HISTORICAL SKETCH. ix 



fished in 1836, wrote (p. 6) as follows : " All species might 

 have been varieties >nce, and many varieties are gradually 

 becoming species by assuming constant and peculiar charac- 

 ters ; " but further on (p. 18), he adds, " except the original 

 types or ancestors of the genus." 



In 1843-44 Professor Haldeman ("Boston Journal of Nat. 

 Hist. U. States," vol. iv. p. 468) has ably given the arguments 

 for and against the hypothesis of the development and 

 modification of species : he seems to lean toward the side of 

 change. 



The " Vestiges of Creation " appeared in 1844. In the 

 tenth and much improved edition (1853) the anonymous 

 author says (p. 155) : " The proposition determined on after 

 much consideration is, that the several series of animated 

 beings, from the simplest and oldest up to the highest and 

 most recent, are, under the providence of God, the results, 

 first, of an impulse which has been imparted to the forms of 

 life, advancing them in definite times, by generation, through 

 grades of organization terminating in the highest dicotyle- 

 dons 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 ; sec- 

 ond, of another impulse connected with the vital forces, tend- 

 ing, in the course of generations, to modify organic structures 

 in accordance with external circumstances, as food, the nature 

 of the habitat, and the meteoric agencies, these being the 

 1 adaptations ' of the natural theologian." The author appar- 

 ently believes that organization 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 coadaptations 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 early editions 

 little accurate knowledge and a great want of scientific cau- 

 tion, immediately had a very wide circulation. In my opin- 

 ion it has done excellent service in this country in calling 

 attention to the subject, 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 

 published in an excellent though short paper ("Bulletins 



r 



