36 THE OLD RED SANDSTONE. 
salamander or crocodile of the Lias, might indulge, consist- 
ently with his theory, in the pleasing belief that he had pos- 
sessed himself of the bones of his grandfather—a grand- 
father removed, of course, to a remote degree of consan- 
guinity, by the intervention of a few hundred thousand 
great-greats. Never yet was there a fancy so wild and ex- 
travagant but there have been men bold enough to dignify it 
with the name of philosophy, and ingenious enough to find 
reasons for the propriety of the name. 
The setting-dog is taught to set; he squats down and points 
at the game; but the habit is an acquired one —a mere trick 
of education. What, however, is merely acquired habit in 
the progenitor, is found to pass into instinct in the descend- 
art: the puppy of the setting-dog squats down and sets 
untaught — the educational trick of the parent is mysterious- 
ly transmuted into an original principle in the offspring. The 
adaptation which takes place in the forms and constitution of 
plants and animals, when placed in circumstances different 
from their ordinary ones, is equally striking. The woody 
plant of a warmer climate, when transplanted into a colder, 
frequently exchanges its ligneous stem for a herbaceous one, 
as if in anticipation of the killing frosts of winter; and, 
dying to the ground at the close of autumn, shoots up again 
in spring. The dog, transported from a temperate into a 
frigid region, exchanges his covering of hair for a covering 
of wool; when brought back again to his former habitat, the 
wool is displaced by the original hair. And hence, and from 
similar instances, the derivation of an argument, good so far 
as it goes, for changes in adaptation to altered circum- 
stances of the organization of plants and animals, and for 
the improvability of instinct. But it is easy driving a prin- 
ciple too far. The elasticity of a common bow, and the 
! 
