(2) a group of Speculative Evolutionists — Diderot, 

 Bonnet, Robinet and Oken— who put forward a number of 

 speculations regarding heredity and evolution that are 

 often interesting on account of their crudeness. 



Buff on (1707-1788) has been called the first of the great 

 pioneers of modern evolution. His most noteworthy con- 

 tribution was a theory of the direct action of the environ- 

 ment in the production of structural changes which are 

 heritable. 



Erasmus Darwin (1731-1802), grandfather of Charles 

 Darwin, was another pioneer evolutionist who had fairly 

 well defined ideas regarding the derivation of plants and 

 animals. Unlike Bufifon he believed that the environ- 

 ment only indirectly modified their organization. His 

 Zoonomia was published in 1794. 



The poet Goethe (1749-1832) was a firm believer in 

 evolution, and contributed an important theory on the 

 metamorphosis of foliar organs and another relating to an 

 innate growth force. His views were published in 1794 

 and 1795. 



Treviranus (1760-1837) was the forerunner of Charles 

 Darwin in the emphasis he laid on the inter-relations be- 

 tween organisms and the environment. He was a 

 Lamarckian with regard to the modifying influence of the 



environment. 



Geoffroy St-Hilaire (1772-1844) was a pupil of Buffon, 

 and shared his views concerning the direct action of the en- 

 vironment — published in 1828. He believed also that de- 

 velopment might occur suddenly by leaps, and produce 

 discontinuous variations. 



Robert Chambers (1802-1871), the author of Vestiges of 

 the Natural History of Creation (1844), prepared the minds 

 of the reading public for Darwin's Origin of Species. His 

 views of evolution, not always accurately expressed how- 

 ever, combined those of Buffon and St-Hilaire with that of 

 Aristotle's idea of a perfecting principle (Read the His- 

 torical Sketch to Darwin's Origin of Species for a review of 

 the progress of opinion on the origin of species). 



The philosophic naturalists who did most to pave the 

 way for the general acceptance of the doctrine of organic 

 evolution were Lamarck and Darwin. They not only fur- 

 nished strong evidences in support of the doctrine but also 

 presented plausible theories regarding the mode of evolution. 



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