Just as the vegetarians unblushingly claim all the advantages of the low-protein and purin-free theories, although the fundamental principle of each is absolutely in opposition to their own, so Dr. Haig avails himself of the athletic feats of the vegetarians to demonstrate the merit of his system as a means unsurpassed for procuring physical prowess and regeneration. He succeeds in impressing the man of ordinary physical capacity with the belief that exclusion of purins from his diet will enable him to attain success in the athletic world, because by this means the circulation is not under the malign influence of uric acid. He agrees with the low-protein advocates in insisting that enough protein should be taken to subserve the nutritive requirements of the body, but differs from them in demanding that the quantity should be materially increased, i.e., that 9 grains per pound weight of the body should be consumed in place of 6 grains. He objects to the use of otherwise excellent foods containing no purins, e.g., eggs, because in his own person they increase the excretion of uric acid, and permits the use of foods containing purins, e.g., potatoes, because they fail to increase his own output of uric acid. This is surely stultifying his own conclusions, and admitting the possibility that principles other than those he has emphasised may be in operation.

But with all its defects, the purin-free system marks a distinct advance in dietetic study and practice. It is an unquestionable fact that many people are quite incapable of metabolising purins, and it is at least doubtful whether this may not be one potent reason for the persistence of the cults of the fleshless feeder and the low-protein advocate. For its adoption a good digestion appears to be necessary, and it is notable that, where such does not exist, cures by its means cannot be safely prophesied. It is usual to find, also, that, after a cure has been effected, only the enthusiasts are willing to go on subsisting on such an unattractive diet. Its chief defect is its great monotony and absence of peptogens, and I have only known two people who had sufficient courage to continue it longer than a year or two.

It is certain, however, that there are many people who cannot live with any degree of comfort unless they approximate as closely as possible to just such a dietary. It would appear that, whatever the explanation be, the fuel must be accommodated to the furnace, and we are all acquainted with furnaces which can consume with ease whatever combustible is thrust upon them. But we recognise that there also exist fireplaces which require a selected fuel of one kind or another before they can be calculated to do their work satisfactorily. So we find that many patients require special diets to rid themselves of certain of their ailments, and that these, unless they desire a recrudescence of their maladies, are compelled to adhere as closely as possible to a rigorous regimen. Having recognised their limitations and submitted to them, they may become more useful members of society than even those with much more effective assimilative functions.

Dr. Haig deserves much credit for so persistently bringing the study of dietetics before the medical profession, and especially for so forcibly evoking the attention of the layman to his excessive consumption of animal food. The dogmatic presentation of his doctrine has contributed to the physical salvation of many, even although his scientific explanations and deductions are neither warranted, corroborated, nor supported. It will be noted that although one of the important features of the system is that it insists upon a sufficiency of protein, the standard laid down, viz., 9 grains per pound weight of the body, is much less than that established by Voit, and more nearly approximates to the gram per kilogram of the body-weight now considered essential. An analysis of one of the typical charts detailed in Haig's shorter treatise shows an energy value of between 2,500 and 2,700 calories, well under the amounts until lately looked upon as necessary for the nutritive requirements of the body. Apart, therefore, from any specific influence it may be thought to exert, we may fairly claim the system as another powerful plea for moderation in eating.