380 HiEMOPROTEUS COLUMB^ [CH. 



incomplete but such as it is does not support Schaudinn's 

 observations on the hfe-cycle of a closely related parasite, Hcbwio- 

 proteus noctucB, occurring in the little stone owl, Athene nodua. 



Life-cycle. Owing to the presence of infected flies in the 

 nests of the pigeons, the young birds frequently become 

 infected, the parasites appearing in the blood after an in- 

 cubation period of from 20 to 30 days. 



The first stages of development take place in the white 

 blood corpuscles and if smears are made of the lungs of a 

 pigeon 13 or 14 days after it has been bitten by an infected 

 insect, the young forms of the Hcemoproteus can generally be 

 found within the leucocytes. At this stage the parasite appears 

 as a small mass of protoplasm about 3 to 4 microns in 

 diameter, containing one or two nuclei. This form lives 

 within the cytoplasm of a leucocyte and by repeated division 

 gives rise to a number of parasites, each of which contains a 

 single nucleus and is provided with a more or less distinct 

 membrane. This stage may be found in the pigeon from 

 15 to 17 days after the bite of the insect. Each of these bodies 

 then commences to grow very rapidly and produces a large 

 mass of cytoplasm 8 to 12 microns in diameter, containing 

 several small particles of chromatin, and surrounded by a 

 more or less definite cyst-wall. The leucocytes containing the 

 parasites undergo hypertrophy and become very large, up to 

 60 microns in diameter. This phase of development is present 

 about the eighteenth or nineteenth day. According to Aragao, 

 at this stage it is possible to distinguish two kinds of cysts 

 by their staining reactions, one of which will give rise to the 

 female and the other to the male-producing merozoites. 



From the twentieth to the twenty-fourth day of development 

 the cysts increase enormously in size, up to as much as 

 50 microns in diameter. The membrane is now very distinct 

 and the numerous nuclei are uniformly scattered throughout 

 the cytoplasm. The cysts cease to grow and their protoplasm 

 breaks up into a number of polygonal masses with the nuclei 

 arranged along their edges (Fig. %y, 18), thus closely resembling 

 the young malaria sporoblasts. This change takes place on the 

 twenty-fifth day and is immediately succeeded by the division 



