66 MARVELS OF POND-LIFE. 



must, nevertheless, be cautious, lest we allow our- 

 selves to be deceived by reasoning so seductive, as 

 the vital operations of the lowest organisms may 

 be merely illustrations of blind obedience to stimuli, 

 in wdiich category we must reckon food, and until 

 we arrive at forms of being which clearly possess 

 a ganglionic system, we have no certainty that a 

 real will exists, even of the simplest kind; and 

 perhaps we must go still higher before we ought 

 to believe in its presence. 



Ehrenberu: was much struck with the restless 

 character of many infusoria — whether he looked at 

 them by day or by night, they were never still. 

 In fact their motions are like the involuntary actions 

 which take place in the human frame; and if at- 

 tached to their bodies we observe cilia that never 

 sleep, the living membrane of some of our own 

 organs, the nose, for example, is similarly ciliated, 

 and keeps up a perpetual though unconscious work. 



