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Natural esters of fatty acids of Rhizopus arrhizus Fischer increased during the first 48 hr of growth. During the 48- to 72-hr period, there was a shift in concentration from the methyl esters to the ethyl esters of fatty acids.

Electron microscope examination of sporangiospore sections from Rhizopus stolonifer (Ehrenb. ex Fr.) Lind. and R. arrhizus Fischer revealed details on intracellular organization not previously reported. Aldehyde fixation followed by chromeosmium postfixation permitted clear depiction of ribosomes hitherto unrevealed in these cells. Mitochondria were diversiform. Spore wall structures in the two species were generally similar, but outer contours differed sufficiently to permit easy species identification in examination of sections. The spores of both species abounded in cytosomes, corresponding in size, shape, and heavy-metal "stain" affinities to spherosomes in cells of higher plants. The osmiophilic response of these spherosome-like inclusions was intensified by treatment of sections with thiocarbohydrazide solution and subsequent application of aqueous osmium tetroxide, which strengthens an assumption that they are lipid-rich. The margins of the spherosome-like inclusions in lead citrate-stained sections included dense particles, about 60 A across, whose crystalline-like arrangements suggested that protein as well as lipid was present. Frequent and close associations between the spherosome-like inclusions and various cell membranes suggested that such bodies participate in membrane elaboration during germination.

Growth of seven spoilage molds on agar plates at several temperatures in both controlled atmosphere (CA) and in air was studied. Each mold responded somewhat differently to CA at each temperature; however, there were some general tendencies. The lag phase was generally increased by CA and, in some cases, was substantially extended when incubation was just above the minimum growth temperature. The mycelial structure of molds seems to be different when grown in CA than when grown in air. With only two exceptions of 24 holding conditions, the maximum amount of mycelia was always less in CA than in air. Spore development varied with each mold at each temperature; generally, it was considerably less in CA than in air. CA storage of cherries above 34 F (1 C) did not retard mold infection to any extent; at 34 F, mold growth was inhibited and storage life was extended several days as compared to air storage. CA storage of strawberries at 34 F resulted in a mold-free product after 7 days of incubation, whereas the air-stored berries were slightly infected. However, when mishandled berries showing some mold growth were stored at 34 F, CA did not stop further mold growth.