Recueil des travaux botaniques néerlandais . ialtheory, mentioned in the introduction gives a possibilitywhich is not to be rejected, but not to be wholly acceptedeither. More convincing proofs must be recorded than onlya few resemblances as those between Lagenostoma andTelangium, observed by Miss Benson (15), and before her by Lan g (84) between themicro- and mega-sporanges ofStangeria. I shall only mentionsome cases which may supportthis theory. It occurs occasionally that twonucelli are présent in one integu-ment, which is observed for Thuya(49, p. 210), and which I hâvefound twice in Ginkg
Recueil des travaux botaniques néerlandais . ialtheory, mentioned in the introduction gives a possibilitywhich is not to be rejected, but not to be wholly acceptedeither. More convincing proofs must be recorded than onlya few resemblances as those between Lagenostoma andTelangium, observed by Miss Benson (15), and before her by Lan g (84) between themicro- and mega-sporanges ofStangeria. I shall only mentionsome cases which may supportthis theory. It occurs occasionally that twonucelli are présent in one integu-ment, which is observed for Thuya(49, p. 210), and which I hâvefound twice in Ginkgo (fig. 12).Hère it is possible that moreFig. 12. Ginkgo biloba; two sporanges of the original sorus, in casu two, hâve developed, andthe others, remaining stérile hâveformed the integument. This isnot a convincing argument at ail,but this may be supplied, when more of thèse cases arepublished. In order to solve in short the questions put in thebeginning, my conclusions are as follows: 1. The integuments of the Pteridosperms and Gym-. nucelli within one integumentsarcotesta with mucilage ca-nals, sclcrotesta dotted stron-gest. a. lysigen cavity. 310 nosperms are homologous and most probably also withthose of the Angiosperms. 2. The integuments are not homolcgous with theindusia of the Ferns and Lycopods, and the first namemay not be used for thèse organs. 3. The integument is originally composed of units. 4. The value of the units is not yet quite certain. LIST OF LITERATURE. 1. Affourtit, M. F. A and La Rivière, H. C. C, Onthe ribbing of the sceds of Ginkgo. — Ann. Bot. Vol. 29. 1915. 2. Arber, Agnes., On the structure of the Palaeozoic seedMitrospetmum Compressttm Will. — Ann, Bot. Vol. 24, 1910. 3. Arber, Agnes., A note on Trigonocarpus.—Ann. 28. 1914. 4. Arber, Agnes., A revision of the seed impressions ofthe British Goal Measures. ^ Ann. Bot. Vol. 28. 1914. 5. Arber, E. A. Newell, and Parkin, J., On the originof Angiosperms. — Journ. Linn. Soc. L
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