The object of this paper is to present the subject of nutrition in its broad general aspects and to suggest the possibility of the practical application of some of the facts which years of labor through many generations of workers have brought to light.
It seems as though mankind had a right to a knowledge of the value of the foods which a bountiful Nature has provided for his use. Even among educated persons one may hear the grossest errors of judgment regarding the nutritive value of a hen's egg and few of those who eat in restaurants realize that the greater quota of nourishment which is brought to them lies not in the specific dish served but in the bread and butter which ostensibly is presented as a gift.
From the earliest times it was evident that although an adult partook of a great deal of food, he did not gain in weight. Hippocrates believed this to be due to a constant loss of insensible perspiration and to the elimination of heat, which he conceived to be a fine form of matter. Galen, six hundred years later than Hippocrates, was no further advanced in his conception of nutrition. For thirteen hundred years after Galen intellectual progress lay dormant under the spell of the Dark Ages.
One of the first inquirers of the Renaissance, the brilliant Paracelsus, explained the phenomenon of nutrition as being under the supervision of an archeus, a spirit which dwelt in the stomach and separated the food into the good and the bad, the good being used by the organs of the body, and the bad eliminated.
A true conception of the nutritive process could only be formulated when a knowledge of the existence of the various gases was revealed. It was Lavoisier who first showed that when an organic substance burned, the products of combustion were equal to the sum of the original substance and oxygen. Oxygen had but recently been discovered by Priestley. Lavoisier burned plants and found that carbon dioxide and water resulted. He, therefore, concluded that they contained carbon and hydrogen. Animals contained nitrogen in addition. This was the first analysis of organic material.
Lavoisier went further and found that an animal or a man, like a burning piece of wood, absorbed oxygen and eliminated carbon dioxide. He discovered that the process of heat production in man was one due to oxidation, that the prevailing idea that particles of air entered the salt and sulphur containing blood and there caused fermentation was untrue. Lavoisier measured the heat given off by a guinea pig by noting the quantity of ice melted by the animal when placed in a hollow block of ice, and he measured the gases given off by the animal in order to determine whether the heat produced could be accounted for by the oxidation going on.
He, furthermore, determined that oxidation in man was increased by giving him food, by causing him to do mechanical work or by subjecting him to the influence of cold. Reflecting upon these facts during the troublous times of the French Revolution, Lavoisier wrote, "Does it not seem a great injustice of Nature that the poor laborer uses more of his body substance, while superfluity, which is unnecessary for the rich, should be his portion?"
To the darkness of the history of the time belongs the fact that Lavoisier, begging, according to Carlyle, for two weeks more of life in order to complete his experiments, was guillotined, thereby becoming the greatest sacrifice of the insensate fury of his age. (For this earlier literature see Carl Voit: Ueber die Theorien der Ernahrung der tierischen Organismus, Miinchen, 1868.)
The progress of science is a history of great discoveries of fact which become established, and of destruction of theories which are temporary mental conclusions shown later to be untenable. Nor can a master mind like that of Lavoisier escape the application of this universal law. He showed that animal heat was due to a process of oxidation but he believed that the heat produced was caused by the union of oxygen with carbon and with hydrogen in the lungs. It was not till sixty years after his death that it was fully realized that the heat production was due to the oxidation of protein, fat and carbohydrate within the different organs of the body.
Carl Voit, to whom more than anyone else the world owes its fundamental knowledge of nutrition, was accustomed to say in his lectures, "Continual decompositions of matter are always going on in the living cells, and the energy liberated in these decompositions is the power upon which the motions of life depend. Phenomena of life are phenomena of motion." In truly poetical language Rubner, the most eminent of Voit's pupils, has written, "Mute and still, by night and by day, labor goes on in the workshops of life. Here an animal grows, there a plant, and the wonder of it all is not the less in the smallest being than in the largest."
The workshops of life require fuel to maintain them, and a necessary function of nutrition is to furnish fuel to the organism that the motions of life continue. Furthermore, the workshops of life are in a constant state of partial breaking down and materials must be furnished to repair the worn-out parts. In the fuel factor and the repair factor lie the essence of the science of nutrition.
These two factors operate to bring about death from starvation, either the body's own store of fuel becomes exhausted or a part of the machinery necessary for life wears out. As regards the course of death from starvation, there exists the written record of the explorer Hubbard. The following words are believed to have been penned a few hours before his death in Labrador. "I am not suffering. The acute pangs of hunger have given way to indifference. I'm sleepy. I think death from starvation not so bad. But let no one suppose I expect it. I am prepared—that is all." Hubbard's biographer quotes the following as showing the spirit of the lost explorer, as it indeed represents the spirit of all investigators:
" Something hidden. Go and find it. Go and look behind the Ranges, Something lost behind the Ranges. Lost and waiting for you. Go."