I THE DARWINIAN HYPOTHESIS 9 



distinct from those that now live. Nor is this un- 

 likeness without its rule and order. As a broad 

 fact, the further we go back in time the less the 

 buried species are like existing forms ; and, the fur 

 ther apart the sets of extinct creatures are, the less 

 they are like one another. In other words, there 

 has been a regular succession of living beings, each 

 younger set, being in a very broad and general 

 sense, somewhat more like those which now live. 



It was once supposed that this succession had 

 been the result of vast successive catastrophes, 

 destructions, and re-creations en masse; but 

 catastrophes are now almost eliminated from 

 geological, or at least palreontological speculation ; 

 and it is admitted, on all hands, that the seeming 

 breaks in the chain of being are not absolute, but 

 only relative to our imperfect knowledge ; that 

 species have replaced species, not in assemblages, 

 but one by one ; and that, if it were possible to 

 have all the phenomena of the past presented to 

 us, the convenient epochs and formations of the 

 geologist, though having a certain distinctness, 

 would fade into one another with limits as 

 undefinable as those of the distinct and yet 

 separable colours of the solar spectrum. 



Such is a brief summary of the main truths 

 which have been established concerning species. 

 Are these truths ultimate and irresolvable facts, 

 or are their complexities and perplexities the 

 mere expressions of a higher law ? 



