8 



THE NATURAL HISTORY OF 



to represent a province diagrammatically, we might 

 colour a nebulous space, in which the intensity 

 of the hue would be exhibited towards the centre, 

 and become fainter and fainter towards the circum- 

 ference. This feature of zoological and botanical 

 provinces gives rise to the term centres of creation, 

 which I and others have applied to them. There 

 may be minor centres within a province. Nowhere 

 do we find a province repeated ; that is to say, 

 in none, except one centre of creation do we find 

 the same assemblage of typical species ; or, in other 

 words, no species has been called forth originally 

 in more areas than one. Similar species, to which 

 the term representative is mutually applied, appear 

 in areas distant from each other, but under the 

 influence of similar physical conditions. But every 

 true species presents in its individuals, certain 

 features, specific characters, which distinguish it from 

 every other species ; as if the Creator had set an 

 exclusive mark or seal, on each living type. Species, 

 the individuals of which are distributed over an 

 unbroken area, exhibit the phenomenon of cen- 

 trality within themselves, i.e., there is some portion 

 of that area, whence all the individuals of the 

 species appear to have radiated. As from all the 

 facts we know, the relationship of the individuals 

 of any species to each other, exhibits the pheno- 

 menon of descent, since every case in which the 

 parentage of an individual or group of similar indi- 

 viduals has been traced, the parent stock has been 



