EXPERIMENTS ON BIRD MALARIA 



383 



quently entirely pushed out. The asexual forms of all three species 

 resemble one another so closely that they are not easily distin- 

 guishable. 



4. Pre patent period. There are also differences in the length of 



Fig. 25. — Gametocytes of the three species of avian malaria, i. Micro- 

 gametocyte of Plasmodium prcccox. Note that the nucleus of the host cell is 

 not displaced. Pigment granules appear at the ends of the parasite, and a 

 rather ribbon-shaped nucleus in the center. 2. Macrogametocyte of Plasmo- 

 dium prcccox. The nucleus is shown as an irregular, somewhat granular mass 

 at the upper end of the parasite. The cytoplasm of the macrogametocytes 

 of all species takes a much heavier blue stain than that of the male forms. 

 3. IMicrogametocyte of Plasmodium inconstans. Note the small, almost dust- 

 like pigment granules. 4. Macrogametocyte of Plasmodium inconstans. 5. 

 Macrogametocyte of Plasmodium cafhcmerium. The pigment granules of this 

 species are much coarser and more rod-like than those of the two species 

 figured above. 6. Microgametocyte of Plasmodium cathemerium. Like the 

 sexual forms of the other two species, the gametocytes of this one differ 

 from one another chiefly with respect to the intensity with which the cyto- 

 plasm takes up the Romanowsky stains, the microgametocytes taking a 

 very faint stain. 



the prepatent period, and as above stated, in the infections pro- 

 duced. Huff (1927) found the prepatent periods to be as follows: 

 Plasmodium cathemerium — 5.78 ±: 0.14 days, Plasmodium prcccox 

 — II. 44 ±0.45 days, Plasmodium iuconstaus — 8.5 ± 0.37 days. 



