Chapter 24 

 Class 3 Sporozoa Leuckart 



THE Sporozoa are without exception parasitic and bear spores. 

 Their hosts are distributed in every animal phylum, from 

 Protozoa to Chordata. As a rule, they are incapable of locomo- 

 tion, 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 conjfined to one host, the spore 

 is usually 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 nutrition is saprozoic or parasitic, 

 the food being dissolved cytoplasm, tissue fluid, body fluid, or dis- 

 solved 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 produces far 

 greater number of individuals than that of protozoans belonging to 

 other classes and often is referred to as schizogony. The sexual re- 

 production is by isogamous or anisogamous fusion or autogamy and 

 marks in many cases the beginning of sporogony or spore-formation. 



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 dis- 

 tinction 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 subclasses as follows : 



Spore simple; without polar filament 



Spore with or without membrane; with 1-many sporozoites 



Subclass 1 Telosporidia 



Spore with membrane; with one sporozoite 



Subclass 2 Acnidosporidia (p. 507) 



Spore with polar filament Subclass 3 Cnidosporidia (p. 515) 



Subclass 1 Telosporidia Schaudinn 



The spore which contains neither a polar capsule nor a polar fila- 

 ment possesses one to several sporozoites and is formed at the end of 

 the trophic life of the individual. In the forms which invade two host 



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