CHAPTER FOUR 

 Palaeontology and Geology 



The Positive Evidence for Evolution 



THE evidence for the evolution of plants and 

 animals is commonly said to be derived from 

 many sources. When, however, we examine these 

 causes for our belief we find that, excepting our de- 

 sire to eliminate special creation and, generally, what 

 we call the miraculous, most of them can be consid- 

 ered only as secondary reasons to confirm a theory 

 already advanced. Darwin, in his Origin of Species, 

 enumerated with the greatest care what factors led 

 him to his adoption of the theory of evolution by 

 natural selection, and what lines of observation and 

 experimentation would be likely to confirm the rea- 

 sonableness of his ideas. It is quite certain that, for 

 positive proof, he relied on the existence of fossil 

 remains of plants and animals and on the geological 

 record which shows that during the long history of the 

 earth it has been occupied by a succession of different 

 forms, many of which are now extinct. He devoted 

 four chapters to the discussion of palaeontology and 

 made it clear that to his mind the discovery and 

 knowledge of fossils is the evidence which alone can 

 change his doctrine of evolution from an abstract 



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