242 THE GEOUSE IN HEALTH AND IN DISEASE 



breadth, as seen in sections. Many relatively large granules occur in the cytoplasm 

 of the macro-gametocyte. As the macro-gam etocyte grows from round to ovoid, 

 these granules gradually concentrate to form larger, roundish, haematoxylin-staining 

 granules, which are albuminoid (PI. xxxv., Fig. 29), the chromatoid granules of many 

 authors. There are also other, non-basic staining, granules known as plastinoid 

 granules ("granules plastiques " of Thelohan and Labbe) composed of coccidin 

 (Labbe). These ultimately are large and round (Figs. 30-32) and are refractile in 

 fresh preparations, where they appear yellow or greyish-green. They tend to shrink 

 in preparations fixed with sublimate or sublimate acetic (Fig. 29). The plastinoid 

 granules occur between and among the chromatoid granules (Figs. 30-32). In 

 stained preparations ^ the granules are best seen by staining with iron-hfematoxyliii 

 followed by Van Gieson's picro-fuchsin, when the chromatoid granules appear 

 blackish, while the plastinoid granules take on a uniform, yellowish hue. The 

 plastinoid granules stain with lichtgrlln in marked contrast with the red of safranin 

 taken up by the chromatoid granules. With Delafield's hsematoxylin, the 

 chromatoid granules stain intensely (Figs. 29, 31, 32) and somewhat misleading 

 appearances result, suggesting multiplication of the cell. 



As the parasite grows, the chromatoid and plastinoid granules travel towards 

 the periphery (Figs. 29-32). The macro-gametocyte at this time encysts within the 

 epithelium, and the chitinoid material of the cyst seems to be formed from the 

 chromatoid granules. At any rate, the inner layer of the cyst-wall seems to take 

 its origin therefrom (Figs. 34-36). The formation of the cyst-wall from the 

 chromatoid granules has been noted by Simond (1897) and Wasielewski (1904) 

 in the case of Coccidium oviforme {Eimeria stiedcB of Stiles). 



The formation of the cyst of Eimeria avivni takes place while the organism is 

 still within the epithelium (Figs. 34, 35), and therefore the parasite encysts pre- 

 cociously. Tlie macrogamete at this stage is ovoid, and the number of chromatoid 

 granules within it is reduced. The cyst formed is ultimately rather thick-walled, 

 but a small aperture or micropyle, which may be in a slight depression, is left for 

 the entry of the microgamete (PI. xxxvi., Fig. 47). 



When Scliaudinn investigated the life-cycle of E. schuhergi, he described a 

 process of maturation of the macro-gametocyte, whereby the karyosome of the 

 nucleus was expelled in fragments. I regret that I am not at all sure as to the 

 fate of the karyosome of the macro-gametocyte of E. avium. Several causes 

 combine to defeat the attempts made to elucidate this subject. In the first place, 



' The reactions of the gi-amiles are discussed by Labbr (189C) and by Mincliin (1903). 



