Several highly purified 3-glycosides of cyanidin were degraded at 100 "C in weak aqueous hydrochloric acid at various pH values between 1 and 4 under both nitrogen and oxygen atmospheres and it was shown that the aglyconesugar bond is the most labile of the glycosidic bonds at pH 2 to 4. At pH 1 .O, however, all the glycosidic bonds are susceptible to hydrolysis.Evidence is presented that phenolic aglycones, and glycosides of undetermined structure, are formed during anthocyanin degradation. An essentially colourless phenolic product, tentatively identified as the chalcone or a-diketone of cyanidin, was observed during the breakdown of all the cyanidin-3-glycosides studied in the pH range 1 to 4. This compound is stable under anaerobic conditions but easily degraded in atmospheres of oxygen.The rate of sugar formation was found to be similar to the rate of red colour loss and to the rate of anthocyanin disappearance in the pH range 2 to 4 showing that glycosidic hydrolysis and not opening of the pyrylium ring is the rate-determining step of the principal reaction leading to red colour loss. At pH 1 .O (anaerobic conditions), the rate of red colour loss lags behind the rate of anthocyanin degradation because the red, cationic form of cyanidin is fairly stable at this low pH. Complete hydrolysis of the anthocyanin takes place at pH 1.0 in contrast to the partial hydrolysis observed in the pH range 2 to 4.The qualitative and, quantitative information reported in this paper led to the proposal of a mechanism for anthocyanin degradation and the red colour loss which accompanies it for the pH range 2 to 4.

The feeding punctures of 36 examples of forms of 19 species of aphids on their host plants were examined histologically. The types of plant penetration by the aphids' stylets were compared with the occurrence of pectinase in the saliva of these insects. In 17 cases the aphids penetrated only between cells, and all these insects possessed pectinase; in 9 cases the aphids penetrated directly through cells, and all these aphids lacked pectinase. In five instances aphids possessing pectinase penetrated directly through cells; and there were five examples, all possessing pectinase, that penetrated both between and through cells in the same probe. No aphid lacking pectinase penetrated between cells in the pectic middle lamella. I t is suggested that pectinase aids intercellular enetration by its hydrolytic action, but that the enzyme is not necessary when t i e aphid penetrates directly through cells.'Manuscript

Pectinase was found in the saliva of 23 species of aphids, one species of leafhopper, and one species of adelgid. The enzyme was not found in four species of aphids in their apterous form, and one species of psyllid, or in the saliva of the alate form of five species of aphids that contained pectinase in the apterous form. These results emphasize the need to consider each form of a species of aphid individually. The discussion considers similarities in the mode of tissue penetration by fungi and insects, and briefly the possibility that cell wall digestion by pectinase may facilitate the extraction of virus particles by insect vectors.

When coccinellid larvae in six different age groups were sprayed with 2,4-D amine and then confined in glass vials, two main effects were seen: first, mortality was increased four times in all age groups; and secondly, the mean time to pupation increased in all age groups except the 1-day-old larvae.

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