150 
namely, to exhibit even to those most slightly ac- 
quainted with natural history very striking analo- 
gies or relations between the most widely separated 
classes of plants and animals. The distinction be- 
tween the greater divisions of objects, as of king- 
doms and classes, is more palpable, and more readily 
apprehensible, than between those of genera and 
species. It is easier to distinguish a crow, for ex- 
ample, from the sheep on whose back he may be 
perched, than from the raven which may be near to 
him. 
Of anatomical analogy, the extensive and varied 
detail must be sought of course in the works of 
those excellent anatomists and authors who have 
especially devoted their attention to that object. 
Hunter and Home are distinguished in Britain, Cu- 
vier and Geoffroi in France, Blumenbach, Meckel, 
and Carus in Germany. From these, especially the 
latter, every portion of animal organization, all 
which contributes to the perfection of the senses, to 
the energies of motion, to growth, nutrition, and 
transmission of life, is compared in every change 
with every analogous condition in every class of 
animals, and in almost every remarkable diversity 
of genus or of species. The connection of such ana- 
logies with the anatomy of plants may be found in 
Mirbel and in Keith. . 
But although in a very general survey of the ter- 
raqueous globe we commonly distinguish some parts 
which we call organized, namely, specially adapted 
to the production of manifest and important pur- 
