554 SUMMARY OF CURRENT RESEARCHES RELATING TO 



accumulation of cytoplasm about it to form the egg-cell. From 1 to 

 3 other nuclei are found near the egg-nucleus, and these may show a 

 more or less regular aggregation of cytoplasm about them, and may 

 possibly be the equivalents of the synergids. They take no part in 

 inrpregnation. Several (usually eight) nuclei fuse to form the endo- 

 sperm nuclei, and are the homologues of the polar nuclei of typical 

 Angiosperms. The embryo remains very small, and shows no differ- 

 entiation when the seed is ripe. The divisions of the endosperm nuclei 

 are always accompanied by the formation of cell-walls. The bard coat 

 of the fruit is mainly formed from the innermost layer of cells of the 

 pericarp. The author regards these phenomena as confirming the view 

 that the fusion of the polar nuclei in typical Angiosperms is in no sense 

 a sexual process. 



In Peperomia, according to the author, we have the most primitive 

 type of Angiosperms yet described. As to its systematic position, it 

 cannot be separated from the other Piperacese, but it shows several 

 significant resemblances to the lower Monocotyledons, especially to the 

 Araceae. 



Cross-Pollination and Self-Pollination. — Dr. W. Taliew* finds in 

 Vicia pannonica and V. striata a similar contrivance for promoting the 

 carriage of pollen by insects to that which exists in other Papilionaceaa. 



J. Eompel and R. Stager f discuss the mode of pollination of Vic- 

 toria regia, which is not at present accurately known. It is in all pro- 

 bability effected by beetles. 



O. Kirchner ^ records observations on the mode of pollination of 

 upwards of 70 European plants. The following may be noted as among 

 the more interesting : — Allium ocliroleucum affords the first recorded ex- 

 ample of gynodioecism in the genus. In Serapias longipetala there is 

 no possibility of spontaneous autogamy, although the flowers are destitute 

 of nectar. Montia rivularis presents points of structure which greatly 

 favour spontaneous autogamy. In Silene Elizabethse the 5 outer and 

 longer stamens mature before the 5 inner and shorter ones ; and although 

 proterandrous, autogamy is at least not impossible. In Polycarpon 

 tetraphyllum and Illecebrum verticillatum the flowers do not always re- 

 main closed, as has been stated. In Lunaria rediviva spontaneous 

 autogamy appears unavoidable, although the flower is very fragrant. In 

 Gapparis spinosa it appears scarcely possible. Of the 47 species of 

 Saxifraga belonging to the German flora, 27 are proterandrous, 8 pro- 

 terogynous, and 8 doubtful. Of the 15 German species of Linum, 10 

 are heterostylic, and 5 homostylic. In Hibiscus trionum, a peculiar 

 bending downwards of the style ensures autogamy. In Hypericum 

 Androssemum, although homogamous, autogamy appears to be impossible. 

 Daphne Laureola is proterogynous, and autogamy scarcely possible. D. 

 Blagayana appears, on the other hand, to be adapted to autogamy by 

 homogamy, although strongly scented. In Orlaya platycarpos autogamy 

 can take place readily. 



* Beih. z. Bot. Centralbl., x. (1901) pp. 139-40. 



t Natur u. OttVnbarung, xlvi. (1900) pp. 449-57, 628-9. See Bot. Centralbl., 

 Ixxxvi. (1901) pp. 59, 60. 



X Jahr-Heft. Ver. vaterl. Naturk. Wurttemberg, lvi. (1900) pp. 347-84; and lvii. 

 (1901) pp. 1-42. See Bot. Centralbl., Ixxxvi. (1901) p. 396. 



