317 



The parasite is closely allied to the malaria para- 

 site, and is especially suitable for the study of the 

 exogenous mosquito cycle. 



Endogenous Cycle (Fig. 67). — The parasite in 

 its earliest stage is unpigmented. Coincident with 

 growth a grain or two of pigment appears, and 

 the characteristic property of the parasite shows 

 itself, viz., the displacement of the nucleus of the 

 red cell, so that the nucleus may take up a position 

 at right angles and away from the normal one. 

 All stages of develo'pment up to segmenting forms 

 are found in the blood at the same time, so that 

 no cycle of development can here be followed ; 

 nor is there any intermission in the clinical 

 symptoms (temperature, etc.) of infected birds. 



Fig. 67. {Upper line) Proteosoma shelving medium-size Parasite 



and Segmenting Form. {Lower line) Halieridium young 



form, Female and Male Gametes, and Vermicule 



Exogenous Cycle. — Besides the asexual, sexual 

 forms occur in the blood. They are spherical 

 hyaline bodies of two varieties, characterized in 

 stained specimens by the same general differences 



