496 THE EVOLUTION OF LIFE. • 



des anomalies operees par I' influence des circonstances d' habi- 

 tation, et par celle des habitudes contractees." These^ and 

 sundry other passages, joined with his general scheme of 

 classification, make it clear that Lamarck conceived adaptive 

 modification to be, not the cause of progression, but the cause 

 of irregularities in progression. The inherent tendency 

 which organisms have to develop into more perfect forms, 

 would, according to him, result in a uniform series of forms; 

 but varieties in their conditions work divergences of struc- 

 ture, which break up. the series into groups: groups which 

 he nevertheless places in uni-serial order, and regards as still 

 substantially composing an ascending succession. 



§ 147. These speculations, crude as they may be con- 

 sidered, show much sagacity in their respective authors, and 

 have done good service. Without embodying the truth in 

 definite shapes, they contain adumbrations of it. Not 

 directly, but by successive approximations, do mankind 

 reach correct conclusions; and those who first think in the 

 right direction, loose as may be their reasonings, and wide of 

 the mark as their inferences may be, yield indispensable 

 aid by framing provisional conceptions and giving a bent to 

 inquiry. 



Contrasted with the dogmas of his age, the idea of De 

 Maillet was a great advance. Before it can be ascertained 

 how organized beings have been gradually evolved, there 

 must be reached the conviction that they have been gradu- 

 ally evolved; and this conviction he reached. His wild 

 notions about the way in which natural causes acted in the 

 production of plants and animals, must not make us forget 

 the merit of his intuition that animals and plants were pro- 

 duced by natural causes. In Dr. Darwin's brief expo- 

 sition, the belief in a progressive genesis of organisms is 

 joined with an interpretation having considerable definite- 

 ness and coherence. In the space of ten pages he not only 

 indicates several of the leading classes of facts which support 



