THE IDENTIFICATION OF ETHYLENE AS A VOLATILE PRODUCT OF RIPENING AVOCADOS

The production of a physiologically active emanation by ripening fruits has frequently been demonstrated by biological tests, including leaf epinasty, respiration effects, potato sprout abnormalities, and the triple response of etiolated legume seedlings (11). HUELIN (8) first noted the analogy between these effects and those produced by small concentrations of ethylene, and GANE (4, 5) first showed by chemical means that the active volatile substance produced by apples was actually ethylene gas. An inferential proof, partly chemical and partly biological, that ethylene is produced by pears was achieved by HANSEN and HARTMAN (7), and NIEDERL, BRENNER, and KJLlJEY (10) demonstrated ethylene production by bananas. PRATT and BIALE (11) found that the climacteric rise in carbon dioxide production by ripening avocado fruits was accompanied by a cycle of production of a gas, presumably ethylene, which caused the triple response of etiolated pea seedlings. The purpose of the present study was to identify chemically this active emanation and to develop a technique which would simplify the isolation and identification of ethylene as a probable volatile product of other fruits.