448 Animal Life and Intelligence. 



basis in intelligence ; many of them probably have not. 

 And tbougb tbe great majority of individually acquired 

 modifications of babits bave owed tbeir origin to intelligent 

 direction, still it is conceivable tbat some of tbem bave 

 not. An animal may bave been forced by circumstances to 

 modify its babits, witbout any exercise of intelligence ; and 

 tbis modification, forced, tbrougb changed conditions, upon 

 all tbe members of a species, may, tbrougb inheritance, 

 bave passed into tbe stereotyped condition of an instinct. 

 Under eacb factor, tben, we bave two several categories. 



1. Elimination . 



2. Selection 



3. Inheritance 



{ a. of unintelligent activities. 

 " \ b. of intelligent activities 



(a. of unintelligent activities. 

 ' \ b. of intelligent activities. 

 a. of unintelligent activities. 



{£ 



of intelligent activities. 



In all cases, however, where intelligence has been a co- 

 operating factor, tbis intelligence has lapsed so soon as the 

 activity became truly instinctive. 



From the co-operation of the factors it is almost im- 

 possible to give examples which shall illustrate tbe exclu- 

 sive action of any one. The following table must therefore 

 be regarded as indicating the probable predominance of the 

 factor indicated : — 



{ 

 {I 



a. Caterpillars spinning cocoons. 



b. Instincts of social hymenoptera. 

 a. Drumming of snipe. 



Procedure of Queensland bower-bird. 

 f a. Ants forming nests in trees in flooded parts of Siam. 

 \ b. Instinctive fear of man. 



In speaking of the instinct of caterpillars spinning 

 cocoons as unintelligent, I am regarding the final purpose 

 of the activity. Intelligence may very possibly bave come 

 into play in modifying the details of procedure. In giving 

 the drumming of snipe as an example of unintelligent 

 activities furthered by selection, I am assuming that it has 

 a sexual import, and that the activity correlated with a 

 narrowing of tbe tail-feathers was not, in its inception, 

 intelligently performed with the object of exciting sexual 



