( Ixvii ) 



ism which lingers under such an expression as "use-inherit- 

 ance," or Button's factor of the "direct action of the environ- 

 ment." On this point I venture to think that the general ten- 

 dency of work and thought in this country has been to strengthen 

 the contention of Prichard,* Galton, and Weismann, that ac- 

 quired characters are not transmitted. It is true that many 

 naturalists, whose opinions are entitled to the greatest weight, 

 and more particularly a certain school of American biologists, 

 are not prepared to accept this doctrine. While admitting 

 that there are difficulties which require further elucidation, 

 it still appears to me that the balance of evidence is in favour 

 of this amendment of the theory. Certainly the transmission 

 of acquired characters cannot be regarded as a general law of 

 nature, in view of the vague conclusions which have resulted 

 from all attempts at the verification of this doctrine by obser- 

 vation or experiment. It is satisfactory to know that the 

 surviving founder of the theory of natural selection, Dr. A. K. 

 ^Yallace, has fully accepted the Weismannian modification. 



The present position of biological theory, apart from any 

 working hypothesis as to the mechanism of heredity, the 

 struggle of parts within the organism, germinal selection, etc., 

 may thus be summed up in the statement that while the broad 

 principle of evolution is on all hands admitted, there are 

 differences of opinion as to the process or processes by which 

 species and (by implication) the higher taxonomic divisions 

 have been produced. But these differences of opinion ulti- 

 mately resolve themselves into the acceptance or rejection of 

 the special method of evolution which is associated with the 

 names of Darwin and Wallace, because, as far as I have been 

 able to follow the course of post-Darwinian biological specu- 

 lation, I cannot come to any other conclusion than that beside 

 the theory of natural selection there is no rival doctrine of 

 organic development which will bear analysis in the light of 

 reason and of fact. Of course it is quite legitimate for any 

 naturalist to deny the adequacy of natural selection as the 



* It lias strangely been ovei'looked that Dr. James Cowles Prichard, iu 

 his " Eesearches into the Physical History of Mankind," ijublished in 182G 

 .(■2nd ed.), should have most distinctly formulated the doctrine that acquired 

 chara-eters are not transmitted. 



