154 SPOROZOA. 



It acquires a cyst-wall and grows still further to become 

 the ripe oocyst. Sporogony takes place in the body-cavity 

 of the mite. Nuclear multipUcation and formation of sporo- 

 blasts and sporocysts take place, each spore containing 

 12 to 24 sporozoites. Re-infection takes place by a rat 

 devouring infected mites. 



Dimensions. — Schizont, young 10 /it, full-grown 30-35 ju, by 

 25-28 ft ; ookinete, young 25 /x by 10 /a, full-grown 50 /* by 25 /a ; 

 oocyst 200-250^. 



Remarks. — According to Miller (1908) and the Japanese 

 workers Kusama, Kasai, and Kobayashi (1919), complete 

 fusion of the two gametocytes takes place, and no formation 

 of micro- or macrogametes is described. Wenyon (1926), 

 however, from what is known of other Hsemogregarines, 

 such as H. stepanowi, thinks it probable that the micro- 

 gametocyte produces microgametes, and that a fertilization 

 of the Adelea type occurs instead of the complete fusion of the 

 two gametocytes. 



Miller succeeded in infecting rats by placing on them 

 infected mites, and also by contaminating food with crushed 

 mites, and as injection of crushed infected mites into the peri-^ 

 toneal cavity did not produce infection, it is obvious that 

 infection takes place by way of the alimentary canal. 



Habitat. — Leucocytes of the brown rat, Rattus norvegicus 

 (Berkenhout) {=^Mus decumanus=Mus norvegicus) : Punjab ; 

 Rattus rufescens (Gray) {=Mus rufescens) ; and the rat-mite, 

 Leelaps echidninus Berlese : India. 



91. Hepatozoon sp. 



•\Hepatozoon sp., Donovan (recorded in Wenyon, 1926, p. 1362). 

 Habitat. — Blood of the flying squirrel, Pteromys petaurista 

 Pallas : India. ' 



Genus KARYOLYSUS Labbe, 1894. 



Heemogregarina (part), Danilewsky, 1886. 



Karyolysus, Labbe, 1894, p. 109 ; 1899, p. 75 ; Minehin, 1903, 



pp. 261, 265. 266 ; 1912, p. 372 ; Reichenow, 1913, pp. 317-63 ; 



1921, pp. 179-291 ; Wenyon, 1926, pp. 1095-101 ; Reichenow, 



1929, pp. 865, 916-19 ; de Mello & de Meyrelles, 1937, pp. 119- 



41. 



Sporogony in the epitheHal cells of the intestine of the 

 Invertebrate host, a mite, produces an oocyst with a number 

 of sporoblasts, which escape from the oocyst as motile 

 vermicules (sporokinetes) and enter the egg of the mite, where 

 they secrete sporocysts within which sporozoites are developed. 

 The mite hatched from the egg has the sporocysts in its 

 intestinal epithehum. The sporocysts enter the intestinal 



