NOTES AND ABSTRACTS. 



233 



surface." The figures show the style of growth and methods of reproduc- 

 tion of these plants very well. — G. S. S. 



Platy cerium of the Congo. By Emile Laurent (Rev. Hort. 

 Beige, xxviii. No. 4, p. 85, and photo). — This describes two species, P. 

 Stemmaria, Dev., or P. (cthiopicum, Hook., and P. angolense, Welw. 



G. H. 



Podalyriae, Seeds Of (Beih. Bot. Cent. xiv. ht. 1, p. 20; plate). — 

 Herr Lindinger gives a very interesting and valuable account of the 

 structure and biology of the seed in this group. He shows that the 

 " strophiola " of Bentham and Hooker includes both a caruncle proper 

 and also a ring-like bulging of the testa as in Baptisia and Piptanthus. 

 The seed consists of the following layers : On the outside (1) cuticular 

 layers (not always present) ; (2) a palisade layer of closely packed, 

 thickened, and usually empty cells ; (3) "hourglass " cells in one or two 

 layers ; (4) the mucilaginous endosperm (" schleimendosperm ") ; and (5) 

 embryo. 



By germinating seeds deprived of the endosperm and testa, he showed 

 that the mucilage does not appreciably assist in nourishing the embryo. 

 He then points out that its thickness varies with the thickness of the 

 palisade layer, and that both are especially well developed in the West 

 Australian seeds (dry hot climate). He then shows that its proper 

 function is to break open the hard and massive testa by absorbing water 

 at the same time protecting the embryo. About G3 species belonging to 

 22 genera are described in detail, and the germination was studied in the 

 case of 35 species. — G. F. S.-E. 



Polemonium confertum. By E. Wocke {Die Gart. p. 356, April 

 25, 1903). — An illustrated article on this lovely North American High 

 Alpine. Raised from seed, it flowers the following year ; planted in a 

 dry exposed position on the rockery, it remains dwarf. The flowers are 

 of a deep blue. The form pidchcrrimum hardly differs from it, but P. 

 confertum var. melitum, a coarser plant with creamy- white flowers, looks 

 almost like a distinct species. — G. R. 



Pollen, Action of, under Stimulus of Alien Stigmas {Bev. 



Hort. March 1, 1903, pp. 99, 100).— M. Pierre-Paul Richer reports 

 result of investigations in this direction to the Academie des Sciences. 

 The emission of the pollen-tube is stimulated normally by the secretions 

 of the stigma, but in some cases the pollen will germinate in pure water 

 or water slightly sweetened. M. Molesch had already ascertained that 

 the pollen of some species which would not germinate in pure water does 

 so if a stigma of the same species be placed in the water. M. Richer 

 therefore conceived the idea of inducing germination by placing in the 

 water stigmas of other species or even genera, and found that Scilla 

 nutans pollen germinated equally readily in the presence of stigmas of S. 

 eampanulata as with its own stigmas. Rhododendron ponticum responded 

 to Kalmia angustifolia and Erica cinerea. Verbascum Thapsus, V. 

 floccosum, and V. Lychnitis responded to each other fully, and Linaria 

 vulgaris to Antirrhinum majus. Verbascum Thapsus responded in a 



