338 THE CHANGING GENERATIONS 



and speculative. In 1790, the great German poet Goethe put forth a 

 u theory of metamorphosis" to account for the transformation of leaves 

 into the parts of flowers. Between 1790 and 1815, Erasmus Darwin (the 

 grandfather of Charles Darwin), in England, and Lamarck, in France, 

 attempted to account for modern organisms by appealing to a long se- 

 quence of changes and modifications from more primitive ancestral 

 stocks. By the second quarter of the nineteenth century such evolution- 

 ary speculation had become rather general. In 1844, Robert Chambers, a 

 popular Scotch essayist, in his Vestiges of Creation made a number of 

 very bold and stimulating suggestions as to the origin of present-day 

 organisms and their relations to the fossil forms of the past. The poet 

 Tennyson was probably influenced by the Vestiges when he wrote the 

 following part of In Memoriam, sometime before 1850: 



Nature . . . 

 So careful of the type she seems, 

 So careless of the single life . . . 



"So careful of the type? but no. 

 From scarped cliff and quarried stone 

 She cries, "A thousand types are gone; 

 "I care for nothing, all shall go." 



All this pre-Darwinian work suffered from two defects — an insuffi- 

 ciency of factual evidence that evolutionary changes had actually oc- 

 curred and failure to show any adequate causes for such change. Biologists 

 therefore found themselves in the predicament of having to abandon the 

 idea of special creation because of its inadequacies, while there was still 

 no acceptable alternative. The proof of the reality of evolution, the 

 formulation of a theory capable of accounting for it, and the testing of 

 this theory against the background of accumulated biological knowledge 

 were the work of Charles Darwin, and constitute one of the great 

 achievements of science. 



THE ESTABLISHMENT OF THE FACT OF EVOLUTION 



Charles Darwin was born in 1809. His education, in preparation first 

 for medicine at Edinburgh and then for theology at Cambridge, gave 

 him a very meager training in technical biology. By natural inclination, 

 however, he became a good field naturalist, with a strong interest in 

 geology as well as in animals and plants. He was particularly stimulated 

 by Sir Charles Lyell's Principles of Geology, in which Hutton's concept 

 of uniformitarianism had been made the basis for a new interpretation 

 of earth history and processes. In 1831, shortly after he had graduated 



