Chapter 23 

 Class 3 Sporozoa Leuckart 



THE Sporozoa are without exception parasitic and bear spores 

 in their development. Their hosts are distributed in every 

 animal phylum, from Protozoa to Chordata. As a rule, they are 

 incapable of locomotion, but some when immature may move 

 about by means of pseudopodia. They possess neither cilia nor 

 flagella, except as gametes. In the forms that are confined to one 

 host, the spore usually is enveloped by a resistant membrane 

 which would enable it to withstand unfavorable conditions while 

 outside of the host body, but in those having two host animals, 

 as in Plasmodium, the sporozoite is naked. The method of nutri- 

 tion is saprozoic or parasitic, the food being dissolved cytoplasm, 

 tissue fluid, body fluid, or dissolved food material of the host. 



Both asexual and sexual reproductions are well known in many 

 species. Asexual reproduction by repeated binary or multiple 

 fission or budding of intracellular trophozoites or schizonts, pro- 

 duces far greater number of individuals than that of protozoans 

 belonging to other classes and often is referred to as schizogony. 

 The sexual reproduction is by isogamous or anisogamous fusion 

 or autogamy and marks in many cases the beginning of sporogony 

 or spore-formation, the initial stage being the zygote or sporont. 



Schaudinn divided the Sporozoa into two groups, Telosporidia 

 and Neosporidia, and this scheme has been followed by several 

 authors. Some recent writers consider these two groups as 

 separate classes. This, however, seems to be improper, as the 

 basis of distinction between them is entirely different from that 

 which is used for distinguishing the other four classes: Sarcodina, 

 Mastigophora, Ciliata, and Suctoria. For this reason, the 

 Sporozoa are placed in a single class and divided into three sub- 

 classes as follows: 



Spore simple; without polar filament 



Spore with or without membrane; with 1-many sporozoites 



Subclass 1 Telosporidia (p. 378) 



Spore with membrane; with one sporozoite 



Subclass 2 Acnidosporidia (p. 446) 



Spore with polar filament Subclass 3 Cnidosporidia (p. 453) 



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