MEMOIR OF LAMARCK. 39 



similar that they ought to have produced important 

 changes'". 



It will likewise be observed as an important 

 defect in Lamarck's argument, that he can cite no 

 positive fact to exemplify the substitution of some 

 entirely new sense, faculty, or organ, in the room of 

 some other suppressed as useless. " All the in- 

 stances adduced," says Mr. Lyell, " go only to prove 

 that the dimensions and strength of members, and 

 the perfection of certain attributes may, in a long 

 succession of generations, be lessened and enfeebled 

 by disuse ; or, on the contrary, be matured and 

 augmented by active exertion, just as we know that 

 the power of scent is feeble in the greyhound, while 

 its swiftness of pace and its acuteness of sight are 

 remarkable ; that the harrier and staghound, on the 

 contrary, are comparatively slow in their move- 

 ments, but excel in their sense of smelling. We 

 point out to the reader this important chasm in the 

 chain of the evidence, because he might otherwise 

 imagine that we had merely omitted the illustrations 

 for the sake of brevity ; but the plain truth is, that 

 there were no examples to be found, and when 

 Lamarck talks of ' the efforts of internal sentiment,' 

 ' the influence of subtile fluids,' and the ' acts of 

 organization,' as causes whereby animals and plants 

 may acquire new organs^ he gives us names for 

 things, and with a disregard of the strict rules 

 of induction, resorts to fictions, as ideal as the 



* Lyell's Principles of Geology, ii. p. 31. 



