Page:Hardwicke's Science-Gossip - Volume 1.pdf/122

While Ethnologists and others are debating the knotty question as to whether our first parents wandered about the garden of Eden in black or white skins, it may be altogether uninteresting to consider wherein consists that striking difference of colour which is found in the skin, hair, and eyes, of the various human races, and which extends from the African negro to the fairest of Europeans. Even at the present day the peace and happiness of the negro is sadly interfered with by the prejudice which is entertained against him by reason of his sable colour, which seems to be warranted to "stand fast," notwithstanding the many efforts which have been made to wash a blackamoor white. But although a black skin has ever rendered the wearer of it liable to a miserable bondage, curiously enough matters are entirely reversed in Europe, where the hard task-master has been supplanted by a gentler nature, and the captive no longer is black, but white.

Much might be said of the all-powerful glance of a woman's eye, whether it proceed from that scrutinizing investigator of a Mrs. Caudle, or the not less potent eyes of the Miss just out of her "teens." Certain it is that the contemplation of sundry black, blue, or hazel eyes, of raven locks and auburn tresses, has given at all times such an amount of occupation to poets to describe as is perfectly alarming to dwell on. It is all very well for dull, prosaic, matter-of-fact people, like Mr. Weller, senior, to exclaim of these glowing descriptions, "Poetry's unnat'ral!" but when so many gentlemen, in and out of confinement, have devoted so much of their valuable time to the task of describing the effects of these colours, we are ready to exclaim, "There must be something in it." As we believe there is much in it which may be profitably investigated by the microscopist, the following notes may not be inappropriate.

On examining a vertical section of the human skin, one of the first things which attracts our attention is the general conformation of the various layers, composed of cells and fibrous tissue, interspersed with numerous delicate blood-vessels and other minute structures, which, in a healthy condition, serve to give to the skin that extreme softness and elasticity, which, mechanically considered, places it so far beyond the skill of man to imitate. The skin is composed chiefly of two parts, the lower part being termed the cutis, or true skin, and the upper or external portion, the epidermis. The latter is the part which not interests us; as it is in and below the epidermis we find those cells containing the colouring-matter, and which are called "Pigment-cells." The many tints and shades of colour which in a great measure serve to distinguish the human races as well as the lower animals are dependent on the presence of these cells, which are more or less distributed throughout the epidermis and its appendages, where the Pigment-cells are usually flat, and of a polygonal form. In dark-coloured races and negroes the skin is very thick, and is most liberally supplied with these cells; but they are also found in the fairest European, although in the latter they are fewer in number and lighter in colour, as extreme paleness of complexion is not an indication of their entire absence, but merely of their pale colour.

The most remarkable accumulation of Pigment-cells is found in the inner lining of that part of the eye known as the choroid membrane, where they exist in several layers, termed the Pigmentum nigrum, and are beautifully-arranged in six-sided cells, measuring from 1-2,000th to 1-5,000th in. in diameter, and abounding in Pigment (fig. 77). Dr. Carpenter^[1] says,

"The black colour is given by the accumulation of a number of flat, rounded, or oval granules of extreme minuteness, which exhibit an active movement when set free from the cell, and even whilst enclosed with in it."

With regard to hair, the colour is given by the presence of these cells, which are thoroughly incorporated with it; hence the difficulty which the few followers of a recent absurd fashion experience, who, possessing blue eyes, deem it necessary to have a particular shade of light hair.

Occasionally it happens that not only animals, but individuals, are entirely devoid of Pigment-cells. We call them Albinos; for, as it is the presence of these cells in the skin, hair, and eyes, which gives colour to those parts of the body, so the entire absence of them gives the unusual appearance to the Albinos. In their case the skin is leprously white, and the hair corresponding with it. The eye is likewise characteristic, for the Pigmentum nigrum being absent, the delicate blood-vessels reflect their bright red colour, which the Pigment would otherwise hide, and they are consequently so extremely sensitive to the light that they are generally only half opened, even in twilight. This peculiarity is, of course, well known with regard to many of the white animals.

A few years ago a paper was read to the Royal Society, giving an account of the desquamation and