The three classes of proximate principles that are neces- sary to be understood in the intelligent study of the food- stuffs, and in the selection of the most efficacious diet in disease are best divided into three distinct divisions ; the inorganic, the CHO, and the CHNOS compounds, or a first, second, and third class. 

First. The inorganic substances, such as water, the phosphates, chlorides, carbonates, sulphates, etc., etc. These chemical compounds all enter the body under their own form, either alone or in combination with the other two classes. They are not oxidized or split up within the system to enter into the chemical formation of other com- pounds, but are united mechanically with the proteid group, in fact, their whole action is, as it were, mechanical. After having served their purpose to the body they pass out of the system with the excretions absolutely unchanged in their composition. All medicinal compounds of a corresponding compo- sition and nature probably act in a similar mechanical manner. 

Second. The CHO substances which have for their chemical composition the elements carbon, hydrogen, and oxygen only as fat, sugar, and starch. These substances are all oxidized or split up within the system, yielding heat, energy, lubrication, and rotundity only, and are finally eliminated from the body as carbon dioxide and water. The medicinal agents of like chemical construction probably are oxidized and broken up to yield their effects by a similar cycle of changes. 

Third. The CHNOS substances or those which have for their chemical composition the elements carbon, hydrogen, nitrogen, oxygen, and sulphur. The common representatives of this group are called proteids, or the albuminous parts of milk, eggs, meats of all kinds, which chemically and histologically include fish, lobsters, crabs, turtles, oysters, clams, etc., also poultry and game. The nitrogenous or albuminous parts of all plant life, which is now commonly called vegetable proteid, is included in this class. 

All these nitrogenous substances, irrespective of specific names, are somewhat slowly oxidized or split up within the system and are absolutely essential to form the different constituents of all the fluids, tissues, glands, and ferments of the body, being united mechanically in varying proportions with water and the mineral salts. 

When these proteid bodies are normally transformed, their excrementitious products are urea, uric acid, kreatinine, carbon dioxide, and water in certain and definite proportions. If for any reason there is an abnormal transformation along this line of proteid metabolism, the relative quantity of urea falls and the uric acid rises. By closely studying these urinary changes and intelligently interpreting them, there is furnished an almost exact key to the perfection or imperfection of the oxidization processes and the nutritive condition of the body. By this method of study it is positively known whether the food-stuffs are absorbed and properly utilized by the system or not. 

Another important phenomena to be remembered in connection with the oxidization of the proteid substances is the fact that a disturbance in their anabolism not only changes the relative proportions between the urea and the uric acid, but tends to develop an almost unlimited number of katabolins, some of which are perfectly inert, while others are as toxic and dangerous to life as the well-known cyanide compound prussic acid. 

The action of the CHNO medicinal agents can he explained largely upon the same principles and chemical laws that govern the usefulness of the proteid bodies. 

With an intelligent conception of these three classes of proximate principles and what results are obtained for the system by their perfect and what by their imperfect oxidization, a comparative table of the common substances rated as food-stuffs is instructive. This table subdivides each kind of food product into its three distinct classes of principles. The inorganic compounds, however, are subdivided into water and the inorganic salts, so that their true position may be more clearly elucidated and the whole subject made plainer. 

[[Table 1]] 

Having in this brief manner outlined the composition of the food-stuffs and intimated at the same time the absolute necessity of understanding thoroughly the chemical and physiological laws that control their usefulness within the system, it becomes possible to advance a step further and state the quantities necessary for the most perfect nutritive condition. 

It also shows clearly how, by indulging too freely in any kind of food or by an unwise selection of the various kinds of proximate principles, the digestive system is constantly overtaxed, assimilation imperfectly effected and a host of diseased conditions developed. These abnormalties are brought about in the most insidious and often almost inappreciable manner, until, in some instances, well-defined symptoms are established by which a distinct name can be applied to the condition before attention is attracted to the malady. In a much larger percentage of the cases, however, the symptoms presented are so vague and changeable that the most learned specialist cannot possibly name the condition and sharply define the abnormalty so that it can be differentiated from many other states of a similar nature. Yet it is perfectly clear to every one, patient and practitioner, that something is decidedly wrong with the physiological mechanism of the system. 

Briefly stated, it may be assumed that the following table, No. II., gives a pretty close and satisfactory basis how the first and second classes of proximate principles should be arranged as to the relative proportions needed of each, from bare subsistence up to the largest amount of mental and physical work. 

[[Table 2]]

Before advancing any further in this physiological problem of food and nutrition, it must be admitted that the oxygenating capacity of the system is a limited one — but, fortunately for the human race, it has a moderately wide margin. There frequently comes a time, however, when this margin is exceeded, which is usually brought about by eating too large quantities of all kinds of food or too freely of the CHO classes of food-stuffs — as fat, sugar, and starches — or of both. As a natural sequence one of three things of necessity follows. 

First. The respirations and circulation must be increased to supply more oxygen or the food-stuffs will be imperfectly oxidized. But Nature has set a limit upon the actions of the heart and lungs so that complete relief cannot be granted in this manner. 

Second. The red blood corpuscles must be increased in number or empowered to carry more oxygen, or the absorbed food-stuffs will be imperfectly oxidized. But here again Nature has set a limit upon the number and carrying capacity of these anatomical bodies so that relief in this direction is wanting. 

