450 GENERAL ZOOLOGY 



he promulgated the theory of natural selection as the main 

 though not the chief factor in evolution. His work was a 

 triumph for the inductive method, for never before had such 

 an array of facts been collected and presented. The battle 

 was first fought over the fixity of species, till belief in that 

 theory no longer became possible. Then investigators sprung 

 up on every side, stimulated by the brilliancy and simplicity 

 of natural selection (to which Darwin afterwards added sexual 

 selection), or anxious to disprove its validity as a factor in 

 evolution. 



When twenty-two years of age Darwin sailed on H.M.S. 

 Beagle on a voyage to South America and around the world. 

 He returned to England, his interest in natural history 

 strengthened and the problems of life outlining themselves 

 to him. This voyage was the beginning of the collection 

 of that vast store of facts which were afterward organized 

 and used with such effect. For over twenty years he worked 

 getting together facts which had to do with the variation of 

 animals and plants, and thinking on the general problem. 

 And now occurred one of the most remarkable coincidences in 

 the whole history of science. While Darwin was elaborating 

 his views on the mutability of species Alfred Russel Wallace 

 (born 1822), an English naturalist then in the Malay Archi- 

 pelago, arrived at practically the same conclusion that Dar- 

 win had reached. By the aid of friends it was arranged that 

 publication should be simultaneously made, and therefore in 

 the Journal of the Linncean Society of London of June 30, 

 1858, we find two papers of transcendent interest. The one 

 by Darwin consists of portions of manuscript written in 1839 

 and 1844, entitled On the Variation of Organic Beings in a 

 State of Nature; on the Natural Means of Selection ; on the 

 Comparison of Domestic Races and True Species. Wallace's 

 paper is On the Tendency of Varieties to depart indefinitely 

 from the Original Type. A year afterward appeared Darwin's 



