 1886), in cattle {S. blanchardi, Doflein, 

 1901 ), in mice (S. mnris, Blanchard, 1885), in opossums (<S. darlingi, 

 Brumpt, 1913) in monkeys (S. Iwrtei, Castellani and Chalmers, 

 1909), and in man (»S'. Undeinanni, Rivolta, 1878). A species from 

 birds was described by Stiles (1893) under the name of S. rileyi. 



Sarcosporidia have been studied by a host of observers and an 

 almost equal number of interpretations has been the result. The 

 best known species is S. imiris from the mouse in which, beginning 

 with Th. Smith's (1901) inoculation experiments by feeding infected 

 tissues to mice, the young stages and their development are now 

 know^n. Observations made by this method of study, particularly 

 by Erdmann (1910 a, h, c, and 1914), and by Crawley (1914 and 

 1916) and Marullaz (1920) permit of a tentative life history of 

 S. muris as follows. 



Infection occurs by eating infected tissues, or as Negre (1907) 

 showed, by eating contaminated feces. The germs, regarded by 



