Page:Popular Science Monthly Volume 14.djvu/373

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HEREDITY.
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organism retain substantially the same form, that when art produces a rapid modification of structure, or desires to seize upon a valuable and marked variety, repeated and careful selection is required to give it permanence.

The principle of atavism explains the curious resemblance often seen in a human family between uncle and nephew; the likeness in such cases is derived from some common ancestor, the grandfather most usually.

Mr. Galton, in his work on "Hereditary Genius," adopts the statistical method to prove that illustrious men arise oftenest from families displaying eminent talent, and have relatives approaching to themselves in ability in a degree proportioned to the nearness of kinship. A man of genius is much more likely to have a remarkable father or son, than a nephew or cousin. Great men, Galton says, seem to arise like islands, isolated and unaccountable; but this is an illusion—they are given to us usually by parents unknown from the necessarily narrow limitations of fame; islands are but the tops of hills whose whole extent is hidden by obscuring ocean. Yet the exceptions to this rule are very numerous: why should Cromwell, Milton, Goethe, and so many others, leave behind them unworthy children? Was it from unfortunate mating with an inferior mother, or because the vitality, physical and mental, was too much drawn upon by the individual life for worthy continuation? How can it be explained that men like Burns and Faraday should come up from families in which even enthusiastic biographers can find nothing to distinguish them from their neighbors?

The wide unlikeness frequently observed between parents and children in talent and character suggests an analogy with a familiar fact in chemistry. A compound's color, weight, and other properties, may be changed almost beyond recognition by adding or eliminating a single element. It is somewhat so in human nature; a father of warm passions or strong acquisitive impulses may transmit all his traits to a son, except prudence; and the omission may cause much sympathy for a reputable and worthy man's being afflicted with a boy so unlike himself. If the lack in inheritance be in perseverance and application, of what value are splendid talents without them?

A lens externally not to be distinguished from a perfect one may, from some slight defect in composition or handling, give images blurred and distorted, instead of true and beautiful. A chain is no stronger than its weakest link, and a small lack or discordance in the elements of character may exclude it from the exacting demands of high place. We often hear regrets that men of genius so rarely have living descendants, but we must not overrate the persistence of ordinary families: taking the first eleven names of acquaintances that occurred to me, I found that three of them were in a fair way of being the last of their race; every old person can recollect the dying out of many once numerous families.