THE MOST IMPORTANT DISEASES OF THE SKIN ;4carcely an infant or young child entirely escapes some kind of skin affection, be it ever so slight: one suffers from intertrigo, another from eczema and another from urticarial manifestations. Very few children remain absolutely free from skin troubles. This is easily explained by the facts that the skin of the newborn has a special tendency for such disorders; that a large number of interior or exterior injuries exert their influence upon the skin of the newborn; that heredity and various diatheses contribute to the abnormal frequency of diseases of the skin.
The skin of the newborn infant i.s soft and tender, in which condition it remains during the finst few years of life; the epithelium is dispro portionately thin and ale epithelial cells are less coherent than those of the adult. The corneal layer has very little power of resistance, and there is slight but regular desquamation. The papillary layer which is only slightly developed, has a very rich vascular plexus which in the first period of life is much more sensitive than later. The blood vessels therefore easily allow serum to exude, which may enter the connective tissue as in urticaria, or may lift the epithelium in the shape of small ve.sicles. The sweat glands are less strongly developed than the sebaceous glands, resulting in a very strong secretion of oil which finds expression in a great accumulation of seborrhmic masses in early childhood. Again, soon after birth a change of the hair takes place which has already been prepared (luring the last part of the fadal life; and all these factors contribute to a predisposition for skin affections. It is especially the overaccumulation of oil which irritates the skin and is responsible for quite a series of dermatoses. After the first, period of childhood the skin follows a regular course of development and only at the time of puberty is the skin again disturbed. We know that at this: period, when the genitals develop, a marked growth of hair takes place and that the epithelial glands undergo decided development. Consequently
there is aside from the growth of hair a considerable accumulation of corneal cells in the follicular infundibula. frequent inflammation in and around the follicles (appearance of eomedones and acne pimples) and an increased reappearance of seborrhceic manifestations.
In the second place the body of an infant is exposed to exterior and interior injuries. We know that both the excretions and secretions of the skin may have an irritating effect. There is an overflow of saliva or, the milk runs down the nursing baby's face irritating the skin by decom position, the feces and urine soil the child and through insufficient atten tion and cleanliness are the cause of many a dermatitis so frequent in the nursing period. On the other hand, excess of cleanliness acts just as injuriously upon the skin as does its absence through decomposition. Frequent washings and rubbings easily deprive the skin of its fat pro tection and remove the sebaceous secretions, exposing the dry and thin epidermis to all kinds of injurious exterior influences.
We know further how vigorously children scratch themselves and that, contrary to the habits of adults, give themselves up to the irritation of itching, thereby- effecting the entrance of dirt into the skin by the action of their finger nails and fingers. A long series of impetiginous and furunculous diseases of early childhood are thereby explainable.
We also know that toxic substances may be resorbed front the intes tinal canal into the blood, finding an entrance into the skin by way of the circulation. Not infrequently autointoxication produces disturbances of assimilation, forming a chief cause of skin affections from the intestine (urticarial affections, etc.).
In the third place microorganisms or their toxins may enter the circulation from the intestine and thereby cause a dermatosis. In this respect I need only remind of the still unsolved question of the origina tion of erythema exudativum through bacteria or their toxins.