390 ON THE SUPPOSED BOTANICAL PROOFS Ob 1 THE 



pletely wanting. It must not be forgotten that the onus prolandl 

 rests with my opponents : they defend the assertion that acquired 

 characters can be transmitted, and they ought therefore to bring 

 forward actual proofs; for the mere fact that the assertion has 

 been hitherto accepted as a matter of course by almost everyone, 

 and has only been doubted by a very few (such as His, du Bois- 

 Reymond, and Pfliiger), cannot be taken as any proof of its validity. 

 Not a single fact hitherto brought forward can be accepted as 

 a proof of the assumption. Such proofs ought to be found : facts 

 ought to be discovered which can only be understood with the 

 aid of this hypothesis. If, for instance, it could be shown that 

 artificial mutilation spontaneously re-appears in the offspring with 

 sufficient frequency to exclude all possibilities of chance, then such 

 proof would be forthcoming. The transmission of mutilations has 

 been frequently asserted, and has been even recently again brought 

 forward, but all the supposed instances have broken down when 

 carefully examined. I think I may here safely omit all further 

 reference to the proofs dependent upon transmitted mutilations, 

 especially as Doderlein 1 has already, in the most convincing manner, 

 disposed of the argument derived from the tailless cats which 

 were so triumphantly exhibited at the last meeting of the Associa- 

 tion of German Naturalists 2 . 



I now come to the real subject of this paper the supposed 

 botanical proofs of the transmission of acquired changes. The 

 botanist Detmer has recently brought forward certain phenomena 

 in vegetable physiology 3 , as a support for the transmission of such 

 changes, and although I do not believe that they will bear this 

 interpretation, the discussion of them may perhaps be useful. I am 

 even inclined to think that these and a few other phenomena in 

 vegetable physiology, upon which I shall also touch, are very likely 

 to throw new light upon the whole question which has been so 

 frequently misunderstood. I should have preferred to leave this 

 discussion to a botanist, but I do not know whether my views will 

 meet w r ith any support from the followers of this subject, and I 

 must therefore attempt the discussion myself. And perhaps it is 

 of some assistance in clearing up the question, for one who is not 



1 See 'Biol. Centralbl.' Bd. VII. No. 23. 

 a See the next Essay (VIII). 



8 Detmer, ' Zum Problem der Vererbung,' Pfliiger's Archiv f. Physiologic, Bd. 41, 

 (1887), p. 203. 



