4 Alfred Russel Wallace, LL. D. 



for many years after his return. His collections were espe- 

 cially important in ornithology and entomology, and his ob- 

 serrations brought to light many new facts in the life-history 

 of animals of all branches. Among a multitude of new 

 species discovered by him I only mention now the beautiful 

 and chastely colored paradise-bird from New Guinea, the 

 Semioptera wattacei Scl. When on the Amazon, Wallace 

 had the opportunity of verifying and extending the observa- 

 tions of Bates on the remarkable phenomenon of mimetic 

 analogy presented by the Lepidoptera of that region. In 

 Malaysia he discovered many equally striking examples of 

 the same thing. He observed not only cases of mimetism 

 between living species of insects, but also wonderful mim- 

 icry of inanimate objects and plants by living animals. His 

 studies of the variations of species by this time led him to 

 formulate a theory to account for their origin and persist- 

 ence identical with that given to the world by Mr. Darwin 

 under the name of Natural Selection. 



Dr. Wallace's first statement of this theory was contained 

 in a letter to Mr. Darwin, written at Ternate in 1858. This 

 letter was afterwards published in the Proceedings of the 

 Linnsean Society of London for 1859 (read August, 1858), 

 under the title On the Tendency of Varieties to depart in- 

 definitely from the Original Type, in conjunction with two 

 papers on the same subject by Mr. Darwin. The letter was 

 shown to Sir Charles Lyell and to Dr. Joseph D. Hooker, 

 who were familiar with the views of Mr. Darwin on the 

 same subject. Mr. Darwin had written a paper as early as 

 1844, in which essentially the same views were propounded, 

 which had been read to Dr. Hooker, but which had never 

 been published. A letter containing the same general views 

 had been also written by Mr. Darwin to Dr. Asa Gray in 

 1857. These two papers were published in connection with 

 Mr Wallace's letter in the Proceedings of the Linnaean So 

 ciety, as above mentioned, by Sir Charles Lyell and Dr. J. D. 

 Hooker. Dr. Wallace's paper endeavors to demonstrate the 

 evolution of species in ordinary descent by the action of 

 two factors : First, that species tend naturally to produce 

 varieties or variations of character ; and, second, that if any 

 of these variations or varieties present superior advantages 

 in the struggle for existence over those possessed by its 

 parent, it will separate or replace the latter, thus accom- 

 plishing the introduction of a new form or species in place 

 of the old one. He cites among his various illustrations the 



