60 University of California Publications in Zoology [Vol. 20 



The extreme anterior tip of the cone-shaped end or liead of the 

 body reveals, in surface view (pi. 6, figs. 7. 12), a central core 

 of endoplasm surrounded by a dark ring at the base of a pitlike 

 depression. This central core of endoplasm extends backward through 

 the tubular part of this darkly staining structure, the centroblepharo- 

 plast complex (pi. 5, fig. 6), and connects with the endoplasm of 

 the body. As shown in figure 3, plate 5, this structure presents the 

 requisites for functioning as a cytopharynx leading into the body. 

 Its size as compared with that of the ingested food particles, would 

 not militate against such a supposition, since the great flexibility of 

 these parts might also be correlated with a considerable degree of 

 elasticity permitting distension. That the centrosome should form 

 part of the mouth structures, however, seems hardly plausible, but 

 scarcely less so than that its food should be taken in at the posterior 

 end of the body. The fact that the operculum appears always to be 

 intact and to cover over the anterior tip of the body militates against 

 this interpretation. 



An analogous condition, in case the core is the gullet of Tricho- 

 nymphu, is found in Diplodinium (Sharp, 1914), where a ring of 

 neuromotor material and connections surrounds the gullet. There is 

 no evidence, however, that this ring has the remotest relation to any 

 centrosome of this ciliate. Ciliates are, moreover, not mononucleate 

 as is Trichonympha. 



Porter (1897) has described for Trichonympha agilis a peculiarity 

 in the structure of the anterior part of the body, which might afford 

 some basis for the view of Kent that a cytostome existed in this 

 region. He described the cone-shaped end or "nipple," as he terms 

 it, as separated from the remainder of the body by a deep constriction, 

 the central axial rod forming the only means of union between the 

 two parts of the body. This appearance is shown in our own material 

 also (pi. 5, fig. 5) but Porter's explanation of the structure of the 

 body at this point does not agree with the actual conditions as we 

 find them. Our own interpretation follows. 



At the base of the tubular portion of the centroblepharoplast and 

 abutting upon its lobes, is a clear area that forms a ring completely 

 surrounding the tube. This is not traversed by the fibers that give 

 to the remainder of the ectoplasm a striate appearance, nor is it granu- 

 lar in its composition. In some individuals this lack of mj-onemes 

 and fibrils maj' be seen to extend to the outer surface which then shows 

 a zone devoid of flagella covering this region. Usually the outer zones 



