DEVELOPMENT OF BIOLOGY 



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artificial and natural selection in the origin of species, but also 

 the propounding of a theory of the origin of variations — that the 

 direct action of the environment brings about modifications in 

 the structure of animals and plants and these are transmitted to 

 the offspring. (Fig. 307.) 



When Buffon's influence had passed its height, Erasmus Dar- 

 win (1731-1802) expressed consistent views on the evolution of 

 organisms, in several volumes of prose and poetry, which lead 



Fig. 309. — Jean-Baptiste Lamarck. 



biologists to-day to recognize him as the anticipator of the La- 

 marckian doctrine that somatic variations arise through the reac- 

 tion of the organism to environmental conditions. "All animals 

 undergo transformations which are in part by their own exertions, 

 in response to pleasures, and pain, and many of these acquired forms 

 or propensities are transmitted to their posterity." (Fig. 308.) 



Lamarck (1744-1829) developed with great care the first com- 

 plete and logical theory of organic evolution and is the one out- 

 standing figure in biological uniformitarian thought between Aris- 

 totle and Charles Darwin. "For nature," he writes, "time is 

 nothing. For all the evolution of the Earth and of living beings, 

 nature needs but three elements, space, time, and matter." In 

 regard to the factors of evolution, Lamarck put emphasis on the 

 indirect action of the environment in the case of animals, and the 



