198 Charles Darwin. 



habited the earth were the descendants, with modi- 

 fication, from previous inhabitants since the dawn of 

 life. A glimmer of the truth had now and then 

 occurred to contemplative students. Philosophers 

 had ventured to think that living forms like ancient 

 ones might have descended from them. The inves- 

 tigators in various departments of biology had 

 gradually deduced generalisations which all tended 

 in a similar direction. The taxologists, in their very 

 nomenclature, compared the animal kingdom to a 

 tree of which the principal types were " branches " 

 diverging from a common trunk, while the minor 

 groups were successive ofTshoots ; and the idea of 

 genetic relationship suggested by the various degrees 

 of likeness was expressed in the names conferred on 

 other groups — -" tribe," " family," etc. The embry- 

 ologists had recognised a coincidence between the 

 stages of development of the "superior" animals 

 and the adults of animals inferior in the system. 

 The palaeontologists had discovered an approximate 

 coincidence between the successive inhabitants of 

 the earth and the successive stages in the develop- 

 ment of the living animals of the same types. The 

 series of facts thus obtained had even, to some 

 extent, been co-ordinated. 



All these series of facts were such as would have 

 been the result of the derivation of existing types 

 from previous ones. But the possibility that the 

 seeming was the real did not commend itself to the 

 consideration of naturalists. Instead thereof, it was 

 assumed that the facts were " in accordance with a 

 plan of the Creator " ; that the Deity had conceived 



