CILIATE FIBRILLAR SYSTEMS 227 



and the protoplasmic sheath as the effector. The basal apparatus com- 

 prises the basal granule and two "Nebenkorner." The latter serve to 

 spread the proximal part of the reflex arc and, with the basal granule, 

 may function as a kind of commutator that regulates the direction and 

 change in direction of the effective stroke of the cilium. 



We may note that while such a mechanism might conceivably account 

 for a reversal in the effective stroke of a given cilium, obviously it does 

 not, as such, provide for the synchronous reversal of the many other 

 cilia, which is an essential part of the problem of coordinated movement. 



In this connection, reference may be made to a fairly recent paper 

 by J. C. Hammond (1935), who would refer the phenomenon of 

 synchronous and metachronous ciliary behavior to an anterior-posterior 

 physiological dominance in the organization of the cell, as opposed to 

 the concept of a neuromotor m'echanism. This thesis might help to 

 account for this more general coordinated behavior (Rees, 1921), but 

 it would presuppose a reversal in anterior-posterior dominance of the 

 physiological axis in order to explain the reversal of ciliary stroke so 

 common in the swimming or creeping behavior of ciliates. Moreover, 

 the well known localized reversal of a few or many of the cytostomal 

 membranelles in the intake or ejection of solids would obviously require 

 a similar presupposition. 



The chief discrepancy between Klein's and von Gelei's interpretations 

 of the fibrillar system of Paramecium concerns the structural and func- 

 tional relations between their outer fibrillar complex and their inner 

 fibrillar complex. Klein (1928, p. 203) regards these two fibrillar com- 

 plexes as a continuum. His "Meridian II. Ordnung" is a derivative of 

 his "Meridian I. Ordnung," as are also all cilia, basal granules, "Neben- 

 k5rner," trichocyst granules, and protrichocyst granules (secretory, or 

 "Tektin" granules). In its re-genesis, observed during reorganization, 

 many more fibrils (Profibrille) are formed than are retained, varying 

 with the species and genus, and of those that persist some may unite to 

 form composite fibrils (Biindelfibrillen), as occurs in Paramecium 

 (Klein, 1932). 



Klein's silverline system incorporates as a unit, therefore, both struc- 

 turally and functionally, the outer and inner fibrillar complexes. In its 

 re-genesis, it functions as a "form-building system," and some of its 

 fibrils become more resistant and rigid by the addition of a secondary 



