CONTENTS 



DARWIN, CHARLES 



The Origin of Species in Summary 



Varieties merge gradually into species. Animals tend 

 to increase in geometrical ratio. Varieties diverge 

 in consonance with diversity of opportunity for life. 

 In the struggle for existence those which best accord 

 with their surroundings will survive and propagate 

 their kind. Sexual selection has put a premium on 

 beauty. The causes which in brief periods produce 

 varieties, in long periods give rise to species. Instincts, 

 as of the hive bee, are slowly developed. Geology 

 supports the theory of Evolution: the changes in time 

 in the fossil record are gradual. Geographical dis- 

 tribution lends its corroboration: in each region most 

 of the inhabitants in every great class are plainly 

 related. A common ancestor is suggested when we 

 see the similarity of hand, wing and fin. Embryos 

 of birds, reptiles and fish are closely similar and un- 

 like adult forms. Slight changes in the course of 

 millions of years produce wide divergences. ... 3 



DARWIN, CHARLES 



How "The Origin of Species" Came 

 to be Written 



During his voyage on the Beagle Darwin saw fossil 

 armadilloes like existing species, and on the islands 

 of the Galapagos grotip a gradually increased diversity 

 of species of every kind. All this suggested that 

 species gradually become modified. Notes gathered 

 of facts bearing on the question. Observes that it is 

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