212 Pang ens in the Nucleus and Cytoplasm 



bases for an assumption of an actual intercellular trans- 

 mission of hereditary qualities. 



The facts of heredity so far known, do not, to my 

 mind, make the assumption of an intercellular transmis- 

 sion of pahgens necessary. When the pangens have once 

 left the nucleus they do not need the power of penetrating 

 back into that nor into any other nucleus. The pedigree of 

 the pangens lies in the nuclei, and its protoplasmic side- 

 branchings all end blindly, although often only after many 

 cell-divisions. 



I believe that the passage of the pangens from the 

 nuclei is a necessary conclusion of our present knowledge 

 concerning the physiological significance of the nuclei. 

 I need not assume a penetration of the extruded pangens 

 or their descendents into other nuclei. And this hypothe- 

 sis would be inevitable if one were to connect Darwin's 

 transportation of gemmules with the results of more re- 

 cent cell-study. In this case one would have to resort to 

 a new ancillary hypothesis in order to explain facts, 

 which, according to the discussions mentioned above, do 

 not at all require such an explanation. 



Let us summarize the difference between the two 

 transmission hypotheses. The pangens of the intracellu- 

 lar pangenesis, having once left the nucleus, need never 

 re-enter it. For the gemmules of Darwin's transporta- 

 tion hypothesis, however, this power is the essential con- 

 dition, because without it, the hereditary properties of 

 which they are the bearers, can never develop into visible 

 characters in the descendants of the respective germ-cells. 



6. The Multiplication of Pangens 



The hypothesis, that the entire living substance of a 

 cell is built up of pangens, naturally implies that in every 