Third. The super-abundance of food-stuffs absorbed must be incompletely oxidized because the system has no means by which the extra amount of oxygen required can be furnished. This statement applies with special force to che proteid bodies on account of well-established chemical laws, which show that the CHO elements are quickly and completely transformed under all circumstances while the CHNOS are only perfectly transformed when everything is most favorable. The CHO compounds, as fat, sugar, and starch, are rapidly and easily oxidized, consequently they are the first elements to be changed, and they are also completely transformed into their final products ; this tends to leave a deficient quantity of oxygen to act upon and accomplish the more difficult task of carrying the nitrogenous com- pounds through their cycle of change and finally into perfect excrementitious substances. This defective supply of oxygen disturbs the perfect metabolism of the proteid bodies and produces an unlimited number of katabolins and furnishes a rational explanation for many, if not all, of the pathological conditions and symptoms that have to be treated. At least it is fair to assume that so long as the anabolic processes of the body are perfectly effected, no pathological lesion or abnormal symptom can be developed. Keeping constantly in mind the table indicating the relative proportions existing between the proteids and the CHO compounds, or the fats, sugars, and starches, and studying a little more closely the composition and comparative merits of the various food products, much valuable information is brought to light. 

First. It is found almost impossible to arrange a mixed or vegetable diet so as to obtain the requisite amount of proteid elements without at the same time taking more than the needed quantity of the CHO compounds, that is, without introducing more than can be safely utilized or oxidized. 

Second. It is found that with an exclusive meat diet composed of the ordinary average meat almost the exact quantities of both the CHNOS and CHO compounds can be obtained from bare subsistence up to that for forced work. Taking four ounces of pure proteid matter as the standard amount required in twenty-four hours to perfectly maintain the constructive forces of the system, the following tables are quite instructive, viz. :

 [[Tables 3-7]] 

Examples of this kind might be multiplied almost ad infinitum. With all of the tables, however, excepting Table No. VI., there is clearly shown a larger quantity of the CHO compounds than is found of proteid elements. This shows that with almost all kinds of food-stuffs and especially when taken in excessive quantities the system is liable to receive a superabundance of the CHO substances. The ease with which the requisite amounts of proteid matter can be rightly adjusted to meet the demands of the system is clearly demonstrated. These tables just as clearly illustrate that it is almost impossible to arrange any form of the mixed food-stuffs in such a manner that the system will not be constantly super- charged with the stimulating and non-nutritious compounds of CHO construction. 

TABLE VIII. 

This comprehensive comparative diet table, compiled and used by Prof. William H. Porter, of the New York Post-Graduate Medical School, has been worked out upon the atomic basis of the proximate principles, which enter into the construction of the ordinary food-stuffs. 

It proves quite conclusively that Professor Porter's animal diet yields all that can be obtained by the use of a mixed diet containing the three elements — proteid, fat, and carbohydrate. 

In fact, in the proportions as here given, it calls for the use of a little more oxygen than the mixed diet based upon the proportions given by Moleschott ; it also yields a little more carbon dioxide and water. 

When it is remembered, however, that in the egg and the ordinary run of good meat, the proteid element is always a little more abundant than the fat, this excess of oxygen used — when taking an ordinary animal diet — will not be required, and the increased amount of carbon dioxide and water will not be produced, but the total results in excrementitious products cast off and the amount of heat and so-called energy evolved will come so very close to the amounts obtained by using Moleschott's mixed diet, that the two are practically the same. 

The conclusion, therefore, is that the relative proportions of these two elements, proteid and fat, as commonly found in eggs, meat, and fish, come so nearly to the required physiological demands of the system that, in this class of food-stuffs, there is found an almost perfect standard for diet. By adding a very small allowance of bread and butter, it becomes absolutely perfect. 

These chemical facts, based upon the atomicity of the Sood elements, explain the higher nutritive vitality developed in the carnivora as compared with the herbivora and vegetable feeding classes. 

Again, in diseased conditions where the nutritive powers are severely overtaxed, the proteid and fat diet is especially serviceable, for by its use the expenditure of vital force in transforming the food-stuffs is kept at the lowest possible standard. Because, in the use of animal fat to the exclusion of the carbohydrates, the system is spared the necessity of laying out force and oxygen to convert the starch and various sugar elements into a diffusible glucose, and then into an alcoholic-like compound before they can be utilized by the animal economy for the production of heat and the so-called energy, which is finally computed in foot pounds of work accomplished. 

This great saving in vital force by the exclusive use of fat — to supply the CHO elements necessary to produce the heat and energy required — is unquestionably the exact factor that enables the system to effect the cure in all the pathological conditions, which otherwise could not be carried on to a complete recovery. 

These same laws make Kumysgen one of the most valuable food products ever produced, because it has been found, that only about one-half of the fat contained in milk is capable of being absorbed, and with the lactose converted into an alcoholic compound there is developed in Kumyss or Kumysgen, particularly in the latter, a partially predigested food-stuff which contains about equal quantities of proteid and fat in a state to be readily absorbed. This then corresponds exactly with the requirements found in Professor Porter's table, which consists of only proteid and fat. 

Practical experience has long since taught that this form of dieting was the only kind available in connection with the successful treatment of the acute diseases. 

This table is further a demonstration and confirma- tion from a chemical and physiological standpoint, of what has been so often repeated in a clinical way, that upon this purely proteid and fat diet, together with the administration of suitable medicinal agents, the most aggravated forms of digestive disturbances can be quickly removed, nutrition improved, and a healthy standard permanently re-established. They show conclusively that this form of animal diet yields the largest working power to the system for a given amount of food taken, and a similar amount of oxygen used to carry the food substances through their anabolic cycle of changes, and finally form and discharge from the body the resulting excrementitious products.