THE HUMAN SPECIES. 123 



expulsion by the Mongolia, to whom the whole expanse 

 is the more genial ; while, for the same reason, this last 

 named stock could not maintain its conquests in Europe, 

 nor to the south of the central ridge in Asia. 



But the white and negro races of Africa readily 

 intermix. The woolly haired form has there no pre- 

 tensions on the debatable land between them. The 

 Caucasian might have assumed mastery beyond it, had 

 not the force of nature interposed ; for this race does 

 not and cannot multiply in the centre of negro exis- 

 tence ; and in the warmer valleys of the intermediate 

 spaces, such as that of the Nile, only a mixed Semitic 

 stock possesses durability. It has been calculated, that 

 since the introduction of the Mameluke power, not less 

 than five millions of well-chosen colonists, of both 

 sexes, from higher central Asia, have been introduced, 

 not to wear out a life of slavery, but one of power and 

 rule, yet no fourth generation of this stock can any 

 where be shown in Egypt, even with all the additional 

 aid of Syrian and Persian females, to supply the defi- 

 ciency.* The force of a true Negro expansion is felt 

 coming from the centre of Africa. It presses upon the 

 Uaftres, the Abyssinees, and the west coast of Nigritia. 

 Morocco is already ruled by black sovereigns; and 

 the antique semi-Caucasian tribes of the north part 

 have greatly diminished. 



* The same result is asserted to be observed on the banks 

 of the Ganges; though, in the South Sea Islands and 

 Australia, the bearded stock multiplies in itself, and with 

 semi-Caucasian Malay races. 



