352 Mr Gray, The Meclmnism of Ciliary Movement 



The Mechanism of Ciliary Movement. By J. Gray, M.A., Balfour 

 Student, and Fellow of King's College, Cambridge. 



[Read 7 March 1921.] 



Ciliary movement is a well-known phenomenon in the animal 

 kingdom, and although there is general agreement concerning the 

 morphological structure of the ciliary apparatus, yet our knowledge 

 of its physiology is small. Most of the theories which have been 

 advanced have been based upon the morphological structure of 

 the cihum, and different authors have attributed different functions 

 to the various structures which become visible in stained prepara- 

 tions. The present paper is a prehminary account of an attempt 

 to throw hght on this vexed problem by the application of experi- 

 mental methods. 



The material used has been the gills of Mytilus edulis, which, 

 as explained elsewhere*, form an admirable subject for study. The 

 main ciha on the gills can be divided into three classes (a) the 

 frontal and terminal cilia, (b) the lateral ciha, (c) the latero-frontal 

 cilia. Of these groups, the first two resemble each other in the fact 

 that they perform work by creating a current of water or bring 

 about the active transport of food and mucus. The function of the 

 latero-frontal ciha is rather difficult to determine, but it seems 

 certain that they do not perform work as do the other types of 

 cihum. These latero-frontal cilia may either serve to keep the 

 filaments of the gill apart, or to direct the water currents formed 

 by the lateral ciha on to the face of the gill. 



There is no doubt that the large latero-frontal ciha are com- 

 posed of a number of cilia or separate fibres fused together. The 

 frontal cilia also have probably the same constitution. There is, 

 further, a wealth of morphological evidence to show that in a very 

 large number of ciliated cells, the cihum itself is composed of 

 fibres fused together, or that part of essential ciliary apparatus is 

 fibrous. The work-performing ciha are remarkably efficient, and 

 are capable of producing a rapid flow of water or food particles. 

 All the ciha possess a very considerable degree of elasticity, since, 

 when deformed by any external agent, they regain their normal 

 shape when the disturbing element is removed. 



A considerable number of workers have taken cognisance of 

 the fact that ciha are essentially elastic bodies, but it is of interest 

 to consider the problem afresh. 



* J. Gray, Quart. Journ. Micros. Science, vol. 64, 1920, p. 345. 



