340 AIM AND PROGRESS OF PHYSICAL SCIENCE. 



different, has already been traced in regularly deposited geo- 

 logical strata, and has come to be beyond question; and since 

 this line of research has been taken up, how numerous are the 

 facts which fully accord with Darwin's theory, and give special 

 effect to it in detail ! 



At the same time, we should not forget the clear interpreta- 

 tion Darwin's grand conception has supplied of the till then 

 mysterious notions respecting natural affinity, natural systems, 

 and homology of organs in various animals; how by its aid the 

 remarkable recurrence of the structural peculiarities of lower 

 animals in the embryos of others higher in the scale, the special 

 kind of development appearing in the series of palseontological 

 forms, and the peculiar conditions of affinity of the faunas and 

 floras of limited areas have, one and all, received elucidation. 

 Formerly natural affinity appeared to be a mere enigmatical, and 

 altogether groundless, similarity of forms ; now it has become a 

 matter for actual consanguinity. The natural system certainly 

 forced itself as such upon the mind, although theory strictly 

 disavowed any real significance to it ; at present it denotes an 

 actual genealogy of organisms. The facts of palseontological 

 and embryological evolution and of geographical distribution 

 were enigmatical wonders so long as each species was regarded 

 as the result of an independent act of creation, and cast a 

 scarcely favourable light on the strange tentative method which 

 was ascribed to the Creator. Darwin has raised all these isolated 

 questions from the condition of a heap of enigmatical wonders 

 to a great consistent system of development, and established de- 

 finite ideas in the place of such a fanciful hypothesis as, among 

 the first, had occui-red to Goethe, respecting the facts of the 

 comparative anatomy and the morphology of plants. 



This renders possible a definite statement of problems for 

 further inquiry, a great gain in any case, even should it happen 

 that Darwin's theory does not embrace the whole truth, and 

 that, in addition to the influences which he has indicated, there 

 should be found to be others which operate in the modification 

 of organic forms. 



While the Darwinian theory treats exclusively of the gra- 



