MODIFICATION OF SPECIES 



301 



types of individuals would tend to preserve them while less favored ones 

 would either suddenly or gradually disappear. If the favorable qualities 

 were hereditary, as he apparently assumed they would be, the result 

 would be the formation of a new species. 



For 20 years Darwin collected facts that seemed to bear on the 

 possible correctness of this natural selection, but he published nothing. 

 Only a few friends, including Lyell and the botanist Joseph Hooker, with 

 whom he frequentl}' discussed his views, knew what conclusions he was 

 reaching. Then a curious coincidence induced him to put a synopsis of 

 his work into print. Alfred Russel Wallace, a young naturalist then in 

 the Orient, sent to Darwin a sketch of a theory of which he desired 

 Darwin's opinion. To the latter's 

 surprise, this theory proved to be 

 none other than the theory of 

 natural selection, or survival of 

 the fittest; and, as Wallace after- 

 wards related, he too had first 

 got the idea from reading the 

 work of Malthus, "Essay on 

 Population." At first Darwin 

 was inclined to withhold his own 

 manuscript and allow that of 

 Wallace to be published. But 

 since Wallace's idea was admit- 

 tedly a sudden one, in favor of 

 which he had collected no facts 

 whatever, whereas Darwin had 

 long been gathering data relati^-e 

 to it, DarA\an's friends protested. 

 It was finally arranged to present 

 extracts from both Darwin's and 

 AVallace's manuscripts simultaneously to the Linnaean Society of London, 

 which was done in 1858. Darwin's theory was developed at length in 

 "The Origin of Species" in 1859. The book was written in language 

 intelligible to the average reader without biological training. Further- 

 more, the time was ripe for such an advance. These facts, coupled with 

 championship b}': T. H. Huxley (Fig. 305), who carried the evolution idea 

 to the general public in lectures and popular articles, Avon a quick victory 

 for the new doctrine. The history of the evolution idea in the last 60 or 

 70 years has been the accumulation of new facts in support of it, the 

 development of theories to account for it, the grouping of animals on the 

 basis of the relationship implied in evolution, and the application of 

 corollaries of evolution to other branches of biology. 



Fig. 305. — Thomas Henry Huxley, 1825- 

 1895. 



