078 L)R. IJ. B. FA.NTIIAM OX THE [j\[ay 3, 



ganietocytes or luother (.-ells of the gametes (PI. LYL. figs. 26-28, 

 PI. LVIT. fig. 37) are modified schizonts wliich are of slow growth, 

 and therefore can accumulate more reserve food-material in the 

 form of granules within their cytoplasm. The processes leading 

 to the formation of the gametes may be termed gametogony, 

 which we may now consider. 



(c) (I'draetoijoiiy. 



Sexual diffei'entiation is characteristic of the gametes of 

 Coccidia, and in the case of Ebneria avium the diffei'entiation 

 is apparent in the gainetocyte phase. Two forms of gametocytes 

 can be distinguished. The first group are intra-celhdar parasites 

 containing large granules of food resei've within their cytoplasm. 

 These are the maci'ogametoc3'tes (PL LVI. fig. 26) which give rise 

 each to one female gamete. On the other hand, the micro- 

 gametocytes (PI. LVII. fig. 37) or male progenitors contain a 

 little reserve food-material in the form of very minute granules, 

 distributed evenly throughout the body substance. Each micro- 

 gametocyte gives rise to many microgametes. 



The Macrogametocyte and Macrogamete. 



The structure of the macrogametocyte and of the single macro- 

 gamete that arises fi'om it is very difficult of interpretation 

 in Einieria avium, on account of the large amount of reserve food- 

 material contained within the cytoplasm. Further, it is very 

 difficult to draw the exact dividing line between the macro- 

 gametocyte and the female gamete, as tlie one gi'adually merges 

 into the other. These forms vary from ll-8/j-17-5/j in length, by 

 (Sfx-Wfi in breadth, as seen in sections. Many relatively large 

 granules occur in the cytoplasm of the macrogametocyte. As the 

 macrogametocyte gi'ows from i-ound to ovoid, these granules 

 gradually concentrate to form larger, roundish, ha3matoxylin- 

 staining granules, which are albuminoid (PI. LVI. fig. 29), the 

 chromutoid granules of many authors. There are also other, non- 

 basic staining, granules known as ])]astiuoid granules ("granules 

 })lastiques " of Thelohan and Labl)e) composed of coccidin 

 (Labbe). These ultimately are large and round (figs. 30-32) 

 and are I'cfi'actile in fresh preparations, where they appear yellow 

 oi- gi'(\yish-green. They tend to shiink in ]ireparations fixed with 

 sublimate or sublimate acetic (fig. 2i)). 'J'lie plastinoid granules 

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

 In stained preparations* the granules are best seen by staining 

 with iron-ha-matoxylin followed by van Gieson's picro-fuchsin, 

 when the chromatoid granules appear blaclcish. while the plas- 

 tinoid granules take on a uniform, yellowish line. The plastinoid 



* The reactions of the Ki'ini'i't'*- ^'"p dincussefl h.v Lalilx' (18!)0) ami liv Miiicliiii 



