The transparency of the crystalline lens depends on the proper utilization of nutrient material supplied by the aqueous. If for any reason there is a local deficiency of some vital constituent, the lens becomes opaque. Cataract has been reported to result from severe inanition,1as well as acute thirst.2Curtis and co-workers3showed that mature cataract developed in rats maintained on a tryptophan-free diet within six to seven weeks. Recently Totter and Day4confirmed these reports. By deprivation of cystine, cataract is produced in larvae of the salamander.5It is possible that deficiencies in other essential amino acids will lead to cataract. Deficiency in riboflavin leads to cataract in rats.6While vitamin D deficiency in itself does not cause cataract, tetany, which is frequently associated with rickets, is often accompanied by opacities in the lens. For example, in some instances of cataract resulting from