190 PHYSICAL INVESTIGATION. [PART I. 



time. Although among some, these peculiarities disappear after 

 a few generations, they are in others preserved after a long 

 series of generations. The latter applies to the so-called 

 " Indians" at Hayti, especially as regards the women. They 

 have symmetrical forms, an olive-coloured delicate skin, large 

 black eyes, and very fine heads of hair. This reminds us of 

 the assertion supported by Geoffroy St. Hilaire, that the cha- 

 racters of an animal race are more constant and permanent in 

 proportion as the race is older, and more changeable the younger 

 the race is. 



The intermixture of the various types is one of the chief 

 agents in the changes produced in mankind. Whoever is in- 

 clined to consider the principal races as specifically different, 

 doubts the vitality and unlimited prolificacy of mongrels ; but 

 still he explains the changes of type from intermixture, because 

 the theory of a specific difference would be untenable if climate, 

 civilization, etc., could by themselves produce that change. 

 With regard to this dilemma, in which the defenders of specific 

 differences find themselves, we would further observe, that it 

 is inconsistent to deduce all changes of types merely from 

 intermixture, as the assertion of the permanence of specific 

 characters would thus partly be refuted. From whatever point 

 of view we may consider the results of the intermixture of 

 different types, we are entitled to maintain that on the whole 

 they are more in favour of the unity of mankind than for the 

 opposite theory. 



SECTION IV. 



REVIEW OF THE PRINCIPAL THEORIES REGARDING THE 

 UNITY OF MANKIND. 



We have hitherto been engaged in enumerating the most im- 

 portant facts bearing upon the question of the unity of man- 



