16 EVOLUTION AND GENETICS 



parent even before his time that the germ cells were the carriers 

 of hereditary characters, and in dealing with the fundamental prob- 

 lems of evolution it was inevitable that he should enter this field. 

 His idea of the distinctness of the germ cells from the body has 

 come down to the present and is even now a prominent factor in 

 evolutionary thought. It furnished the basis for other theories 

 which were necessary to harmonize known facts with his idea of 

 the germinal origin of characters. None of his theories are now 

 regarded as adequate explanations of the process of evolution. 



Sir Francis Galton (1822-1911), a cousin of Charles Darwin, 

 carried on extensive studies of human heredity and published three 

 books, of which the two best known, Hereditary Genius and Natural 

 Inheritance, appeared in 1869 and 1889 respectively. He is re- 

 garded as the founder of biometry, for the nature of his material 

 made necessary some statistical treatment. The complexity of 

 human heredity is so great and its inadaptability to experimental 

 methods so complete that Galton could not approach the results of 

 his contemporary, Mendel, but his work is even now of great value. 



Johann Gregor Mendel (1822-1884) (Fig. 3) must be given the 

 credit for laying the foundation of our modern knowledge of hered- 

 ity. He was an Austrian monk, and a botanist. In his monastery 

 garden at Briinn he experimented with inheritance in garden peas 

 and formulated from his results the laws of inheritance that bear 

 his name. By using peas of several varieties, hybridizing the 

 various kinds, and rearing them through several generations he 

 learned definitely how characters may behave in heredity, and in 

 1866 published his conclusions in the proceedings of the natural 

 history society of Briinn. This epoch-making paper was lost to the 

 scientific world until the beginning of the twentieth century. Its 

 rediscovery at that time found a number of biologists ready to 

 accept and verify the conclusions which it expressed, and progress 

 in the study of heredity has since been rapid. 



Modern Evolution. During the twentieth century many fa- 

 mous names have been linked with progress in our knowledge of 

 evolution. Darwin's and Lamarck's theories have come to be the 

 basis for two leading schools of thought on the subject, and there 

 is an abundance of literature which deals with their extension and 

 verification. Darwin himself, in the later years of his work, indi- 

 cated his belief that natural selection was not a sufficient explana- 

 tion for evolution, ])ut that there was also much evidence for the 



