240 DARWINISM AND THE PROBLEMS OF LIFE 



below. However, the ancestral forms of the snails are 

 in the sea, and are gill-breathers. How were the lungs 

 formed when they came to live on land ? The organ 

 for breathing air could not be large enough from the 

 start to perform its function. How was it possible, 

 then, for variations which represented the rudiment of 

 an organ that could not yet act, and so were useless, to 

 be preserved and favoured by selection ? 



Here we have what is considered to be the radical 

 objection to the theory of selection ? The action of 

 natural selection is made possible by the variations that 

 bring about differences between animals, and cause some 

 of them to be retained and others extinguished on the 

 ground of their better or worse qualities. But these 

 variations are insignificant in themselves. Hence if an 

 animal only differs very little from its fellows, we can 

 hardly say that it has on that account more chance of 

 surviving or perishing than they. 



Let us take an instance. In the craw-fish the eyes 

 are fixed on mobile stalks, and so the animal, the whole 

 fore part of the body of which is rigid, is able to see over 

 a larger area. In its ancestors the eyes were set deep 

 in the head, as is still the case with the centipedes and 

 the smaller crabs. According to our theory, those 

 crustaceans must have been selected whose eyes stood 

 out a little higher than those of their fellows, so that 

 they were favoured in the struggle for life. But, it may 

 be asked, could this trifling elevation of the eyes really 

 be such an advantage to its possessor ? The field of 

 vision would only be the smallest degree larger than in 

 the other crabs. If individuals arose amongst those 



