The reduction of foods to a homogeneous, soft mass, or to a liquid, is virtually included in any form of predigestion, and, in the mechanic sense, may even be considered as part of the predigestion.

Predigestion of fats, in the sense of forming soaps and glycerine, is not feasible, as those products are nauseating and irritating. Thus, the claim of predigestion of fats in a proprietary food means nothing. The digestion of fats is facilitated by emulsification as occurs naturally in milk and cream. Various mucilaginous and gelatinous solutions may be employed to emulsify fats, or egg yolk or the whole raw egg may be used. Such emulsions are variously flavored. Chocolates, rich in fat, may be considered as solid emulsions, ready for mixing with water, milk or cream. The addition of pure biliary salts to oils, facilitates their osmosis. One part in a hundred may be used.

Predigestion of carbohydrates is partially effected by cooking, the starch granules being ruptured and the starch partially hydrated. Bread crust and toasted bread and crackers also have part of the starch further changed to dextrin. Cane sugar is more or less completely inverted into dextrose and levulose by boiling. However, the simplest and most complete form of carbohydrate predigestion is to administer pure dextrose. While concentrated solutions of sugar are somewhat irritating to mucous membranes, dextrose solutions are less so than those of cane sugar, and the prejudice against grape sugar has no physiologic basis, though, obviously, commercial impurities should be excluded.

Predigestion of proteins is practically limited to the production of albumoses, true peptone being bitter and toxic, at least as artificially prepared. While predigestion may be practiced by imitating either gastric or intestinal digestion or that of certain plants, the method in common use consists in the addition of pancreatic extract - pure trypsin not having been prepared, at least not on a commercial scale - and an alkali, usually sodium bicarbonate, to milk or a mixture of milk and egg, at about the body temperature. The exact amounts used are immaterial, but a fair allowance is 25 centigrams of each to the pint of milk or egg-and-milk mixture. Digestion is allowed to progress for 20 - 30 minutes, stopping when the faintest bitter taste has developed. If not used immediately, further peptonization should be stopped by cooling and keeping on ice. Various sealed tubes of peptonizing powder may be used, as a matter of convenience. For domestic use, an ordinary double boiler may be used or the peptonizing dish may be set in a larger one containing water of about the body temperature. With due precautions against too high temperature, the back of a stove, a register, or the top of some piece of furniture in a warm room may be used to maintain a fairly uniform temperature of about the right grade.

While the digestive ferments act somewhat at lower temperatures than that of the body, the so-called cold process (with animal ferments) is not reliable. However, if the alkaline solution of copper used for testing for sugar in the urine shows a distinct violet tinge on adding an equal quantity of peptonized milk, it may be assumed that sufficient formation of albumoses has occurred.

Meat peptonoids are prepared commercially, both in liquid and pultaceous forms. There is no reason why meat should not be peptonized extemporaneously by adding pepsin and hydrochloric acid, about 1 part in 500 of each, or pancreatin and soda as for milk, with due regard to temperature and time, as before. The acid method certainly should not be practiced in a metal dish and, in general, glass or porcelain is preferable for all such manipulations. The vegetable ferments, especially those from paw paw, are more active than the animal, and it is not necessary to secure a decided acid or alkaline reaction nor to maintain the body temperature.

In many instances it seems preferable to practice artificial digestion in the stomach, using alkali and pancreatin if there is a decided lack of gastric secretion, or reinforcing the gastric secretion with hydrochloric acid or pepsin, or both. It should be remembered that the failure of pepsin in the stomach practically never - absolutely never, so far as the writer is aware - occurs if there is any free hydrochloric acid spontaneously present. Still there are cases in which, clinically, it seems that nutrition is increased by reinforcing the pepsin.

As a rule, stomachs which fail, for more than a brief period, to secrete pepsin, and which do not do so after the hydrochloric acidity is restored artificially, remain permanently apeptic. In many cases, intestinal digestion is fully competent to digest all the proteins and, indeed, the gastric condition is discovered only accidentally and, apparently, after a long time. In others there is gastric cancer, degeneration of the mucous membrane or other serious condition, and considerable irremediable lack of pancreatic digestion. In the former cases, predigestion or concomitant administration of digest-ants is unnecessary; in the latter it is inadequate and, still, indicated as the best we can do, aside from direct therapeutic measures aimed at the underlying condition.

In the normal hydrolysis of proteins, the first step consists in the combination of albumin with hydrochloric acid, forming svntonin. This method deserves wider use as an artificial form of predigestion. The acid, well diluted, is stirred into the mass, drop by drop. The following amounts of gaseous acid (the officinal dilute hydrochloric acid is ten per cent strength) are taken up by different food stuffs:

Ehrlich.