DE VRIES'S THEORY OF MUTATIONS. 221 



Still, although the mutation experiments of de Vries have consid- 

 erably strengthened the argument of Scott and other paleontologists, 

 that slow, simultaneous mutation has also taken place among those 

 fossil animals — the same experiments have, moreover, proved beyond 

 any doubt that there is no such thing in nature as predetermined 

 mutation in one special direction, but that, on the contrary, mutation 

 occurs in very different and very divergent directions. 



When once the mutation process leading to the formation of species 

 has begun, the most different mutations, as we have seen above, arise. 

 From our point of view, some of these may be called good, others bad 

 or indifferent. About the permanence of any of them, it is, however, 

 the surrounding conditions, acting by means of selection, that decide. 

 And often the decision lies in another direction than would have been 

 surmised from the human adjectives just named. 



By the phenomenon of mutation the possibility exists that useless, 

 and even to a certain extent prejudicial or noxious, specific characters 

 may appear, a phenomenon which could never be reconciled with the 

 views of Wallace. 



For the greater part these characters are sure to be eliminated, 

 but if other circumstances happen to be or to become favorable to a 

 mutation, which was originally without any particular significance, it 

 can then gradually develop and become adapted to certain modifica- 

 tions in the surrounding factors of life. The majority of the muta- 

 tions, however, soon perish in the struggle for existence. Of those 

 many elementary species that were doomed from the first, nothing has, 

 of course, come down to us. in the archives of the fossil remains; only 

 when their number has considerably increased in comparison with the 

 parent species will it have been possible for them to survive, but then 

 they have already risen to be a side branch, or may even be supplanting 

 the parent stock. 



The theory of mutation, as well as that which ascribes the origin 

 of species to the selection of fluctuating varieties, enables us to under- 

 stand how efficiency and adaptation in organic nature have come about 

 by the mutual interaction of natural processes without the aid of 

 supernatural intervention. The struggle for existence between species 

 and mutations comes about in the same way as does the struggle for 

 existence between individuals in the older view. Spencer's expression, 

 however, 'the survival of the fittest,' must henceforth be interpreted 

 as meaning 'the survival of the fittest species.' When we agree with 

 de Vries that the gradual mutation of species is not necessarily the 

 revelation of a foreordained design, this should be interpreted in the 

 spirit of greater humility which befits the naturalist when he is con- 

 fronted by the gigantic problems of organic nature. As long as a 

 natural coordination of facts furnishes us with an intelligible causal 



