MANNOSE AND THE FIRST SUGAR OF PHOTOSYNTHESIS

Abstract

The absence of mannose from leaves of 42 representative species of higher plants confirms the widely held opinion that mannose is not one of the first sugars of photosynthesis. It is well known that mannose arises from glucose together with fructose in alkaline solutions, but since mannose is not present in the leaf sap it is concluded that fructose does not arise from glucose in plants but that its origin is simultaneous with that of glucose. It is thought probable that glucose and fructose together are the first sugars of photosynthesis.