But, unfortunately for the value of this hypothesis, there is no proof that _nucleinic acid_ is actually present in the blood; for, as Fürth remarks, is this inhibition of the precipitation of uric acid, in the presence of nucleinic acid, “necessarily indicative of a true acid combination with nucleinic acid,” “but such inhibition of precipitation is rather to be referred to the general group of variations of solubility which are manifested by crystalloid substances in the presence of all sorts of colloids.” Complex phenomena of solubility of this nature must be considered in connection with the circulating uric acid. Nucleinic acid is not the only important substance, but “the general mass of the blood proteins must be particularly thought of.” Continuing, Fürth reminds us that uric acid is much more soluble in _blood serum_ than in water, and forthwith envisages this disparity in light of the factors that affect solubility of uric acid in the _urine_. The latter is markedly influenced by the presence of urea and di-sodium phosphate, and the relation of this to mono-sodium phosphate. Nor, he reflects, is there any doubt “of the importance of such inter-relations, too, in the formation of _uric acid deposits in the tissues_.” But he adds, “Although the importance of these complex conditions of solubility as they prevail among colloid and crystalloid substances in the animal juices may be accepted in relation to the formation of uric acid concretions, there is no real reason for seeking the explanation of gout in this sphere.” TOPHI IN RELATION TO URICÆMIA It might be thought that some relationship might be established between uratic deposits and the degrees of uricæmia, but the data to hand give no countenance to the assumption. Thus, His has recorded the case of a gouty subject with multiple tophi whose blood did not yield an excess of uric acid. Pratt, again, could trace no relation between the amount of uric acid in the blood and the severity or character of the disease. Two of his patients had numerous and widely distributed large deposits of sodium urate beneath the skin, yet the _blood content_ of _uric acid_ in both was less than the average amount found in gout. Thus, on a purin-free diet, one had 2·4, the other 2·2 mg. These findings, he considers, show that the presence of _multiple tophi_ is no indication that a state of _hyper-uricæmia_ exists.