22 The Selection Theory 



addition to other factors, he laid special emphasis on the increased 

 or diminished use of the parts of the body, assuming that the 

 strengthening or weakening which takes place from this cause 

 during the individual life, could be handed on to the offspring, and 

 thus intensified and raised to the rank of a specific character. 

 Darwin also regarded this Lamarckian principle, as it is now 

 generally called, as a factor in evolution, but he was not fully con- 

 vinced of the transmissibility of acquired characters. 



As I have here to deal only with the theory of selection, I need 

 not discuss the Lamarckian hypothesis, but I must express my opinion 

 that there is room for much doubt as to the cooperation of this 

 principle in evolution. Not only is it difficult to imagine how the 

 transmission of functional modifications could take place, but, up to 

 the present time, notwithstanding the endeavours of many excellent 

 investigators, not a single actual proof of such inheritance has been 

 brought forward. Semon's experiments on plants are, according to 

 the botanist Pfeffer, not to be relied on, and even the recent, beautiful 

 experiments made by Dr Kammerer on salamanders, cannot, as I hope 

 to show elsewhere, be regarded as proof, if only because they do not 

 deal at all with functional modifications, that is, with modifications 

 brought about by use, and it is to these alone that the Lamarckian 

 principle refers. 



III. Objections to the Theory of Selection. 

 (a) Saltatory evolution. 



The Darwinian doctrine of evolution depends essentially on the 

 cumulative augmentation of minute variations in the direction of 

 utility. But can such minute variations, which are undoubtedly 

 continually appearing among the individuals of the same species, 

 possess any selection-value; can they determine which individuals 

 are to survive, and which are to succumb; can they be increased 

 by natural selection till they attain to the highest development of a 

 purposive variation ? 



To many this seems so improbable that they have urged a theory 

 of evolution by leaps from species to species. Kolliker, in 1872, 

 compared the evolution of species with the processes which we can 

 observe in the individual life in cases of alternation of generations. 

 But a polyp only gives rise to a medusa because it has itself arisen 

 from one, and there can be no question of a medusa ever having 

 arisen suddenly and de novo from a polyp-bud, if only because both 

 forms are adapted in their structure as a whole, and in every detail 

 to the conditions of their life. A sudden origin, in a natural way, of 

 numerous adaptations is inconceivable. Even the degeneration of a 



