i 3 o PERIOD V. 



The succession in the same area of the same types- 

 armadillos succeeding- armadillos in South America, 

 marsupials succeeding marsupials in Australia was 

 enough of itself to render independent creation highly 

 improbable. This was not all. Darwin's mind being 

 charged with facts and reasonings, the accumulations of 

 many years of travel and meditation, he sketched in- 

 rapid outline conclusions which have given a new form 

 to the distribution question. The subject had hitherto 

 been treated by collecting masses of facts and inter- 

 preting them by recent physical geography ; Darwin 

 showed that the history of the continents and islands 

 may be far more influential than soil, elevation, or 

 climate. 



The scientific discussion of the facts of distribution is 

 as old as the sixteenth century, when L'Obel pointed out 

 that the mountain plants of warm countries descend 

 to low levels in the north. Linnaeus remarked that 

 fresh-water plants and alpine plants are often cosmo- 

 politan. Another early and well-founded generalisation 

 is the statement of Linnasus that the plants common to 

 the old and the new world are all of northern range. 

 Buffon made the same remark about the animals, and 

 offered the probable explanation viz., that since the 

 two great land-masses approach one another only in 

 high latitudes, it is only there that animals have been 

 able to cross from one to the other. 



In the nineteenth century theories involving prodi- 

 gious changes of land and sea were much in the minds 

 of naturalists. Darwin lost his temper (a rare thing 

 with him) over the land-bridges, hundreds, or even 

 thousands, of miles long, which were created in order 

 to explain trifling correspondences in the population of 

 distant countries. A belief in the comparative stability 



