6 PROCEEDINGS OF THE CANADIAN INSTITUTE. 
Another explanation of some of these facts, that possesses a certain 
degree of probability, is, that difference of colour in the same country 
is due to mode of life. It may be maintained that the Samangs of 
Malaca, and the Aétas of the Philippine Islands are darker than 
the other inhabitants, because the poorness of their dwellings, and 
their consequent practically constant exposure to sun or wind, renders 
it an advantage for them to be dark. 
Another explanation to which I shall make reference later, is that 
humidity is probably not the sole climatic influence that operates. 
I may say here that I do not attach importance to the direct in- 
fluence of climatic. conditions. It is, indeed, a matter of common 
observation that these produce considerable effects on the individual. 
Pruner-Bey, for example, states that he has noticed that “the Euro- 
pean acclimated in Egypt acquires after some time a tawny skin, 
and in Abyssinia a bronzed skin; he becomes pallid on the coast of 
Arabia, cachectic white in Syria, clear brown in the deserts of Arabia, 
and ruddy in the Syrian mountains.” But there is no proof that 
these cutaneous changes are inherited. If, however, it can be shown 
that a particular kind of skin is better than others for resisting the 
deleterious influences of a given climate, it stands to reason that 
those members of a race whose skins vary in the direction of this 
type, will, in each generation have the best chance of surviving and 
begetting children, and that by the continued increment of successive 
variations in the same direction, the skin and the climate will ulti- 
mately be brought into accord. 
The skin consists of two layers: the inner, dense and fibrous, 
furnished with blood vessels and nerves, called the derma or true 
skin ; the outer, horny, nerveless and bloodless, called the epidermis, 
cuticle, or scarf-skin. The cells which compose the latter originate 
in the rete Malpighii, its lowest part, are gradually forced outward 
by new cells and finally exfoliate. In some of these epidermic cells 
a pigment is found which varies in different races, but always con- 
tains a yellow element. The hue of the skin does not depend on 
this colouring matter alone, but is a compound effect resulting from 
the white of the dermis, the red of the blood in the minute vessels 
near the surface, the colour and quantity of the pigment, and the 
thickness of the cuticle. Where the cuticle is thick, the colour of the 
pigment will predominate over the other elements on account of the 
greater depth of pigment-cells. Where it is thin, and the colouring 
