6 Author's Introduction 



repeatedly emphasized these doubts, and to have shat- 

 tered the rather generally accepted doctrine of the hered- 

 ity of acquired characters. 2 



But even if, with this investigator, one rejects the 

 second proposition, that is no reason for likewise doubt- 

 ing the other part of the hypothesis of pangenesis. On 

 the contrary, it seems to me that by doing so its great 

 significance only becomes clearer. Besides, there have 

 been no convincing arguments brought forward against 

 this first dogma, and no other hypothesis concerning the 

 nature of heredity takes account of the facts in so simple 

 and clear a manner. 



Yet most authors have considered that, by refuting 

 the transportation hypothesis, they have also refuted that 

 of the bearers of individual hereditary characters, and 

 they have hardly devoted any special discussion to it. In 

 consequence of this Darwin's view has unfortunately not 

 borne such fruit for the development of our knowledge 

 as its originator had a full right to expect. 



My problem in the following pages will be to work 

 out the fundamental thought of pangenesis independently 

 of the transportation hypothesis, and to connect with it 

 the new facts which the doctrine of fertilization and the 

 anatomy of the cell have brought to light. 



I shall be guided by the thought that the physiology 

 of heredity, and especially the facts of variation and of 

 atavism indicate the phenomena which are to be explained, 

 while microscopic investigation of cell-division and fer- 

 tilization will teach us the morphological substratum of 

 those processes. We shall not try to explain the mor- 



2 The designation "acquired" is not exactly well chosen. The 

 question is: Can characters which have originated in somatic cells 

 be communicated to the germ -cells. This possibility is rejected by 

 Weismann. Compare Part II, 5. (p. 93). 



