« ПредыдущаяПродолжить »
THE SKIN AS AN ORGAN OF THE BODY.
HE skin is to be regarded from two points of view,—as an organ of the body, and as its finished exterior. The first of these relates to the health of the whole body, the second to its final touch of beauty in a surface soft, pliant, and exquisitely delicate in color. Health and beauty, therefore, the two topics of this work, being both concerned, and beauty being (as cannot be too earnestly impressed upon the reader) entirely dependent upon, although not constituted by health, the natural order in which to consider the skin will be, first, as it is subservient to health, and then, as it is conducive to beauty. Accordingly, the present chapter will be devoted to an examination of its relation to health, and the one immediately following to that of its relation to beauty.
The skin consists of the subcutaneous connective tissue, the corium, and the epidermis. In the subcutaneous connective tissue originate the most deeply seated of the structures which have relation to the skin, arteries, capillaries, lymphatics, nerves, sweat-glands, and the bases of the roots of the hair which penetrate deepest. The blood-vessels there are large, and after supplying the nutrition of the hair, the sweat-glands, and the fatty lobules that are present for the nourishment of the parts, branch into the corium. The subcutaneous connective tissue sometimes, as on the seat, which is quite a thick cushion, blends with the corium by means of little fatty columns, which there reach the base of the roots of the finer hair. Passing through the skin are involuntary muscles sometimes accompanying these, which muscles, under the influence of sudden chill of the surface of the body, or of fear or other great cerebral excitement, erect the hair.
The corium is termed the true skin. It corresponds to what, when tanned, we call in the lower animals leather. It consists of two layers, the only difference between which in character is that the upper layer is the more compact. It is richly nourished with blood-vessels and lymphatics, and as the greater number of hair-roots are there, so also are present the greater number of sebaceous glands, which are glands secreting for the benefit of the hair and skin an oily liquor called sebum, similar in constitution to suet.
The epidermis, or scarf-skin, consists of four distinct layers. These are, in the descending order, the stratum corneum (the horny layer), the stratum lucidum (the transparent layer), the stratum granulosum (the granular layer), and. the stratum mucosum (the mucous layer). The epidermis means simply the top skin, the outermost portion of which is, as stated, the horny layer. When, as is often seen, a blister detaches the upper from the lower skin, it is the whole of the four layers just described which have been separated from the corium, or true skin. It is therefore apparent that the layers are very thin.
Without proceeding farther in investigation of the epidermis, it will suffice to say that, through its four layers, cells graduate from the corium, gradually changing in constitution and shape as they ascend, until, in their final transformation, they become the scales of the horny layer of the scarf-skin. We regret, in the interest of the reader's memorizing, that there are so many layers to the epidermis, but the fact being that there are, and they having been enumerated, it will suffice for the purpose here in view to consider the skin as simply formed of the subcutaneous connective tissue, the corium, and the epidermis.
The sweat-ducts, proceeding from the sweat-glands, in the subcutaneous connective tissue, pass through the corium and epidermis, and debouch on the outside of the latter with trumpet-mouthed orifices. Thus are discharged from the body
its perspiration, with many humors, carbonic-acid gas, and other noxious matter, as well as the oily products by which the skin is lubricated, which find their way to the surface through the sebaceous ducts, but, to some degree, through the sweat-gland ducts. When a person has been unwontedly exposed to the ardent sun's rays, nature comes with a profusion of oil to the aid of the parching skin. Hence, if such a person as suddenly ceases to be exposed, the skin assumes a glistening appearance, especially on the cheeks near the outside flaps of the nostrils,-the wings of the nose, as they are anatomically designated. Such has been within our experience the superabundance of oil under these circumstances, that it made the face look as if it had been greased. If no further exposure to the sun is to take place immediately, reduction of the oiliness of the skin to its normal amount should be effected by means of a saturated solution of borax, applied with a fine sponge.
The sebaceous glands are either free or attached in clusters to the roots of the hair. When free, their ducts deliver sebum directly at the surface of the skin; when associated with hair, they deliver it directly at the roots. According to Dr. Erasmus Wilson, these ducts also act as sweat-ducts.
Upon the corium stand an immense number of minute, elongated teats, of exquisite sensitiveness, for they are furnished with nerves, which, passing upward through the papillæ, as these teats are called, reach the under surface of the horny layer of the scarf-skin. These in the skin constitute the seat of feeling, producing what, related to the hand, we call the sense of touch, The papillæ rising, as has been said, to the under side of the horny layer of the scarf-skin, receive its protection from friction and contact with the atmosphere. It is from the circumstance that the stratum mucosum of the epidermis thus becomes riddled by these upright papillæ that it derives its other name of the rete mucosum, its appearance under the microscope being
reticulated, or having the appearance of net-work. quisitely sensitive these papillæ are every one realizes who, from a burn or other cause of abrasion, loses a small portion of the scarf-skin, and exposes them to contact with the atmosphere.
These are only some of the details of this wonderfully organized membrane called the skin. A description of it, condensed for the benefit of the general reader, might be given as follows: It consists of the subcutaneous connective tissue, the corium, and the epidermis. It is supplied with sebaceous glands and their ducts, sweat-glands and their ducts, hairs and their erecting muscles, pigment which gives it color, lobules of fat which nourish it, and, in the thickest parts, interlacing fatty columns, which support other structures and contribute largely to its elasticity. The scarf-skin, being partially horny in character, is only slightly elastic, but the corium is highly so, and the subcutaneous connective tissue so organized as to allow the whole thickness of the skin to play freely on the parts which lie immediately below, the muscles and the fascia.
The skin is therefore of exquisite organization, and, as complexity and delicacy of structure imply complexity and delicacy of function, we shall not be surprised, upon pursuing our inquiry farther, to ascertain that, upon the condition of the skin and the vicissitudes to which it is subjected, the health is more dependent than upon any other agency in life over which we have some control. Even this statement conveys but a faint notion of the relations of the skin to the higher order of beings, for it is only the higher order of beings which possess true skin.
It is at the skin that man ends and the outlying universe begins. He is there in the most intimate of all his contacts with the universe. The judgments formed by vision itself were originally educated by the sense of touch. Through specially organized portions of the skin the senses of touch and smell become agents in producing distinctive impressions on the brain. Through