128 GEOLOGICAL BIOLOGY. 



Lamarck, who looked upon species as mutable, still found his 

 ignorance impelling him to use the theory of spontaneous 

 generation to start his series. However much they may- 

 seem to be independent of a first cause, no scientific theory 

 even of evolution is complete without recognizing the potency 

 of the things as existing before their appearance. 



Conclusions. It will be apparent now that the discussion 

 of the relation of organisms to environment, or geographical 

 distribution, touches the fundamental problems of natural 

 history. Forbes was of the Linnaean school, who with 

 Cuvier and all that earlier school of naturalists held to the 

 conception of a species immutable; but his studies of distri- 

 bution were among the more important agencies in clearing 

 the way for the abandonment of that conception of species. 

 The explanation he gave of the origin of species was the 

 most rational one so long as the species was supposed to be 

 immutable. We often imagine that evolution, which has 

 been made the watchword of the new view, is a newly dis- 

 covered truth ; not so. The processes of evolution have beeii 

 elaborately investigated by the new school, but evolution of 

 organisms, in the abstract sense,' had been promulgated 

 almost from the beginning of philosophy, as already stated. 



Darwin, in his li Origin of Species," frequently, and with 

 apparently no more hesitation than he had for the use of 

 species, spoke of Creation; he adopted, too, Forbes' term 

 "Centres of Creation." Haeckel, one of the most radical 

 defenders of the new views, entitled one of his most impor- 

 tant books " The History of Creation."* These illustrations 

 show that the attempt to explain the process and cause of 

 Evolution is quite distinct from the recognition of the facts 

 of Evolution, and we may conclude that mutability of organic 

 species and the evolution of organisms in geological time are 

 established facts, in the accomplishment of which both ancestry 

 and the conditions of environment have played a part. 



* "Nattirliche SchopfunjiSgeschichte." Berlin, 1868. 



