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 unifornf through natural selection, 

 though any which were injurious would have been thus 

 eliminated. Uniformity of character would, however, 



