258 



THE INFLTJUNCE OF INANIJIATE StJRROUNDIKGS. 



been the only efficient cause ; and, moreover, the further enquiry 

 ■whether this auxiliary cause, in combination with a slow up- 

 heaval, might not have been perfectly competent to give ii>e to 

 every form of reef, simultaneously and side by side on the same 

 area. Many celestial phenomena can be explained, and long 

 vs^ere explained, by assuming that the sun moved round the 

 earth ; the consideration that it was insufficient to exjjlain other 

 f.icts allowed us to perceive its complete absurdity. But it is 

 not always the case that one explanation pei-fectly excludes the 

 other. We know that in most plants chlorophyll is formed only 

 under the influence of light ; an exception is found in many 



J ntff/,r„l „i:h^ 





Fig, 70, — «, section tbrongb Erianplp; 6, section tlirough Babeltlump near Aibukit; 

 c, section through Pelelew. 



Coniferss, in which the same leaf-green is elaborated even in the 

 dark. Hence we must conclude that other causes besides those 

 that act on broad-leaved plants are capable of producing the same 

 results. We know, generally, that nature has in many cases 

 made use of different means to produce results which to our 

 eyes seem identical. Thus, to return to the matter in hand, 

 we stUl have to investig.ate the question whether the same 

 results might not have been produced by the auxiliary cause, 

 assuming an upheaval, as by the hypothetical subsidence ; since. 



