Despite the numerous experimental data acquired especially since 1923, there are still defects in the knowledge of calcification in normal tissues, that is in calcified cartilage, teeth and bone. During this twelve year period, great advances in the subject have been made; much greater confidence is now held in the ideas of the state of calcium in the circulating blood and of the nature of the bone salts. Moreover, progress has been made in elucidating mechanisms by which transference is accomplished from the former, a liquid phase, to the solid phase found in calcified normal tissue. The importance of these mechanisms is obvious. It is elementary but axiomatic that improvements in knowledge of biologic mechanisms are reflected in improved clinical efficiency. The purpose of the present communication is to indicate briefly some of the recent advances in this field and to present several experiments which perhaps integrate the subject further.