QUALITY OF LEMONS and of Other citrus fruits is affected by the concentrations of acids in the fruit juice. For this reason information concerning the synthesis and accumulation of the acids is important and has been the subject of intensive studies. Until recently organic acids were thought to be synthesized in leaves and then later translocated to the fruit. Sufficient biochemical systems have now been isolated from fruits to warrant the conclusion that lemon and other citrus fruits are quite capable of the acid synthesis.