Alfred Russel Wallace, LL. D. 5 



following : " Even the peculiar colors of many animals, es- 

 pecially insects so closely resembling the soil or the leaves 

 or trunks on which they habitually reside, are explained on 

 the same principle, for though in the course of ages varieties 

 of many tints may have occurred, yet those races having 

 colors best adapted for concealment from their enemies 

 would inevitably survive the longest." 



The way in which Mr. Darwin reached the same result 

 in his letter of 1844, above mentioned, is slightly different 

 only in being a little more comprehensive, as it includes one 

 more factor viz., the necessarily enormous increase of ani- 

 mals and plants by reproduction and the consequent sever- 

 ity of the struggle for existence. He applies the Malthusian 

 idea to the lower creation, and shows how that any one of 

 the numerous species which exist would soon fill the earth 

 were not checks present on every hand which only permit 

 the survival of those individuals which possess exceptional 

 facilities for success in the pursuit of subsistence. In this 

 way profitable variations of structure have survived and been 

 perpetuated ; in other words, new species have originated 

 and continued. The two papers by Drs. Darwin and Wal- 

 lace embrace all the factors involved in the process of natu- 

 ral selection. Later elucidation of the doctrines of these 

 two able expositors, and by others subsequently, have con- 

 vinced thoughtful persons that it is an expression of a great 

 fact of the evolution of life. Its acceptance has been gen- 

 eral, and the impetus given to research and to thought has 

 been great. 



In the acceptance of the doctrine of natural selection 

 the public has often confused it with the general doctrine 

 of the evolution of animals by descent, of which natural se- 

 lection is an explanation. The general doctrine of descent 

 is as old as human thought, but it awaited the expositions 

 of Darwin and Wallace before receiving general acceptance. 

 Even the authority of Lamarck, who formulated it a half- 

 century previously, was not sufficient to gain credence for it. 

 Lamarck's principal explanation of the process, the change 

 .of structure through use and disuse, lacked the necessary 

 evidence, and, although he taught the law of natural selec- 

 tion as a corollary, it did not compel assent as did the mas- 

 terly presentation of Darwin and Wallace. 



Dr. Wallace's first book on evolution was published in 

 1870, and was entitled Contributions to the Theory of Natu- 

 ral Selection. This work contains the germs of all of his 



