332 DARWINISM AND THE PROBLEMS OF LIFE 



since even the most favourable variation of the latter 

 could not perform a single function of the trunk ? 



The whole difficulty would be avoided if we could 

 suppose that variations that have once arisen have 

 in themselves a tendency to advance in the same direction 

 in each generation ; in that case, if the elephant's nose 

 happened to be rather longer than those of its fellows, it 

 would be still longer in this elephant's offspring, and if 

 the family became isolated, each succeeding generation 

 would have longer noses. In the end a point would be 

 reached when the nose would be long enough to be of 

 service. Then selection would set in, and still further 

 develop it. 



If there were definitely directed variations, it would 

 be easier to solve a number of other problems. The 

 importance of amphimixis would be greatly enhanced. 

 By means of it different directions of variation would be 

 brought together in one individual, and co-adaptations 

 would be effected much more quickly. At the same 

 time, amphimixis would convey both upward and 

 downward variations to a number of individuals, and 

 thus generalise useful characteristics, and prevent 

 injurious ones from spreading, with fatal consequences 

 to their possessors. 



There are many advantages in the theory of definitely 

 directed variations. Many scientists, in fact, believe 

 we need the hypothesis, as the theory of selection is, 

 they say, unable without it to explain the origin of 

 species. We will now see if there is sound reason for 

 crediting nature with definitely directed variations. 



The expert who has made most use of the principle of 



