Chap. IV. 
MANNER OF DEVELOPMENT. 
153 
inherited effects of habit, and slightly by the direct 
action of the surrounding conditions. Nevertheless I 
was not able to annul the influence of my former 
belief, then widely prevalent, that each species had 
been purposely created; and this led to my tacitly 
assuming that every detail of structure, excepting rudi- 
ments, was of some special, though unrecognised, ser- 
vice. Any one with this assumption in his mind would 
naturally extend the action of natural selection, either 
during past or present times, too far. Some of those 
who admit the principle of evolution, but reject natural 
selection, seem to forget, when criticising my book, that 
I had the above two objects in view ; hence if I have 
erred in giving to natural selection great power, which 
I am far from admitting, or in having exaggerated its 
power, which is in itself probable, I have at least, as I 
hope, done good service in aiding to overthrow the 
dogma of separate creations. 
That all organic beings, including man, present many 
modifications of structure which are of no service to 
them at present, nor have been formerly, is, as I can 
now see, probable. We know not what produces the 
numberless slight differences between the individuals of 
each species, for reversion only carries the problem a few 
steps backwards ; but each peculiarity must have had 
its own efficient cause. If these causes, whatever they 
may be, were to act more uniformly and energetically 
during a lengthened period (and no reason can be 
assigned why this should not sometimes occur), the 
result would probably be not mere slight individual 
differences, but well-marked, constant modifications. 
Modifications which are in no way beneficial cannot 
have been kept uniform through natural selection, 
though any which were injurious would have been thus 
eliminated. Uniformity of character would, however. 
