352 THE HISTORY OF CKEATION. 



If all the phenomena of the geographical and topographi- 

 cal distribution of organisms are examined by themselves, 

 without considering the gradual development of species, and 

 if at the same time, following the customary superstition, the 

 individual species of animals and plants are considered 

 as forms independently created and independent of one 

 another, then there remains nothing for us to do but to gaze 

 at those phenomena as a confused collection of incompre- 

 hensible and inexplicable miracles. But as soon as we 

 leave this low stand-point, and rise to the height of the 

 theory of development, by means of the supposition of a 

 blood-relationship between the different species, then all 

 at once a clear light falls upon this strange series of 

 miracles, and we see that all chorological facts can 

 be understood quite simply and clearly by the supposition of 

 a common descent of the species, and their passive and 

 active migi^ations. 



The most important principle from which we must start 

 in chorology, and of the truth of which we are convinced by 

 due examination of the theory of selection, is that, as a rule, 

 every animal and vegetable species has arisen only once in 

 the course of time and only in one place on the earth — its 

 so-called " centre of creation" — by natural selection. I share 

 this opinion of Darwin's unconditionally, in respect to the 

 great majority of higher and perfect organisms, and in 

 respect to most animals and plants in which the division of 

 labour, or differentiation of the cells and organs of which 

 they are composed, has attained a certain stage. For it 

 is quite incredible, or could at best only be an exceedingly 

 rare accident, that all the manifold and complicated circum- 

 stances — all the different conditions of the struggle for life, 



