In 1924, attention was drawn to the fact that in the course of routine examinations of infants, extending over a period of several years, a distinctive pliability or lack of resistance of the wall of the chest had frequently been noted.1 When pressure was exerted on the anterior or lateral thoracic wall, an abnormal yielding was elicited; in some cases the ribs offered surprisingly little resistance. This observation seemed of significance when it was noted that the phenomenon often was not associated with symptoms or signs of rickets; beading of the ribs was absent, roentgenograms of the epiphyses at the wrists did not show any abnormality, and the concentration of inorganic phosphorus and calcium of the blood was normal. This "nonrachitic softening of the ribs," as it was termed, was noted in 34 of the 375 children in the institution, 10 of whom had been born prematurely. Seasonal variation,