The kidneys are entrusted by the organism with two very important functions: (1) to excrete waste products, unnecessary material, and superfluous fluids (water) from the body; (2) to retain all material valuable to the system. The blood in passing through the glomeruli is subjected to a scrutinous examination by the renal cells, and the double function just mentioned is in this way carried out.

In disturbances of the kidneys two sets of phenomena are noticeable: (a) accumulation in the blood of substances which should have been eliminated; (6) excretion from the blood of material that should have been retained.

The symptoms encountered in renal affections are all more or less dependent upon the above two factors, which are present either in association with each other or separately. The gravity of the disease is likewise subject to the extent of functional failure in these two directions.

1 The Medical Clinics of North America, November, 1917.

Alimentation which consists in the introduction and working up of new nutritive material manifestly increases the difficulties against which the kidneys have to battle. The importance of diet has therefore, always been recognized as one of the principal factors in the treatment of renal affections.

I chose this subject for discussion on account of the many interesting points it presents to the clinician.

The views regarding nephritis have undergone many changes in the course of the last century. At first it was generally believed that the main object of diet should consist in replenishing the lost albumen and for this reason richly protein foods (meats) were given. Soon, however, it was discovered that under this regime the nephritics did not show the desired improvement, and rather became worse. This led to the selection of a diet containing very little protein, and as such, milk was recommended. This valuable food still forms the mainstay in this disease.

If we take into consideration the great variety of symptoms met with in nephritics, it is at once clear that one and the same diet will not fit every case. Thus a patient with edematous swellings all over and chloride of sodium retention will require a salt-free diet and restriction of fluid, while another with almost natural water and chloride of sodium excretion, will be able to take fluids and a moderate amount of salt.

With regard to diet, the affections of the kidneys will have to be divided into the following groups:

1. Acute conditions (nephritis acute), including exacerbations of chronic states.

2. Chronic affections:

(a) parenchymatous nephritis. (6) interstitial nephritis. (c) congestive nephritis.

3. Complications:

(a) Uremia; (b) Dropsy.