CILIATES 209 



some, topped by a cupped diaphragm and a distinct axial granule, 

 typically contains in its lumen a single dense granule. It is closed 

 proximally by an intimate junction with the basal rod of its row. 

 The rod is a massive, dense structure, somewhat greater in 

 diameter than the kinetosomes themselves, and marked by rather 

 regular variations in diameter and in opacity (Fig. 87, PI. XXIV). 

 In spite of the continuously oriented aspect of the infraciliature, 

 the cilia in action group themselves into discrete clumps. Accord- 

 ing to Noirot-Timothee these should be called syncilia rather than 

 membranelles, since their cohesion is loose and is not reflected in 

 the infraciliature. In thin sections cut above the level of the cell 

 surface they appear as well-ordered groups of six to nine rows of 

 about 15 synchronized cilia each, arranged as a double tier of 

 syncilia along the spiral band. This means that cilia arising from 

 a single oblique row (subtended by a single continuous basal rod) 

 contribute to at least two syncilia. 



In addition to their oblique linkage via the basal rods, kineto- 

 somes are connected to each other along, and probably between, 

 rows by lateral bridges. Furthermore, slender dense fibrils arise 

 from one border of each basal body and run past at least the next 

 kinetosome in the row. These are identified as probable 

 kinetodesmal fibrils by Noirot-Timothee. 



From the basal rods beneath the kinetosomes arise series of 

 retrociliary fibers of very specific structure (Figs. 87 and 88, 

 PL XXIV). Like so many other intracellular fibrous bodies, they 

 consist of numbers of tubular fibrils, about 15 m/x in diameter, 

 arranged in orderly parallel planes. They are encountered in 

 sections at many locations within the anterior ectoplasm, and it is 

 not possible to determine their course from electron micrographs. 

 Light-microscope studies show that they vary considerably in 

 length and that groups of them pass toward and perhaps into the 

 esophagus or along its ectoplasmic surface, toward the base of the 

 cytoplasmic lips surrounding the ciliated zones, toward the 

 skeletal plates, and perhaps in a spiral beneath and parallel to the 

 ciliated bands. 



Over the surface of the peristomal disc within the adoral 

 ciliated zone and down its canal to the cytostome, the pellicle 

 lacks the three inner layers described for the general body surface. 

 Instead there exists a series of regularly spaced fibrous sheets lying 



