CILIATE FIBRILLAR SYSTEMS 245 



extends from each basal granule, and a second small granule is found 

 at the junction of the ectoplasmic and endoplasmic layers. The ectoplasmic 

 layer is quite thin, except at the anterior end of the organism, where it 

 is deep and the distance between the granules of each cilium correspond- 

 ingly long. The rootlets of the row of adoral cilia around the margin of 

 the peristome, the "radial fibrils," are exceedingly long, ending in about 

 the posterior third of the body without connection or attachment. The 

 cilia immediately posterior also have long rootlets, but they become 

 shorter as they approach the base of the apical cone (Fig. 88) . 



Methods 



Vital stain: Neutral red (differentiates the neuromotor apparatus). 

 Fixatives: Schaudinn's, Zenker's, Formalin, osmic acid, picrocuric, 



60-80° C. 

 Whole mounts and sections 

 Stains: Iron haematoxylin, Mallory's triple stain (particularly for sections). 



pe//. ___ 

 b.gr. --- 

 cil.r. 



/ 



Figure 88. BaLvitidium coli, cross section of peripheral region. (McDonald, 1922.) 

 b. gr. — basal granule gr. b. — granular band 



cil. r. — ciliary rootlet hy. b. — hyaline band 



endo. — endoplasm pell. — pellicle 



Balantidium sushilii (Ray, 1932). — Fibrils associated with the con- 

 tractile vacuoles have been described in Balantidium sushilii. Each of the 

 two lateral vacuoles has a fibril running from the wall of its outer half 

 to the neighboring pellicle. The neck of the terminal vacuole is sur- 

 rounded by a diaphragm of fibrils running from the wall of the neck 

 to the surrounding pellicle. These unusual fibrils are described and figured 

 in the extended as well as the contracted condition. 



An axial and a peripheral system of fibrils can be seen also in the 

 living organism. Stained preparations show that the former consists of 



