182 MR. DARWIN'S CRITICS 
waves which break upon the sea-shore are inde-_ 
finite, fortuitous, and break in all directions. In 
scientific language, on the contrary, such a state- 
ment would be a gross error, Inasmuch as every — 
particle of foam is the result of perfectly definite 
forces, operating according to no less definite laws. — 
In like manner, every variation of a living form, 
however minute, however apparently accidental, is — 
inconceivable except as the expression of the 
operation of molecular forces or “ powers ” resident 
within the organism. And,as these forces certainly 
operate according to definite laws, their general 
result is, doubtless,in accordance with some general — 
law which subsumes them all. And there appears 
to be no objection to call this an “evolutionary 
law.” But nobody is the wiser for doing so, or has 
thereby contributed, in the least degree, to the 
advance of the doctrine of evolution, the great 
need of which is a theory of variation. 
When Mr. Mivart tells us that his “aim has 
been to support the doctrine that these species 
have been evolved by ordinary natwral laws (for 
the most part unknown), aided by the subordinate 
action of ‘ natural selection’ ” (pp. 332-3), he seems 
to be of opinion that his enterprise has the merit 
of novelty. All I can say is that I have never had 
the slightest notion that Mr. Darwin’s aim is in 
any way different from this. If I affirm that — 
“species have been evolved by variation + (a natural — 
1 Including under this head hereditary transmission. 
