ALKALOIDS, GLYCOSIDES AND OTHER CHEMICALS 119 



metachronal wave velocity (by 48 • 5 per cent) of Mytilus lateral 

 cilia at a concentration of 2 x 10~^ mol. Yet another preparation 

 digitamin, has been found to cause a slight increase in the ciliary 

 activity of frog pharyngeal epithelium (Ishikawa and Ohzono, 



0-5 1-0 1-5 



Digiioxm concentration (mg /I ) 



20 



Fig. 29. The effect of digitoxin concentration on the frequency 

 of beat and the metachronal wave "velocity of Stentor membra- 



nelles (from Sleigh, 1956a). 



1931). A summary of the effects of these glycosides, and also of 

 strophanthin (ouabain) which has a digitalis -like action on the 

 heart and accelerates the activity of frog pharynx cilia, is given 

 in Table 1 1 . 



