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 likewise 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 intelligence, 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 laying 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 
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