SECT. I.] CLIMATE. 35 



enables us to say that, in consequence of such circumstances in 

 different climates, various changes are produced in the animal 

 economy, without our being able exactly to trace out their 

 origin. 



These circumstances, in combination with other causes which 

 J. W. de Miiller 1 has treated of, lend at first sight a certain 

 probability to the explanation of the black skin of the Negro, 

 namely, that in hot climates the amount of oxygen inspired is 

 insufficient to change the carbon into carbonic acid, and that 

 the unconsumed carbon is deposited in the pigment-cells of the 

 skin. Berthold 2 gives a similar explanation, namely, that in 

 spite of the great development of the liver in hot climates, and 

 a diminished activity of the lungs, a sufficient quantity of car- 

 bon is not removed from the body; hence the vessels carry a 

 large quantity of carbon which, with an increased perspiration 

 is retained beneath the epidermis. It is, however, difficult to 

 admit that the browning of the skin in our climate in summer, 

 is produced by the same causes as the black colour of the 

 Negro, and that it would only require a greater intensity and a 

 longer duration to become so entirely. Nor can it be admitted, 

 that the tawny skin of many pregnant women and the examples 

 quoted by Blumenbach, 3 of the black spots on certain parts of 

 lying-in women, as well as the tawny colour of such women 

 who have never menstruated, prove in any way that the colour 

 of the Negro is not owing to specific causes ; for the objection 

 would still remain, that under the tropics in East India, South 

 America, and one part of Africa, there live no blacks, and that 

 neither as regards Negroes nor other peoples, the colour of the 

 skin is exclusively determined by the absorption of oxygen. 

 Those who insist upon an explanation must rest satisfied with 

 that given by Foissac, 4 who attributes the colour of the Negro 

 to the predominant vegetable diet containing much more carbon 

 than animal diet. This explanation offers the same difficulties 

 as the former, and is open to similar objections, as is also 



' " Causes de la Coloration de la Peau," p. 24, Stuttg., 1853. 



2 " Lehrb. der Physiol." 2 Aufl., ii, p. 325. 



8 " De generis humani var. nat.," 3rd edit. p. 156. 



* " Ueber den Einfluss des Klimas auf den Menschen," p. 67, Gott., 1840. 



D 2 



