46 THE PLAY OF ANIMALS. 



useful becomes the necessary as soon as it comes to be 

 possible." * 



Darwin himself attached greater importance to con- 

 genital qualities than to the inheritance of acquired ones, 

 as clearly appears in his definition of instinct. He says 

 in his Origin of Species: "It would be the most serious 

 mistake to suppose that the greater number of instincts 

 have been acquired by habit in one generation, and then 

 transmitted by inheritance to successive generations. It 

 can be clearly shown that the most wonderful instincts 

 with which we are acquainted — namely, those of the 

 hive-bee and of many ants — could not possibly have been 

 thus acquired." And in the Descent of Man: " Some 

 intelligent actions — as when birds on oceanic islands 

 first learn to avoid man — after being performed during 

 many generations become converted into instincts, and 

 are inherited. . . . But the greater number of the more 

 complex instincts appear to have been gained in a wholly 

 different manner through the natural selection of varia- 

 tions of simpler instinctive actions." f 



We see, then, that Darwin derives instinct from two 

 distinct sources. The principal source is natural selec- 

 tion; the less important is the inheritance of intellec- 

 tual capacity and then of acquired characters. Eo- 

 manes follows him closely in his distinction between 



* A. Weismann, Amphimixis, Jena, 1891, p. 159. [The anfhor 

 here includes a quotation from Kant's Physische Geo.ijrraphie (TT. 

 Th., Abs. i, § 3) showing that that philosopher had the idea of pro- 

 gressive development resulting from artificial selection, which in 

 Darwin's mind led to the doctrine of Natural Selection. He refers 

 also to Fischer's Geschichte d. neu. Philos., third edition, iii, p. 

 161.] 



■f The Descent of Man, chap, ii. See also a similar passage 

 from Darwin's manuscript in Romanes's Mental Evolution in Ani- 

 mals, p. 209. 



