NATURAL HISTORY OF MAN T . 497 



insensibly interblended, we find no lines strong enough to form 

 a limit to the supposed multiplicity of pairs, though many 

 sufficiently marked to furnish a basis for the division of races. 

 We think the evidence of facts never likely to go beyond 

 this ; and that future knowledge will tend further to confirm 

 the belief that all these distinctions of races are subordinate 

 to one single source of human life on the earth. 



Of the arguments to this effect, beyond those already 

 stated, the most important undoubtedly is the analogy 

 derived from all other species of organic life. We doubt 

 whether unequivocal proof has ever been produced of the 

 same species, admitted as such, having even two primitive 

 habitats on the surface of the globe. We have no means, in- 

 deed, of demonstrating the negative ; and the argument there- 

 fore must be rested on the remarkable fact, now recognised 

 by most naturalists, that different species, whether animal 

 or vegetable whether terrestrial, aquatic, or atmospheric 

 had originally definite seats and localities on the globe, 

 whence their various diffusion has been effected by accident 

 or design, modified by their locomotive powers and several 

 capacities for bearing changes of climate and place. There 

 is now a Greography of animals and plants, as well as of 

 mountains, rivers, and kingdoms. The importance of this 

 discovery will at once be obvious ; and not less so the great 

 value of the facts in natural history, by which it has been 

 established. The systematic division into provinces may 

 undergo alterations in effect of future revision, and increased 

 knowledge. But the general law remains good as to this 

 primitive distribution of the forms of life, and time can only 

 bring fresh attestation of it. 



Few minds would have been hardy enough to conceive all 

 this a priori ; to admit, for instance, the likelihood of such 

 facts as the insulated geology and botany of the Gralapagos 

 Isles or St. Helena ; or those curious relations of typical form 



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