As the precautionary rules which medical science has to offer are in many cases unknown, and in more numerous intances unheeded, injudicious marriages are constantly being formed. Children are therefore daily born into the world, with dispositions more or less marked towards heredi tary affection. Much may even yet be done to stay the mischief commenced. Efforts to maintain the health of such infants cannot be instituted too early. By intelligent care, continued through life, the appearance of the disease may be suppressed, and in some cases the predisposition eradicated. The first attention should be directed to the nourishment of such an infant. It should not be brought up by hand. If it cannot be suckled by the mother, it must be placed at the breast of a healthy nurse. The child should be warmly clad, and carried daily in the open air, unless the weather be inclement. The use of the bath and other requisites to infantine health must not be lost sight of. This constant watchfulness over the well-being of the child should not be remitted during the whole period of youth. Great care ought also to be taken not to overexcite the brain by encouraging precocious exhibitions of talent. Active play m the open air with romping companions, will do more for the future of the child than any knowledge it can at an early age acquire with books. Much harm is done by competitive examinations about the period of puberty. This is especially the case in those inheriting a disposition to epilepsy or consumption. These diseases are at this age most liable to appear, and the intense application and undue anxiety which attend such examinations may develop them Those disposed to hereditary afflictions should extend then care of themselves even to the choice of their avocation. Such pursuits as are sedentary and exposed to the debilitating influence of impure, in-door air are to be avoided. So also are those which require at times exhaustive mental or bodily exertion. Regular exercise in the open air, by walking or riding, is of the utmost moment every day. Where there is a tendency to consumption, epilepsy, or insanity, it is particularly valuable, and can do more than is generally sup-Dosed to avert them.

Dr. "Winn speaks in strong terms of the value of cod-liver oil as a preventive remedy in inherited dispositions to disease. It is to be taken in small quantities (a teaspoonful three times a day is ordinarily sufficient). It must be con-tinued for such a long period of time as to become a customary portion of daily food.

We might dwell much longer upon the nature, prevention, and treatment of hereditary disease, as we have not exhausted the subject. But have we not said enough to impress upon the reader the prominence which it ought to occupy in the hygiene of the marriage relation ?

As a rule, diseases are transmitted directly from the parents to the children, thence to the grandchildren, and so on uninterruptedly from generation to generation. In some cases the transmission takes place from the grandparents to the grandchildren, one generation escaping altogether. This resemblance of a child to its grandparents or great-grandparents, rather than its own father or mother, is known under the scientific name of atavism.

It is owing to this influence that diseases and deformity, as well as strength and beauty, pass by one generation to appear in another. A child resembles in form or feature its grandfather, or it inherits the epileptic fits or the consumption for which its grandfather is remembered, the father being entirely healthy. A remarkable instance, which, however, is not solitary, of the influence of atavism is related by the celebrated anthropologist, Dr. Pritchard. A black woman, the wife of a black man, had a white child. In groat fear of her husband because of this, to her, unaccountable occurrence, she tried to conceal the child from him. When he saw it and noticed her trepidation, he said: " You are afraid of me because my child is white, but I love it the better for that, for my own father was a white man, though my grand-father and grandmother were both as black as you and myself; and although we came from a place where no white people were ever seen, yet there was always a white child in every family that was related to us."

Another manner in which disease may appear in the children through parental influence has been well pointed out by Dr. Elam. "The parents may be free from disease, yet produce unhealthy children, owing probably to some unfitness in the union; these affections stamp themselves as hereditary, by affecting all, or nearly all, the members of the family. Sir Henry Holland mentions a family consisting of three sons and one daughter, all of whom had a paralytic attack before the age of forty-five, though neither of the parents had suffered from anything similar; and another of a family where four children died in infancy from affections of the brain, without any of the relations having been so affected. I am acquainted with a large family, all of whom suffered when young from enlarged tonsils, and almost all of whom are short-sighted in the extreme, though neither father nor mother have experienced either inconvenience. At the Deaf and Dumb School in Manchester there were, in 1837, forty-eight children taken from seventeen families, of which the whole number of children was one hundred and six; amongst these, only one parent was known to have been similarly affected."

The likeness of a child to its grandparents rather than to its immediate parents is, although a noteworthy fact, one which does not excite much comment from us. But when, as is sometimes the case, the child partakes of the characteristics of a very remote ancestor or of the traits of some far removed representative of a collateral line, descended from a common progenitor, then a feeling of astonishment arises.

Such examples are, however, only illustrations of the law of atavism just mentioned.

The physical characteristics of the age of the parent at the time of conception are transmitted. Maturity reproduces itself. The stag, when born of mature parents, grows faster and stronger than when born of young parents. Old age is inherited. Breeders of animals are well aware of the inferior character of the progeny of old parents. The children of parents far advanced in years are peculiarly prone to senile affections, and from birth bear the marks of senility. Dr. Prosper Lucas, a French author who wrote a work of 1562 pages on the subject of inheritance, gives among others the following illustrations of the above remarks.

" The wife of one of the coachmen of Charles X. became, to the surprise of himself, her husband, and her children, who were thirty or forty years old, enceinte at sixty-five years of age. Her pregnancy followed the usual course, but the child presented all the marks of the senility of the parents.

"Marguerite Cribsowna, who died in 1763, aged one hundred and eight years, was married for the third time when aged ninety-four, to a man aged one hundred and five. From this union were born three children, who were living at the death of their mother; but they had gray hair and no teeth ; they lived only upon bread and vegetables. They were sufficiently tall for their age but had the stoop, the withered complexion, and all the other signs of decrepitude."

While speaking of the physical effects of inheritance wo cannot forbear to notice a form of bodily weakness impressed upon certain social classes by transmission. Mr. Whitehead, a writer upon " Hereditary Diseases," says : -

" The offspring of parents, both possessing great intellectual capacities, are liable to inherit such capacities in still greater proportion; but along with this refinement, so to speak of the cerebral faculties, is usually conjoined a degree of physical delicacy, or of disproportionate development, which con stantly endangers organic integrity; and the peril is further increased if education be urged, in early life, beyond a certain limit. The mind which seemed capable of comprehending intuitively the most abstract problem, is soon shaken and unbalanced, merging at length into insanity.