gth March, 1(^15. 



Mr. R. M. Young, M.A., J.P., in the Chair. 



THE SENSE ORGANS OF PLANTS. 

 By Professor R. H. Yapp, M.A. 



{Abstract.) 



If I were to ask each member of my audience to-night to 

 enumerate the characters which distinguish plants from animals, 

 the answers would probably be very varied. Everybody would 

 admit that plants have life, though many might regard the life of 

 plants as different to that possessed by animals. Some, no doubt, 

 would point out that anim.als possess consciousness, and have the 

 power of thought. Others might lay stress on the active movements 

 exhibited by animals, or would state that they, unlike plants, 

 possess sense-organs, and can therefore see, hear, taste, smell and 

 teel. I hope, however, to be able to convince those of you who 

 have perhaps not considered these matters very deeply, that the 

 differences between animals and plants, though admittedly great, 

 are, after all, less than might appear at first sight. For instance, 

 many plants are able to perceive, at least to some extent, what is 

 going on in the world around them, and to regulate their behaviour 

 accordingly. The organs, which are sensitive to changes occurring 

 in the environment, and thus form the seat of perception, may 

 fittingly be termed ' sense organs.' 



Take the power of movement. It is perfectly true that in 

 most cases a plant remains rooted to one spot all its life, and is 

 unable to execute those active locomotory movements so familiar 

 to us in the animal kingdom. None the less, plants can and do 

 carry out active movements of various kinds. Let me recall a few 

 well known instances. The flowers of the garden Escholtzia, as 

 well as those of the tulip, daisy, pimpernel, and many ether plants, 

 open widely during the day, but close at night. A similar 



