208 AFFINITIES AND GEOGRAPHICAL 



also, if the latter supposition appear preferable, how far the 

 facts agree with the plan of animated nature delineated in 

 the preceding pages. 



It is remarkable at the very first that there is any variety 

 of species in different regions, more especially as the species 

 of one region usually thrive when transplanted to another of 

 generally similar character in point of soil and climate. Had 

 organisms been produced by special attention taking this 

 according to any ideas we can form of it we might rather 

 have expected to see identical plants in similar countries. It 

 will not avail here to attribute the variation to the cultivation 

 of variety as a principle on the part of the Divine Disposer, 

 for the differences evidently follow no such principle, being 

 of various intensities in near and in remote situations. In this 

 consideration, there is a great obstacle to the reception of the 

 special-exertion hypothesis. It seems much more likely that 

 organisms took their rise in germs springing from inorganic 

 elements ; which germs being different in accordance with 

 such slight local differences in the combinations of the ele- 

 ments as physical studies inform us of, and the external con- 

 ditions attending their development being also locally diffe- 

 rent, the resulting vessels of life were various accordingly. 

 Such variations of result are exactly of a piece with hundreds 

 of other simply natural events for example, the difference 

 of animals born at one birth ; and similar natural causes are 

 therefore presumable for them. 



The facts respecting the geographical distribution of 

 organisms are in perfect harmony with the plan of their 

 origin, which, from the geological history, the principles of 

 organic development, and their external affinities, has here 

 been sketched. That plan necessitates the facts of distribu- 

 tion, which the other hypothesis does not. First, a develop- 

 ment of vegetable organisms, we shall say, taking place in the 

 sea, it is exactly what we would expect that they should 

 spread upon the neighbouring shores in every direction, and 

 that we should thus, for example, have one flora surrounding 

 the Mediterranean, which is the fact. So it is also likely 

 that islands should botanically and zoologically partake of the 



