And Dr Kellogg has pointed out[11]:
“Another property possessed in a high degree by the gastric juice of carnivorous animals is its antiseptic or germicidal quality. When exposed to the conditions of warmth and moisture, flesh, whether that of mammals birds or fish, readily decomposes or decays, giving rise to poisonous substances of the most offensive character. The gastric juice of the dog is capable of preventing this putrefactive change while the food is undergoing the process of stomach digestion. That such changes occur later, however, while the food residue is lying in the colon previous to expulsion from the body, is evidenced by the extraordinarily offensive character of the fæcal matters of this class of animals.”
In man, this secretion is very weak, comparatively speaking, and hence of small value in preventing such putrefactive changes as those mentioned above. Take any piece of meat, and expose it for some considerable period to an environment of heat and moisture, and see the result! Putrefaction soon occurs—except where the meat is “embalmed” or preserved by powerful chemicals—thus rendering it unfit for human food. But it will be seen that just such conditions prevail in the human alimentary tract as are most suitable for the speedy and deadly decomposition of the food eaten; and, in the case of flesh-foods, the resulting products are poisonous in the last degree. The gastric juice of the human stomach being so far weaker than that of the carnivorous animal, the flesh is far less completely acted upon and digested in the stomach—much more work being passed on to the intestines, in consequence. Now comes in a most important factor. The bowel of the carnivorous animal is, as we have seen, short, (three times the length of the body) when compared to the frugivora, whose alimentary tract is about twelve times the length of the body. That is, the digestive tract in man is, roughly, about four times as long as in the carnivorous animal. The result of this is that any food eaten would take, ceteris paribus, four times as long to pass through the tube in the one case as in the other. This fact alone is sufficient to condemn the use of flesh-foods in any form for frugivorous animals, since the less active antiseptic and germicidal properties of the gastric juice in these animals render unsafe the long retention of such easily decomposable substances as flesh.
But more than that, and worse still; the character of the internal structure of the tract is not alike in the two cases! In the carnivora, this is smooth, and offers but few impediments to the free passage of the food through it. In man, on the contrary, as with the higher apes and the herbivora, the intestine is corrugated or sacculated—this being for the express purpose of retaining the food as long as possible in the intestine, and until all possible nutriment has been abstracted from it. This is admirably suited to such foods as the herbivora and frugivora enjoy, but is quite unsuited for flesh-foods of all kinds—being, in fact, the worst possible receptacle for such foods. The intestine, in the carnivora, is suited for its particular food—it is short and smooth, and well adapted to dissolve the food quickly and pass it out of the system as rapidly as possible; while in frugivora, on the other hand, the intestine is adapted to retain the food a much longer time—the sacculated surface retaining the food as long as possible. The result of this is that, when flesh-foods are eaten, disastrous results are sure to follow.
As previously shown, the liver is much larger, proportionately, in the carnivora; and not only is this the case, but the amount of bile secreted is far greater in the carnivora than in man. It has been found, by careful experiments upon dogs, that the quantity of bile might increase fifty per cent., and even more, under a purely meat diet; but rapidly decreased when the quantity and proportion of the meat was reduced. Thus it appears that the use of a meat diet requires a far greater degree of activity on the part of the liver than any other diet. This is amply provided for in the carnivore by the increased size and power of that organ, but in man and the frugivora such is not the case, and the result is that if meat be eaten by man, the liver is called upon to do an extra amount of work, and this may ultimately result in its premature breakdown.
The kidneys also are greatly affected by the diet. It is now well known that uric acid is created in large quantities by a flesh diet—the measured excretions showing that from three to ten times as much uric acid is secreted when flesh is eaten as when no meat is ingested; and when we bear in mind the exceedingly disastrous effects of uric acid upon the system, and what a powerful disease-producing agency it is, I think that we must conclude that this symptom is strongly suggestive, and strongly indicative of the fact that man cannot eat meat without running grave chances of diseasing and ruining his organism.
