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White grapes darken during drying and subsequent storage of the resulting raisins; the freshly expressed, unheated juice becomes brown on standing; and white wines slowly darken during aging. Since it appears that oxidizing enzymes are involved, at least to a considerable extent, in these changes, the investigation reported in this paper was undertaken upon some of the properties of the oxidizing enzymes occurring in certain Vinifera grapes, particularly of the Sultanina (Thompson seedless) variety.

The bitter glucoside of olives, olive 'leaves and olive bark was studied by Bourquelot and Vin-tilesco1 2345in 1908. They described it as a noncrystalline, intensely bitter substance, readily soluble in alcohol, fairly soluble in water and practically insoluble in ether. Its specific rotation was given by them as -127°and its reducing power on Fehling's solution as 0.412 that of dextrose. They christened it "oleuropein."Power and Tutin,2,3,4 in 1908, prepared a bitter mixture of several amorphous compounds from olive leaves and bark by the method of Bourquelot and Vintilesco. They inferred that the "oleuropein" of these investigators was not a pure substance. Vanzetti,6 in 1909, obtained an intensely bitter levorotatory amorphous substance from olive twigs. Hilts and Hollingshead6 (1920), in a report of studies on the chemical changes that occur during the ripening and pickling of olives suggested that the bitter principle is a tannin-like substance.

IIISTORICAL DATAIn California, as well as in all other important wine-producing regions, wines are subject to attack and spoilage by a group of several species of rather closely related nonmotile, rod-like bacteria.According to Semichon (1905) one of these, the "mannitie ferment, " B a t . mannitopoeum, develops principally during fermentation of grape must a t high temperatures, 38 t o 40" C. (100.4 to 104" F-), and is characterized by production of considerable (often one per cent or more) mannite from levulose. He states that the disease known as "Tourne" and which in many respects resembles the mannite disease, usually develops after yeast fermentation has ceased or has become very slow, and is due t o a filamentous, anaerobic bacterium that converts tartrates into acetic and propionic acids. He states that it forms Iactic acid. snccinic acid and mannite, as well as acetic acid, from sugar. A similar organism, according to Semichon, is responsible for the disease known as "pousse" which differs from "tonme" in that gas, carbon dioxide, is produced abundantly, often giving the appearance of yeast fermentation. A third disease, "l'amertume'' (bitterness) is attributed by Semichon to a filamentous, anaerobic bacterium, similar to the tourne and pousse organisms.Other French authors Pacottet (1926), Chancrin (10th edition), Dugast (1930), Gayon and Dabourg (1894) and Eayser (1913) have expressed similar opinions. Recently a British author, Couche (1935), expressed views and used nomenclature very similar to those of the French authors cited above. His book summarizes very well the work and opinions of the old French school. Sannino (1925) refers briefly Bcbcilhs sapr-cqenzcs viwi I and I1,Bacillu.s m e u s vini of BaciE7us amrcrylus of Voisenet and Bacillzu. Iacticws as rod-shaped bacteria capable of growing in wine in the absence of air. Voisenet (1911) has studied extensively H. a m r c r y l u s that decomposes glycerine with formation of acrolein.Some of the most thorough research on the rod-shaped bacteria of wines was conducted by MiilIer-Thnrgau and OsterwaIder (1913, 1922, 1917 have described Bact. ma?zfinitopoeum, Bacd. Lder-113 FOOD RESEARCH, Tor.. 1, KO. 2