36 



ESSENTIALS OF ZOOLOGY 



every institution in the land. He was a recognized paleontologist 

 as well as zoologist. He is responsible for one of our first and oldest 

 Marine Biological Laboratories. 



Charles Darwin (1809-1882), an Englishman, made extensive 

 studies on the problem of the manner and means by which new 

 species of organisms arise. He very effectively developed the thesis 

 that they originate by a process of natural selection. This was based 

 on the idea that no two individuals are exactly alike, that new varia- 

 tions are constantly appearing, and finally that those individuals 

 or groups best suited to their environment would be the ones to 



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Pig. 8. — Charles Darwin (1809-1882), the author of Origin of Species. (From Garri- 

 son, History of Medicine, W. B. Saunders Company.) 



persist and produce progeny. His conception of the factors and 

 limitations determining the development of new species, pictures a 

 constant struggle for existence among organisms, with those whose 

 natural variations happen to fit them best to the changing features 

 of the environment persisting as dominant species and others being 

 crowded out. Those least fitted to the environment would naturally 

 become extinct. 



Darwin did not claim originality in his idea. Lamarck, Buffon, 

 and Erasmus Darwin, grandfather of Charles, had presented similar 

 ideas before him. It was the vast accumulation of facts covering 



