Pollination and seed setting in ficus sycomorus have been investigated in East Africa. Ficus sycomorus is monoecious, each fig bearing both male and female flowers. Inside the figs 6 sycophilous wasps develop: Ceratosolen arabicus, Ceratosolen galili and sycophaga sycomori (primary sycophiles), and Apocrypta sp., Eukoebelea sp. and Sycoryctes sp. (secondary sycophiles). The structure and behavior of these wasps and their bearing on pollination and seed productionare studied. Ceratosolen arabiacus is the legitimate pollinator of Ficus sycomorus. It oviposits chiefly into short—styled female flowers, thus ensuring seed setting in the long—styled ones. It is a mutualistic symbiont of the fig. Sycophaga sycomori oviposits into both short— and long—styled flowers, and does not cause seed setting. It is a competitor of Ceratosolen, but a parasite of the fig. Eukoebelea, Apocrypta and Sycoryctes are inquilines, making use of galls induced by the activity of the primary sycophiles. They do not interfere with seed production in pollinated flowers not occupied by Ceratosolen or Sycophaga.

SUMMARYFlowering cycles in the 'Balami' variety of Ficus sycomorus, the sycomore, were studied in connection with the sycophilous wasps Svcophaga sycomori and Apocrypta longitarsus. In the coastal plain of Israel the syconia of Ficus sycomorus may follow either of two developmental courses: most of the syconia swell rapidly, when still at an early stage of anthesis, thus producing genuinely 'vegetative parthenocarpic' fruit; some of them, however, become inhabited by Svcophaga svcomori and then follow a full developmental course, ultimately producing 'stimulative parthenocarpic' fruit. The latter type of fruit is seedless, as is the former, and the stimulus for its development is provided by the wasps ovipositing in the flower ovaries and by the subsequent activity of the wasp larvae within. In order to ascertain the reason for the absence of seeds, controlled pollination experiments were conducted. These experiments, and also systematic observations on the sequence of flowering generations throughout the year, have yielded information on seed-setting and the interrelations between the sycomore and its wasps.

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SUMMARYThe constituents of a normal monoecious fig, namely the male and female flowers, the shortand long-styled female flowers and the male and feinale wasp galls, are arranged in deflnite spatial and numerical relations. The normal development of the syconium depends on a balance of these difl^erent elements. Occasionally various types of aberrant figs are found in nature, differing from normal figs in development and in flnal structure. These are purely gall figs, seed figs and male wasp or female wasp figs. Such abnormal figs were obtained experimentally by introducing specially treated female wasps into receptive young syconia at the receptive B phase.

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