The same observer states that, given _intravenous_ injection of acid into a _normal_ man, its elimination is spread over several days, and the total amount injected fails to appear in the urine. But if the injection be administered during a course of _atophan_, then the uric acid excretion is completed within twenty-four hours, and the whole amount injected can be recovered from the urine. Now if in a _gouty_ subject the same method of procedure be adopted, the sequence of events is precisely similar, and like results have been reported, following the administration of _sodium salicylate_ to vegetarians of five or more years’ standing. To sum up, the above findings would appear to indicate that:— (1) A gouty subject can excrete exogenous purins as adequately as a normal man, but he takes longer to do so. (2) If the extra purins be taken during a course of atophan, even this departure from normal is obliterated, _i.e._, the customary delay in excretion is obviated.[18] But, unfortunately for the diagnostic valency of this symptom in gout, viz., _retarded exogenous purin output_, it has not been found to be _invariable_. Thus Magnus Levy has shown that, in some instances of gout, the elimination of exogenous purin is neither reduced nor protracted. Pratt, too, has confirmed this observer’s findings, while, as we shall see later, this authority, also McClure, Mallory, and others, have placed on record the still more disconcerting fact, viz., that a diminished and retarded output of exogenous purin is _not peculiar to gout_. The inference then would appear to be that:— (1) Reduction and retardation of the excretion of exogenous purin, though common in gout, is not invariable. (2) The same is not peculiar to gout, but occurs in other disorders. (3) Its diagnostic valency, as a characteristic feature of gout, is correspondingly depreciated. LOWERED ENDOGENOUS URIC ACID OUTPUT As a rule, gouty subjects, on a _purin-free_ diet, excrete less endogenous uric acid than _normal_ persons. Thus, according to Walker Hall, the average daily endogenous urinary uric acid output of a _normal_ adult is about 0·5 gramme, while that of a gouty subject is about 0·45 gramme. Brugsch and Schittenhelm hold that in about 80 per cent. of cases the average endogenous excretion is lower than normal.[19] According to these same observers, “the maximum fluctuation during attack-free periods was at first believed to be less than in the normal cases; more recent examinations, however, have shown that in the same case of gout there may be _periods of high, and periods of low, endogenous uric acid excretion_.” These variations, they hold, are not to be accounted for by either mild or severe attacks of gout, for they occur in the _attack-free_ period.