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Quantitative changes in the antifungai compound, l-acetoxy-2-hydroxy-4-oxo-heneicosa-12.15-dienc, in freshly harvested avocado fruits during the initial stages of fungal development were investigated to determine the possible involvement of the compound in quiescent infections of Colletotrichum gloeosporioides. The concentration of tbe antifungai compound in the peel decreased to subfungitoxic concentrations 16 b after harvest. Fifty-six hours later the antifungai diene had increased to c. 3800 ngl% fresh weight. At this stage, germinated appressoria had penetrated the cuticle to the epidermal cells but no fungal development was observed until 7 days later when the concentration of the diene had decreased to 100-110/Jg/g fresh weight. Following a dip treatment at 55 Cfor5or 10 min, the antifungai diene concentration decreased as in the controls, but it remained at subfungitoxic concentrations for a longer period enabling fungal development and early symptom expression.The concentration of tbe diene in the flesh of freshly harvested fruit decreased to 120 ^g/g fresh weight 24 h after harvest. Inoculation of peeled fruits with spores of C. gloeosporioides showed germination without appressoria formation and symptom expression occurred 24-48 h later. Symptom expression was delayed if fruits were inoculated after coating the fiesh with epicuticular wax extracts or if the Hesh was inoculated 3 days after harvest when tbe antifungai diene had regained a fungitoxic concentration. Disease symptoms were expressed in soft fruits containing subfungitoxic concentrations of tbe diene.We conclude tbat the diene in unripe avocado fruits inhibits fungal development of germinated appressoria or conidia, Tbe quiescent structure of C, gloeosporioides in unripe avocado fruit is a subcuticular bypba.

An extract from Jatropha curcas seeds, purified by gel filtration on Sephadex G‐75 and Sephacryl S‐200, yielded an active hemagglutinin of high purity as assessed by electrophoresis and isoelectric focussing. The hemagglutinin had a molecular weight of around 660,000 and a pI value of 5.75. The molecule was composed of two different subunits of molecular weights 23,450 and 11,500. Amino acid analysis suggested that the molecule lacked 1/2 cystine but contained a high proportion of acidic and basic amino acids. Agglutination of trypsinized erythrocytes, groups A, B and O, took place over the range pH 4–10, and was prevented by D‐galactose, D‐galactosamine and N‐acetyl‐D‐galactosamine. The hemagglutinin has only a weak binding capacity for D‐galactose. Its activity was stable up to 60°C; at 80°C activity was lost in 50 min.

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