45 2 Animal Life and Intelligence. 



This is sexual selection through preferential mating. And, 

 I think, the importance of these activities, their wide range, 

 and their perfectly, or at any rate incompletely instinctive 

 nature, justifies me in emphasizing this factor in the origin 

 of instinctive activities. It has hitherto, I think, not 

 received the attention it deserves in discussions of instinct. 



A few more words may here be added to what has 

 already been said on the influence of intelligence on 

 instinct. The influence may be twofold it may aid in 

 making or in unmaking instincts. We have seen that 

 instincts may be modified through intelligent adaptation. 

 A little dose of judgment, as Huber phrased it, often comes 

 into play. The cell-building instinct of bees is one which 

 is remarkably stereotyped ; and yet it may be modified in 

 intelligent ways to meet special circumstances. When, 

 for example, honey-bees were forced to build their comb 

 on the curve, the cells on the convex side were made of a 

 larger size than usual, while those on the concave side 

 were smaller than usual. Huber constrained his bees to 

 construct their combs from below upwards, and also 

 horizontally, and thus to deviate from their normal mode 

 of building. The nest-construction of birds, again, may 

 be modified in accordance with special circumstances. 

 And, perhaps, it is scarcely too much to say that, when- 

 ever intelligence comes on the scene, it may be employed 

 in modifying instinctive activities and giving them special 

 direction. 



Now, suppose the modifications are of various kinds 

 and in various directions, and that, associated with the 

 instinctive activity, a tendency to modify it indefinitely be 

 inherited. Under such circumstances intelligence would 

 have a tendency to break up and render plastic a previously 

 stereotyped instinct. For the instinctive character of the 

 activities is maintained through the constancy and uni- 

 formity of their performance. But if the normal activities 

 were thus caused to vary in different directions in different 

 individuals, the offspring arising from the union of these 

 differing individuals would not inherit the instinct in the 



