VISCOSITY 



83 



3. Viscosity of the Medium and Ciliary Activity 



Viscous solutions have been used to slow^ up the movement of 

 ciHated protozoans for the study of the Hving animals (see 

 Marsland, 1943). By this means Pigon and Szarski (1955) found 

 that the velocity of forw^ard movement of Paramecium is inversely 

 proportional to the relative viscosity of the medium (increased 

 With dialysed gum arabic). It would be expected from Stokes' law 



3-1 r 



T16 



O0034 



00035 



00036 



1 



Temperature (°A.) 



Fig. 19. The effect of temperature on metachronal wave 

 velocity and frequency of beat of Stentor membranelles (see 



text) (from Sleigh, 1956a). 



that the movement of any body propelled by a constant force 

 through a viscous medium would be slowed in this way; however, 

 the retardation is the result not only of an increased resistance to 

 the movement of the whole body, but also of a slowing of the 

 ciliary beat. 



The effects of viscosity on the frequency and metachronal wave 

 velocity of Stentor membranelles seem to be different at high 

 viscosities from those found at lower viscosities, (i.e. up to about 

 3 J times the viscosity of water). Table 6 shows the changes of 



