evident in the general dimensions of the brain, the principal organ of that system; it is very often apparent in the size, and even in the form, of the cerebral convolutions. This fact was observed by Gall, who thereby accounted for the transmission of mental faculties. We need not here dwell upon this point, for we shall have frequent occasion to revert to it in the course of the present work. Heredity of the internal elements occurs in the fluids of the organism, as well as in the solid parts: the blood is more abundant in some families than in others, and this superabundance transmits, or may transmit, to the members of such families, a predisposition to apoplexy, hemorrhage, and inflammation. Thus there exists in some families such a liability to hemorrhage that even the prick of a pin may cause in them a flow of blood that cannot be checked. The same may be said with regard to the bile and the lymph. Nor is it merely, as might be supposed, the structure, whether internal or external, that is thus transmissible; some quite peculiar characteristics of the mode of existence pass from parent to child. Heredity governs the subordinate no less than the dominant characteristics. Thus fecundity, length of life, and those purely personal characteristics which physicians call idiosyncrasies, are hereditarily transmitted. A few facts will confirm this. There is no doubt of the influence of heredity on the reproductive power. Some families are noted for their fecundity, and this fecundity descends either through the father or through the mother. A mother gave birth to twenty-four children, among them five girls, who in turn gave birth to forty-six children in all. The daughter of this woman's son, while still young, was brought to bed with her sixteenth child. (Girou.) The sons, daughters, and grandchildren of a couple who were the parents of nineteen children were nearly all gifted, says Lucas, with the same fecundity. Several families belonging to the old French nobility possessed extraordinary powers of propagation. Anne de Montmorency (who when over seventy-five years of age was still able, at the battle of St. Denis, to break with his sword the teeth of the cotch soldier who gave him his death-blow) was the father of twelve children. Three of his ancestors—Mathieu I., Mathieu II., and Mathieu III.-had altogether eighteen children, of whom fifteen were boys. The son and grandson of the great Condé reckoned nineteen children between them; and their great-grandfather, who was slain at Jarnac, had ten. The first four Guises had, in all, forty-three children, thirty of them boys. Achille de Harlay, father of the first President, had nine children; his father, ten; his great-grandfather, eighteen. In some families this fecun dity has persisted for five or six generations.1 It is now generally understood that longevity depends far less on race, climate, profession, mode of life or food, than on hereditary transmission. If we consult special treatises on this subject, we find centenarians as well among blacks as among whites; in Russia and Scotland as in Italy and Spain; among those who take the greatest care of their health as among those who have led the hardest lives. A collier in Scotland prolonged his hard and dreary existence over one hundred and thirty-three years, and worked in the mines after he was eighty. Similar facts are to be met with among prisoners, and even galley-slaves. The average of life,' says Dr. Lucas, 'plainly depends on locality, hygiene, and civilization; but individual longevity is entirely exempt from these conditions. Everything tends to show that long life is the result of an internal principle of vitality, which privileged individuals receive at their birth. It is so deeply imprinted in their nature as to make itself apparent in every part of their organization.' This kind of heredity has long been observed in England, where life-assurance companies require information as to the longevity of the ancestors of those who desire to effect an insurance. There are, also, on the other hand, many families in which the hair turns grey in early youth, and in which the vigour of the physical and intellectual faculties fails prematurely. In others, early death is of such common occurrence that only a few individuals can escape it by great precaution. In the Turgot family the fifty-ninth year was rarely passed. The man who made that family 1 Benoiston de Châteauneuf, Mémoire sur la Durée des Familles Nobles en France. illustrious, when he saw that fatal term approaching, remarkedthough he had then every appearance of health and strength—that it was time for him to put his affairs in order, and to finish the work he had then in hand, because in his family it was usual to die at that age. He died in fact at the age of fifty-three. The immunity from contagious diseases, and especially from small-pox, with which some families are endowed, is a well-established fact. Heredity may transmit muscular strength, and the various forms of motor energy. In ancient times there were families of athletes, and there have been families of prize-fighters. The recent researches of Galton as to wrestlers and oarsmen show that the victors generally belong to a small number of families among whom strength and skill are hereditary. As for motor energy, a point of special importance in horses, experience long ago taught breeders that speed, on the turf-just like faulty action, or cribbiting is transmitted. Among men there are families nearly all of whose members are possessed