A delicate biological test for calcium-depositing substances

Abstract

Some time ago we described two diets, Nos. 2638 and 2677, which we used with a view to the development of a biological test which would show the calcium-depositing power of any given substance.1 The test was carried out as follows: The faulty diet was first fed to a group of young rats for the purpose of making the epiphyseal cartilage free from calcium, and producing a rachitic metaphysis. After a sufficiently long period had elapsed, the test substance was added to the diet of those animals which were to serve as test subjects, while the faulty diet without the test substance was continued in the case of the control rats. Substances, which when added to the faulty diets enabled the organism to deposit lime salts, caused the reappearance of the provisional zone of calcification in the bones. This biological test we called the “line test,” because the new provisional zone of calcification appeared as a line of calcium salts extending transversely across the bone with a limeless cartilage on one side of it...