FIRST ORDINARY MEETING. 17 



matter light, the tint of the skin will be much affected by any 

 change in the supply of blood to the capillaries at the surface of the 

 body. This is the reason why the whites alone can turn pale and 

 blush. 



Closely related to the pigment of the skin are the colouring matters 

 of the eye and hair. Dark-skinned people usually have black eyes 

 and hair ; fair hair and blue eyes are seldom found except in con- 

 junction with a fair skin ; and the eyes and hair of albinoes, in whom 

 the pigment of the skin is wanting, are likewise destitute of colouring 

 matter. The pink hue of their eyes is due to minute blood-vessels, 

 whose colour is masked in ordinary organs by the pigment of the iris. 



It is noteworthy that the colouring matters of the epidermis and 

 the iris serve a very important purpose ; they protect the tender un- 

 derlying parts from the injurious effects of too much heat and light. 

 Albinoes everywhere find it necessary to protect their skins and eyes 

 from the action of the sun's rays. In warm countries they seldom go 

 out except at night. There is this difference between them and other 

 men, that long-continued exposure to the sun, which ordinarily 

 develops a condition of the skin capable of resisting its rays, does not 

 do so in their case. It may here be remarked that, the greater the 

 quantity of the pigment, the less transparent will the epidermis be, 

 and the more effective will it be as a protective agency. On the con- 

 trary, the smaller the quantity, the greater the transparency, and the 

 less the protection. 



Under certain circumstances the exposed parts of our bodies 

 become tanned, that is to say, an increase in the colouring matter 

 which they contain takes place. Dark whites tan brown, fair whites, 

 tan red. The change is caused by the influence of the sun or wind, 

 and is obviously protective in its character, as the unpleasant feelings. 

 which result from the first exposure do not recur when we have 

 become thoroughly tanned. This fact, I believe, contains the key 

 which explains the distribution of colour among the races. The 

 climate, or the mode of existence of most races, renders it an 

 advantage to them to begin life more or less deeply tanned. 



As an excretory organ, it is the function of the skin to discharge, 

 water, carbonic acid and urea — the first in large, the others in small; 

 quantities. Perspiration, or the excreting of water with some saline 

 matter in solution, is effected in two ways. In the first place, 

 sudoriparous glands, imbedded in the true skin, secrete sweat from, 

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