DARWINISM AND MODERN GENETICS 



uncertain that the environment has any direct effect in pro- 

 ducing new variation. On the other hand, it seems quite cer- 

 tain that selection for response to environmental stresses is a 

 process of the greatest importance. On the one hand, it can, 

 over an evolutionary time scale, lead to characters which were 

 originally acquired, becoming later inherited. On the other 

 hand, it produces organisms whose developmental systems have 

 certain characteristics of stability and instability, which must 

 profoundly influence the expression of random changes oc- 

 curring in hereditary materials. The ideas of Darwin, allied to 

 those arising from embryology and Mendelian genetics, can take 

 over whatever was of value in the earlier speculations of La- 

 marck. 



LITERATURE CITED 



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Press, Cambridge. 

 Benoit, J., P. Leroy, C. Vendrely, and R. Vendrely. 1957. C. R. Acad. 



Sci. (Paris) 244:2321. 

 Clausen, J., and W. H. Hiesey. 1958. Genetic structure of ecological 



races. Carnegie Inst. Washington Publ. 615. 

 Crow, J. F. 1957. Ann. Rev. Entomol. 2:227. 

 Dobzhansky, Th. 1951. Genetics and the origin of species. Columbia 



Univ. Press, New York. 



1955. Cold Spring Harbor Symp. Quant. Biol. 20:1. 



1957. Cold Spring Harbor Symp. Quant. Biol. 22:385. 



Dubinin, N. P. 1934. Biol. Zhur. 3:166. 

 East, L. M. 1910. Am. Naturalist 44:65. 

 Fisher, R. A. 1930. The genetical theory of natural selection. Clarendon 



Press, Oxford. 

 Glouschenko, I. E. 1957. Agrobiologia. 

 Haldane, J. B. S. 1932. The causes of evolution. Longmans, Green, New 



York. 

 Heslop- Harrison, J. W. 1920. J. Genet. 9:195. 



Johannsen, W. 1909. Elemente der exakten Erblichkeitslehre. Fischer, Jena. 

 Kettlewell, H. B. D. 1955. Heredity 9:323. 

 Kushner, K. F. 1958. Trudy Inst. Genet. 

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