220 PHYSICAL INVESTIGATION. [PART I. 



sume a fixed specific form are inclined to admit. In the face 

 of the above facts, the only alternative for such as contend for 

 a plurality of human species, is to multiply them still more. 

 We have already indicated the difficulties of such an alternative, 

 for such it is ; we would therefore only add, that the same rea- 

 sons may be urged against the assumption of a hundred or 

 more species, as against the assumption of only two species. 

 In members of the same family, diversities are as frequently ob- 

 served as in individuals of a foreign stock ; and in individuals of 

 the same stock, without intermixture, differences such as are 

 exhibited by distinct races. However few may be the tribes 

 included within one species, there will always be found diver- 

 sities amongst them, among their families and individuals, as 

 great as the differences exhibited by the assumed number of 

 species ; on which account they cannot be considered as specific 

 distinctions. 



He who assumes only as many species of mankind as there 

 are principal forms of cranial and bodily shape, at most from five 

 to seven, will in the end find himself obliged to abandon his 

 theory. He obtains specific characters fluctuating as much be- 

 tween extreme limits as the individual who assumes but one 

 species of man, and he is therefore obliged to admit, like the 

 latter, the great influence of external agents. At any rate, it 

 is perfectly arbitrary to consider certain principal forms as spe- 

 cifically different which are partly extreme forms (as the 

 Negro-type), partly intermediate (the American type), and 

 subordinate types. " The break up of one principal form 

 into physically and morally distinct families of man, is not 

 much more explicable than the races themselves." 1 If it be 

 contended, with regard to the first, that they have become de- 

 veloped in the course of time by the agency of external and 

 internal forces, there is no reason to deny it as regards the 

 latter. If minor differences of each species could arise in this 

 manner, it only requires sufficiently long periods and appro- 

 priate conditions to produce greater differences. There is not 

 even any necessity to adduce a frequently expressed assump- 



1 " Deutsche Vierteljahi-sclirif't/' ii, p. 247, 1838. 



