386 General Biology 



holder of the Lamarckian principles, and Goethe (1749-1832), the famous 

 poet, who was also a famous scientist of his day, became a disciple of 

 the new doctrine. 



Lyell (1797-1875), the Englishman, in the early thirties of the last 

 century wrote his Principles of Geology which convinced men that the 

 same causes now in action always had been, and that we could, therefore, 

 by studying the time it took to make present changes in the earth's 

 surface, estimate the length of time and the age of the various strata 

 of the earth. 



With the intellectual soil prepared in this way, Charles Darwin 

 (1809-1882), published his epoch-making book, The Origin of Species 

 by Natural Selection, in 1859. Darwin accepted, without explaining, 

 the fact that variations do occur. He assumed that the origin of existing 

 species could be explained by accepting the fact that variations did 

 occur, and that nature then selected the organisms which should con- 

 tinue to exist by killing off those which did not inherit as many varia- 

 tions of a survival value. He assumed that acquired characteristics were 

 inheritable, and that the struggle for existence eliminated the unfit. 

 Darwin had spent twenty years in gathering the facts on which he based 

 his theory, but Alfred Russel Wallace (1822-1913) had reasoned out a 

 similar theory without having the facts that Darwin had, and it is an 

 interesting coincidence that both men were working independently on 

 the same thought at the same time. Darwin was willing to surrender 

 all his work to the younger man, but Wallace insisted that Darwin was 

 to have the credit as the latter had done such an immense amount of 

 work on the matter. 



Evolution now serves the biological world as a sort of general plan 

 of the results of heredity, while genetics deals with the factors which 

 produce these results. 



Thomas Huxley (1825-1895), though not a believer in the Darwinian 

 theory of natural selection, sprang to the defense of Darwin, primarily, 

 as Professor Poulton says, because Darwin was so constantly and per- 

 sistently treated unjustly. It was Huxley who made Darwinism popular. 

 Hooker (1817-1911) in England, Haeckel (1834-1919) and Weismann 

 in Germany, and the botanist Gray (1810-1888) in America, were early 

 converts. Haeckel, however, was too much of the showman, and was 

 always willing to sacrifice truth and accuracy to win his point. 



Summing up what has been said, we may say that the basis of great- 

 ness in science is not the brilliancy of an individual discovery, but the 

 finding and enunciating of a principle which can find many applications 

 by those who follow. 



The great findings, considered from this point of view of obtaining 

 principles which have a wide influence in Biology, may be said to be 

 the discovery of protoplasm; the establishment of the cell-theory; the 



