Page:Popular Science Monthly Volume 32.djvu/712

692 no reason to doubt that genius is hereditary, though, from the obvious conditions of the case, it is rarely transmitted in like quality and degree from parent to child. The subject is too large to be advantageously considered here; but those interested in it will find a vast mass of striking information and ingenious reasoning in Mr. Francis Galton's admirable work on "Hereditary Genius."

A case is on record of a man who possessed the habit of sleeping on his back with the right leg crossed over the left. His daughter, while still an infant in the cradle, exhibited the same peculiarity. The possibility of imitation, conscious or unconscious, is here obviously excluded. A case has been reported to the writer of a man who had the habit of alternately flexing and extending his great toe while lying in bed. His grandson developed the same habit, though quite ignorant of his grandfather's peculiarity. Ribot records a curious instance of a domestic servant who exhibited an incurable vice of loquacity. She talked incessantly to any one who would listen, to animals, to inanimate objects, and even to herself. When upbraided with her folly, she said it was not her fault, as her father had possessed just the same habit, and had almost driven her mother distracted by it!

Instinct is strongly hereditary in animals, even under the most unfavorable conditions. Ducklings hatched by a hen take to water immediately on breaking their shell; and every one is familiar with the spectacle of the distracted mother wildly running to and fro on the margin of the duck-pond, while her youthful family, heedless of her terror, disport themselves delightedly upon its surface. If the eggs of the wild duck be placed under one of the domesticated species, the young, when their feathers are complete, immediately take to the wing. Birds hatched in confinement construct in their cages the same kind of nest as their more fortunate brethren of the same species build in the virgin forest. Many curious and apparently mysterious facts are explicable on the hypothesis of the permanence under changed conditions of traces of aboriginal instincts. Thus, the domesticated dog, even when thoroughly well cared for, is very fond of burying a bone in some secret spot—a lingering trace, probably, of the time when he ran wild in the woods, and the secreting of surplus food for a future occasion was a matter of practical importance to him. When the squirrel is reared in confinement, it stores away in a corner of its cage a portion of the nuts supplied to it, an instinctive preparation for the coming winter, unnecessary, indeed, for this individual squirrel, but highly important for its ancestors and congeners living in the wild state. Every one must have observed how difficult it is to make the common ass leap over a stream, however small. This unwillingness is not the result of an inherent incapacity for jumping, as the ass leaps over other obstacles with ease, while it hesitates obstinately at the tiniest streamlet. We have here, in all probability, a remnant of