DARWINISM CHAP. 



universe as a system of growth and development, and it Avas 

 argued that the various species of animals and plants had 

 been produced in orderly succession from each other by the 

 action of unknoAvn laws of development aided by the action 

 of external conditions. Although this work had a consider- 

 able effect in influencing public opinion as to the extreme 

 improbability of the doctrine of the independent "special 

 creation " of each species, it had little effect upon natui'al- 

 ists, because it made no attempt to grapple with the problem 

 in detail, or to show in any single case how the allied species 

 of a genus could have arisen, and have preserved their 

 numerous slight and apparently purposeless differences from 

 each other. No clue whatever was afforded to a law Avhich 

 should produce from any one species one or more slightly 

 differing but yet permanently distinct species, nor was any 

 reason given why such slight yet constant differences should 

 exist at all. 



Scientific Opinion before Darwin. 



In order to show how little effect these -wTiters had upon 

 the public mind, I will quote a few passages from the 

 AATitings of Sir Charles Lyell, as representing the opinions 

 of the most advanced thinkers in the period immediately 

 preceding that of Darwin's Avork. When recapitulating the 

 facts and arguments in favour of the invariability and 

 permanence of species, he says : "The entire variation from 

 the original type which any given kind of change can pro-" 

 duce may usually be effected in a brief period of time, after 

 which no further deAdation can be obtained by continuing to 

 alter the circumstances, though ever so gi-adually, indefinite 

 divergence either in the Avay of improvement jar deterioration 

 being prevented, and the least possible excess beyond the 

 defined limits being fatal to the existence of the individual." 

 In another place he maintains that " varieties of some species 

 may differ more than other "species do from each other 

 Anthout shaking our confidence in the reality of species." 

 He further adduces certain facts in geology as being, in his 

 opinion, "fatal to the theory of progressive deA^elopment," 

 and he explains the fact that there are so often distinct 

 species in countries of similar climate and vegetation by 



