The PiUKjcncs. 643 



character on them, and this assumption furnislies an ex- 

 planation of the fact that the functions of the cell-organs 

 conform to the hereditary characters of the plants t(j 

 which they belong. This migration from the nuclei is 

 repeated at intervals,^ and thus the body of the cell 

 soon comes to consist almost solely of pangenes which 

 have recently emerged from the nucleus. 



§ II. THE PANGENES AS BEARERS OF THE HEREDITARY 



CHARACTERS. 



As an hypothesis, pangenesis serves a heuristic ob- 

 ject; as a theory, it must serve as a basis from which a 

 deeper insight into the nature of living substance may 

 be obtained. I have not much to sav here as to its 

 heuristic value, since for myself pangenesis has always 

 been the starting-point of my inquiries; at first only in 

 a theoretical way, but afterwards also for the experi- 

 mental investigations described in this book.- 



Especially is it this hypothesis Avhich has led me t<> 

 search for mutations in the field, '"^ because I hoped in tlii-^ 

 way to find facts which would tb.row a more immediate 

 light on the bearers of hereditary characters, and thereby 

 on the theory of heredity in general. 



The doctrine of pangenesis only touches the kernel 

 of the general theory of heredity and leaves the details 

 to special theories; but experience has taught nie thaf 



*My belief that tlic transportation of the panpcne;^ is larpjcl\ 

 l)roii.c:ht about by the so-called streaming: of the protoplasm and that 

 this is a normal and general occnrrence has not in the least bee!) 

 shaken by the arguments which have 1ieen urged against it. 



" Sc the bibliography at the beginning of this volume. 



^ T should like to insert here the following little coincideiu-* 

 My IntraccUnlarc Pan (genesis was written during the summer h«'li 

 days, spent near Hilversum in 1888. and the often described localit> 

 of Oenothera Lamarelciaiia was only about ten minute^ walk away. 



