Idiosyncrasy is a peculiarity, in which one person is in some way affected in a different manner, under the same conditions, from ordinary people. It is applied to foods when there is a great dislike to some particular food, or where some particular food exerts an effect entirely foreign to what it usually produces. Idiosyncrasia is the term applied to peculiarities of smell. Both are closely related in their effects, and have not been given sufficient attention in their relation to health and disease. We are led to do so, because many people believe that individual peculiarities are so great that knowledge of food is of little or no use. If any of our readers take such a view, we have a troublesome question to ask: What makes the peculiarities? At first thought most people will say that they are "born that way;" but suppose we go farther and ask why people are born with idiosyncrasies? Do they come from some unknown realm, or are they transmitted characteristics? Here is the real key. Transmitted peculiarities were at some time acquired, and every one knows that acquired peculiarities are mainly due to habits or education.

Who can doubt that if an American child a few months old, was taken to the heart of China, and reared as a Chinaman, but what it would eat substantially the same foods as the Chinese? This fact has so often been illustrated by taking children from civilization to barbarism, and barbarism to civilization, that it strongly tends to disprove the belief that people are "born that way." Take an illustration from the lower animals. A Texas cow or Texas pony that never saw corn will not eat it when first offered, but can easily be trained to do so. Idiosyncrasies are either mainly acquired by habit or are the heritage of ancestral habits. A small per cent, are doubtless due to some strong mental impressions made upon the individual or upon the mother while carrying her unborn child. A careful study of the subject leads us to believe that idiosyncrasies toward food might properly be divided into three classes:

1. Those that are physiological.

2. Those that are due to habit.

3. Those that are due to mental impressions.

It must not be understood that individuals always manifest either of these independent of the others; for doubtless many have peculiarities about what they eat, which may be due to either or all the causes mentioned. The physiological idiosyncrasies are due to inability to digest certain foods, so that, as a matter of fact, most idiosyncrasies of which we take notice, are not idiosyncrasies at all, but irregular physiological action. Upon this we predicate the declaration, that one food will agree with one person as well as with another person under the same conditions. This sweeps away the notion that people's peculiarities make it useless to study food. It really does more; it proves the great importance of such study, because when we know why foods disagree, and the properties of foods, we will know why they agree at one time and disagree at another. The stomach that secretes but little acid, will poorly tolerate large quantities of lean meat, and such a diet will produce a feeling of weight in the stomach entirely independent of any gaseous fermentation. Those who have an excess of acid will be distressed when they eat starchy foods, especially bread, potatoes, beans, etc.

Such persons say they cannot live without meat, and when they do not have it they always feel hungry, for the reason that they cannot digest starch. This is the most serious indigestion. Some physicians confound acid secretion with acid fermentation. Sour stomachs and heartburn are most common where the gastric secretions are weak and do not call for a meat diet, as many suppose, but an aseptic (not readily fermentable) one. Lack of ability to digest certain foods, indicates physical abnormality. Examples might be multiplied wherein various foods agree or disagree, depending upon the needs of the system, the activity of the stomach, and the condition of the intestines, pancreas and liver. It may also depend upon the blood at the time the food was eaten. If the blood be laden with effete matter and poor in quality, because of a previous unsuitable diet, the general tone of the digestive organs will be impaired. All of these are factors which make it difficult to determine what agrees and what disagrees. And people are often mistaken about their supposed peculiarities, but as the incompatibilities of foods and weakness of digestion have been previously discussed, the idiosyncrasies due to habit will be most interesting.