In regard to urea and, as I shall presently show, the sulphates, we encounter great difficulties. I will discuss both of them together, because both of them are derived from the protein molecule. In order to reduce the amount of urea in the blood and the tissues we must reduce the amount of protein in the food.

From numerous investigations and debates on the demands of the human organism for protein and on the minimum amount of protein that must be introduced daily, we have learned one important fact, namely, that it is permissible to administer very small quantities for a short time without injuring the health of normal subjects, and without causing an excessive disassimilation of organic protoplasm, provided of course that corresponding quantities of carbohydrates and fat are administered at the same time. A perfectly healthy, strong and muscular individual can without detriment, sustain a reduction of the normal amount of protein to 6o g. a day for two or three weeks. It is certainly rational to utilize this empiric fact and to apply it to the treatment of acute nephritis.

As soon as we recognize this to be a fact we must surely hesitate to consider an exclusive milk diet to be the ideal dietetic treatment, for milk contains a relatively large proportion of albumin; 6o g. of protein the quantity I mentioned above, are contained in about three half to seven quarter liters of good cows' milk. If, as is usually done, the amount of milk is increased to about three liters a day, the subject receives from no to 120 g. of protein. From this amount, after deduction of the nitrogen that is excreted in the feces and in other nitrogenous constituents of the urine, about 30 to 35 g. are converted into urea and have to be excreted by the kidneys. The kidneys in nearly all acute disease are functionally unable to excrete such large quantities of urea; in this way a colossal retention of urea occurs that is by no means counteracted by energetic diaphoretic procedures. In addition the kidneys are permanently irritated by the large quantities of urea circulating in the blood, for urea is the most powerful stimulant of renal activity that we know. Milk, therefore, if we investigate the subject thoroughly, is not as innocent as it appears. A preparation of milk called Gaertner's fat milk possesses considerable advantage over ordinary milk, for it contains only one-half to two-thirds as much protein as ordinary milk.

In view of all these considerations I have for a number of years avoided an exclusive milk diet in acute diseases of the kidneys. I rarely give over three half liters of milk a day, and I may add that my results are very good. In order to render the milk more nutritious I add a little cream; this does no harm because cream contains very little protein, and consists almost exclusively of milk fat. I have found that the addition of one-quarter of a liter of cream to a liter of milk is the most suitable mixture in kidney diseases. It is not immaterial what kind of cream is used; ordinary cream as it is sold may be excellent as far as its taste and its constitution are concerned, but I hesitate to prescribe it for patients suffering from kidney diseases or from diseases that predispose to dyspeptic disturbances. Ordinary cream can only rarely be boiled without coagulation and unboiled cream, according to my experience and that of many of my colleagues, is not suitable; for this reason I use almost exclusively sterilized cream. Until recently I used a Swiss cream that was very rich, but that was not satisfactory as far as its taste was concerned; nowadays I use a preparation made from Holstein cream that has been introduced by the firm of O. Rademann, in Frankfurt a.M. This preserved article has good keeping properties and tastes as well as fresh cream; in addition it is very rich (30 to 33 per cent. of fat). A mixture of 1500 c.cm. of milk and 3/8 of a liter of cream contains about 55 g. of protein, 70 g. of milk sugar, and 165 to 170 g. of fat. This represents a total nutritive value of 2,050 to 2,100 calories, that is as many calories as are contained in 3 1/4 liters of good milk. The percentage of protein in the milk-cream mixture, however, is about one-half lower than the protein of 3 1/4 liters of milk.

The amount of nutriment contained in the milk cream mixture (1 1/2 liters and 3/8 liter) is in the majority of cases sufficient to maintain a good state of nutrition in patients who are forced to remain in bed. Those physicians will find this quantity of food perfectly sufficient who, on the one hand wish to avoid overloading the stomach and intestine in renal disease, and on the other hand do not care to give patients with kidney disease who are forced to remain in bed too much fat. I wish to warn expressly against over-feeding with fat, and I wish to emphasize this particularly because I have frequently seen patients with acute parenchymatous nephritis receive an enormous amount of nutriment for the purpose of giving them "strength." We may positively assume from our knowledge of the human economy, that as long as the disease persists and convalescence has not begun, nearly all the superfluous fat is deposited as fat, and is not utilized for the increase of protoplasm. However useful therefore over-feeding with fat may be in other diseased conditions, it can only do harm in nephritic cases, for in this disease the action of the heart must be considered exclusively; I have actually found that this method of treatment does harm and that the patients suffer from this source as soon as they get up from a long period of rest in bed after having gained from 1o to 20 kg. of fat.

If under particular circumstances, for instance, in very large and strong subjects who are used to large quantities of food, or in subjects who are very much reduced, the administration of an excessive number of calories in the food seems indicated, soups, porridge or pudding made of amylaceous material containing little protein (as oat meal, flour, groats, maizena, etc.), with the addition of a little butter, sugar and fruit syrup and prepared to suit the personal tastes of the patient, may be given. Aside from very small quantities of albumin and traces of ash these substances contain nothing that is excreted by the kidneys or that overtaxes the diseased organs.

We see therefore that without adhering strictly to a pure milk diet in the form in which it is ordinarily administered, we can feed sufferers from renal disease very well, in fact the principle of sparing the kidney that originally led to the adoption of milk diet can be carried out much more systematically under this mixed diet than with the customary pure milk diet.

When in the subsequent course of acute nephritis the stage of abundant diuresis is reached and the excretion of water remains normal or even hypernormal for some time (usually about a week), then we may assume positively that the power of the kidneys to eliminate urea and different salts is also approaching normal. I at least have never seen a case of acute nephritis in which increased diuresis was not at the same time accompanied by a great increase in the elimination of residual excrementitious substances. In this respect acute nephritis differs from contracted kidney, for in the terminal stages of the latter disease free diuresis may appear, while at the same time the solid metabolic waste products are retained. In this stage of acute nephritis when the disease of the kidney is improving, there is no good reason why the administration of proteins should not be increased; at the same time this increase should be gradual, and the same precautions should be exercised as in thé administration of carbohydrates after they have been withheld for some time in diabetes.

It is unnecessary to give more than 100 to no g. of protein pro die as long as any trace of nephritis remains. The most practical way to increase proteins in the healing stage of acute nephritis is to gradually increase the amount of milk to 2, or at most 2 1/2 liters, with the addition of cream and some cereal, legumes, fresh vegetables, and boiled fruit. There is no objection to small quantities of meat and eggs provided the amount of protein ingested is allowed not to exceed the quantity I have mentioned above.