574* POPULAR SCIENCE MONTHLY. 



varied structure where this in a predominant degree aids them in 

 fulfilling the vital requirements of their lives. 



Mark, now, how the strong contrast set forth in the preceding 

 section is thus strengthened. We saw that the evolution-hypoth- 

 esis is indirectly supported by five great classes of observed facts ; 

 and that the perpetual adaptation and re-adaptation of constitu- 

 tion to conditions is a general cause of the kind required to ac- 

 count for these facts. Here we see that, of the special causes 

 which effect adaptation, the chief one, survival of the fittest, is 

 not only one the operation of which we can clearly conceive, but 

 one which it is impossible to conceive as not operating. On the 

 other hand, we saw that there are absolutely no observed facts 

 which yield indirect support to the hypothesis of special creation ; 

 but that, contrariwise, all the observed facts of daily experience, 

 proving a constant order among phenomena, negative the hy- 

 pothesis. And we also saw that while the process of special crea- 

 tion can not be rationally conceived, the negation of it is perfectly 

 conceivable. Thus, bringing the contrast to a focus, it appears 

 that the one is credited both a posteriori and a priori, and the 

 other is discredited both a posteriori and a priori. No stronger 

 contrast in credibility can well be imagined. 



Authoritative expositions of the process of natural selection 

 afford no basis for that burlesque of it with which Lord Salisbury 

 amused the public. The Origin of Species does not assume, as a 

 requisite, the chance meeting of similarly varied individuals ; and 

 in Chapters III. and VI. of Mr. Wallace's Darwinism, where are 

 assigned evidences which have accumulated since Mr. Darwin 

 wrote, there are described processes quite other than that which 

 Lord Salisbury describes. After referring to artificial selection, 

 and implying that the success of breeders in producing a desired 

 variety depends on their skill " in bringing the right mates to- 

 gether," he goes on to ask : 



"But in natural selection who is to supply the breeder's place? . . . 

 What is to secure that the two individuals of opposite sexes in the primeval 

 forest, who have been both accidentally blessed with the same advanta- 

 geous variation, shall meet, and transmit by inheritance that variation to 

 their successors ? " 



Even in the absence of the expositions above referred to, 

 knowledge of familiar facts should have excluded this represen- 

 tation of the requirements. The contents of stud-books and herd- 

 books might have been expected to suffice. It needs but to re- 

 member the care with which is specified a descent from some 

 noted sire which lived several generations ago, to recognize the 

 prevailing belief that a variation existing in a particular animal 

 is transmitted in a greater or less degree to posterity, quite apart 



