The inference that rickets in the child can be cured by exposure to the elements, particularly of the seashore and high altitudes, is far from being of recent date; but it is to the observations of Huldschinsky,1in 1919, that we owe the definite incontestible laboratory demonstration that it is light which is the specific curative agent. As a result, heliotherapy or, more specifically, actinotherapy, is gaining for itself a position in the physician's armamentarium that should have been its own long ago. Hand in hand with the recognition of light as an important therapeutic agent there has developed a growing conviction that cod liver oil represents a remedial agent of such efficacy in the treatment of rickets that it, too, was credited with being a specific in the treatment of this disease. As a matter of fact, cod liver oil has been used almost from time immemorial by