n.i THE NATURE OF INSTINCT 169 



to germ, waiting for chance to add fresh improvements 

 to it by the same method. The other type regards instinct 

 as lapsed intelligence: the action, found useful by the 

 species or by certain of its representatives, is supposed 

 to have engendered a habit, which, by hereditary trans- 

 mission, has become an instinct. Of these two types of 

 theory, the first has the advantage of being able to bring 

 in hereditary transmission without raising grave objection; 

 for the accidental modification which it places at the 

 origin of the instinct is not supposed to have been acquired 

 by the individual, but to have been inherent in the germ. 

 But, on the other hand, it is absolutely incapable of ex- 

 plaining instincts as sagacious as those of most insects. 

 These instincts surely could not have attained, all at once, 

 their present degree of complexity; they have probably 

 evolved ; but, in a hypothesis like that of the neo-Darwin- 

 ians, the evolution of instinct could have come to pass only 

 by the progressive addition of new pieces which, in some 

 way, by happy accidents, came to fit into the old. Now 

 it is evident that, in most cases, instinct could not have 

 perfected itself by simple accretion: each new piece really 

 requires, if all is not to be spoiled, a complete recasting 

 of the whole. How could mere chance work a recast- 

 ing of the kind? I agree that an accidental modifica- 

 tion of the germ may be passed on hereditarily, and may 

 somehow wait for fresh accidental modifications to come 

 and complicate it. I agree also that natural selection 

 may eliminate all those of the more complicated forms 

 of instinct that are not fit to survive. Still, in order that 

 the life of the instinct may evolve, complications fit to 

 survive have to be produced. Now they will be produced 

 only if, in certain cases, the addition of a new element 

 brings about the correlative change of all the old elements. 

 No one will maintain that chance could perform such a 



