MEMOIR OF LAMARCK. 39 
similar that they ought to- hare produced important 
changes*. 
It will likewise he 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 hanier 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 rales 
of induction, resorts to fictions, as ideal as the 
Lyell’s Principles of Geology, ii. p. 31. 
