SPECIAL SENSES 



diversity 



their sensibility." From this experiment he 

 justly concludes ''that the animal and plant 

 organisms have with their common structure 

 common properties, and if we call one of these 

 properties sensibility in the animal, we must 

 call it thus in the plant." 



Modern investigations have more and 

 more confirmed the fundamental unity of Primafy 

 the primary functions of animals and plants, «nity 

 but at the same time have increasingly em- ^^* ^^^^^ 

 phasized the great divergence they have ob- 

 tained in developing along lines of specific 

 adaption to the needs of the energy -liberating 

 animal on the one hand, and of the energy- 

 conserving plant on the other hand. Until 

 recently the difficulty of interpreting the 

 movements of plants without recourse to the 

 assumption of a structural device in some way 

 comparable to the neuro-muscular mechanism 

 of animals has seemed very great. But the 

 wonderful advance in studying the plant's 

 minute structure and general physiology dur- 

 ing the last few decades has revealed unsus- 

 pected and ample vegetal methods of bringing 

 about movement as the result of stimulation, 

 which bear no analogy and no counterpart to 

 those of animals, but have been developed 

 with a trend as different as the physical basis 

 of tissues in the plant is different from that in 

 the animal. 



