SPECIAL MORPHOLOGY AND TAXONOMY OF SPOROZOA 441 



Sub-family 8. Angeiocystinae, L^ger (1911). A single genus represents 

 this group at the present time, the individuals are elongate and similar to 

 Orcheobms (see above) , the zygotes form four sporoblasts each with numer- 

 ous (up to thirty) sporozoites. 



10. Genus Angeiocystis, Brasil (1904). Parasite of marine annelid Cirra- 



tulus. 



Sub-family 9. Leucocytozoinae, Doflein (1915). The single genus 

 Leucocijtozoon, Danilewsky is a comparatively frequent parasite of birds 

 where it is found in the peripheral blood as elongate macro- and microgame- 

 tocytes in leukocytes. It has been variously placed in classification but its 

 many coccidia-like phases justify Doflein 's decision to include it here. 



11. Genus Leucocytozoon, Danilewsky. Blood of different types of birds. 



Sub-family 10. Aggregatinae, Doflein (1916). These are complex forms 

 of Eimeriidse in which the life history involves a change of hosts. The 

 asexual cycle including a^amogony occurs in the gut wall of crabs, here 

 large numbers of agametes are formed, these, with the crabs are eaten by 

 cephalopod molluscs in the intestinal walls of which they develop into 

 gametocytes. Many biflagellated microgametes are formed, the zygote 

 forms many sporoblasts each forming a small number of sporozoites (three, 

 eight, twelve). 



Dobell (1925) finds that reduction in number of chromosomes occurs in 

 Aggregala immediately after fertilization and not during the formation of 

 the gametes. This agrees with Jameson's account of reduction in the 

 gregarine Diplocystis scheideri, Kunstler. 



12. Genus Aggregata, Frenzel (1885). Several species in different decapods 



and in cephalopod molluscs. 



Order 2. Haemosporidia, Danilewsky, em. Doflein. 



The Hsemosporidia are Coccidia-like forms specifically adapted 

 for parasitic life in the blood, particularly of the erythrocytes, 

 although some forms become intracellular parasites of the inner 

 organs. Vertebrates of all classes— mammals, birds, reptiles, 

 amphibia and fish— are subject to infection by one type or other 

 and man is particularly susceptible, the malarial organisms causing 

 serious human diseases which in the tropics are frequently fatal. 



Haemosporidia are minute forms, particularly in the agamous 

 stages during which they frequently show highly motile amoeboid 

 forms, but in other cases they are more rigid and appear like the 

 hsemogregarines. Contractile vacuoles are absent but cytoplasmic 

 non-contractile vacuoles, probably connected with nutrition, are 

 characteristic. Pigmented granules (Melanin) are also character- 

 istic and are formed as a product of haemoglobin break-down and 

 liberated only at periods of reproduction. Other products of 

 metabolism, in the form of toxins, may be liberated at the same 

 time. 



Alternation of asexual and sexual generations is the rule, the 

 former taking place in the blood of vertebrates, the latter in the 



