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 
