Pitt, Napier, Fox, Herschel, Darwin, and many more, is evidence that mind and will are as transmissible as complexion and stature. This is more apparent in a country like England, where the institutions and customs favor and confirm the results of heredity, than in America, where there is no law of entail, and as yet little of the ambitious founding of families.
There is abundant testimony to prove that heredity can be moral as well as physical and intellectual. The Stuarts were as constant in the presentation of certain moral traits as the family of the Churchills or the American Adamses are in others. Imprudence, penuriousness, dishonesty, or good judgment, once thoroughly established in a stock, persists with quite as much tenacity as the familiar eyes or nose. The inheritance by posterity of the changes wrought on individuals by their experience is the basis of the modern explanation of the growth of instinct and the evolution of human intelligence. Darwin has developed this theory in a masterly manner. He gives as an illustration that between the finished skill of the honey-bee and the rude capabilities of the humble-bee stand the intermediate powers of the Mexican melipona. This last insect constructs a comb of wax, almost regular in form, consisting of cylindrical cells, in which the larvae are hatched, and a certain number of large cells to hold its store of honey. The latter cells are nearly spherical and situated at a considerable distance from each other. Now, any slight variation of organization or instinct, by which the melipona would construct its cells more uniformly and compactly, would economize its wax and labor, and bring it up toward the plane of the honey-bee. The generations of insects succeed each other so rapidly that no modification can be detected among species low in the scale. Honey-bees, however, are not possessed of unadaptable and rigid instincts, for they have been observed to spring arches and buttresses in their hives to avoid glass rods purposely inserted. An organism's advantage plainly lies in an increase of its skill and ingenuity, and any slight advance made by individuals is preserved by heredity, persists in tendencies and habit, and becomes fixed as instinct.
The development of intelligence among mankind is accounted for in the same manner: efforts at first painfully made by our ancestors in new paths were at last rewarded by the facility that comes with repetition; their immediate descendants were born with new aptitudes and an organization with a wider range of powers; the acquisitions thus gained and transmitted have grown into the varied faculties of the men and women of to-day. "Mankind," Comte says, "is as one man, always living and always learning." The passing away of one generation and the birth of another do not interfere with the constant progress of the race.
The method applied to the explication of the growth of instinct and intelligence has been used by Darwin in approaching the problem
