LECTURE V. ' 123 



the various gradations througli all tints, from yellow, copper- 

 colour, and brown, to jet black, are scattered over the globe, 

 and that irrespective of climatic conditions. Generally speaking, 

 brown and black peoples are met with in hot countries, fair 

 and yellow races in the temperate zones ; but there is no 

 general rule, and the many exceptions prove that climatic con- 

 ditions and the sun exercise but a secondary influence. 



As regards the skin, its structure is not essentially different 

 from that of mammals, and in the various races of mankind it 

 only differs in the grouping of some structural elements, but 

 not by the development of special tissue elements. It has 

 been declared, absurdly enough, that the layers of the skin in 

 the respective races should exhibit different tissue elements, if 

 there really existed different species of mankind, in forgetful- 

 ness of the fact, that it would be exceedingly difficult to detect 

 such fundamental differences in many different genera and 

 orders of mammals. Let anyone try to establish the differ- 



Fig. 38. Sectional view of the skin of a white man. a. Superficial horny 

 layer. 6. Eete mucosum. c. Papillae of the corium ; the middle with a tac- 

 tile corpuscle, the rest with vascular meshes, d. Vessels, e. f. Efferent 

 ducts of the sudoriferous glands, g. h. Fat. i. Nerves. 



