ii.j THE PLANT AND THE ANIMAL 113 



mobility and consciousness of the vegetable cell are not 

 so sound asleep that they cannot rouse themselves when 

 circumstances permit or demand it; and, on the other hand, 

 the evolution of the animal kingdom has always been re- 

 tarded, or stopped, or dragged back, by the tendency it 

 has kept toward the vegetative life. However full, how- 

 ever overflowing the activity of an animal species may 

 appear, torpor and unconsciousness are always lying in 

 wait for it. It keeps up its role only by effort, at the 

 price of fatigue. Along the route on which the animal 

 has evolved, there have been numberless shortcomings 

 and cases of decay, generally associated with parasitic 

 habits; they are so many shuntings on to the vegetative 

 life. Thus, everything bears out the belief that vegetable 

 and animal are descended from a common ancestor which 

 united the tendencies of both in a rudimentary state. 



But the two tendencies mutually implied in this rudi- 

 mentary form became dissociated as they grew. Hence 

 the world of plants with its fixity and insensibility, hence 

 the animals with their mobility and consciousness. There 

 is no need, in order to explain this dividing into two, to 

 bring in any mysterious force. It is enough to point out 

 that the living being leans naturally toward what is most 

 convenient to it, and that vegetables and animals have 

 chosen two different kinds of convenience in the way of 

 procuring the carbon and nitrogen they need. Vegetables 

 continually and mechanically draw these elements from an 

 environment that continually provides it. Animals, by 

 action that is discontinuous, concentrated in certain 

 moments, and conscious, go to find these bodies in organ- 

 isms that have already fixed them. They are two different 

 ways of being industrious, or perhaps we may prefer to 

 say, of being idle. For this very reason we doubt whether 

 nervous elements, however rudimentary, will ever be found 



