CILIA. 



5 



sumed its erect condition, perhaps half a dozen of its suc- 

 cessors are in different degrees of flexure. This sort of 

 motion will probably be better understood by referring to 

 that beautiful and familiar spectacle, the waves produced 

 by the breeze upon a field of standing corn. The motion 

 is exactly the same in both cases. The wind, as it sweeps 

 along, bends each stalk in turn, and each in turn reas- 

 sumes its erect posture ; thus the wave-runs steadily on, 

 though the stalks of corn never remove from their place. 

 The appearance of the ciliary wave, when viewed under 

 favourable circumstances with a good microscope, is so 

 exquisitely charming, that even those who have been 

 long familiar with it can scarcely ever behold it without 

 admiration. 



