438 BIOLOGY OF THE PROTOZOA 



in the digestive tract of some blood-drawing invertebrate. The red cells 

 of fish, amphibia, reptiles, birds and mammals may be infested and in some 

 cases the white cells; blood-sucking leeches, ticks, lice and fleas supply the 

 needed environment for the sexual generation. In form and in movement 

 as well as in pseudoconjugation they recall the gregarines. 



9, Genus Hcemogregarina, Danilewsky (1885). Life history complex and 

 for the larger number of species incomjilete. The best known species 

 is H. stepanowi of the turtle the life history of which, worked out by 

 Reichenow, is verj^ complex. The agametes are formed as a result 

 of multiple division and are about twenty-four in number in the red 

 blood cells of the turtle , ultimately the agamonts instead of forming 

 twenty-four products form only four which develop into gameto- 

 cytes. These conjugate in the gut of the leech as in Adeleo, the 

 microgametocyte forming four microgametes, the zygote gives rise 

 to eight sporozoites, hosts, turtles and leeches {Placobdella catenigera 

 for H. stepanowi) . 



10. Genus Karijolysus Labbe (1894). Blood parasites of reptiles (snakes, 



turtles and lizards), K. lacertarum, Danil. of the lizard best known, 

 here individuals are dimorphic, one type forming larger agametes 

 the other, smaller, the larger agametes serve for asexual reproduc- 

 tion, the smaller, form gametocytes (Reichenow) which form 

 gametes in Liponyssus saurarum; two individuals of similar size come 

 together in pseudoconjugation and form a delicate cyst wall, the 

 macrogamete grows much larger than the microgametocyte which 

 forms two microgametes, the zygote forms twenty to thirty sporo- 

 zoites, infection of new host is brought al)out by feeding on infected 

 mites. 



11. Genus Hepatozoon, Miller (1908). Hsemogregarine of the rat with 



sexual cycle in the mite Lelaps echidninus; rats infected by eating 

 infected mites, sporozoites liberated in rat's intestine penetrate the 

 gut wall and enter the blood stream where they are carried to the 

 liver, agamonts develop in liver cells where agamogony occurs with 

 the formation of from twelve to twenty agametes, some penetrate 

 leukocytes in the blood and develop into gametocytes. These 

 taken into the mite unite in pairs in the gut, the macrogamete 

 becomes very large and partly encircles the microgametocyte 

 which becomes a single inicrogamete; fusion is complete and the 

 zygote penetrates the intestinal wall of the mite and encysts in the 

 body tissues; it ultimately forms from fifty to a hundred sporoblasts 

 with capsules, and each sporoblast forms about sixteen sporozoites. 

 A similar history is described by Christophers (1906) and 1)}^ Wenyon 

 (1911) for H. canis of the dog with transmission and sexual cycle in 

 Rhipicephalus sanguineus, and several other species are known from 

 rodents other than the rat. 



12. Genus Lankesterella, Labbe. Small worm-like forms in the red blood 



cells of the frog and urodeles the full life history of which is unknown 

 although many hypotheses have been given. 



Sub-family 4. Dobellinse, Ikeda (1914). The one genus and species 

 included in this group is similar to other Adeleidse in forming pairs in pseudo- 

 conjugation t>ut differs from others in having a small microgametocyte 

 which forms many microgametes. According to Ikeda the agametes are 

 sexually differentiated and have different relations with the host cells, 

 those destined to form macrogametes penetrate the nucleus of the host cell 

 and later become cytoplasmic, those destined to form microgametocytes 

 develop on the periphery of the host cell. The zygote forms about a 

 hundred sporozoites without caj^sules. 



