SUMMARY 77 



developed by the parent under the influence of use or injury is 

 profoundly different from one which is developed by the child 

 under the stimulus of nutriment. The doctrine assumes that all 

 structures in all living beings are capable of growth under the 

 stimulus of use, and that the amount of this growth is compara- 

 tively trivial ; whereas the truth is that only some structures in 

 some living beings can grow in this way, and in some types the 

 amount of growth so made is by far the major part of the total 

 normally achieved. It pretends to account for adaptive variations, 

 but in almost every instance a character transferred from the 

 category of those produced by use or injury to that of those 

 produced under the stimulus of nutriment would become less 

 adaptive, and often positively harmful. It professes to account for 

 evolution, but, were it true, every species would drift swiftly out 

 of harmony with the surroundings, and therefore to destruction. 

 Except miracle, we can conceive no means through which the 

 power of transferring characters from one category to another can 

 have originated. Lastly, there is massive evidence not only that 

 have inborn traits not replaced acquirements, but that the contrary 

 has happened. 



124. The Lamarckian hypothesis is dead as an accepted inter- 

 pretation of the facts. Probably none of the younger students of 

 heredity accept, or will ever again accept it. Indeed, so far as I 

 am able to judge, nobody, even if he happens to be a professional 

 biologist, now holds it unless he is unaware of, or ignores much 

 that has been published of recent years on the subject. At 

 any rate, while such arguments as those which were used, for 

 example, by Spencer about the horns of the elk are still advanced, 

 the reasoning which has demonstrated their invalidity is invariably 

 ignored. 



