42 Marvels of Pond-Life. 



cules^ but in proportion as these observations are pro- 

 longedj the student will be impressed with the difficulty 

 of assuming that anything like a reasoning faculty and 

 volition^ is proved by movements that bear some 

 resemblance to those of higher animals^ whose cerebral 

 capacities are beyond a doubt. It is, however, almost 

 impossible to witness motions which are neither con- 

 stant nor pel iodic, without fancying them to be dictated 

 by some sort of intelligence. We must, nevertheless, 

 be cautious, lest we allow ourselves 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 which category we must reckon 

 food, and until we arrive at forms of being which 

 clearly possess a ganglionic system, we have no cer- 

 tainty 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. 



Ehrenberg was much struck with the restless cha- 

 racter 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 attached 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 per- 

 petual though unconscious work. 



