66 botanical gazette. [ March r 



to plasm are the means by which alimentary and other sub- 

 stances are transported through the vegetable body\ ^ 



But it must be borne in mind that if the possibility of a 

 migration of pangens from cell to cell be conceded from an 

 anatomical point of view, this by no means suffices for the 

 assumption that it actually does take place. And as Weis- 

 mann has shown that there are no facts in heredity impera- 

 tively requiring such an explanation, a migration of pangens 

 through the whole body is excluded from the hypothesis of 



intracellular pangenesis. 



r 



the limits of a single protoplast, there is only assumed that 

 inactive pangens can leave the nucleus and sooner or later 

 become active in other parts of the protoplast. But if the 

 assumption of free migration through the whole body shall 

 have any connection with the facts of heredity, a further 

 hypothesis is necessary, viz. ; that pangens, coming from all 

 parts, are able to enter into the nuclei of those cells, which 

 will serve for propagation. But, as has been shown, this- 

 hypothesis can be dispensed with. 



It would, of course, be a delusive fancy to think that on 

 so complex a subject as that which has been so ably treated 

 by Prof, de Vries, the greater part of scientific men will at 

 once, or even at a not very distant period, become of the 

 same mind ; and he himself is probably well aware that some 

 of his propositions will be vigorously attacked. Moreover, 

 he has chiefly treated his subject from a botanical point of 

 view, and in a few cases, perhaps, there will be some diffi- 

 culty in applying his hypothesis to the animal organism. 

 But there is a great probability that such difficulties will not 

 prove to be permanent ones. 



At all events, even those most opposed to his views w r ill 

 be forced to acknowledge that intracellular pangenesis has 

 been expounded by one who has fully mastered his subject, 

 and that it certainly deserves to be carefully considered in all 

 its parts, be the conclusion to which such consideration leads 

 what it mav. 



J 



It is from this conviction that I have not thought it use- 

 less to give a short account of Prof, de Vries's book to the 

 readers of this journal. 



Utrecht* Holland. 



