WAYS OF NATURE 



birds would adopt the new sites as a matter of course. 

 Or take the phcebe, which originally built its nest 

 under ledges, and does so still to some extent. It, 

 too, would find a more abundant food supply in the 

 vicinity of farm-buildings and bridges. The pro- 

 tected nesting-sites afforded by sheds and porches 

 would hkewise stimulate its nesting-instincts, and 

 attract the bird as we see it attracted each spring. 



Nearly everything an animal does is the result of 

 an inborn instinct acted upon by an outward stimu- 

 lus. The margin wherein intelligent choice plays a 

 part is very small. But it does at times play a part 

 — perceptive intelUgence, but not rational intelli- 

 gence. The insects do many things that look like in- 

 telligence, yet how these things differ from human 

 intelligence may be seen in the case of one of our soli- 

 tary wasps, — the mud-dauber, — which sometimes 

 builds its cell with great labor, then seals it up with- 

 out lajdng its egg and storing it with the accustomed 

 spiders. Intelligence never makes that kind of a 

 mistake, but instinct does. Instinct acts more in 

 the invariable way of a machine. Certain of the 

 solitary wasps bring their game — spider, or bug, 

 or grasshopper — and place it just at the entrance 

 of their hole, and then go into their den apparently 

 to see that all is right before they carry it in. 



Fabre, the French naturalist, experimented with 

 one of these wasps, as follows : While the wasp was 

 in its den he moved its grasshopper a few inches 

 158 



