56 ORGANIC EVOLUTION 



to the history of many of their predecessors, have 

 persisted and more than persisted through the 

 subsequent epochs, and now reign in the vegetable 

 kingdom as effectively as the vertebrates in the 

 animal kingdom. 



Meanwhile a vast number of species have suc- 

 ceeded in persisting from palaeozoic and mesozoic 

 times ; many of them, so far as can be judged, 

 without having undergone any change through 

 all these ages. To this fact of the persistence of types, 

 which is exemplified in both the vegetable and the 

 animal kingdom, we shall revert in a later chapter, 1 

 since upon it has been founded a specious objection 

 to the theory of organic evolution, and since it is 

 incompatible with that popular misreading of the 

 theory which regards it as expressing a principle of 

 necessary " progress," or ascent from lower to higher 

 forms. 

 « 



CHAPTER X 



A CONCLUSIVE INSTANCE 



We have now considered, in brief, the main lines 

 of evidence in favour of organic evolution ; we have 

 noted the conditions upon which it depends, and 

 the factors of its course ; but sceptical readers — 

 of whom I would rather have ten than ten 

 times ten of the credulous — may yet be inclined 

 to exclaim that " all this is very well, hangs nicely 

 together, is plausible and interesting ; hut is there, 

 or is there not, any conclusive instance of the 



1 See Chapter XII. 



