This necessarily brief review deals with the literature in the period from August, 1944 to August, 1947 on subjects traditionally included in the field of the assigned topic. However, emphasis is placed on several promising trends , particularly the application of information from precise physical investigations of model systems (interfacial films, coacervates, tactoids and protein-enzyme sys­ tems), and the interpretation of observable physical properties of protoplasmic systems in terms of their molecular structure .