INTR on UCTION. 5 



and rational actions of men. They formulate the 

 existence of a different kind of mentality, which they 

 frequently call " instinct," " sagacity," etc. But this 

 old-fashioned way of disposing of the psychology of 

 the lower animals will soon become extinct. Com- 

 parative animal psychology is rising to the dignity 

 of a special science, and it has already fairly demon- 

 strated that the intelligence of the dog, horse, and 

 elephant, differs mainly in degree, and not in kind, 

 from that displayed by man. 



If animals have been regarded as mere automata 

 — as living machines moved from without — we 

 cannot be surprised that plants should still be un- 

 questionably placed in that category. To speak of 

 Vegetable Psychology would cause a smile to ripple 

 over the faces even of those who have granted the 

 identity of the intelligence between man and the 

 brute. But the near future may have occasion to 

 show there can be no life absolutely without /jrj/<r//^- 

 logical action — that the latter is the result of the 

 former. It may some day be shown that life is 

 conditioned by psychological action ; and that there 

 is in plants the equivalent of " instinct " in animals 

 — the power of gaining individual experience, and 

 of transferring such experience to descendants to 

 profit thereby, not altogether unconsciously ! 



It is true that natural selection, by weeding out 

 of existence all plants which cannot adapt themselves 

 to their environment, sternly insists upon the adapta- 



