CILIATE FIBRILLAR SYSTEMS 215 



men)." This would account for the interlaced appearance of the ciliary 

 ring. Above the ring, in the bell part of the body, this set of fibrils could 

 not be detected except in the peristome border, where it forms a fairly 

 strong spiral, narrowly wound. Its occurrence there was described by 

 earlier authors as a "sphincter ring" of the peristome border (Fig. 80). 



On the disk, this fiber appears as a fairly thick strand, one end of 

 which originates in the center of the disk and, after following at their 

 base the several turns of the adoral membranelles along the outer margin 

 of the disk and through the mouth into the gullet, it continues down the 

 inner surface of the gullet the whole length. Along the gullet wall Entz 

 thought that, in some preparations, he could observe this fiber branching 

 into many increasingly fine fibrils. 



The inner, longitudinal layer of the second fibrillar complex is a 

 direct continuation of the Spasmonem (Stielmuskel) of the contractile 

 stalk. Upon entering the body this Spasmonem breaks up into its com- 

 ponent fibrils, which diverge and so form the "funnel muscle" (Fig. 80) 

 of earlier authors. Higher in the funnel, these fibrils may rebranch, then 

 anastomose into a network. At the ciliary ring, the fibrils curve round 

 it as crescent-like spans, which are somewhat larger and apparently more 

 dense, and continue directly up the wall of the bell to the peristome 

 border. These meridional myonemes (Fig. 80) may end singly on this 

 border or, as Engelmann (1875) noted, they may bifurcate and unite, 

 each of a pair with its adjacent neighbor, to form "arcades" just below 

 the peristome border. The fibrils then span this projected border, much 

 as they curved over the ciliary ring, and thereupon proceed as radii to 

 the center of the disc. Toward this center, these fibrils may sometimes 

 branch and anastomose to form varied and striking patterns. 



Finally, it may be mentioned that, in addition to the four layers of 

 fibrils noted above, Entz (1893) describes a fairly thick strand of other 

 fibrils which originate from the middle of the disc and project down- 

 ward through the endoplasm and finally disappear in the region of the 

 cytostome. 



B, INTERPRETATION 



The essential structural components of the fibrillar systems of several 

 representative ciliates have been briefly reviewed in the foregoing para- 

 graphs. It remains now to consider the several functions that have been 



