LECTURE V 



EVIDENCE FROM GEOGRAPHICAL DISTRIBUTION 



The geographical distribution of animals and 

 plants over the surface of the globe was a subject of 

 interest and importance even in pre-Darwinian days 

 and great attention was paid to it as to so much 

 statistical information. Under the then prevailing 

 theory of special creation and the immutability of 

 species, no explanation of the facts could be expected 

 or even looked for; organisms were created and 

 placed where we find them and that, if true, was an 

 ultimate fact, of which no explanation was possible. 

 As was pointed out in the first lecture, Darwin tells 

 us in his autobiography that it was the facts of dis- 

 tribution which he observed in South America and, 

 above all, in the Galapagos Islands, that first turned 

 his thoughts in the channel of his great work, be- 

 cause these facts seemed to demand an evolutionary 

 explanation. 



Every one knows that different animals and plants 

 are to be found in different parts of the world; the 

 polar bears and musk-oxen occur in the treeless 

 wastes of the Arctic lands, lions and tigers, elephants 

 and rhinoceroses and tall palms must be sought in 

 warm countries and, on hasty consideration, it might 



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