GENERAL TENDENCY AND HEREDITARY DISPOSITION.
Experience teaches that not all men under equal conditions accu mulate fat, but that many persons may be safely as immoderate in eating and as inactive as others in whom within a brief period an ample accumulation of fat in the body becomes perceptible and in whose families a pronounced tendency to an abnormal fat formation and deposition has been hereditary through many generations. Thus we find in the literature so large a number of cases recorded, and every practitioner has observed so many similar instances, that the hereditary disposition to corpulence is established as an undis puted fact. StatisticS permit the assumption that among the corpu lent patients coming under observation at least fifty per cent. have an hereditary tendency to this disturbance of nutrition.
The hereditary disposition usually manifests itself in early life by an abnormally great development of fat, either in all the chil dren or only in a certain larger or smaller number; but on the other hand it may not appear until a more advanced age, especially under favorable nutritive conditions, either in all or in only a few members of the family, or in women after the first pregnancy. Fur thermore, the hereditary tendency in general is said to be more fre quent in women than in men. As in other hereditary taints, that leading to the hyperplasia of fat may skip one or more generations and pass from the father to the grandchild. But the statement that the heredity is more pronounced in the same sex, passing from the father to the son and from the mother to the daughter, has not been generally confirmed (Kisch.). I myself have likewise thus far failed to find any confirmatory evidence.
To cite a few instances from the literature of obesity in early life: Barkhausen reports the case of a boy aged fifteen months weighing 35 pounds; Heyfelder, that of a girl aged three and a half years weighing 491 pounds; Kastner, that of a girl aged four years weighing 82 pounds; Benzenberg, that of a girl aged four years Weighing 137 pounds; Weinberger, that of a boy aged five years weighing 189 pounds; Don, that of a Hindoo aged ten years weighing 266 pounds.
In more recent times Wolf has described a new-born child weighing over 18 pounds. Kisch observed a girl of six weighing 110 pounds; one of eleven, 132 poundA; one of sixteen, 312 pounds. I myself have observed several families in which all the children, numbering two, three, and five respectively, showed an enormous development of fat; in one case a girl of seven weighing 124 pounds. It would not be difficult to swell these figures greatly with cases from the literature.
It is as yet impossible to give a satisfactory explanation of the causes upon which the hereditary tendency to an abnormal accumu lation of fat in the body may be based. Many attempts have been made in this direction.
1. We might try to ascribe the cause to a congenital difference with reference to the quantity, functional and proliferative power of a preformed fatty tissue existing as an independent organ, or of the fat-bearing connective tissue with its vascular apparatus. The as sumption is not without some supporting facts, since the question as to the histological character of the adipose tissue has not been finally decided, as there are different views concerning the formation and deposition of fat. A priori, therefore, the idea cannot be rejected that the hereditary tendency may possibly have an histological foun dation and that the inherited quality of the preformed adipose tissue may become the predisposing cause of obesity.
2. We might also assume a congenital difference in the tropho plastic energy of the tissues of the body by which the amount of de posit of albumin may be determined. Persons whose albumin-bear ing tissue, especially muscular and glandular tissue, exhibits a strong power of growth, in order to satisfy this cellular vital requirement need a larger amount of nutriment and therefore are less liable to be come obese than others whose hereditary constitution lacks this energy of growth and nutrition.