Fuel value, however, should be increased somewhat during the winter months in our climate. Fat promises the largest amount of energy, but there is more of a tendency to store up excess of fat than of carbohydrate, hence the latter foods have certain advantages as a source of the additional energy needed during cold weather. In warm weather, it should be our aim to diminish unnecessary heat production as much as possible, though it must be remembered that the body is to be maintained approximately at least in equilibrium, and this calls for au adequate amount of food. Lighter foods, however, may be advantageously employed, such as fruits, vegetables, fresh fish, etc. Fats and fat meats especially are to be avoided, not only because there is no specific MM fot them, but particularly on account of a greater sensitiveness of the gastro-intestinal tract during the hot seasons of the year that is liable to result in a disturbance whenever undue quantity of rich or heavy food is taken. Further, in hot summer weather we may advantageously live more largely on foods served cold, and thereby avoid the heat ordinarily introduced into the body by hot fluids and solids. These, however, are all obvious physiological truths, constituting a form of physiological good sense the application of which calls for no special expert knowledge.

Less obvious, though no less important, is the partial protection that can be afforded to weakened or disabled kidneys by judgment and discrimination in the matter of diet. In acute or chronic nephritis, forms of so-called Blights disease, is there not danger of overtaxing organs already weakened by placing upon them the daily duty of excreting large amounts of solid nitrogenous waste, as well as of the various inorganic salts which are so intimately associated with many of the organic foodstuffs? The consumption of excessive and unnecessary amounts of proteid food simply means the ultimate formation of just so much more urea, uric acid, etc., which must be passed out through the kidneys. In the words of Bunge, "There is no organ in our body so mercilessly ill treated as the kidneys. The stomach reacts against overloading. The kidneys are obliged to let everything pass through them, and the harm done to them is not felt till it is too late to avoid the evil consequences." It would seem the part of wisdom, therefore, to adjust the daily intake of proteid food to as low a level as is consistent with the true needs of the body, in those cases where the kidneys are at all enfeebled, or where it seems desirable to exercise due precaution as a possible means of prevention.

Equal care is frequently called for in connection with the mineral matters which enter so largely into many natural foodstuffs, or which are introduced as condiments. As an illustration, we may note one or two peculiarities in the distribution of sodium and potassium salts in the tissues of the body. Potassium is an indispensable constituent of every living cell, and the latter has the power of absorbing and holding on to such amounts of this particular element as may be necessary for the functional activity of the tissue of which it is a part. Sodium, on the other hand, stands in a different relationship to living structures. It is widely distributed, but in the higher animals, as in man, sodium salts are most abundant in the fluids of the body, notably in the plasma of the blood. Herbivorous animals have a strong liking for sodium chloride or common salt, but this is not true of carnivorous animals; indeed, the latter animals have a great dislike for salty articles of food. Vegetable products are all rich in potassium salts, whereas ordinary animal foods, such as meat, eggs, milk, and blood, are relatively poor in this element.

It is claimed that the abundance of potassium salts in vegetable foods is the cause of the apparent need for sodium chloride by herbivorous animals, and in leaser degree by man. This is explained by supposing that when the salts of potassium reach the blood by absorption of the vegetable foods, an interchange takes place with the sodium chloride of the blood plasma. "Chloride of potassium and the sodium salt of the acid which was combined with the potassium are formed. Instead of the chloride of sodium, therefore, the blood now contains another sodium salt, which did not form part of the normal composition of the blood, or at any rate not in so large a proportion. A foreign constituent or an excess of a normal constituent, i. e, sodium carbonate, has arisen in the blood. Rut the kidneys possess the function of maintaining the same composition of the blood, and of thus eliminating every abnormal constituent and any excess of a normal constituent. The sodium salt formed is therefore ejected by the kidneys, together with the chloride of potassium, and the blood becomes poorer in chlorine and sodium. Common salt is therefore withdrawn from the organism by the ingestion of potassium salts. This loss can only be made up from without, and this explains the fact that animals which live on a diet rich in potassium, have a longing for salt" (Bunge). It is certainly a fact worthy of note that man takes only one salt as such in addition to those that are naturally present in his food, and it is equally significant that sodium chloride is by no means lacking in ordinary foodstuffs. If the individual lives entirely on animal foods, he has for salt, hut as soon as he adopts a vegetable diet the craving for salt shows itself. Vegetable foods, however, are not all alike in their content of potassium salts; some, like rice, contain relatively little, while others, like potatoes, peas, and beans, are comparatively rich in this element

We may recognize in these statements a physiological demand for a certain amount of salt, especially when vegetable foods enter into the daily dietary, but there is no justification for the employment of such quantities as are generally made use of. Where the vegetable food is largely rice, a small fraction of a gram of is really sufficient for all physiological purposes; and in those cases where ordinary cereals, legumes, potatoes, etc., constitute the chief part of the dietary, a few grams of salt at the most will suffice to meet the daily needs. Common usage, however, frequently raises the amount consumed to 25 grams or more per day, the bulk of which is at once eliminated through the kidneys; thereby entailing a certain amount of renal activity, which must, it would seem, constitute something of a strain upon organs ordinarily hard worked at the best. "Do we not impose too great a task upon them, and may it not be fraught with serious consequences? When on a diet of meat and bread, without salt, we excrete not more than from 6 to 8 grams of alkaline salts in twenty-four hours. With a diet of potatoes, and a corresponding addition of salt, over 100 grams of alkaline salts pass through the kidneys in the day. May not there be danger in this? The habit of drinking spirituous liquors, which moreover is reckoned one of the causes of chronic nephritis, also brings about the immoderate use of salt, and thus one sin against nature leads to another" (Bunge).

The moral we would draw (from these observations) is that in weakened conditions of the kidneys there is reason in reducing the rate of proteid exchange to the lowest level consistent with the maintenance of equilibrium and the preservation of strength and vigor, thereby diminishing the amount of nitrogenous waste to be eliminated and the consequent strain upon these organs. Further, there is suggested moderation in the amount of salt to be used daily, and some circumspection in the amount and quality of vegetable foods consumed in order to regulate more effectually the quantity of saline waste to be handled by the kidneys. These conclusions are just as worthy of consideration as the more obvious rule that in diabetes or glycosuria proper precaution must be observed in the eating of carbohydrate foods. In gout and rheumatism, accumulated physiological knowledge teaches plainly the necessity of avoiding those foods that are rich in purin-con-taining compounds. Uric acid owes its origin in part at least to substances of this class; and as an ounce of prevention is worth more than a pound of cure, we may by proper moderation in the use of such foods save ourselves from the disagreeable effects of accumulated uric acid deposits.

In conclusion, the nutrition of man, if it is to be carried out by the individual in a manner adapted to obtaining the best results, involves an intelligent appreciation of the needs of the body under different conditions of life, and a willingness to accept and put in practice the principles that scientific research has brought to light, even though such principles stand opposed to old-time traditions and customs. The master words which promise help in the carrying out of an intelligent plan of living are moderation and simplicity; moderation in the amount of food consumed daily, simplicity in the character of the dietary, in harmony with the old saying that man eat$ io live and not lives to eat. In so doing there is promise of health, strength, and longevity, with increased efficiency, as the reward of obedience to Nature's laws.