The fact that proteins are completely digested, that is broken up into their constituent amino acids before absorption proves, we believe, that highly complex proteins are not really wanted as foods. While it is true that it is part of the function of the digestive tract to extract impurities and non-congenial substances from the food and avoid these, it is not well to abuse the digestive system by foods that are too rich, that is, too complex. This will be made more clear in the chapter on food allergies.

The plant is the best and original source of building materials that our diet can supply. The really "vital and abiding union sought after in animal nutrition, is between the amino acids of the plant and the blood of the animal." In conformity with the principle of reciprocity and reciprocal differentiation operating in the organic world, we want in our diet proteins quite different from our own.

There is a tendency in many quarters to exalt meat proteins as superior to all other forms of protein. The adequacy of flesh proteins as growth factors is especially stressed. That flesh proteins contain all of the essential amino acids is frequently asserted. Meat (flesh) protein is the most valuable of all forms of protein, is a frequent assertion. Berg points out that "this cannot be accepted as a positive fact as regards the protein of individual muscles, only as regards the aggregate proteins of an animal body used as food." Abderhalden also points out this fact. This is especially true if the meat is not accompanied with a large supply of base-forming foods. Berg points out that carnivorous animals, living in a state of nature, "ensure a supply of bases by drinking the blood of their victims and devouring the bones and the cartilages as well as the flesh." It is also true that wild carnivores consume considerable quantities of fruits, berries and buds. Cats are often observed to eat vegetable foods. Wild carnivora especially eat such foods in the Autumn, although in the Spring they are likely to subsist exclusively upon the fruits of the kill.

It has long been known that if a dog is fed on flesh from which the juice has been extracted, he becomes emaciated after a time, toxic symptoms develop, and death rapidly follows. Skeletal changes characteristic of osteoporosis and oteomalacia are found upon postmortem examination. The extraction of the salts of the flesh causes death.

It is well to keep in mind that the different organs of the animal body differ in their amino acid content. As has been pointed out before, not merely every species of animal, but also, within each animal, every organ, has its own peculiar kind of protein. For this reason the different organs of the animal body are not equally complete or "valuable" as sources of amino acids. One advocate of flesh eating deplores the fact that "some patients are unfortunately averse to eating entrails. Entrails, like liver," he says, "kidneys, heart, spleen, etc., are extremely rich in certain vitamins and other valuable constituents and their regular use in this diet is to be greatly encouraged." To receive all the value of a flesh diet, it is necessary to eat the whole animal--not, however, as is the case in eating whole oysters, the feces, also.

We want, not merely amino acids, but amino acids in ideal combination with other indispensable substances--minerals, vitamins, carbohydrates--such as only plants can furnish. These other substances are essential to the full utilization of proteins. Meat protein, when deprived of its minerals, destroys life. Animal proteins are not ideally combined with these other substances. The most ideal substances for animal and human nutrition and the most ideal blends of these substances are to be found in the spare products of plants.

There is also a tendency of the experimenters to place too much importance on gains in weight. They find more rapid growth, or a greater gain in weight, or even greater ultimate growth, on some diets than on others. Too much reliance should not be placed in reported gains unless the kind of weight gained is specified. We are not interested in fattening beef cattle nor in mere bigness. Accelerated growth and precocious development are far from desirable accomplishments. Nor are results in one generation nor in a short time sufficient to establish the ultimate effects of a particular diet.

It is now asserted by all experimenters that the duration of the earlier dietetic experiments was usually too short. Berg says that his own first experiments lasted for a week. Later he extended them to two weeks, then to several months. It is now known that an experiment must often run through several generations to yield dependable results. Unfortunately the importance of the time factor is not yet fully appreciated. Nature has carried on countless dietetic experiments, lasting not just a few weeks, or a few generations, but for ages. Our experimenters have failed to notice the results of long-time experiments of this nature. Their belief in "struggle" and "survival" has prevented them from recognizing the role of nutrition in integration, disintegration and re-integration--in two words, evolution and degeneration.

The advocates of flesh eating are particularly prone to close their eyes to the results of ages of flesh eating. With no valid standard of normal growth, they fix their attention upon the growth promoting effects of flesh. They ignore the evils of precocious development and an accelerated growth. Their standard of mere bigness is the same as that of the stock raisers. One could easily think that they are growing children for the market; that the children, after they reach the "fryer" or "broiler" stages are to be sold by the pound. The larger they grow, the more money they will bring. Accelerated growth tends to be unbalanced growth. There is likely to be overgrowths and undergrowths that render the finished organism inferior. But, I must again emphasize, one generation or even three generations of such feeding is not sufficient to unfold its ultimate results.