THE SHAPES OF BIRDS 



THE enormous and sudden advance made 

 by zoological science in the latter half of 

 the nineteenth century has been followed 

 by a reaction. During the last ten or 

 twelve years that particular branch of knowledge has 

 made comparatively little progress. Darwin and 

 Wallace completely revolutionized biology. They shed 

 the light of the highest genius on the darkness which 

 had hitherto brooded over the study of life. Their 

 researches gave an enormous impetus to natural science. 

 Nor were these the only stimuli. The theory of natural 

 selection met at first with very bitter opposition on all 

 sides. This opposition stirred up the Darwinians to 

 new exertions. 



Unfortunately the opposition was very shortlived. 

 The triumph of the theory of natural selection was as 

 speedy as it was complete. It would, I believe, have 

 been more profitable to biological science had the con- 

 flict been of longer duration. Natural selection has 

 won all along the line. It has proved itself able to 

 explain a large number of phenomena, it has overcome 

 a multitude of difficulties. Facts which were at one 

 time urged against it are now held to be among the 



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