ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 583 



composed of carpels, while those of the Araucariacese are true spikes, 

 the bracts of which produce the coalcsceut carpels in their axils. 



The mode of formation of the anthers differs in Gymnosperms 

 and Angiosperms. The type of stamen in the Coniferse and Gnetaceae 

 is derived from that in the Equisetaceae, and more remotely from that 

 in the Ophioglossaceae ; the stamens of Cycadeae corresponding to the 

 more or less peltate type in ferns with sori on the under side, 

 especially in Gleicheniaceas and Marattiacese. 



The anther of Angiosperms is developed from a sporophyll of the 

 Ophioglossaceae, but in a dififerent way from that of Coniferse, viz. 

 from the form in OpMoglossum rather than in Botrychium or Helmin- 

 ihostachjs. The dift'erence between a pollen-sac of Coniferae and a 

 loculus of the anther of Angiosperms, is that the former is homo- 

 logous to a single sporangium, the latter to a row of coalescent 

 marginal sporangia. The normal anther of Angiosperms is also dis- 

 tinguished by the peculiarity of having not two but four loculi, as is 

 clearly shown by the phenomena of phyllody of the stamen. 



Influence of Light and Heat on the Germination of Seeds.* — A 

 fresh series of experiments on this subject, undertaken by A. Cieslar, 

 leads him to the conclusion that the effect of light on the germination 

 of seeds is very complicated, and varies with the species, depending 

 greatly on the amount of reserve food-material in the seed. The rays 

 of different refrangibility also produce different effects. In white 

 and yellow light much greater development takes place than in violet 

 light or in the dark ; and this difference increases with increase of 

 temperature. He believes the effect to be greatly due to a trans- 

 formation of light into heat. The production of substances which 

 cause osmose in seedlings growing in white or yellow light is favour- 

 able to germination, by bringing about increased root-pressure. 

 Seeds with but a small amount of reserve food-material germinate 

 better in light than in darkness ; light promoting not only the 

 penetration of the roots into the soil, but also the copious production 

 of roots. 



A. Ritter von Liebenbergj confirms these conclusions on the 

 whole, and regards the intermittent heat resulting from alternation of 

 day and night as distinctly favourable to the germination of seeds. 



Origin of the Placentas in the Alsinese (Caryophyllese).t — Miss 

 G. Lister, in view of the fact that in Lychnis the first developed ovules 

 are developed along the unattaclied margins of the dissepiments iu 

 the upper unilocular portion of the capsule, the placentas being 

 therefore carpellary, considers that as the capsule in AlsinoiT) is 

 developed on essentially the same plan as tliat of Lychnis, wo are 

 bound to admit that the placentas in the Alsincae, from Scujina apclala, 

 which most resembles Lychnis, to Cerastium triviale which most widely 

 differs from it, are carpellary also. 



♦ Wollny'rt Untcra. aun d. Gcb. dor Agricnltiir-pliysik, vi. (1883). Sfo Bot. 

 CVntnilbl., xviii. (1884) p. i:5. 



t Bot. (J<i.tn.lbl., xviii. (1881) pp. 21-«. 



{ .Joiirn. [.inn. Hoc. Iv*ii«l.-Bot,, xx (1884) pp. 42.'{-'J (4 j.Ih.;. 



