For many years cod liver oil has been regarded as the sovereign remedy for rickets. Its claim to therapeutic virtue rests not only on many years of clinical experience but also on metabolism tests showing its
beneficial effect on the retention of calcium. It may be properly regarded as one of the well established therapeutic agents and one which should be widely utilized. It seemed, therefore, worth while to investigate whether its usefulness could not be extended to the prophylactic treatment of rickets.
No doubt cod liver oil has frequently been employed in individual instances in this way. As far as we know, however, no extensive test, embodying a considerable number of cases and continuous and careful observations, has been carried out. This is the task to which we set ourselves.
For various reasons we decided to carry on the investigation among a negro community, and for this purpose selected