CENTRES OF CREATION. 353 
which influence the origin of a new species by natural 
selection—should have worked together in exactly the 
same agreement and combination more than once in the 
earth’s history, or should have been active at the same time 
at several different points of the earth’s surface. 
On the other hand, I consider it to be very probable that 
certain exceedingly imperfect organisms of the simplest 
structure, forms of species of an exceedingly indifferent 
nature, as, for example, many single-celled Protista, but 
especially the Monera, the simplest of them all, should have 
several times or simultaneously arisen in their specific form 
in several parts of the earth. For the few and very simple 
conditions by which their specific form was changed in the 
struggle for life may surely have often been repeated, in 
the course of time, independently in different parts of 
the earth. Further, those higher specific forms also, which 
have not arisen by natural selection, but by hybridism (the 
previously-mentioned hybrid species, pp. 147 and 275), may 
have repeatedly arisen anew in different localities. As, 
however, this proportionately small number of organisms 
does not especially interest us here, we may, in respect 
of chorology, leave them alone, and need only take 
into consideration the distribution of the great majority 
of animal and vegetable species in regard to which the 
single origin of every species in a single locality, in its 
so-called “central point of creation,’ can be considered as 
tolerably certain. 
Every animal and vegetable species from the beginning 
of its existence has possessed the tendency to spread beyond 
the limited locality of its origin, beyond the boundary of 
its “centre of creation,” or, in other words, beyond its 
VOL. I. 2A 
