456 University of California Publications in Zoology [Vol. 19 



specialized, conducting elements in their protoplasm. That such ele- 

 ments in the ciliate, Euplotes patella., have become unified into an 

 efficient, integrated system for the coordination of its associated 

 oganelles, is supported, it is believed, by experimental evidences set 

 forth in foregoing paragraphs. 



Should further experimentation substantiate these results, then 

 their significance is clear. The most salient feature of structures and 

 functions in the Protozoa as in the Metazoa is not cellularity but 

 organization. The external organelles of a protozoan body are not 

 mere continuations of the protoplasm as the fingers are a part of the 

 glove. They are rather modifications which are sometimes distinctly 

 specialized, as the cirri and membranelles of E. patella clearly indi- 

 cate. Moreover, the complex, integrated fibrillar apparatus of this 

 organism signifies higher specialization in its intracytoplasmic struc- 

 tures. From these considerations it would follow that any general 

 conception of the Protozoa which assumes that any and all of this 

 extensive and diversified group of organisms are so simple and primi- 

 tive as to lack specific organization — the specialization of intra- and 

 extracytoplasmic organelles — is inadecpiate and will assuredly be 

 abandoned. 



SUMMARY 



The fibrillar system in Euplotes patella, found and described by 

 Yocom (1918) as a "neuromotor apparatus," has been identified in 

 the living organism both with and without the aid of vital dyes. 



Other structures of this system not previously described are : 



(a) membranelle fiber plates, each of which is contiguous with a mem- 

 branelle basal plate and is attached at one end to the membranelle fiber; 



(b) dissociated fiber plates contiguous with the basal plates of the 

 frontal, ventral and marginal cirri, to each of which are attached the 

 "dissociated fibers." 



The rectangular anal fiber plates, a modification of the posterior 

 ends of the anal fibers, directly approximate the basal plates of the 

 anal cirri. 



The fairly rigid pellicle is amply sufficient to maintain the normal 

 shape of Euplotes under considerable stress and after an incision fully 

 two-thirds the width of the body has been made. 



