THE SENSES OF PLANTS. 



293 



situation, or even when placed between the leaves 

 of a book. This is by no means a general mode 

 of reproduction in the species, nor does it take 

 place under ordinary circumstances. We can even 

 conceive it possible for centuries to elapse without 

 its being utilised, yet the power remains, and can 

 be easily proved by hanging up a leaf in the house. 

 Under certain conditions the pseudo-bulbs and 

 stems of orchids produce young plants, as do also 

 the leaves of a few ferns. These may be considered 

 as survivals from some former time when the plants 

 propagated themselves in this way, and, as such, 

 good examples of inherited capabilities, of which 

 more will be said in the next chapter. Nevertheless 

 sensation must be concerned in these revivals of 

 ancient modes of reproduction, and no doubt they 

 are the result of most delicate processes set in 

 motion by feeling. 



