446 CAUSES OF THE VARIETIES 



dicate the same temperature of climate. Some secondary 

 causes must be taken into consideration^ as correcting and 

 limiting its influence. The elevation of the land, its vici- 

 nity to the sea, tlie nature of the soil, the state of cultiva- 

 tion, the course of winds, and many other circumstances, 

 enter into this view. Elevated and mountainous countries 

 are cool, in proportion to their altitude above the level of 

 the sea*," &c. &c. 



Blumenbach informs us how climate operates in modi- 

 fying the colour of the skin, but does not attempt to explain 

 its effects on the stature, proportions, and other points. He 

 states that the proximate cause of the dark colour of the 

 integuments is an abundance of carbone, secreted by the 

 skin with hydrogen, precipitated and fixed in the rete muco- 

 sum by the contact of the atmospheric oxygen f. He 

 observes further, that this abundance of carbone is most 

 distinctly noticeable in persons of an atrabilarlous tempera- 

 ment ; which fact, together with many others, proves the 

 intimate connexion between the biliary and the cutaneous 

 organs; that hot climates exert a very signal influence on the 

 liver ; and thus, that an unnatural state of the biliary secre- 

 tion, produced by heat, and increased through many gene- 

 rations, causes the vessels of the skin to secrete that abund- 

 ance of carbone, which produces the black colour of the 

 Negro J. 



If any one can believe that tlie Negroes and other dark 

 people, whom we see in full health and vigour, and with every 

 organic perfection, labour under a kind of habitual jaundice, 

 he may think it worth while- to Inquire further into this as- 

 sumed secretion and precipitation of carbone. It will then 

 be necessary to explain how this jaundice is produced in the 

 numerous dark races which dwell in temperate climates ; 

 and why it does not occur in the white people wlio occupy 

 hot countries. 



It cannot be supposed that men of undoubted talents and 

 learning would take up these opinions without any founda- 



* Essay^ pp. 8, 10. + De §en, hum. var.nat. p. 124. 



:|: Ibid. pp. 120, 137. 



