408 THE EVOLITTION OF LIFE. 



ganisation suhit, ga et la, dans la serie generale des aninnaux^ 

 des ano?naUes operees par Vinfluence des cir Constances d^habi^ 

 tation, et par celle des habitudes contracteesJ^ These, and 

 sundry other passages, joined mth 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 tend- 

 ency 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 

 structure, which break up the series into groups : groups 

 which he nevertheless places in uni-serial order, and rsgard^ 

 as still substantially composing an ascending succession. 



§ 147. These speculations, crude as they may be considered, 

 show much sagacity in their respective authors, and have 

 done good service. Without embodying the truth in a de- 

 finite shape, 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 as to the way in which natural agencies acted in the 

 production of plants and animals, must not make us forget 

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

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

 position, the belief in a progressive genesis of organisms^ is 

 joined with an interpretation having considerable definite- 

 ness and coherence. In the space often pages he not only 

 indicates several of the leading classes of facts which support 



