46 THE HISTORY OF CREATION. 



some zoologists will be more in favour of the supposition 

 that all placental animals are derived from a single pouched 

 animal ; others will be more in favour of the opposite sup- 

 position, that several different groups of placental animals 

 have proceeded from several different pouched animals. In 

 regard to the human race itself, some will prefer to derive 

 it from a single form of ape, while others will be more 

 inclined to the idea that several different races of men have 

 arisen, independently of one another, out of several different 

 species of ape. Without here expressing our opinion in 

 favour of either the one or the other conception, we must, 

 nevertheless, remark that in general the moTiopJiyletic 

 hypothesis of descent deserves to he preferred to the 

 polyphyletic hypothesis of descent. In accordance with the 

 chorological proposition of a single "centre of creation" 

 or of a single primaeval home for most species (which has 

 already been discussed), we may be permitted to assume 

 that the original form of every larger or smaller natural 

 group only originated once in the course of time, and only 

 in one part of the earth. We may safely assume this 

 simple original root, that is, the mono25hyletic origin, in the 

 case of all the more highly developed groups of the animal 

 and vegetable kingdoms. (Compare vol. i. p. 353). But it is 

 very possible that the more complete Theory of Descent of 

 the future will involve the polyphyletic origin of very 

 many of the low and imperfect groups of the two organic 

 kingdoms. 



For these reasons I consider it best, in the mean time, to 

 adopt the monophyletic hypothesis of descent both for the 

 animal and for the vegetable kingdom. Accordingly, the 

 above-mentioned six tribes, or phyla, of the animal kingdom 