of exquisite dexterity and grace of movement. Heredity has oftentimes transmitted a talent for dancing, of which the celebrated Vestris family is an example. It is the same with regard to the voice. Every animal possesses the voice peculiar to its kind; but even individual characteristics are transmitted; as, for instance, stammering, speaking through the nose, and lisping. There are many families of singers, and there are also families that have no ear at all for melody. Loquacity, too, is hereditary-Most of the children of talkative persons,' says Dr. Lucas, are chatterboxes from the cradle. Words-idealess, aimless, and unbridled-appear in them to be prompted by a sort of elastic spring over which they have no control. We once saw at a friend's house a servant-girl of irrepressible loquacity. She would talk to people, who could scarcely get in a word edgewise; she would talk to dumb beasts and to inanimate things; she would talk aloud to herself. She had to be sent away. "But," said she to her employer, "it is no fault of mine: it comes to me from my father; the same fault in him drove my mother distracted; and one of his brothers was like me." The heredity of anomalies of organization is a well-ascertained fact. One of the strangest and best known instances of this is the case of Edward Lambert, whose whole body, with the exception of the face, the palms of the hands and the soles of the feet, was covered with a sort of carapace of horny excrescences which rattled against each other. He was the father of six children, all of whom, from the age of six weeks, presented the same singularity. The only one of these who survived transmitted it to all his sons; and this transmission, going from male to male, was kept up during five generations.1 Albinism, rickets, lameness, ectrodactylism and polydactylism, harelip-in fact, all deviations from the type, whether they be the result of an excess or of an arrest of organic development are transmissible. These facts are of great interest, as showing that the individual type is subject to the law of heredity, no less than the specific type. It is a disputed question whether we must conclude that deviations from the specific type, anomalies of all kinds-such as strabismus, myopia, atrophy and hypertrophy of members-remain fixed for ever, or that heredity in such cases is only of a restricted and temporary nature. These individual deviations from law are sometimes transmitted, sometimes not. Experience would appear to show that there is a tendency towards a return to the primitive type. Thus, in the Colburn family, which presented one of the most curious instances of sexdigitism-the members of this family had each a supernumerary finger and toe-the anomaly continued. through four generations; but, says Burdach, the normal was steadily gaining on the abnormal. The return, therefore, to the normal type took place rapidly. This brings us to the important and difficult question of the heredity of acquired modifications. All of which we have spokenthe transmission of internal and external structure, of longevity, fecundity, and idiosyncrasies-is involved in the very nature of the being as virtually constituted by the act of generation, and belongs 1 Philosophical Transactions, vol. xvii. and vol. xlix. to its essence; hence it is perfectly natural that all these qualities and modifications should be transmitted to its descendants. But man cannot, any more than other animals, live without contracting habits; without undergoing, under the influence of circumstances, or from an excess or deficiency in the exercise of each organ, modifications of all kinds, which remain fixed in him. Are these transmitted? Are they destined to perish with the individual, or do they become in his descendants a new, an acquired character? The brain, for example, like every other organ, is developed by exercise. If this increase, whether of size or of energy, is transmissible, some important consequences for the mental faculties must be the result; progress will then be determined, not only outwardly and traditionally, but inwardly and organically. We will consider this question in the course of the work; for the present we consider only the physiological phenomena. Habit is defined to be an acquired disposition. We ask if any purely individual habits are transmitted. Instances of this are cited. Girou de Buzareingues observes that he had known a man who had the habit, when in bed, of lying on his back and crossing the right leg over the left. One of his daughters had the same habit from birth; she constantly assumed that posture in the cradle, notwithstanding the resistance offered by the napkins. 'I know many girls,' says he, 'who resemble their fathers, and who have derived from them extraordinary habits, which cannot be attributed either to imitation or to training, and boys who have habits derived from their mothers.1 But it is impossible to enter upon any details on this subject.' Darwin notes the following instance, which came under his own observation :—a boy had the singular habit, when pleased, of rapidly moving his fingers parallel to each other; and when much excited, of raising both hands, with the fingers still moving, to the sides of his face on a level with the eyes; this boy, when almost an old man, could still hardly resist this trick when much pleased, but, from its absurdity, concealed it. He had eight children. Of these, a girl, when pleased, at the age of four and a half years, moved her fingers in exactly 1 De la Génération, 282. |