152 
RELATIONS. 
ture of corn-mills. Whilst the two sides of the gizzard per 
form the office of the mill-stones, the craw or crop supplies 
the place of the hopper. AVhen our fowls are abundantly 
supplied with meat they soon fill their craw: but it does 
not immediately pass thence into the gizzard; it always 
enters in very small quantities, in proportion to the progress 
of trituration;—in like manner as, in a mill, a receiver is 
fixed above the two large stones which serve for grinding 
the corn; which receiver, although the corn be put into it 
by bushels, allows the grain to dribble only in small quan¬ 
tities, into the central hole in the upper mill-stone. 
But we have not done with the alimentary history. There 
subsists a general relation between the external organs of 
an animal by which it procures its food, and the internal 
powers by which it digests it. # Birds of prey, by their 
talons and beaks, are qualified to seize and devour many 
species, both of other birds and of quadrupeds. The con¬ 
stitution of the stomach agrees exactly with the form of the 
members. The gastric juice of a bird of prey, of an owl, 
*This subject of the relation of parts, and the correspondence of one 
part of the animal structure to all the others which is here briefly spoken 
of by our author, has since been made, in the hands of some distinguished 
anatomists, of immense importance in a scientific point of view. The 
following extract from Mr. Bell’s Treatise on Animal Mechanics , 
shows how extensively it is capable of being considered, and what inter¬ 
esting results may be drawn from it.— Ed. 
“ What we have to state has been the result of the studies of many 
naturalists; but although they have labored, as it were, in their own de¬ 
partment of comparative anatomy, they have failed to seize upon it with 
the privilege of genius, and to handle it in the masterly manner of Cuvier. 
“ Suppose a man ignorant of anatomy to pick up a bone in an unex¬ 
plored country, he learns nothing, except that some animal has lived and 
died there; but the anatomist can, by that single bone, estimate, not mere¬ 
ly the size of the animal, as well as if he saw the print of its foot, but 
the form and joints of the skeleton, the structure of its jaws, and teeth, 
the nature of its food, and its internal economy. This, to one ignorant of 
the subject, must appear wonderful, but it is after this manner that the 
anatomist proceeds; let us suppose that he has taken up that portion of 
bone in the limb of the quadruped which corresponds to the human wrist; 
and that he finds that the form of the bone does not admit of free motion 
in various directions, like the paw of the carnivorous creature. It is ob¬ 
vious, by the structure of the part, that the limb must have been merely 
for supporting the animal, and for progression, and not for seizing prey. 
This leads him to the fact that there were no bones resembling those of 
the hand and fingers, or those of the claws of the tiger; for the motions 
which that conformation of bones permits in the paw, would be useless, 
without the rotation of the wrist—he concludes that these bones were 
formed in one mass, like the cannon-bone, pastern-bone, afld coffin-bones 
of the horse’s foot. 
‘ The motion limited to flection and extension of the foot of a hoofed 
