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Many of the flowers on field bean plants fail to produce pods even when fully pollinated. When insect pollination is prevented pod production on the lowest inflorescences, which normally produce most pods, is reduced but a compensatory increase on the upper ones ensures a moderate yield. This change in the distribution of pods may be a useful indication of insufficient pollination.Areas in which crops requiring pollination are grown usually contain some pollinating insects, such as honey-bees kept by local beekeepers, solitary bees and bumble bees. It is desirable that growers should be able to judge when additional bees are needed. Information useful for this purpose has now been obtained for the field bean. The investigation was undertaken because doubts had been expressed as to whether this crop was being adequately pollinated at Rothamsted. EXPERIMENTS (a) The capacity of the plant to produce mature pods when adequately pollinatedIn 1956, zoo fully open bean flowers were marked. After a fortnight about 50% had produced pods but later many of these fell off and very few remained until harvest. Thus more flowers were pollinated than produced mature pods. However, the further conclusion that pollination had been more than adequate depended on the assumption that the pods which fell off were in positions where mature pods could be produced under suitable circumstances. Pods mostly fell from the upper inflorescences and the upper flowers of the lower ones and it seemed possible that only imperfect pods could occur in these positions.This possibility was investigated in 1957. Plants chosen at random w q e divided into three groups, each of which was given a distinguishing mark. Only the main stems were used for the experiment but the side shoots were not removed, The lowest four inflorescences on the stems were removed in one group and the lowest three flowers on each inflorescence in another. The third group was left untreated. At the end of the season the pods and beans on each inflorescence were counted ( Table I). Removal of flowers from the positions where mature pods are normally produced resulted in compensatory increases in production on the other parts of the plants. The removal of these flowers from a few plants in the crop could not have caused the pollinating insects to give increased attention to the remaining flowers. The increased yield of the latter shows that pollination was not the factor

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SYNOPSISAn account is given of the salivation process in Apis mellifera. The mechanisms by which the hairs of the tongue are erected and the ligula retracted, and the action of the salivary pump, are described, and their effect on the discharge of saliva and intake of food are discussed.

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