ENTOMOLOGY

DISEASES TRANSMITTED BY BLOODSUCKING FLIES :!13zygotes and sporozoites. Parasites were found in the blood of thepigeons !e8 days after the flies were first put on them.In the pigeon the asexual cycle is passed. The sporozoites are inoculatedby the bite of the fly. They enter the red blood corpuscles in thelung capillaries where they develop into trophozoites and schizonts anddivide into merozoites, which may continue the asexual cycle by enteringother corpuscles and becoming trophozoites. On the other hand theymay remain in peripheral circulation and develop into the sexual forms,the macro- and microgametocytes. These forms may persist in thepigeon's blood over winter. They are ultimately taken up from theCYCLE OFSCHIZOGONY INCO~UMB" llv,,, ~IG£Jl~.ICYCLE orSPOROGONY INl YNGHIA M"URA, (FLY).LIFE CYCLE OF HAEMOPROTEUS COLUMBAEFIG. 41.(l>ierce.)pigeon's blood by the fly and pass from its proboscis into the gut. Theydevelop into gametes which conjugate to form zygotes in the lower portionof the mid-gut. These become ookinetes and develop into oocystsin the gut wall. The oocysts divide into a multitude of sporozoites whichfind their way through the body cavity into the salivary glands and areready for inoculation.The life cycle is graphically shown in the chart (fig. 41) whichshould be compared with that of Plasmodium (fig. 47) in the lectureon mosquito-borne diseases.H aemoprotcus mansoni Sambon, the cause of HAEMOPROTEASISOF THE RED GROUSE, is transmitted by the grouse fly, Ornithomyialagopodia Sharp in which Sam bon found ookinetes in the stomach.