SUDDEN ADAPTATIONS 459 



intermediate sort, each element being always hereditary 

 unless it gives place to a new element through mutation. 

 While the parent form may continue to be inherited un- 

 changed by certain descendants for innumerable generations 

 the descendants of a mutation to which it has given rise may 

 mutate again and again, until finally a form has arisen charac- 

 terized by so many new elements that it is no longer capable 

 of producing offsjjring like those of the original ancestral 

 form. Then a new species has appeared; and by a similar 

 differentiation through many successive mutations, there 

 would arise genera, families, and groups of higher order. 



Whether the peculiarities of a mutation are beneficial or 

 not is immaterial provided only they do not unfit the or- 

 ganism for living under the conditions where it occurs. If 

 it can gain a foothold either in the same environment as that 

 of its parent or under some other set of conditions a new race 

 or new species may be started. It has been commonly as- 

 sumed by naturalists that every slightest peculiarity of an 

 organism must have some important relation to its welfare 

 whether apparent to us or not, since otherwise we could not 

 understand its fitting into the environment under which it 

 thrives. On this view we should have to suppose that all 

 the peculiarities of the new forms of -escaped primroses repre- 

 sent sudden adaptations; but in that case it must be admitted 

 that very diverse adaptations fit al^out equally well into the 

 same environment. The assumption that every trait must 

 he connected with some use, seems, however, to be quite 

 gratuitous. This supposition is not at all necessary to the 

 theory of mutations, although, as we have seen, it is a neces- 

 sary incumbrance to the theory of natural selection. On 

 the new view we may suppose that a mutation presents fea- 

 tures which may be more or less beneficial, indifferent, or 

 even more or less injurious; yet if it gets into an environ- 

 ment which permits such a form to live, then the traits 

 of each description may become characteristic of a sur- 

 viving group. We all know that however useless or un- 

 desirable defects or bad habits may be, they are not neces- 

 sarily fatal, and are sometimes perpetuated. Thus we can 

 account for the fact that many characters of the highest 



