Historical Sketch. xvii 



highest dicotyledons and vertebrata, these grades being few in 

 number, and generally marked by intervals of organic character, 

 which we find to be a practical difficulty in ascertaining affinities ; 

 second, of another impulse connected with the vital forces, tending, 

 in the course of generations, to modify organic structures in accor- 

 dance with external circumstances, as food, the nature of the 

 habitat, and the meteoric agencies, these being the ' adaptations ' 

 of the natural theologian." The author apparently believes that 

 organisation progresses by sudden leaps, but that the effects 

 produced by the conditions of life are gradual. He argues with 

 much force on general grounds that species are not immutable 

 productions. But I cannot see how the two supposed " impulses " 

 account in a scientific sense for the numerous and beautiful co- 

 adaptations which we see throughout nature ; I cannot see that we 

 thus gain any insight how, for instance, a woodpecker has become 

 adapted to its peculiar habits of life. The work, from its powerful 

 and brilliant style, though displaying in the earlier editions little 

 accurate knowledge and a great want of scientific caution, imme- 

 diately had a very wide circulation. In my opinion it has done 

 excellent service in this country in calling attention to the sub- 

 ject, in removing prejudice, and in thus preparing the ground 

 for the reception of analogous views. 



In 1846 the veteran geologist M. J. d'Omalius d'Halloy pub- 

 lished in an excellent though short paper (< Bulletins de l'Acad. Boy. 

 Bruxelles, torn. xiii. p. 581), his opinion that it is more probable 

 that new species have been produced by descent with modification 

 than that they have been separately created: the author first 

 promulgated this opinion in 1831. 



Professor Owen, in 1849 (' Nature of Limbs,' p. 86), wrote as 

 follows :— " The archetypal idea was manifested in the flesh under 

 diverse such modifications, upon this planet, long prior to the 

 existence of those animal species that actually exemplify it. To 

 what natural laws or secondary causes the orderly succession and 

 progression of such organic phenomena may have been committed, 

 we, as yet, are ignorant." In his Address to the British Association' 

 in 1858, he speaks (p. li.) of "the axiom of the continuous 

 operation of creative power, or of the ordained becoming of living 

 things." Farther on (p. xc), after referring to geographical distri- 

 bution, he adds, "These phenomena shake our confidence in the 

 conclusion that the Apteryx of New Zealand and the Bed Grouse 

 of England were distinct creations in and for those islands respec- 

 tively. Always, also, it may be well to bear in mind that by the 

 word < creation' the zoologist means 'a process he knows not 



b 



