1910.] MORPUOLOGY OF EIMEIUA AVIUM. 679 



granules stain with Lichtgriin in marked contrast with tlie red of 

 safranin taken up l)y the chroniatoid granules. With Delafield's 

 h;emato.xylin, the chromatoid granules stain intensely (figs. 29, 

 31, 32), and somewhat misleading appearances i-esult, suggesting 

 multiplication of the cell. 



As the parasite grows, the chi-omatoid and plastinoid granules 

 travel towards the periphery (figs. 29-32). The macrogainetocyte 

 at this time encysts within the epithelium, and the chitiiioid 

 material of the cyst seems to be foi'med 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 CocckUuni 

 oviforme [Eiineria stiedce of Stiles). 



The formation of the cyst of Eimeria avium takes place while 

 the oi-ganism is still within the epithelium (figs. 34, 35), and 

 therefore the parasite encysts precociously. The 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 micro pyle, which may be in a 

 slight depression, is left for the entry of the microgamete 

 (PL LYII. fig. 47). 



When Schaudinn investigated the life cycle of E. schuhergi, he 

 described a process of maturation of the macrogametocyte, 

 Avhereby the karyosome of the nucleus was expelled in fragments. 

 I I'egret that I am not at all sure as to the fate of the karyosome 

 of the macrogametocyte of E. aviavi. Several causes combine to 

 defeat the attempts made to elucidate this subject. In the first 

 place, the entire pai"asite {E. avium) is much smaller than 

 E. schuhergi and its karyosome is not nearly so well differentiated 

 a structure. Further, the presence of the chromatoid granules, 

 which stain deeply with basic stains, much confuses the structure. 

 Similar causes prevail in E. oviforme {E. stiedoi), as I can vouch 

 from personal observ^ation, and Wasielewski (1904, p. 54) 

 states that he is unable to follow the maturation process in 

 E. oviforme. 



It may be that E. aviwn is like some other Coccidia (e. g. 

 C. lacazei, C. j)ro2)rium, Adelea ovata) where the karyosome is 

 retained in the gamete and is left behind in the residual proto- 

 plasm of the oocyst. On a few occasions, I have obsei'ved a 

 small, chromatin-like granule in the oocyst residuum (PI. LYII. 

 fig. 57), and this body may be the karyosome of the macro- 

 gametocyte. E. avium is distinguished by having a veiy small 

 c^^stal residuum, which, together with the sirallness of the karyo- 

 some, and indeed of the whole parasite, increases the difficulty 

 of investigation. However, at the time of fertilisation, the 

 distinctness of the kaiyosome of the macrogamete has disappeared 

 (PI. LYl. figs. 29-36), and the nucleus of the macrogamete a])pears 

 to contain granules of chromatin which are rather indistinct. 



