166 Darwin and his Teachings. | April, 
distinctive and beneficial feature in the offspring, and a new variety 
is formed. The gradual accumulation of such differences, trans- 
mitted from generation to generation, at length forms, according to 
Darwin’s view, a new species, then a new genus, a new “ family,” &e. 
The varieties, species, genera, or families not possessing these advan- 
tageous modifications, die out in “the struggle for existence,” from 
their unfitness to cope with new natural obstacles, and to live under 
the changed conditions by which they are surrounded. 
Now it will at once strike the reflecting reader, that before 
“Natural Selection” can lay hold of any divergences of character 
(physical or instinctive), those divergences must have made their 
appearance, and the inquiries naturally suggest themselves: How 
do these differences origmate? And how does it happen that the 
new features have been of such a nature as to render their fortunate 
possessor better adapted for the conditions of existence? (Of course, 
we do not lose sight of the fact that changes injurious to the animal 
or plant may also present themselves, and these, the author tells us, 
are neglected or unheeded by “Natural Selection,” which only 
seizes upon advantageous peculiarities, “favouring the good and 
rejecting the bad.’’*) 
That there may be no misunderstanding, we will hear what 
the author himself says on the subject: 1. “ Natural Selection ” 
cannot produce any variation in structure or instinct ;{ and it 
can only act for the good of each being,t by the preservation and 
accumulation of inherited modifications, each profitable to the 
preserved being.§ It acts only by “very short and slow steps,” 
and cannot produce any great, or sudden modification. | 
Here we must stop to inquire: If no visible external infiuence 
can give rise to fresh variations in structure, what other natural or 
secondary cause can do so? The answer is, “sexual causes,” or 
sexual phenomena; for such terms as “tendency to variation” 
or “laws of growth” do not indicate causes, but imply ignorance of 
them. 
What, then, does the author tell us about sexual causes? With 
him it is “ sexual selection,” and he thinks, 2. That “a change in 
the conditions of life,” by specially acting upon the reproductive 
system, causes or increases variability. But is this not reasoning 
in a circle, or, worse still, is 1 not a direct contradiction of his own 
proposition, that “natural selection” cannot produce variability ? 
We are not splitting hairs, nor cavilling about words, for he tells us 
distinctly in one place that natural selection “can act on every 
internal organ, on every shade of constitutional difference, on the 
whole machinery of life.”** And again, in another place: “It 
* ‘Origin of Species, p. 502, par. 2; and in many other parts of the work. 
t Ibid., p. 107, par. 2, “ Unless favourable.” &e ; p. 84, par. 2; p. 100, par. 2. 
+ Ibid., p. 86, par. 2. § Ibid., p. 151, par. 1: and p. 492, par. 2. 
|| Ibid., p. 504, par. 2. q Ibid., p. 86, par, 2. ** Thid., p. 87, par. 2. 
