io 4 THE HUMAN SPECIES 



influence of the sun cannot have been the sole cause of the differ- 

 ence in colouring ; still less can we regard the paleness as due 

 to a deficiency of light, for the aboriginal race of the Eskimos 

 is dark, in spite of living for several consecutive months of 

 the year in snow -huts. Klaatsch therefore suggests other 

 factors : on the one hand, food ; on the other, the immunity 

 against certain poisons and infections imparted to the body by 

 a particular colouring of the skin. This character, acquired by 

 natural and sexual selection, was first theoretically assumed, but 

 later abundantly confirmed by observations made in the tropics. 



One of the most interesting discoveries of modern times is 

 that of the blue Mongolian spots in European children. These 

 spots are dark blue in colour and were first found imbedded in the 

 corium of the inguinal region in Eskimo children of West Green- 

 land, and later on in other Mongolian children ; B. Adachi and 

 K. Fujisawa 1 have now found them to be present in European 

 children also. 



Adachi has devoted special study to the pigment in man and 

 gives his results as follows : 



In Europeans the pigment of the epidermis is generally 



limited to the rete Malpighi and is deposited in and between 



^____^_ the cells in the form of 



?jx-: : .X; ; ; <v.v,-v p^uliar pigmentary struc- 



^sifei^'--^^.:^;-.' '&&-'':---'ir^\iifcZ--S-' : -- . . - ,1.1 



tures consisting or a thick 



' ' '3 bod y with branches ( Ad - 



i achi's Chromatophores} . 



' ' /-* -11 



i Circular, spindle or star- 



} shaped cells are rarely 

 ] observed in the upper 

 layers of the corium, and 

 (i'-jJj never occur in the epi- 

 ^ dermis. Those large pig- 



FIG. 55. Inguinal skin of a European woman, ment Cells which cause the 

 blonde, thirty-eight years. (Adachi.) ,_ .. 



Mongolian spots and colour 



the skin even of adult Europeans are situated deep in the 

 corium. The only difference is that Mongolian children possess 

 more numerous and more strongly coloured pigment cells in 

 the lower layers of the corium, than do European children. 



1 Zeitschrift f. Morphologic und AnthropoL, vol. vi., p. 132. 



