GENERAL 3 UMMAR Y AND CONCL U8I0N. 695 



logical importance, acme indeed of considerable ImportaEnee, 

 have been gained through sexnal selection. 



No doubt man, ae well as erery other animal, presentB 

 structures, which seem to our limited knowledge, not to be 

 now of any service to him. nor to have been so formerly, 

 either for the general conditions of life, or in the relations 

 of one sex to the other. Such structures cannot be 

 accounted for by any form of selection, or by the inherited 

 effects of the use and disuse of parts. We know, however, 

 that many strange and strongly marked peculiarities of 

 stmctiire occasionally appear in our domesticated produc- 

 tions, and if their unknown causes were to act more uni- 

 formly, they would probably become common to all the 

 individuals of the species. We may hope hereafter to 

 undergtand something about the causes of such occasional 

 modifications, eqiccially through the study of monstroeities: 

 hence, the Idbon of experimentalists, such as those of M. 

 Camille Dareste, are full of pr omae for the future. In 

 general we can only say that the amm of each slight varia- 

 tion and of each waaasLnmkf iieB nuch more in the con- 

 stitution of the orginlw thm in the nature of the sur- 

 rounding conditions; tluNi^ arw and changed conditions 

 certainly play an imporiat part in exciting organic 

 changes of many kinds. 



Through the mesne jost specified, aided perhaps by 

 others as yet unditoofeicd, bjui has been raised to his 

 present state. But since he attained to the rank of man- 

 hood, he has diverged into distinct laces. or. as they may 

 be more fitly caUed, sob-species. Some of these, such as 

 the negro and Enropcttn, are so distinct that, if specimens 

 had been brought to a naturalist without any further in- 

 formation, they would undoubtedly have been considered 

 by him as good and true species. Nevertheless, all the 

 races agree in so many unimportant details of structure and 

 in so many mental peculiarities that these can be ac- 

 counted for only by inheritance from a common progenitor; 

 and a progenitor thus characterized would probably deserve 

 to rank its man. 



It must not be supposed that the divergence of each race 

 * 'om the other races and of all from a common stock can 

 traced back to any one pair of progenitors. On the con- 

 trary, at every stage in the process of modification, all the 

 individuals which were in any way better fitted for their 



