The intestines are also identical with those of herbivorous animals, which present a larger surface for absorption and have ample and cellulated colons.  The caecum also, though short, is larger than that of carnivorous animals; and even here the orang-outang retains its accustomed similarity.

The structure of the human frame, then, is that of one fitted to a pure vegetable diet, in every essential particular.  It is true that the reluctance to abstain from animal food, in those who have been long accustomed to its stimulus, is so great in some persons of weak minds as to be scarcely overcome; but this is far from bringing any argument in its favour.  A lamb, which was fed for some time on flesh by a ship’s crew, refused its natural diet at the end of the voyage.  There are numerous instances of horses, sheep, oxen, and even wood-pigeons, having been taught to live upon flesh, until they have loathed their natural aliment.  Young children evidently prefer pastry, oranges, apples, and other fruit, to the flesh of animals; until, by the gradual depravation of the digestive organs, the free use of vegetables has for a time produced serious inconveniences; FOR A TIME, I say, since there never was an instance wherein a change from spirituous liquors and animal food to vegetables and pure water has failed ultimately to invigorate the body, by rendering its juices bland and consentaneous, and to restore to the mind that cheerfulness and elasticity which not one in fifty possesses on the present system.  A love of strong liquors is also with difficulty taught to infants.  Almost every one remembers the wry faces which the first glass of port produced.  Unsophisticated instinct is invariably unerring; but to decide on the fitness of animal food from the perverted appetites which its constrained adoption produces; is to make the criminal a judge in his own cause:  it is even worse, it is appealing to the infatuated drunkard in a question of the salubrity of brandy.

What is the cause of morbid action in the animal system?  Not the air we breathe, for our fellow-denizens of nature breathe the same uninjured; not the water we drink (if remote from the pollutions of man and his inventions (The necessity of resorting to some means of purifying water, and the disease which arises from its adulteration in civilized countries, is sufficiently apparent.  See Dr. Lambe’s “Reports on Cancer”.  I do not assert that the use of water is in itself unnatural, but that the unperverted palate would swallow no liquid capable of occasioning disease.)), for the animals drink it too; not the earth we tread upon; not the unobscured sight of glorious nature, in the wood, the field, or the expanse of sky and ocean; nothing that we are or do in common with the undiseased inhabitants of the forest.  Something, then, wherein we differ from them:  our habit of altering our food by fire, so that our appetite is no longer a just criterion for the fitness of its gratification.  Except in children, there remain no traces of that instinct which determines, in all other animals, what aliment is natural or otherwise; and so perfectly obliterated are they in the reasoning adults of our species, that it has become necessary to urge considerations drawn from comparative anatomy to prove that we are naturally frugivorous.