30 STRUCTURE AND PROPERTIES 



an opposite conclusion. Although it may be a 

 poetical and an agreeable idea to imagine the whole 

 vegetable world welcoming and rejoicing in the 

 return of spring, and basking in the warm beams 

 that are so congenial to our own nature and 

 necessities, yet the satisfaction this notion might 

 afford would be far more than counterbalanced 

 by the reflection that we could not pluck a rose 

 or gather a peach without inflicting pain ; and 

 that the pruning knife was an instrument of tor- 

 ture. One strong reason to conclude against the 

 sensibility of plants, arises from the great contrast 

 between the provision made for them and for 

 animals during the winter. It is known that 

 animals liable to exposure to cold are well de- 

 fended against it by their fur or down ; while 

 trees, stripped bare at the season when all sen- 

 tient beings look for shelter, would indeed un- 

 dergo a heavy penalty if they could feel the chill 

 blasts that howl around them. 



23. It was formerly supposed that vital ex- 

 citability was seated exclusively in the vessels, 

 but M. de Candolle's reasoning is conclusive 

 against this theory, as he shews that the power 

 is possessed by plants wholly formed of cellular 

 tissue ; that is to sav> they offer the same facts 

 from which the existence of vital excitability in 



