CRITIQUE OF DARWINISM 249 
order to prevent swamping out through intercrossing with the 
parent-type. 
5. Objection has frequently been made to Darwin’s idea of the 
purely fortuitous or chance character of variations. According to 
this view variations occur in all structures arid in all directions at 
haphazard, so that there would be the widest possible opportunity for 
a given adaptive variation to occur just when the circumstances 
would demand. It now appears that variations do not occur in all 
directions in random fashion, but that they tend to follow certain 
definite paths of change; in other words, variations are, to a consider- 
able extent at least, orthogenetic. If variations really tend to follow 
certain definite lines, owing to purely internal causes, natural selection 
would be unnecessary, at least until orthogenesis went too far for the 
good of the species, or far enough to be of real importance in the 
struggle for existence. 
6. The difficulty of explaining how natural selection could make 
use of the initial stages of adaptive structures is obvious. It is incon- 
ceivable that the first, almost imperceptible variation in a favorable 
direction could be of selective value, so as to effect the survival of the 
individual or the relative number of its offspring. What would be the 
advantage of the first few hairs of a mammal or the first steps 
toward feathers in a bird when these creatures were beginning to 
diverge from their reptilian ancestors? This objection is, of course, 
based on the fluctuating-variation idea. If the mutation idea were 
substituted, the difficulty would, to a great extent, clear up; for a 
mutation might be of sufficient importance in one generation to have 
selective value from the very first. 
7. Natural selection is said to be incapable of explaining the origin 
of coadaptive and highly complex adaptations whose effectiveness 
depends upon the perfection of their adjustments to one another. For 
example, we may refer to some of the perfected adaptations described 
in chapter xiv. In the case of the electric organs of certain fish, the 
Darwinian assumption would be that the first step in the direction of 
an electric organ would be a very small one, and that it was built up 
little by little by means of natural selection. But, say the critics, the 
‘electric organ would be of no value until it became powerful enough 
to impart an effective shock to the intruder, and this would not be 
possible if the character began in a small way.. The whole phenome- 
non of protective resemblance is open to the same type of criticism. 
As a specific example of this we may cite the case of the dried-leaf 
