"GROUSE DISEASE"— COCCIDIOSIS 243 



the entire parasite {E. avium) is much smaller than E. schnbergi, 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. stiedce), as I can vouch from 

 personal observation, and Wasielewski (1904, p. 54) states that he is unable to 

 follow the maturation process in E. oviforme. 



It may be that E. avium is like some other Coccidia (e.g., C. lacazei C. proprium, 

 Adelea ovata) where the karyosome is retained in the gamete and is left behind in 

 the residual protoplasm of the oocyst. On a few occasions, I have observed a small 

 chromatin-like granule in the oocyst residuum (PI. xxxvi., Fig. 57), and this body 

 may be the karyosome of the macro-gametocyte. E. avium is distinguished by 

 having a very small cystal residuum, which, together with the smallness of the 

 karyosome, and indeed of the whole parasite, increases the difficulty of investiga- 

 tion. However, at the time of fertilisation, the distinctness of the karyosome of 

 the macrogamete has disappeared (PI. xxxv.. Figs. 29-36), and the nucleus of the 

 macrogamete appears to contain granules of chromatin which are rather indistinct. 



The micro-gametocyte ^ (PI. xxxvi., Fig. 37) is an ovoid cell about 13/* long and 

 Sfi. broad in the specimens that I have seen. It possesses a central nucleus contain- 

 ing a karyosome. The process of the formation of the microgametes of 

 E. avium is as follows : — The chromatin of the nucleus, laroely concen- ^^'^''°" 



' & J gametocyte 



trated in the karyosome, breaks up (Figs. 38-40) into minute granules or '^^^ "uoro- 



•' r \ o I o gametes. 



chromidia which pass towards the surface of the cell, where they appear 

 to form a very fine chromidial network (Fig. 38). The chromidia then collect into 

 groups or patches, arranged in the form of minute, irregular loops with central 

 hollows (Figs. 38, 39). These chromatic loops form a number of minute, fiexible, 

 rod-like bodies, composed almost entirely of chromatin (Figs. 41-45). These are 

 the young microgametes (Figs. 43-46). The adult microgametes are small parasites, 

 their chromatic bodies measuring 3m to 4m in length, possessing a rod-like, some- 

 what curved body composed of a core of chromatin, which is surrounded by a 

 tenuous film of cytoplasm, prolonged outwards to form two fine flagella (Figs. 

 44, 46). The flagellum, which I term the posterior flagellum, trails behind the 

 organism, and is practically a continuation of its body ; the other flagellum is at 

 the opposite end of the body, and so is termed the anterior flagellum. In life, the 

 microgametes are capable of serpentiform movements. Owing to the minute size 



1 Uni - nucleate micro - gametocytes seemed rare in preparations, for the cell rapidly proceeds to form 

 many microgametes. 



