distinctions which nature has made.
It is to anatomy and physiology we should look, when vindicating the
liberty of human nature, to see that its dignity and best interest be
preserved. "Among the Romans," says Mr. Jefferson, "emancipation
required but one effort, but with us a second is necessary, unknown to
history." This second belongs properly to natural history; the
difference in the last not being artificial, as among the Romans, or the
present Britons, requiring only an act of legislation or a revolution to
efface forever, but natural, which no human laws or governmental changes
can ever obliterate. The framers of our Constitution were aware of these
facts, and built the Constitution upon the basis of natural distinctions
or physical differences in the two races composing the American
population. A very important difference between the two will be found in
the fact of the greater amount of oxygen consumed by the one than the
other. If the Constitution be worth defending, surely the great truths
of natural history, on which it rests as a basis, are worth being made
known and regarded by our statesmen. That negroes consume less oxygen
than the white race, is proved by their motions being proverbially much
slower, and their want of muscular and mental activity. But to
comprehend fully the weight of this proof of their defective haematosis,
it is necessary to bear in mind one of the great leading truths
disclosed by comparative anatomy. Cuvier was the first to demonstrate
beyond a doubt that muscular energy and activity are in direct
proportion to the development and activity of the pulmonary organs. In
his 29th lesson, vol. vii, p. 17, D'Anatomie Comparee, he says, "_Dans
les animaux vertebres cette quantite de respiration fait connaitre
presque par un calcul mathematique la nature particuliere de chaque
class_." In the preceding page he says,--"That the relations observed in
the different animals, between the quantity of their respiration and the
energy of their motive force, is one of the finest demonstrations that
comparative anatomy can furnish to physiology, and at the same time one
of the best applications of comparative anatomy to natural history." The
slower motions of the owl prove to the natural historian that it
consumes less oxygen than the eagle. By the same physiological principle
he can tell that the herring is the most active among fish, and the
flounder the slowest, by merely seeing the gills of each