THE FLORA OF JAPAN. 135 



Indeed, so many species are now known to be common to east- 

 ern and northern Asia and eastern North America, — some 

 of them occurring also in northwestern America and some 

 not, — and so many genera are divided between these two 

 regions, that the antecedent improbability of such occurrence 

 is done away, and more cases of the kind may be confidently 

 expected. However others may regard them, it is clear that 

 De Candolle would now explain these cases in accordance 

 with the general views of distribution adopted by him, under 

 which they naturally fall, — so abandoning the notion of a 

 separate creation. 



I know not whether any botanist continues to maintain 

 Schouw's hypothesis. But its elements have been developed 

 into a different and more comprehensive doctrine, that of 

 Agassiz, which should now be contemplated. It may be de- 

 nominated the autochthonal hypothesis. 



In place of the ordinary conception, that each species ori- 

 ginated in a local area, whence it has been diffused, according 

 to circumstances, over more or less broad tracts, — in some 

 cases becoming widely discontinuous in area through climatic 

 or other physical changes operating during a long period of 

 time, — Professor Agassiz maintains, substantially, that each 

 species originated where it now occurs, probably in as great a 

 number of individuals occupying as large an area, and gener- 

 ally the same area, or the same discontinuous areas as at the 

 present time. 



This hypothesis is more difficult to test, because more 

 ideal than any other. It might suffice for the present pur- 

 pose to remark, that, in referring the actual distribution, no 

 less than the origin, of existing species to the Divine will, it 

 would remove the whole question out of the field of inductive 

 science. Regarded as a philosophical question, Maupertius's 

 well-known " principle of least action " might be legitimately 

 urged against it, namely, "that it is inconsistent with our 

 idea of Divine wisdom that the Creator should use more 

 power than was necessary to accomplish a given end." This 

 philosophical principle holds so strictly true in all the me- 

 chanical adaptations of the universe, as Professor Pierce has 



