In connection with this contrast, it appears to me that we detect one of the objections to Hare's theory. He asserts that in common with every other function of the body the functions of digestion and absorption depend upon the supply of protein, and cites the case of dogs from whose diet all protein had been excluded, in consequence of which the food ceased after a time to be digested, and consequently remained unabsorbed. It is at least open to doubt whether by the selection of a typically carnivorous animal, whose diet includes a quantity of protein proportionally much greater than that of man, one is establishing a fair comparison. Besides, it is straining the analogy to a very fine point indeed, because it would be quite fair to respond that, the greater the quantity of protein supplied, the more effective would the functions of digestion and absorption become; and we know that this is not the case. He relies upon this statement to infer that on account of the restriction of protein, carbohydrates and presumably fats would fail to be assimilated, and hence that any good effects of vegetarianism, the low-protein diet, and the purin-free diet are to be attributed to the diminution of carbonaceous material in the blood, Now, whatever may be alleged against the purin-free diet as promulgated by Haig, it cannot be said that it lacks a proper quantity of protein. It does not certainly contain as much as the Voit standard diet, but it has well over the gram per kilogram of body-weight now considered satisfactory. It suffers in no way from its quantity of protein. Its defects lie more in the fact of its exclusion of the peptogenic purins and the substitution of proteins to which the digestive organs are not accustomed. Again, during Chittenden's long experiment there is not the slightest evidence that there was any lack of absorption of fats or carbohydrates, although Benedict does suggest that an abnormally low protein supply may affect the absorption of nitrogenous material from the alimentary tract. But Benedict goes further, and asserts that the body absorbs the nutriment from food practically in the same proportions without regard to the amount ingested, whether that amount be large or small.

The vegetarian diet likewise, as served at Battle Creek Sanitarium, only contains 10 per cent. of protein to 30 per cent. of fats and 60 per cent. of carbohydrates, and yet the fasces contain no more than the usual proportion of undigested fat and carbohydrate, viz., 5 per cent. and 2 per cent. respectively. These facts have been proved abundantly by the daily examination of faeces carried out in the laboratory in a large number of cases over a very long period of time. So great, indeed, is the absorption of carbohydrate material in the case of vegetarians, that it is not at all uncommon to find that some of it escapes by the kidney, and can be detected as glucose in the urine. We should, therefore, find that vegetarians would suffer from hyperpyraemic attacks of one kind or another, whereas, on the contrary, we know that in them, at any rate, migraine and epilepsy are quite rare.

The vegetarian's explanation of this fact we have already considered, viz., that the carbonic acid resulting from the combustion of fats and carbohydrates is quickly eliminated through the lungs, while the products of protein metabolism are highly toxic products, which require for their elaboration and elimination a very considerable amount of work, in which not only the liver and kidneys are concerned, but various other organs. So long as these organs are fairly healthy and not overtaxed with excessive quantities of toxin, it is hardly likely that they will be injuriously affected, or will allow the body to suffer. It is, however, conceivable that they may be almost continuously just below high-water mark, and in these circumstances a little extra dose of toxin, or even the absorption of some of the acid products of carbohydrate fermentation not pronounced enough to be noticeable as intestinal indigestion, would be liable to turn the scale.

It is necessary to emphasise the fact that although the ideal decomposition of carbohydrates has carbon dioxide and water for its end-products, this theoretical termination is never realised practically. Butyric acid, at least, is always found in the contents of the intestine, and if we are to judge by its acrid taste, its presence in excess is not likely to be unattended by discomforting sensations, and also other disagreeable toxic by-products. We also know that more than one alcohol and various acids, such as lactic acid, acetic acid, caproic acid, propionic acid, besides carbonic acid, are often, if not always, met with. We know that carbonic acid is quickly absorbed by the walls of the intestine and expired through the lungs without unpleasant symptoms, but that is no reason why the excretion of some of the other acids by the bronchial, gastric, or nasal mucous membrane should not be accompanied by asthma, bronchitis, biliousness, or nasal catarrh. Migraine and epilepsy may well be excited by the presence of toxins and various acids in the circulation, while the enforced starvation in the one case and the muscular contractions in the other may have much to do in destroying the toxins. It is remarkable how an alkaline purge, such as an old-fashioned magnesia or any of its modern prototypes, is capable of clearing the situation.

In any case, a moderate degree of restriction of the protein - and none of the systems we have been studying recommend more - cannot be considered as being accompanied by diminished digestion and absorption. It is hardly probable, therefore, that the reduction of the carbonaceous material of the blood is the explanation of the undoubtedly beneficial therapeutic effects of the three dietetic systems we have already discussed. I am inclined to believe that the valuable therapeutical influence of this dietetic system, as well as of the other three, must be attributed to the diminished caloric value of the food in each. It is true that Hare recommends a slight increase in the protein allowance, but there is little danger of injury resulting from this moderate nitrogenous excess, accompanied as it is by an enormous lessening in the carbonaceous ration. If we calculate the caloric value of one of his daily diet prescriptions, e.g., 8-12 ounces of cooked lean meat or fish, 1 1/2 ounces of bread or toast and a little butter, a little green non-starchy vegetable, a little tea or coffee with milk but no sugar, we find that it easily fails short of 1,000 calories, and this is practically starvation compared with any of the other three systems.