In the case of the domestic rabbit Darwin notices that the bones of the
legs have (relatively) become shorter by an inch and a half. But as the
leg-bones have _not_ diminished in relative weight,[37] they must
clearly have grown _thicker_ or denser. If disuse has shortened them, as
Darwin supposes, why has it also thickened them? The ears and the tail
have been lengthened in spite of disuse. Why then may not the ungainly
hind-legs have been shortened by human preference independently of the
inherited effects of disuse? By relying on apparently favourable
instances and neglecting the others it would be easy to arrive at all
manner of unsound conclusions. We might thus become convinced that
vessels tend to sail northwards, or that a pendulum oscillates more
often in one direction than in the other. It must not be forgotten that
it would be easy to cite an enormous number of cases which are in direct
conflict with the supposed law of use-inheritance.