266 HANDBOOK OF PROTOZOOLOGY 



distinguishing the other four classes: Sarcodina, Mastigophora, 

 Ciliata, and Suctoria. For this reason, the Sporozoa are put 

 together in a single class and divided into three subclasses as 

 follows: 



The spore with the polar filament which is typically coiled within a 



polar capsule Subclass 2 Cnidosporidia 



The spore without polar filament 



The spore simple, with one sporozoite; incompletely known 



Subclass 3 Acnidosporidia 



Simple spore with one to several sporozoites or without resistant 

 envelope; asexual and sexual reproduction typically alternate . . . 

 Subclass 1 Telosporidia 



SUBCLASS 1 TELOSPORIDIA SCHAUDINN 



In this subclass of the Sporozoa the spores have neither 

 polar capsule nor polar filament. Each spore contains one to 

 several sporozoites and is formed at the end of the trophic life 

 of the individual. In the forms which parasitize two hosts, 

 there occur naked sporozoites instead of spores. 



The infection of a new host begins with the entrance of 

 mature spores through the mouth, or with the introduction of 

 the sporozoites by blood-sucking invertebrates directly into the 

 blood stream, of the host. The sporozoites enter specific host 

 cells and there grow at the expense of the latter. In the Coc- 

 cidia and the Haemosporidia, the trophozoite continues its 

 intracellular existence, but in the Gregarinida it leaves the host 

 cell and grows in an organ cavity of the host. Except Eugre- 

 garinina, the trophozoite of the Telosporidia undergoes schi- 

 zogony and produces a large number of schizonts, or merozoites, 

 which invade new host cells, thus spreading the infection within 

 the host body. The schizonts sooner or later develop into game- 

 tocytes. 



In the Coccidia and the Haemosporidia, anisogametocytes 

 are often noted. Each macrogametocyte develops into a single 

 macrogamete and each microgametocyte into several micro- 

 gametes. Anisogamy results in the formation of a large number 

 of zygotes. Each zygote develops into a spore which contains 

 one to many sporozoites or into a number of naked sporozoites. 

 In the Gregarinida two fully mature trophozoites (gametocytes) 



