124 University of California Publications in Zoology [Vol. 20 



decolorized cysts and to study lateral as well as ventral views to obtain 

 a clear conception of this organ system. 



The centrosome (figs. A, B, cent.) in Chilomastix is a discrete and 

 separate structure, independent, in both free and encysted stages, 

 of the blepharoplasts. There is no centroblepharoplast here, as in 

 Trichomonas, where the two organs are combined in one granule, but 

 the relations of the two are similar to those found in Giardia. It is 

 a small granule flattened against the antei'ior end of the nucleus 

 where it forms a small hemisphere on the nuclear membrane. As 

 mitosis ensues in the cyst, it divides and one daughter centrosome 

 migrates posteriorly on the membrane of the nucleus (pi. 16, figs. 

 13, 15), spinning out the paradesmose between tlje two. In early 

 stages the paradesmose is applied to the nuclear membrane ( pi. 17, 

 figs. 17, 19), but, in later stages, as the daughter nuclei part, it 

 stretches out between them across the intervening cytoplasm (pi. 17, 

 fig. 23). At no stage have we seen the centrosome detached from the 

 nuclear membrane. 



The blepharopla^t in Chilomastix is a complex of three granules. 

 In the free stages it is lodged on or near the anterior end of the 

 nucleus and its structure is generally obscured by the crowding of 

 organs anteriorly in a restricted area (pi. 15, figs. 2-6). It consists 

 of three granules or individual blepharoplasts, which may be desig- 

 nated, according to their positions in relation to the nucleus, as the 

 primary (figs. A, B, prim, hleph.), secondary {sec. bleph.), and ter- 

 tiary {tert. ileph.) blepharoplasts respectively. In the free stage 

 they are appressed against one another so that there may appear 

 only two blepharoplasts, and the free flagella seem to emerge rather 

 close together. Closer inspection, however, reveals the fact that the 

 right flagellum is slightly removed from the other two. In stained 

 flagellates (pi. 15, figs. 2-6) the nucleus crowds upon the blepharo- 

 plasts, obscuring the centrosome and rhizoplasts, while the two 

 blepharoplasts of the right side generally appear as a single granule, 

 often somewhat larger than the tertiary blepharoplast. The two (in 

 reality three) granules usually lie at the anterior end of the nucleus 

 and eytostome, but only one of them is actually attaelied to the peri- 

 stomal fiber. 



It is in the encysted stage that the structure, individuality, and 

 relationships of the three blepharoplasts can be clearly distinguished 

 (pi. 16, figs. 7, 8) as follows. The left or primary ilepharopl-ast (fig. 

 B, prim, bleph.) gives rise to two anterior flagella (pi. 15, fig. 1), is 



