SPECIAL MORPHOLOGY AND TAXONOMY OF SPOROZOA 443 



its way by gregarifomi movement to the wall of the gut. These 

 motile zygotes, termed ookinets by Schaudinn, either enter the 

 epithelial cells of the gut or penetrate them and come to rest against 

 the inner membranes of the gut wall. Here a delicate sporocyst 

 membrane is formed and the amphinucleus divides repeatedly with- 

 out cytoplasmic division until a vast number of nuclei results. The 

 cytoplasm then divides to form as many naked sporozoites as there 

 are nuclei. The delicate sporocyst membrane is ruptured and the 

 sporozoites are liberated into the body cavity from which they are 

 passed into the blood of the vertebrate and the cycle repeated. 



The life cycle of the hemosporidian thus has many points of 

 resemblance to that of the coccidian; the same intracellular mode 

 of life, the same asexual generation and agamete formation, the same 

 formation of gametocytes and dimorphic gametes. The micro- 

 gametes, however, have no flagella as a rule but move like spiro- 

 chetes and the zygote, as noted above, forms naked sporozoites. 

 In many cases, however, there is a reminiscence of sporoblast forma- 

 tion, when, after the amphinucleus has divided for a certain limited 

 number of times, the cytoplasm separates into the same number of 

 sporozoite forming centers. The resemblance to the coccidian 

 would be complete if such centers were provided with definite 

 capsules. 



Classification of the Hsemosporidia has not yet been perfected. 

 Many blood parasites are minute and their life histories are incom- 

 pletely known so that even their protozoan affinities are question- 

 able. Such forms will be briefly treated in an appendix to the 

 present chapter. The classification adopted here is not original 

 nor final but is frankly based on expediency, although two of the 

 families— Plasmodidse and Babesidae— will probably stand. 



Family 1. Hsemoproteidae, Doflein (1916). These are blood parasites 

 of birds showing some of the characteristics of the hemogregarines. There 

 is no apparent asexual increase in the blood cells in which the parasites store 

 up pigment and develop into gametocytes which are earlier known as 

 Halteridium. The gametes are formed in the gut of a biting fly such as 

 Lynchia which is louse-like and creeps about in the plumage of birds. 

 Zygotes are formed in the gut of the insect (or may be formed on the slide 

 as first observed by MacCallum, 1898) and as zygotes make their way 

 through the stomach wall into the body cavity of the fly. Here they do 

 not develop further but are transmitted by the bite of the fly to the bird 

 host where metagamic divisions and sporozoite formation do not take place 

 in blood cells but in endothelial cells of the host (Aragao) or in leukocytes. 

 The sporozoites enter erythrocytes and grow into large halter-shape para- 

 sites without displacing the nucleus of the cell. These are the gametocytes 

 which are early differentiated as macro- and microgaraetocytes. 



1. Genus Hcenioproteus, Kruse. Several species in birds of different 

 groups, H. noclum in the little owl Glaucidium noctua; H. columbce 

 Celli and Sanfelice in pigeons, H. danilewskyi, Grassi and Feletti 

 (1890), in larks, ravens, etc. 



