March 31, 1916] 



SCIENCE 



463 



the world at large. Tlie implied feeling led me 

 ever since to use the expressions ' ' natural selec- 

 tion" and "survival of the fittest" with some- 

 thing like equal frequency. 



In the same volume, page 531, in referring 

 to " natural selection," lie says : 



This more special mode of action Dr. Darwin 

 has been the first to recognize as an all-important 

 factor, though, besides his co-discoverer, Mr. A. R. 

 Wallace, some others have perceived that such a 

 factor is at work. To him we owe due apprecia- 

 tion of the fact that "natural selection" is capa- 

 ble of producing fitness between organisms and 

 their circumstances. 



Here we have " Darwin's discovery " specif- 

 ically pointed out, and Spencer's acknowledg- 

 ment of his own indebtedness. 



Of course, it would have been no great mat- 

 ter even if the idea of natural selection had 

 presented itself to Spencer before Darwin pub- 

 lished the " Origin of Species " in 1859. 

 Twenty years prior to that time it had sug- 

 gested itself to Darwin and, being almost con- 

 stantly at work on its application, he must 

 have communicated the idea directly or in- 

 directly to many of his friends. In fact he 

 says in the short sketch of his life, prefixed to 

 his " Life and Letters " : 



I tried once or twice to explain to able men 

 what I meant by natural selection, but signally 

 failed. 



Possibly Spencer was one of these " able 

 men." 



Of course priority with respect to the idea 

 of natural selection is of comparatively little 

 importance. It flashed upon Darwin's mind, 

 just as it did upon Wallace's, from reading a 

 paragraph in " Malthus on Population." Dar- 

 win says: 



In October, 1838, that is, fifteen months after I 

 had begun my systematic enquiry, I happened to 

 read for amusement "Malthus on Population," 

 and being well prepared to appreciate the struggle 

 for existence which everywhere goes on from long- 

 continued observation of the habits of animals 

 and plants, it at once struck me that under these 

 circumstances favorable variations would tend to 

 be preserved, and unfavorable ones to be de- 

 stroyed. The result of this would be the forma- 

 tion of a new species. Here then I had at last got 

 a theory by which to work. 



It was with both of these men an original 

 idea, but it was foreshadowed by Aristotle, 

 who, in his " Physicse Auscultationes " (lib. 2, 

 cap. 8, s. 2) said that: 



Whatsoever, therefore, all things together (that 

 is all the parts of one whole) happened like as jf 

 they were made for the sake of something, these 

 were preserved, having been appropriately consti- 

 tuted by an internal spontaneity; and whatsoever 

 things were not thus constituted; perished and still 

 perish. 



It was clearly recognized by Dr. W. C. Wells, 

 in a paper read before the Royal Society in 

 1813 entitled : " An account of a white female, 

 part of whose skin resembled that of a negro," 

 and published in 1818. It was stated pre- 

 cisely by Mr. Patrick Mathew in 1831 in his 

 work on " Naval Timber and Arboriculture." 

 Everybody knows the story of how Darwin 

 was " forestalled with a vengeance " by A. R. 

 Wallace. It seems strange, then, that Spen- 

 cer, who was writing more or less on biological 

 subjects during the many years in which Dar- 

 win was at work on the idea of natural selec- 

 tion, does not appear to have gained even an 

 inkling of the idea. He and Darwin were 

 corresponding, and Darwin had complimented 

 him on his admirable discussion of the devel- 

 opment theory. 



Perhaps the nearest approach of Spencer to 

 the idea of natural selection occurs in an essay 

 entitled " A Theory of Population Deduced 

 from the General Law of Animal Fertility," 

 published in 1852, although Spencer says he 

 entertained as early as 1847, possibly earlier, 

 the idea it embodies. In this essay, after de- 

 claring that the pressure of population has 

 been the proximate cause of progress, Spencer 

 goes on to say: 



And here it must be remarked that the effect 

 of pressure of population, in increasing the abil- 

 ity to maintain life, and decreasing the ability to 

 multiply, is not a uniform effect, but an average 

 one. . . . All mankind in turn subject themselves 

 more or less to the discipline described; they 

 either may or may not advance under it; but, in 

 the nature of things, only those who do advance 

 under it eventually survive. . . . For as those 

 prematurely carried off must, in the average of 

 cases, be those in whom the power of self-preser- 



