Apparently in the rat the profound disturbances in the deposition of lime salts in cartilages and bone and the changes in the cells of those tissues which give rise to the pathological complex known as rickets, may be produced by disturbances in the diet of the optimal ratio within certain limits between calcium and phosphorus, in the absence of a sufficient amount of the organic substance contained in cod liver oil to prevent them. It would seem from the results of a large number of experiments now available, that the physiological relation in the diet within certain limits between the two elements is of much greater importance in insuring normal calcification, than the absolute amount of the salts themselves (20).