CRITIQUE OF DARWINISM 251 
legs and that any decrease in their size, which would be enhanced by 
disuse, would be of advantage. This might seem reasonable during 
the main period of limb reduction, but, after the limb is redyiced to a 
subcutaneous rudiment, there could be little advantage in carrying 
the rudimentation still farther. Some whales have the hind limbs 
much more profoundly reduced than others, although they are all 
thoroughly out of the way and involve no hindrance in swimming. 
Any number of similar cases of the same kind might be cited. Darwin 
had no explanation to offer except a resort to Lamarckism; but 
Weismann, the ablest neo-Darwinian, offered the theory of panmixia 
to cover this objection, a theory which is mentioned in chapter i and 
will be discussed later. 
11. It is objected that, unless favorable variations occur in a large 
number of individuals at the same time, the character would be 
swamped out by intercrossing with individuals not possessing the 
favorable variation. The probability that such a swamping-out 
would occur was shown mathematically by various critics. By way 
of answer to this objection there arose a number of “isolation theo- 
ries,’ according to which favorably varying individuals would be 
protected from back-crossing with the non-varying individuals. We 
might also point out that the Mendelian laws of dominance and 
segregation would serve to prevent loss of any new favorable character. 
12. It is objected that natural selection might explain the “sur- 
vival, but not the arrival, of the fittest.” But Darwin met this 
perfectly when he said: “Some have even imagined that natural 
selection induces variability, whereas it implies only the preservation 
of such variations as arise and are beneficial to the being under its 
conditions of life.” 
13. Criticism has been directed against natural selection because 
of the fact that some of the supporters.of Darwinism, notably Weis- . 
mann, have made the claim that, natural selection is the sole cause of 
evolution. This idea of the Allmacht or all-sufficiency of natural 
selection was not Darwin’s, as is clear from the following statement: 
“T am convinced that natural selection has been the most important, 
but not the exclusive means of modification.” 
14. It is objected that many, if not most, of the fluctuating varia- 
tions with which Darwinism deals are purely quantitative or plus- 
and-minus variations; whereas the differences between species are 
qualitative. This is a serious objection and difficult to meet, yet a 
fair defense has been formulated by leading neo-Darwinians. 
