252 METHODS AND RESULTS OF ETHNOLOGY iv 



the forests of Louisiana, a negro stock would even- 

 tually people the region. 1 Again, how often, by 

 such physical changes, must a stock have been iso- 

 lated from all others for innumerable generations, 

 and have found ample time for the hereditary 

 hardening of its special peculiarities into the 

 enduring characters of a persistent modification. 

 Nor, if it be true that the physiological differ- 

 ences of species may be produced by variation and 

 natural selection, as Mr. Darwin supposes, would it 

 be at all astonishing, if, in some of these separated 

 stocks, the process of differentiation should have 

 gone so far as to give rise to the phenomena of 

 hybridity. In the face of the overwhelming 

 evidence in favour of the unity of the origin of 

 mankind afforded by anatomical considerations, 

 satisfactory proof of the existence of any degree of 

 sterility in the unions of members of two of the 

 " persistent modifications " of mankind, might well 

 be appealed to by Mr. Darwin as crucial evidence 

 of the truth of his views regarding the origin of 

 species in general. 



P Mr. Pearson, in his very interesting work On National 

 Life and Character, justly dwells upon the obstacles to the 

 existence of the white races within the Tropics. There is, how- 

 ever, this point to be considered, that the fevers to which the 

 white men succumb are probably caused by microbes ; and that 

 modern therapeutic science is daily teaching us more and more 

 about the ways of obtaining immunity from or alleviating these 

 attacks. What would become of black competition if fever 

 " vaccination" proved effectual ? 1894.] 



