H^MOSPOBIDIA. 209 



III. Order H.EMOSPORIDIA 



Danilewsky. 



The H^MOSPOBiDiA are Coccidia-like forms specially modi- 

 fied for parasitic life in the blood. There is alternation of 

 hosts, asexual reproduction or schizogony taking place in the 

 blood of Vertebrates and sexual reproduction or sporogony 

 in the ahmentary canal of some blood-sucking Invertebrates. 

 They are minute, usually intracellular parasites of red blood- 

 corpuscles, showing motile amoeboid forms in their schizo- 

 gonous cjT^cle in the Vertebrate host. Gametocytes and 

 dimorphic gametes are formed, as in the Coccidia ; but the 

 microgametes have no flagella as a rule and move like spiro- 

 chetes, fertihzing a spherical macrogamete in the body of 

 the Invertebrate host. The zygote is motile, and is known as 

 an ookinete ; after becoming encysted it gives rise to a large 

 number of naked sporozoites, which are introduced into the 

 blood of a Vertebrate host. As they do not pass any stage 

 of their hfe-history outside the body of a host, the sporozoites 

 are not enclosed within a resistant membrane. 



Vertebrates of all classes — mammals, birds, reptiles, 

 amphibians, and fish — are parasitized by different species. 

 A number of them are known to occur in man and cause malaria, 

 which works such havoc in India and other tropical countries. 

 The Arthropods were their primary hosts, and they became 

 secondarily introduced into the Vertebrates and adapted to 

 a parasitic mode of hfe in the blood of the latter. 



The H^MOSPORiDiA are divided into four famihes. 



Identification Table of Families. 



1 (4). Parasites form hsemazoin pigment (with 



the exception of Leucocytozoon) 2. 



2 (3). Schizogony in the endothehal cells of the 



blood-vessels of internal organs of 



Vertebrates. Gametocytes in the peri- [Dofleiu, p. 210. 



pheral blood-corpuscles Hsemoproteidae 



3 (2). Schizogony in the peripheral blood of [p. 244. 



Vertebrates PlasmodiidaB Mesnil, 



4(1). Parasites do not form hsemazoin pigment. 5. 

 5 (6). Schizogony in the endothelial cells of the 



blood-vessels of Vertebrates ; finally the 



parasites invade the red corpuscles, 



within which they occur as round, ovoid, 



rod-like or irregular forms. Show no [p. 294. 



tendency towards a paired arrangement . Theileriidse Du Toit, 

 SPOR. P 



