at does he know about maple trees and the spring
flow of sap? Nothing as a mental concept, as a bit of concrete
knowledge. He often finds the sap flowing from a crack or other wound
in the limbs of a maple, and he sips it and likes it. Then he sinks
his teeth into the limb, as his forbears undoubtedly did.

When I was a boy and saw, as I often did on my way to school, where a
squirrel had stopped on his course through the woods and dug down
through two or three feet of snow, bringing up a beech-nut or an
acorn, I used to wonder how he knew the nut was there. I am now
convinced that he smelled it.

Why should he not? It stands the squirrel in hand to smell nuts; they
are his life. He knows a false nut from a good one without biting into
it. Try the experiment upon your tame chipmunk or caged gray squirrel,
and see if this is not so. The false or dead nut is lighter, and most
persons think this fact guides the squirrel. But this, it seems to me,
implies an association of ideas beyond the reach of instinct. A young
squirrel will reject a worthless nut as promptly as an old one will.
Again the sense of smell is the guide; the sound-meated nut has an
odor which the other has not. All animals are keen and wise in
relation to their food and to their natural enemies. A red squirrel
will chip up green apples and pears for the seeds at the core: can he
know, on general principles, that these fruits contain seeds? Does not
some clue to them reach his senses?

I have known gray squirrels to go many hundred yards in winter across
fields to a barn that contained grain in the sheaf. They could have
had no other guide to the grain than the sense of smell. Watch a
chipmunk or any squirrel near at hand: as a friend of mine observed,
he seems to be smelling with his whole body; his abdomen fairly
palpitates with the effort.

The coon knows when the corn is in the milk, gaining that knowledge,
no doubt, through his nose. At times he seems to know enough, too, to
cut off his foot when caught in a trap, especially if the foot becomes
frozen; but if you tell me he will treat his wound by smearing it with
pitch or anything else, or in any way except by licking it, I shall
discredit you. The practice of the art of healing by the application
of external or foreign substances is a conception entirely beyond the
capacity of any of the lower animals. If such a practice had been
necessary for the continuance of the species, it would probably hav