418 
DARWINISM 
CHAP. 
not have been effected by “ simultaneous fortunate spontaneous 
variations.” But this difficulty is fully disposed of by the 
facts of simultaneous variation adduced in our third chapter, 
and has also been specially considered in Chapter VI, p. 127. 
The best answer to this objection may, perhaps, be found in 
the fact that the very thing said to be impossible by variation 
and natural selection has been again and again effected by 
variation and artificial selection. During the process of forma¬ 
tion of such breeds as the greyhound or the bull-dog, of the 
race-horse and cart-horse, of the fantail pigeon or the otter- 
sheep, many co-ordinate adjustments have been produced ; and 
no difficulty has occurred, whether the change has been effected 
by a single variation—as in the last case named—or by slow 
steps, as in all the others. It seems to be forgotten that most 
animals have such a surplus of vitality and strength for all the 
ordinary occasions of life that any slight superiority in one 
part can be at once utilised ; while the moment any want of 
balance occurs, variations in the insufficiently developed parts 
will be selected to bring back the harmony of the vdiole 
organisation. The fact that, in all domestic animals, variations 
do occur, rendering them swifter or stronger, larger or smaller, 
stouter or slenderer, and that such variations can be separately 
selected and accumulated for man’s purposes, is sufficient to 
render it certain that similar or even greater changes may be 
effected by natural selection, which, as Darwin well remarks, 
“ acts on every internal organ, on every shade of constitu- 
tutional difference, on the whole machinery of life.” The 
difficulty as to co-adaptation of parts by variation and natural 
selection appears to me, therefore, to be a wholly imaginary 
difficulty which has no place whatever in the operations of 
nature. 
Direct Action of the Environment. 
Mr. Spencer’s last objection to the wide scope given by 
Darwinians to the agency of natural selection is, that organisms 
are acted upon by the environment, which produces in them 
definite changes, and that these changes in the individual are 
transmitted by inheritance, and thus become increased in 
successive generations. That such changes are produced in 
the individual there is ample evidence, but that they are in- 
