360 Darwin, and after Darwin. 
view of adaptation. Still, on the doctrine of chances, 
it is to be expected that sometimes a change of 
structure which has thus been indirectly produced by 
correlation of growth might happen to prove useful 
for some purpose or another; and in as many cases 
as such indirectly produced structures do prove useful, 
they will straightway begin to be improved by the 
direct action of natural selection. In all such cases, 
therefore, we should have an explanation of the orzgzz 
of such a structure, which is the only point that we 
are now considering. 
I think, then, that all this effectually disposes of 
the doctrine of “prophetic germs.” But, before 
leaving the subject, I should like to make one 
further statement of greater generality than any which 
I have hitherto advanced. This statement is, that we 
must remember how large a stock of meaningless 
structures are always being produced in the course of 
specific transmutations, not only by correlation of 
growth, which we have just been considering, but also 
by the direct action of external conditions, together 
with the constant play of all the many and complex 
forces internal to organisms themselves. In other 
words, important as the principle of correlation 
undoubtedly is, we must remember that even this is 
very far from being the only principle which is con- 
cerned in the origination of structures that may or may 
not chance to be useful. Therefore, it is not only 
natural selection when operating indirectly through 
the correlation of growth that is competent to produce 
new structures without reference to utility. In all 
the complex action and reaction of internal and ex- 
ternal forces, new variations are perpetually arising 
