In previous publications1 evidence was presented that the relative deficiencies of hexokinase and adenosine triphosphatase in extracts of lenses obtained from young rabbits were limiting factors of the rate and extent of glycolysis. It was further observed that the enzymatic activity of homogenates of young lenses was essentially the same as that of extracts,2 thereby indicating that the relative deficiences of hexokinase and adenosine triphosphatase did not result from the removal of the enzymes with the readily precipitable particulate cellular debris.3 Similar conclusions2 were reached in experiments with homogenates of lenses obtained from 3-year-old rabbits. Because of the relative deficiency of hexokinase in homogenates of rabbit lenses, the ability of these preparations to produce lactic acid from glucose in an otherwise fortified medium was not very marked. This together with the relatively high concentration of lactic acid present in the lens dictated against achieving a reasonable