EVOLUTION 189 



is a poor interpreter of individual events, and has no 

 means of deciding whether they contribute to advance 

 or not. Hence it must lead to cautious and charitable 

 judgments; but at the same time it supplies a strong 

 ground of confidence that there must be eventual 

 progress. Some of the minor details of evolution may 

 be useful to the pessimist, but its whole sweep justifies 

 the broadest optimism. 



GUIDE TO FURTHER READING 



"Variation, Heredity, and Evolution," by R. H. Lock. 



"Heredity and Environment," by E. G. Conklin. (Princeton 

 Univ. Press.) 1916. 



"Genetics," by H. E. Walter. (Macmillan.) 1913- 



" Fundamentals of Plant Breeding," by J. M. Coulter. (Apple- 

 ton.) 1914. 



"Readings in Evolution, Genetics, and Eugenics," by H. H. 

 Newman. (University of Chicago Press.) 



