106 



SCIENCE-GOBSIP. 



[May ], 1865. 



PIGMENT-CELLS. 



WHILE Ethnologists aud otliers are debating 

 the knotty question as to wlietlier our first 

 parents wandered about tlie garden of Eden in black 

 or wliite skins, it may not 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 hira by reason of his sable 

 colour, which seems to be warranted to " stand fad" 

 notwithstanding the many efforts which have been 

 made to wash a blackamoor v/hite. But although a 

 black skin has ever rendered the vi'carer 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 natui\'^, 

 and the captive no longer is bla,ck, but vvhite. 



Much might be said of the all-powerfid glance of 

 a woman's eye. whether it proceed from that scni- 

 tinizing 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 v/ell 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 confine- 

 ment, 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 wliich 

 may be profitably investigated by the microscopist, 

 the following notes may not be inappropriate. 

 V On examining a vertical section of the Imman 

 skin, one of the first things which attracts our atten- 

 tion is the general conformation of the various 

 layers, composed of cells and fibrous tissue, inter- 

 spersed with numerous delicate blood-vessels aud 

 other minute structures, which, in a healthy condi- 

 tion, serve to give to the skin that extreme softness 

 and elasticity, wliich, 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, aud the upper 

 or external portion, tlie epidermis. The latter is the 

 part which now 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 tlic lower animals are 

 dependent on the presence of tliese cells, wliich 



are more or less distributed throughout the epi- 

 dermis 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 Pigmenttim nigrum; 

 and are beautifully-arranged in six-sided cells, mea- 

 suring from l-2,000th to l-5,000th in. in diameter, and 

 abounding in Pigment (fig. 11). Dr. Carpenter'-^' says, 



^ © © © o 



Fig. 75. — From Bal's-v.ir.g-. 



77.— From Ox-eye 



" 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 incor- 

 porated with it ; hence tlie difficulty whicli 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. 

 ^'Fe then call them Albinos ; for, as it is the presence 

 of these cells in the skin, hair, and eyes, wliich 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 tlie Plgmentum nigrum. 

 being absent, the delicate blood-vessels reflect their 

 bright red colour, which the Pigment would other- 

 wise liide, 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 



* "The Microscope and its Revelations." 



