CILIATE FIBRILLAR SYSTEMS 257 



Stains: Iron-haematoxylin, Mallory's triple (Sharp's modification). 



AUcrodis'section 



U role plus halseyi Calkins (Calkins, 1930). — The conspicuous parts 

 of this kinetic system are the motoviinn near the right side of the gullet 

 and, leading from it, the longitudinal anterior fibril which links a row of 

 endoplasmic granules. Each basal plate of the membranelle series is con- 

 nected by a short fibril to one of these basal granules, in regular order, 

 and additional connectives unite the basal granules of each frontal cirrus 

 with the chain. One short anterior fibril from the motorium extends to 

 the margin of the peristome; the other leads to the undulating membrane, 

 and two posterior fbrils are soon lost in the endoplasm. (Fig. 92) . 



Methods 



Fixatiies: HgCl,, saturated in 95-percent alcohol. 

 Stain: Iron-haematoxylin. 



Conclusions 



It is evident from the review presented in foregoing paragraphs that 

 the differentiation of fibrils in ciliates has been established for various 

 representatives of their major groups beyond any doubt. Such differ- 

 entiations, as revealed in fixed and stained material, are not artifacts, 

 for many may be seen in living or in slowly disintegrating organisms 

 (Worley, 1933). 



It is not certain, however, that all of the structures thus identified are 

 actually fibrillar. Some may represent rather a sculptural, fibrillar-like 

 pattern in the pellicle. 



It is also clear that the fibrils are not all alike, either structurally or as 

 related to other protoplasmic differentiations of the cell. This was well 

 illustrated in the several complexes of fibrils in the contractile stalk 

 of the vorticellids. Here the structural elements composing the Spironeni, 

 for example, differed partly in kind, but especially in arrangement, 

 from those of the Axonem. Also, their relations to the fibrillar com- 

 plexes of the bell were found to be different. 



Again, it is known that many fibrillar complexes of various ciliates 

 are intimately associated with the basal apparatus of the motor organ- 

 elles. This was shown for the inner fibrillar complex, or the injracilia- 



