The Making of Species 



believe that this long course of development from 

 the simple to the complex is due to the action 

 of a blind force, to the survival of those whose 

 fortuitous variations happen to be best adapted 

 to the environment. The result seems out of 

 all proportion to the cause. There must be some 

 potent force inherent in protoplasm, or behind 

 organisms, impelling them upwards. This objec- 

 tion is as difficult to refute as it is to establish. 

 It is purely speculative. 



3. A very serious objection to the Darwinian 

 theory is that the beginnings of new organs 

 cannot be explained by the action of natural 

 selection on fortuitous minute variations, and 

 natural selection can act on an organ only when 

 that organ has attained sufficient size to be of 

 practical utility to its possessor. When once 

 an organ has come into being it is not difficult 

 to understand how it can be improved, modified 

 and developed by natural selection. But how 

 can we explain the origin of an organ such as 

 a limb by the action of natural selection on 

 minute variations ? 



The theory of the change of function goes 

 some way towards meeting the difficulty, for by 

 means of it we are able to understand how certain 

 organs, as, for example, the lung of air-breathing 

 animals, might have come into existence. This 

 is said to have been developed from the 

 swimming-bladder of fishes. This bladder is, 



36 



