416 ON THE SUPPOSED BOTANICAL PROOFS OF THE 



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 commencement 

 of flowering, together with similar physiological phenomena 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 explanation 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. Accord- 

 ingly, 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 

 between the characters primarily acquired by the soma, and the 

 secondary characters which follow from changes in the germ- 

 plasm. 



If the author had appreciated this distinction he would not 

 have attempted to strengthen his opinions by following up the 

 botanical facts which exclusively belong to the second class of 

 characters, with the enumeration of certain instances selected from 

 the animal kingdom (viz., the supposed transmission of mutila- 

 tions), all of which belong to the first class. I ^11 not discuss 

 these latter instances, for most of them are old friends, and they 



