In 
 1813, 
Dr. W. C. Wells read before the Royal Society 'An Account of a White Female, part of whose 
 skin 
resembles that of a 
 Negro'; | Negro'; 1872 |  | Negro;' 1866 1869 |  
  
but his paper was not published until his famous 'Two Essays upon Dew and Single Vision' appeared in 1818.  In this paper he distinctly recognises the principle of natural selection, and this is the first recognition which has been indicated; but he applies it only to the races of man, and to certain characters alone.  After remarking that negroes and mulattoes enjoy an immunity from certain tropical diseases, he observes, firstly, that all animals tend to vary in some degree, and, secondly, that agriculturists improve their domesticated animals by selection; and then, he adds, but what is done in this latter case "by art, seems to be done with equal efficacy, though more slowly, by nature, in the formation of varieties of 
 mankind, | mankind, 1866 1872 |  | man-kind, 1869 |  
  
fitted for the country which they inhabit. Of the accidental varieties of man, which would occur among the first few and scattered inhabitants of the middle regions of Africa, some one would be better fitted than the others to bear the diseases of the country. This race would consequently multiply, while the others would decrease; not only from their inability to sustain the attacks of disease, but from their incapacity of contending with their more vigorous neighbours. The colour of this vigorous race I take for granted, from what has been already said, would be dark. But the same disposition to form varieties still existing, a darker and a darker race would in the course of time 
 occur: | occur: 1872 |  | occur; 1866 1869 |  
  
and as the darkest would be the best fitted for the climate, this would at length become the most prevalent, if not the only race, in the particular country in which it had originated."  He then extends these same views to the white inhabitants of colder climates.  I am indebted to 
 Mr. Rowley, | Mr. Rowley, 1869 1872 |  
| the Rev. Mr. Brace, 1866 |  
  
of the United States, for having called my 
 attention, | attention, 1869 1872 |  | attention 1866 |  
  
 through Mr. Brace, to | through Mr. Brace, to 1869 1872 |  
| to 1866 |  
  
the above passage in Dr. 
 Well's | Well's 1872 |  | Wells' 1866 1869 |  
  
work.  | 
 The | The 1866 1869 1872 |  
| In England the 1861 |  
  
Hon. and Rev. W. Herbert, afterwards Dean of Manchester, in the fourth volume of the 'Horticultural Transactions,' 1822, and in his work on the 
 'Amaryllidaceæ' | 'Amaryllidaceæ' 1861 1866 1872 |  | 'Amaryllidaccæ' 1869 |  
  
(1837, p. 19, 339), declares that "horticultural experiments have established, beyond the possibility of refutation, that botanical species are only a higher and more permanent class of varieties."  He extends the same view to animals.  The Dean believes that single species of each genus were created in an originally highly plastic condition, and that these have produced, chiefly by intercrossing, but likewise by variation, all our existing species.  |