PuRNELL. — 0)1 the Animal Mind in Organic Evolution. 251 



stimuli. Experience teaches every raan that his own mental 

 capabilities are confined within certain limits, and while man- 

 kind has accmxiulated vast stores of ktiowledge by the acquisi- 

 tions of successive generations, there is no reason to suppose 

 that men possess greater mental capacity now than they did 

 in the days of the ancient Greeks and Eomans. We know, 

 too, that nations once intellectually powerful have ceased to 

 be so. Bain has striven to prove that the reason why man's 

 mental powers are limited is because the number of nervous 

 elements by means of which the mind acts in the human 

 body is necessarily limited ; and whatever of truth there 

 may be in this theory will apply also to the lower animals. 

 There is an old age of the species as well as of the in- 

 dividual, and the time comes when the species can learn no 

 more. 



Before one species can be transformed into another, how- 

 ever gradual the transformation, there must at some stage be 

 a new mental departure. Before the reptile could have been 

 converted into a bird the reptile must have manifested bird- 

 like desires. Before the ancestor of the ant could have taken 

 the first step which ultimately led to the present social organi- 

 zation of this insect it must have manifested a desire and 

 aptitude to live and labour in common with its fellows, and 

 this desire and aptitude, gaining strength through long genera- 

 tions, has not only produced a complex social economy which 

 is truly remarkable, but likewise resulted in the physical or- 

 ganization of the insect being fundamentally altered to facili- 

 ' tate division of labour. The same observations apply to the 

 honey-bee. In both cases we must ascribe the origin of the 

 special physical development of the insect to its peculiar 

 mental organization. It has often been urged as an argument 

 against Darwin's theory of development that slight modifica- 

 tions of bodily structure could seldom be of any use to an 

 animal, or serve to originate novel structures. No doubt this 

 is true if we merely regard such modifications as of them- 

 selves assisting the animal in the struggle for existence, 

 but if we view them as means whereby individuals with 

 a slightly different mental character from the rest of the 

 species can give vent to their idiosyncracies, such modifi- 

 cations assume a greater importance. They may be of 

 no consequence in an animal of the ordinary mental capacity 

 of its race, but of great importance to one possessing in- 

 dividuality of character. 



The climbing-perch {Perca scandens), of Tranquebar, 

 climbs the fan palm in search of certain crustaceans upon 

 which it feeds. When climbing it suspends itself by its open 

 gill-covers, deflects its tail laterally upwards, so as to bring to 

 bear upon the bark some little spines with which its anal fin 



