DISEASES TRANSMITTED BY BLOODSUCKING FLIES 213 



zygotes and sporozoites. Parasites were found in the blood of the 

 pigeons 28 days after the flies were first put on them. 



In the pigeon the asexual cycle is passed. The sporozoites are inocu- 

 lated by the bite of the fly. They enter the red blood corpuscles in tlie 

 lung capillaries where they develop into trophozoites and schizonts and 

 divide into merozoites, which may continue the asexual cycle by entering 

 other corpuscles and becoming trophozoites. On the other hand they 

 may remain in peripheral circulation and develop into the sexual forms, 

 the macro- and microgametocytes. These forms may persist in the 

 pigeon's blood over winter. They are ultimatel}^ taken up from the 



MOCULATION 

 0* PiCEON BY 

 Sire OF FLV 



CYCLE OF 



Schizogony in 

 Columba Livia [PlOtONJ. 



CYCLE or 



Sporogony in 

 Lynchia Maura. (Fly). 



LIFE CYCLE OF HAEMOPROTEUS COLUMBAE 



The Cause Of Pigeon Malaria. 

 Fig. 41. (Pierce.) 



pigeon's blood by the fly and pass from its proboscis into the gut. They 

 develop into gametes which conjugate to form zygotes in the lower por^ 

 tion of the mid-gut. These become ookinetes and develop into oocysts 

 in the gut wall. The oocysts divide into a multitude of sporozoites which 

 find their way through the body cavity into the salivary glands and are 

 ready for inoculation. 



The life cycle is graphically shown in the chart (fig. 41) which 

 should be compared with that of Plasmodium (fig. 47) in the lecture 

 on mosquito-borne diseases. 



Haemoproteus mansoni Sambon, the cause of HAEMOPROTEASIS 

 OF THE RED GROUSE, is transmitted by the grouse fly, Ornithomyia 

 lagopodis Sharp in which Sambon found ookinetes in the stomach. 



