TRANSMUTABLE. 193 



on my theory, distinct species of the same genus 

 must have spread from one parent source." 



And thus he thinks are to be explained all 

 the leading facts of geographical distribution- 

 migration localization of genera sub-genera 

 species why the inhabitants of South America, 

 in the mountains and plains, are linked together 

 and to extinct beings why oceanic islands should 

 have few inhabitants why whole groups of or- 

 ganisms, as batrachians and terrestrial mammals, 

 should be absent from oceanic islands, whilst iso- 

 lated islands possess their species why the in- 

 habitants of an archipelago should be closely 

 related, and to those of the nearest continent 

 why in two areas, however distant, there should 

 be a correlation in the presence of identical 

 species of varieties of doubtful species, and of 

 distinct but representative species. 



A tolerable long list of explanations, which we 

 are told, by reason of two categories of ignorance 

 and a doubt, to add as support to the theory of 

 natural selection ! ! 



Upon the subject of geographical distribution 

 of species, I will make one or two remarks and 

 extracts from the works of eminent men. And 

 first as to Plants. 



The number of species of plants throughout 

 the world is estimated by Meyen at two hundred 

 thousand. 



"If we now look over this immense variety of 

 plants, we shall find that nature, under similar 

 conditions of climate, has always produced similar, 



