these means of defense have been multiplied over and over again for still greater precaution, so that the final outcome is a seed almost absolutely fortified against the onslaught of every possible aggressor.
In England, where there are only three native nut-eaters of any importance—the squirrel, the dormouse, and the nut-hatch—most of our indigenous trees have not found it necessary to arm themselves to any large extent against this class of depredators; and consequently there are only three kinds of nuts in the truly aboriginal English flora, namely, the beechnut, the acorn, and the filbert. Chestnuts, walnuts, and horse-chestnuts are cultivated in the British Isles to some slight extent, but they do not thrive, and the two former seldom produce fertile nuts. These three native English kinds, therefore, may be taken as good examples of very simple and undeveloped forms of nuts, far inferior to the most advanced American specimens. The acorn, in all countries, is comparatively little armed with protective coverings: it has only a thin shell, and is guarded from depredations mainly by its slightly bitter taste, as well as by its cup, or saucer, which acts as a barrier against the attacks of insects who try to lay their eggs at its tender base. Beechnuts have a rather more leathery shell, and are externally protected by their prickly husk, which makes them difficult for the delicate noses of squirrels to tackle as they grow upon their native boughs. Filberts, specially exposed to the attacks of the cunning dormouse and the persistent nut-hatch, are far more effectually guarded by a double coat-of-mail: their shell is solid and woody in texture, while their outer husk, which completely envelops them from stem to tip, is thickly sprinkled with stiff and annoying hairs, very painful to our human fingers, and still more so, no doubt, to the tender skin on the naked noses of the inquiring rodents.
None of these nuts belong to the same family as the hickory; they are all independent modifications of totally different forms, which have simultaneously hit on somewhat the same protective method. But on the Continent of Europe, where a larger number of nut-devouring animals are to be found, the hickory tribe is represented by the common walnut. Everybody must have noticed (in conducting his biological studies at dessert) that the distribution of the two lobes which make up the kernel in the walnut is extremely like that of the hickory; and the resemblance is equally close in all other important structural matters. The walnut shows decidedly more protective care in its coverings than any of the few and simple English nuts. Its outer husk is very bitter and nasty—so nasty that even a little of the flavoring matter off fresh walnuts clinging to one's fingers is enough to give a very unpleasant taste to any food one may touch afterward; and the inner shell, though evidently rendered easier to open for the lazy human consumers by being previously kiln-dried to preserve the kernel from decomposing, is in its native state extremely hard to crack, and
