272 University of California Publications in Zoology [ V OL. 20 



tion, the rootlet is invariably seen to run from the basal granule 

 toward the observer's right into the contiguous granular band on that 

 side. Thus, to avoid any confusion that might arise from the terms 

 right and left, in a cross-section of the animal viewed from the anterior 

 surface (such a view is shown in fig. L) the ciliary rootlets swerve in 

 the counter-clockwise direction and enter the granular band lying 

 immediately in that direction. 



As the rootlet enters into the granular band it apparently enlarges 

 thus forming a secondary basal granule. In some cases this may stain 

 even more deeply than the basal granule itself, and appear as a definite 

 body somewhat elongated in the direction of the circumference of the 

 animal. It was thought at first that this might be the cross-section of 

 a longitudinal fiber or myoneme. But the study of numerous tan- 

 gential sections has failed to show the presence of any longitudinal 

 fiber within the granular band. The stainability varies greatly and 

 in preparations which have stained lightly the ciliary rootlets appear 

 to fray out and merge into the granular band, while still retaining 

 deeper color than the rest. Which interpretation is correct it is 

 difficult to say, but the latter seems the more probable, especially in 

 view of certain relations with the neuromotor apparatus which will 

 be discussed later. 



Putter (1903) reproduces a figure from Studnicka (1899) showing 

 in a schematic way five types of attachment of the cilia with their 

 basal apparatus. Of these, two, at least, represent cases in which two 

 basal granules or a diplosome are present. Saguchi (1917) in his 

 studies on ciliated cells of Metazoa says in part regarding the basal 

 granules of certain ciliated cells from amphibian larvae, ' * With favor- 

 able staining the basal corpuscles appear as diplosome or dumbbell 

 shaped granules. One of these is situated at the upper the other at 

 the lower border of the cuticle." In Balantidium coli the arrange- 

 ment with respect to protoplasmic layers is quite different, though 

 the cilia seem to follow somewhat the same plan of structure even to 

 the presence of rootlets. 



The most fruitful comparison may be made with the .basal appa- 

 ratus of cilia in Isotricha prostoma as described and pictured by 

 Braune (1913). In this organism he describes diplosomic structure 

 of the basal apparatus, in which the basal granule lies directly beneath 

 the pellicle. The cilia, however, extend beyond the basal granule into 

 the underlying layer the * * Zwischenschicht " of Eberlein, and ter- 

 minate in the "Grenzschicht" with a second granule, which upon 



