134 SCIENCE PROGRESS 



of the Khasias of Assam, who dwell in the midst of Tibeto- 

 Burman tribes, compared with that of their Burmese cousins 

 the Monds, is to be attributed to their environment in Assam, 

 where they continue to speak their own language, though 

 assimilated in physical type to the Assamese tribes around. 



Sir H. H. Risley, K.C.I.E., has called my attention to some 

 very interesting facts lately published respecting the difference 

 of the arterial pressure and blood constituents of Bengalis as 

 compared with our European standards in the same respects, 

 from which we must infer that one race differs morphologically 

 from another. 



As Mr. Houghton's strictures on my principles are based 

 entirely on the dogmatic assertion of Sir E, Ray Lankester that 

 Man had once for all cut himself free from the action of natural 

 laws, it is a pity that he did not make himself acquainted with 

 the footnote which I have cited, in which his master admits the 

 activity of Natural Selection at the present moment in the human 

 family. But Mr. Houghton himself makes admissions which 

 cut away the ground from under his feet. He writes : " When 

 he (Ridgeway) goes on to say that the skins of mankind tend 

 to get lighter in gradations from the Equator to the Pole he 

 stands on firmer ground. Undoubtedly the skin of races long 

 inhabiting the tropics evinces a deeper pigmentation than in 

 those residing in more temperate regions. The reason for this 

 is obvious : although histologists are not agreed as to the cyto- 

 logical facts of pigmentation, it undoubtedly tends, just as do 

 freckles, to protect the outer layers from the actinic rays of the 

 sun." Yet when he comes to deal with my theory that the 

 white skin of the blond race of Northern Europe is due also 

 to climatic causes, analogous to those which have produced 

 the white hares and white bears, and make the ptarmigan turn 

 white in winter, he declares that such a view " implies a singular 

 inability to grasp the relevant facts of the case or to frame 

 inductions upon them. The whiteness of animals inhabiting 

 northern regions, whether perennial or seasonal, is a very simple 

 case of adaptive colouring first demonstrated by Dr. A. Russell 

 Wallace, and now obvious to the merest tyro in biology. Who 

 will assert that blondness of hair in any way favours a race in 

 a northern habitat ? Does Prof. Ridgeway mean to assert that 

 in winter our ancestors pursued game or eluded their foes in a 

 §tate of nudity ? " 



