Page:Popular Science Monthly Volume 14.djvu/370

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356
THE POPULAR SCIENCE MONTHLY.

HEREDITY.
By GEORGE ILES.

HAWTHORNE in his masterpiece, the "Scarlet Letter," makes his heroine, Hester Prynne, a woman who has sinned, resolutely refuse to tell the name of her partner in guilt when the Puritan inquisitors urge her to do so. The ministers of justice and vengeance then turn to her child, and sharply scrutinize her features, to find if possible some trace of her father's look, that the wrong done may be punished. Here, too, they are unsuccessful—the face of the little elf tells no story that they can read, gives them no clew in their task of detection; they are obliged to withdraw, baffled and surly. This incident in the greatest of American romances is true to experience; while the inheritance from parents of form and character is general, yet it is not universal, and while some of the exceptions, when explained, afford very interesting studies of the play of natural forces, too subtile to be noticed by simple inspection of their results, yet many anomalies exist in heredity which the science of to-day is quite incompetent to explain.

The inheritance of the peculiarities of physical structure is a matter of daily and hourly observation, and the minute fidelity of it is at times very remarkable. Agassiz placed on record cases where traces of surgical operations had been transmitted. Sometimes parent and child are not only alike in form and feature, but even in tricks of tone and gesture, handwriting and gait.

The predisposition to certain diseases, like gout or insanity, often developed after maturity, is transmissible; and also the liability to die about a certain age. The famous Turgots, for more than a century, rarely exceeded fifty years of age; and insanity often appears after the meridian of life in several successive generations of a family. The remarkable faithfulness of reproduction in the majority of cases is a fact somewhat parallel to the growth and maintenance of an organism, wherein, with the constant succession of cells each of brief existence, substantial identity is kept up. There do not seem to be very marked differences in babes, yet from the same food one will become a man of muscle and energy, another of nerve and brain, a third a portly man of ease-loving habits. All the original peculiarities of each tiny human nucleus pick out from a common nourishment elements like themselves, rejecting the rest.

Inheritance is not only physical, but intellectual as well; great ability in mathematics, painting, music, and other departments of effort, has clearly been received at birth in many thousands of examples. The Bach family for two hundred years maintained exalted rank in music. The direct succession of very able men in the families of