PREFACE. 259 



of which they are composed. Such new characters as these 

 do not at present admit of an exact analysis : we have to be 

 satisfied with the undoubted fact of their occurrence. The 

 transmission or non-transmission of acquired characters must 

 be of the highest importance for a theory of heredity, and 

 therefore for the true appreciation of the causes which lead to 

 the transformation of species. Any one who believes, as I do, 

 that acquired characters are not transmitted, will be compelled 

 to assume that the process of natural selection has had a far 

 larger share in the transformation of species than has been as 

 yet accorded to it ; for if such characters are not transmitted, 

 the modifying influence of external circumstances in many 

 cases remains restricted to the individual, and cannot have any 

 part in producing transformation. We shall also be compelled 

 to abandon the ideas as to the origin of individual variability 

 which have been hitherto accepted, and shall be obliged to 

 look for a new source of this phenomenon, upon which the 

 processes of selection entirely depend. 



In the following pages I have attempted to suggest such 

 a source. 



A. W. 



Freiburg i. Br., 



November 22, 1885. 



S 2 



