FLAGELLATE FAUNA OF CCECUM OF SQUIRREL. 29 1 



The cyst is typically lemon-shaped (Fig. 6). The size is 

 markedly constant, every mature cyst measuring almost exactly 

 10 by 7.5 micra except one, which measured 12 by 8 micra. By 

 way of comparison the writer measured twelve cysts of Chilo- 

 mastix mesnili. These measured from 6 by 5 micra up to 8 by 7 

 micra. This indicates that the cyst of Chilomastix magna is 

 somewhat larger than that of Chilomastix mesnili, but there is not 

 the difference in size that there is in the free stages. The cyst 

 contains a nucleus, the cytostomal structures, and the "parabasal 

 body." 



There is nowhere in the literature anything like a complete 

 account of the cell division of Chilomastix. For this reason it was 

 thought to be quite worth while to spend a large amount of time 

 searching for dividing specimens, although they were extremely 

 rare. As a result a fairly complete account of the process can 

 now be given, although not all points have been cleared up. 



What the writer conceives to be the resting nucleus is repre- 

 sented in Figs, i, 7, and 12. There may be one blob of chromatin 

 on the inner anterior surface of the nuclear membrane, or there 

 may be one blob here and another in the posterior portion of the 

 nucleus (Figs, i, 12), or there may be a large number of smaller 

 granules lying on the nuclear membrane (Fig. 7). There is a 

 cloud of chromatin granules scattered thruout the entire nucleus. 

 Very often at this time a small deeply staining spot, an endobasal 

 body, or intranuclear kinetic element is visible (Figs. 7, 12). 



A little later the granules become more concentrated and form 

 a large endosome (Figs. 2, 9, 10). Careful study of this endosome 

 shows that it is sometimes a concentration of granules (Fig. 2) and 

 sometimes apparently a "chromatin knot" (Figs. 9, 10). Often a 

 deeply-staining intradesmose is visible at the points where it 

 passes from the endosome to the blobs of chromatin at one or 

 both poles of the nucleus. 



The endosomal chromatin becomes resolved into chromosomes, 

 which appear to be dumbbell-shaped. It was not possible to 

 count them exactly in any case, but the number is near ten. 

 Strangely enough, the intradesmose could not be observed at this 

 stage. Perhaps it lay too close to the nuclear membrane, for 

 which there is some evidence to be given later. 