The Excretions.—There is also a marked difference in the excretory products of the various animals. While, in the carnivora, the action of the urine is acid, it is alkaline in the herbivora (or should be). In man it is frequently acid—though this varies with the nature of the food. Thus, if the diet be largely one of flesh, the urine will become far more acid, and will also become very offensive; the perspiration will also be tainted, and very noticeable to those with a keen sense of smell, and who do not eat meat themselves! This has frequently been observed, and may account for the fact that flesh-eating animals will always eat a horse or a sheep in preference to man, if it be possible. Doubtless, their keen sense of smell detects the fact that man is (usually) largely carnivorous in his habits, and their instinct teaches them that the flesh of the purely herbivorous animal is for this reason superior to that of man. Has anyone thought why it is that a cat will kill a mouse, and eat it, while a dog will kill a cat, but will not eat it? It is because the mouse is a vegetarian animal, and the cat is a carnivorous animal. Instinct teaches the cat that the tissues of the mouse’s body are more or less pure and inoffensive—owing to the nature of the diet; while the same instinct teaches the dog that the cat’s body is impure and more or less poisonous, for the reason that its flesh is tainted and full of poisons, because of its diet. If any animal lives upon flesh, that animal’s body is bound to be tainted more or less in consequence; and those animals which prey upon others know that fact, by reason of their sense of smell and instinct. This is a remarkable and most instructive fact; a rule which will rarely be found to fail. Its significance and interpretation is obvious. Professor Schlickeysen also informs us that “the overloading of the blood with flesh-food causes, in order to effect their decomposition, an excessive consumption of oxygen, and hence the difficulty of breathing, and asthmatical affections of many flesh-eaters, and their excessive excretion of carbonic acid.” I have referred to some of these poisons, formed within the system, and the harm they must doubtless exert upon the organism, elsewhere.
In addition to all these arguments, there are other forcible reasons for considering man as one of the non-flesh-eating animals—which reasons may be included in this chapter. The habits of any animal are distinctive; and they, collectively, indicate man’s position—though this argument must always be confirmatory, and not proof in itself. For instance, all naturally carnivorous animals sleep in the daytime, and prowl about in search of their prey at night; while with the vegetarian animals (man included) this is not the case. The manner of eating and especially of drinking, is also highly characteristic—all carnivorous animals lapping their liquids—while the herbivora and frugivora drink—as I have previously pointed out. The peculiar mode of functioning of various organs might also be pointed out and insisted upon. But one of the most striking arguments is that based upon the anatomical structure of the skin. As before stated, this perspires, in the case of all vegetarian animals, while the glands are atrophied and inactive in all carnivora. Let us now consider the significance of this fact.
“Recent researches show us that uric acid arises from the decay of cell nuclei. That portion of uric acid which has its origin in the digestive organs is, like other alloxanic bases, changed into urea—or rather should be. But a diseased liver (or a healthy one which is overworked, owing to an excessive ingestion of food containing cell nuclei, and therefore an excessive amount of uric acid) is unable to transform all the uric acid formed into urea. The quantity of uric acid arising from the normal decay of the tissue is small; in fever, when there is a more rapid decay of cells, the quantity of uric acid and other related alloxanic bodies is considerably increased. The greater the quantity of useless body-material, and the worse (more dysæmic) it is in quality, the greater is the danger of a more rapid decay of cells, and a precipitation of uric acid and related products taking place.... The uric acid, passing through the liver, may perhaps be transformed into urea by a special action of the cells; but the uric acid drawn directly from the digestive canal, and that formed directly from the assimilated food or from the body-material, has to be oxidised, in order to be excreted in the innocuous form of urea. An organism possessed of the faculty of oxidation is protected against a precipitation of uric acid, but in a dysæmic organism, the faculty of transforming uric acid into urea is lessened.... It is a fact well worth considering that the urine of carnivorous animals—e.g. dog and cat—is often quite free from uric acid, while human urine varies in this respect according to the food taken: if vegetable food alone is consumed, the urine will contain, like the urine of herbivorous animals, only traces of uric acid (from ·2 to ·7 grammes in 24 hours); but if a large proportion of flesh-food be taken, the urine will contain 2 grammes or more. Man is the only creature which suffers from the uric acid diathesis; is it not likely that this arises from a wrong choice of food?