CILIATE FIBRILLAR SYSTEMS 213 



ing to Entz (1893), is not homogeneous but distinctly sculptured (Fig. 

 78) as if composed of "Stabchen" that overlap, somewhat as tile on 



a roof. 



The fibrillar system of the body lies immediately beneath the pellicle 

 and comprises an outer and an inner complex of fibrils, or myonemes. 

 Each such complex is in turn composed of ( 1 ) an outer circular layer, 

 and (2) an inner longitudinal layer, making in all, then, four fibrillar 



layers. 



Lachmann (1856) was first to describe the outermost circular layer. 



Ion. my 



o.sp.mt/' 



Figure 79. Myonemes of stalk sheath of Vorticella. (Entz, 1893.) 

 Ion. my. — longitudinal myoneme o. sp. my. — outer spiral myoneme 



It was later recognized also by Stein (1867), but apparently overlooked 

 by other investigators previous to Entz (1893). As a single fibril, it 

 spirals directly beneath the pellicle and may be followed from the 

 attachment of the stalk uninterruptedly to the center of the disc. Its 

 spiral course accounts for the annular appearance of the pellicle. Entz 

 (1893) thinks also that the birefringence of the pellicle may be due 

 to this underlying fibril, since, as shown by Engelmann (1875), all the 

 fibrils are refractive in polarized light. 



The fibrils of the next layer, the longitudinal fibrils, lie immediately 

 below layer (1), noted above, and likewise pass from the style's attach- 

 ment to the center of the peristomal disc. On this disc they of course 

 are radially arranged. This layer was found by Greeff (1871), but 

 Bijtschli (1889) questioned its existence. 



It should further be noted also that this outer fibrillar complex is 

 continued uninterruptedly into the protoplasmic lining of the style sheath 

 (Fig. 79). This will be referred to again in later discussion. 



