16 HISTORICAL SKETCH 



periods, and then restocked; and he gives as an alterna- 

 tive, that new forms may be generated "without the pres- 

 ence of any mould or germ of former aggregates." I am 

 not sure that I understand some passages; but it seems 

 that he attributes much influence to the direct action of 

 the conditions of life. He clearly saw, however, the full 

 force of the principle of natural selection. 



The celebrated geologist and naturalist, Von Buch, in 

 his excellent "Description Physique des Isles Canaries" 

 (1836, page 147), clearly expresses his belief that varieties 

 slowly become changed into permanent species, which are 

 no longer capable of intercrossing. 



Rafinesque, in his "New Flora of North America," 

 published in 1836, wrote (page 6) as follows — "All species 

 might have been varieties once, and many varieties are 

 gradually becoming species by assuming constant and 

 peculiar characters"; but further on (page 18) he adds, 

 "except the original types or ancestors of the genus." 



In 18-43-44 Professor Haldeman ("Boston Journal of 

 Nat. Hist. United States," vol. iv. page 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 "V'estiges of Creation" appeared in 1844. In the 

 tenth and much improved edition (1853) the anonymous 

 author says (page 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, JiJ'sl, of an impulse which has been 

 imparted to the forms of life, advancing them, in definite 

 times, by generation, through grades of organization ter- 



