XXXIV 



the usual ignorance of evolutionary change, — the springtime generation, is 

 nothing but a less far advanced evolutionary stage of the same species, that 

 is, therefore, exactly the same as is found in the above mentioned forms of 

 Callidryas Hilaria Cram, and Terias Blanda Bsd. 



I must now, although it may lead to some repetition, return to the muta- 

 tion theory, so popular at present, but which I have already said I do not 

 agree with. According to the old school, a species was usually taken to be 

 a form of life created by a higher power, independent and immutable, always 

 reproducing itself in the same way. There were also some who thought that 

 only the larger groups, the genera, had been created, and that from these, 

 by what was called the natural way, but what in reality was a mysterious 

 incomprehensible process, such as splitting, other kinds were formed which became 

 the species, and from which again in the same way so-called varieties were 

 produced, suddenly bij abrupt changes. Darwin, on the other hand, believed 

 that all animal and vegetable forms have developed by a natural process from 

 other forms, but always in a gradual way. Recently the so-called theory of 

 mutation has arisen, which maintains that each species is immutable in itself, but 

 that sometimes a new form suddenly develops itself from it, which in its turn 

 continues as an independant and immutable species. In this way it accounts for 

 the origin of species, discording Darwin's gradual change of existing forms. But 

 notwithstanding that the name of my compatriot, the learned botanist Prof. Hugo 

 DE Vries in connected with this theory, I am still unable to support it. It is, in 

 my opinion, nothing but a reactionary endeavour to fit the old idea of species, 

 still lingering as a relic, to the new doctrine. By his experimental studies Prof. 

 DE Vries considers that he can support it ; my studies which, it is true cannot 

 be called so purely experimental, but which are based more upon many and 

 accurate observations, and upon the logical working out of the results thus obtained, 

 force me to a different conclusion. I may say at once that the whole idea 

 appears to me to be intimately related to the ancient doctrine of original creations, 

 for the so-called elementary species are really nothing else. This doctrine does 

 not necessarily imply only one single original creation, it allows a continual 

 activity of the same creative power. Neither does it only refer to the calling 

 into being of something out of nothing, the biblical legend of the creation of 

 woman out of the rib of Adam proves the contrary. That which characterises 

 what we mean by creation, is its sudden appearance, and the inexplicability 

 upon natural grounds of the reason for its origin and of the manner in wich it 

 arises. In what way, then, do mutations differ from this? Moreover the study 

 of such evolutionary processes as govern the destruction of special organs — that 

 of the disappearance of the horn of the Sphingidae larvae mentioned above 



