INTRODUCTION
The work reported in this and subsequent papers was undertaken at the request of the trustees of the Elizabeth McCormick Memorial Fund of Chicago. This organization has been interested for a number of years in the practical task of attempting to overcome, by the organization of nutrition classes and by work in the home, undernutrition in children of school age. The work has, in general, been successful, but a small proportion of the children who have come under observation could not be made to gain, in spite of the fact that no evident cause of the undernourished state could be detected. It was to determine the metabolic abnormality, if any actually existed, of such "refractory" children that the Nelson Morris Institute was asked to investigate the subject at the suggestion of Dr. I. A. Abt, consulting pediatrician of the fund. In outlining the work to be undertaken, it was