Note 8 — Chapter VI · NUCLEIN METABOLISM
Reading edition
Recent researches by S. R. Benedict show that uric acid, in the blood of most mammals, exists in combination, but not in that of the bird. Fresh ox-blood (Folin method) contains only 0·30005 gram, free uric acid per 100 grams of blood. But after boiling the protein-free blood filtrate with hydrochloric acid the uric acid content was about ten times as high. Moreover, this same augmented uric acid content was found to exist “in whole blood that had been allowed to stand for some time, indicating that the uric acid compound can be split by means of an enzyme.” The compound exists, not in the plasma, but in the corpuscles. MacLeod, to whose work on bio-chemistry we are indebted, remarks that “It is of some significance that after thus setting free the uric acid, there should be about 50 per cent. more of it present in the blood of the ox than in that of the bird, where most exists in a free state in the serum, although the urine of the ox contains only the smallest trace of uric acid, and that of the blood is loaded with it. Investigation of the condition of uric acid in human blood is at present in progress.”