150 UNITY OF THE SPECIES OF MAN. 



for the belief in the common origin of the human family, which 

 seem to give it the rank of a scientific fact. Thus there is a 

 complete agreement amongst all rac js of Man, however different 

 they may be in aspect and habits, as to the manner in which 

 the most important functions of the body are performed, the 

 periods at which they take place, the average duration of life, 

 &c. ; or, at least, whatever variations may present them- 

 selves in these respects between different races, they are not 

 greater than those which are found among individuals of the 

 same race, under different circumstances in regard to climate, 

 food, &c. If the test which has been laid down for the distinc- 

 tion of species ( 14, note) be really valid, its application to this 

 question removes all doubt ; for it is well known, that not only 

 does a mixture of different races produce offspring, but the indi- 

 viduals of the mixed race thus originated are fertile with each 

 other, so that the mixed race is continued, which is not the 

 case with hybrid races, that originate in a crossing of different 

 species. Moreover, the mixed race is generally equal in personal 

 qualifications, and sometimes even superior, to either of the 

 parent stocks ; and, instead of having a tendency to degenerate 

 and die out, its fertility is usually greater, so that it rapidly 

 increases. It is probable that, in many parts of the world, 

 such as South America and Hindostan, the races that have been 

 produced by the intermixture of Europeans with the natives of 

 those countries, will ultimately attain the predominance. Now, 

 even if it should ever occur in Animals, as it sometimes does in 

 Plants (YEGET. PHYSIOL. 454), that a hybrid race, produced 

 between distinct species, should be able to keep itself up for a 

 few generations, it would be safe to affirm that it would ulti- 

 mately cease to exist, either being lost altogether, or merging 

 into one of the parent races, by intermixture with it. Conse- 

 quently it is evident, from this test, that we are justified in 

 regarding the different races of Man, not as distinct species, but 

 as varieties, which have arisen in course of time, and under the 

 influence of peculiar circumstances, in the same manner as the 

 breeds of the domesticated races ( 107 114). 



140. The same conclusion has been arrived at from a com- 



