VII.] TRANSMISSION OF ACQUIRED CHARACTERS. 429 



The fixation of the time at which flowering begins, is an 

 adaptation which formerly could have been very well explained 

 as the direct result of external conditions. The question we 

 have to decide is wltether such an explanation is the true one. 

 We might imagine that the plant would be forced into quicker 

 development by an earlier appearance of the warm season. 

 Hence when transferred into a warmer climate the plant would 

 at first flower rather earlier, the habit would then be trans- 

 mitted, and would increase in successive generations from the 

 continued influence of climate, until it advanced as far as the 

 organization of the plant permitted. But in this explanation, 

 as in so many others of the same kind, it has unfortunately 

 been forgotten that the transmission of acquired characters 

 which is presupposed in the explanation is a totally unproved 

 hypothesis. It is sufficiently obvious that by interpreting a 

 phenomenon in a manner which presupposes the transmission 

 of acquired characters, we cannot furnish a proof of the 

 existence of such transmission. 



It always seemed to me that the fixation of the commence- 

 ment of flowering, together with similar physiological pheno- 

 mena in the animal kingdom (for example, the hatching of 

 insects from winter eggs), could be explained very satisfactorily 

 by the operation of natural selection : and even now this ex- 

 planation appears to me to be the simplest and most natural. 

 In Freiburg, where the vine is largely grown, the harvest is 

 often injured by frosts in spring, which kill the young shoots, 

 buds and flowers. Accordingly, different kinds of vine, which 

 do not push their buds so early, have now been planted. Any 

 one, who has seen all the shoots of the former destroyed by 

 the frosts at the end of April, while the latter, not having 

 opened their buds, were spared, would not doubt that the 

 former must have been long ago exterminated, if they had been 

 compelled to struggle for existence with the others, under 

 natural conditions. Now the time of flowering fluctuates 

 slightly in the individuals of every species of plant, and can 

 therefore be modified by natural selection. It is therefore 

 difficult to see why the time at which each plant flowers should 

 not have been fixed in the most favourable manner for each 

 habitat, by natural selection alone. 



Hoffmann is obviously unaware of the fundamental distinction 



