1920] Kofmd-Swczy : Morphology and Mitosis of Chilomastix 129 



The Encysted Flagellate 



The cysts (fig:. B; pis. 16, 17) of Chilomastix are small, ovoidal, 

 pyriform, or lemon-shaped bodies in some cases remarkably similar 

 in general appearance to the smaller cysts of the species of amoeba 

 with which they are associated in the intestine of man. In fresh 

 smears in physiological salt solution the cysts are bluish green bodies 

 with distinct walls and often a few highlj' refractive granules strewn 

 within. In iodine-eosin stain the cysts quickly become tinged with 

 the iodine to a light yellow, and, according to the amount and 

 diffusion of the contained glj^cogen, gradually assume an olive or 

 brownish tint. If the glycogen is massed, the brown color is very 

 evident in the glycogen vacuole, if it is diffuse, a dark olive or brown- 

 ish tint spreads through the whole cyst. If glycogen is not present 

 the cyst remains yellow. As the iodine penetrates, the outlines of 

 the nuclear membrane and of the fibrillar sling in the walls of the 

 cytostome become visible. The cysts are not uniformly lemon-shaped. 

 In not a few cases all trace of the pyriform contraction is lacking and 

 the cyst is ovoidal, spheroidal, or broadly ellipsoidal (pi. 16, figs. 

 11, 12). 



In the pyriform ej'sts the length is from 1.21 to 1.24 times the 

 greatest diameter, which is slightly below the level of the middle of 

 the body, assuming that the narrower end is the anterior one. They 

 are thus broadly pyriform in contour. In other instances the neck 

 of the cyst is not contracted and the contour becomes broadly ovoidal 

 with the length 1.24 to 1.31 times the greatest diameter which is located 

 at 0.6 of the total length from the anterior end. In still other instances 

 the cyst may be spheroidal (pi. 16, fig. 8), with the longer axis reduced 

 to 1.08 times the greatest diameter and the anterior projection forming 

 only a verj' obscure and slight eminence. It is only in lateral view 

 that this departure from sphericity is detected. 



The cyst varies from 6.5 to 9/t in length and averages 7 to 7.5/x, 

 while its greatest diameter is from 5.8 to 7.5/x and averages 6.5/x. Its 

 dimensions are thus very close to those of a red blood corpuscle, and 

 to the small races of Endolinuix huetschlU and Eiidmnoeba dysen- 

 teriae, an important point in the microscopical diagnosis of these 

 infections. 



The cyst tvall is a transparent, homogenous substance, without 

 structural modification except at the tip of the stout projection, where 

 it is locally thickened across the end to double the thickness elsewhere, 



