CHAPTER 3 



FACTORS WHICH AFFECT 

 CILIARY ACTIVITY 



1. Ciliary Activity and its Measurement 



Contractions of either cilia or flagella in a fluid medium result in 

 movements of the medium v^^ith respect to the organelle, although 

 the form of beat shown by these tvi^o types of organelle and the 

 water movements caused are rather different. Our knowledge of 

 the effects of various factors on flagella (including sperm tails) is 

 rather scanty, so that most of the information given in this chapter 

 will concern the activity of cilia sensu stricto. 



The rate at which fluids are moved by cilia must depend on a 

 variety of anatomical and physiological characteristics of the 

 organelle as well as on the effects of the environmental factors 

 which are discussed in this chapter. Thus, the dimensions and 

 compounding together of cilia are important, and so is the arrange- 

 ment of cilia which are able to beat in a co-ordinated fashion, 

 while the form and rate of beat of cilia and the mode of their 

 co-ordination are fundamental in determining the effectiveness of 

 the ciliary activity in the performance of a particular function. 

 Ciliary co-ordination includes not only the characteristic ability 

 of cilia to beat in a metachronal rhythm, but also the phenomena 

 of reversal and inhibition, all of which are discussed in detail in 

 Chapter V. It appears, then, that measurements of the mechanical 

 work done by a group of cilia will not tell us much about the 

 working of the ciliary mechanism, xyox will an analysis of effects 

 of many factors on any one part of ciliary activity be sufficient for 

 an understanding of the complete system, for both the beating of 

 cilia and their co-ordination are undoubtedly complex. It is the 

 purpose of this chapter to review investigations on the modifica- 

 tions of ciliary activity caused by changes in the physical and 

 chemical nature of the environment; only in a few cases is 



77 



