16 INTEODUCTION. 



mere physical character and irrespective of psychical endow- 

 ment, as unscientific. 



For the above reasons our investigation respecting the unity 

 of mankind is divided into two parts ; the first has to examine 

 whether all human beings are to be considered of the same 

 species on physical grounds ; the second, whether or not they 

 are so on psychological grounds. 



