ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 775 



source of light, but rapidly recovered as if by a rebound as soon as 

 tbe light was removed and the roots of the plant watered. 



Eelation of Heat to the Sexes of Flowers.* — T. Meehan 

 referring to his former communication t as to male flowers entering 

 on active growth at a much lower temperature than the female, 

 exhibited catkins and flowers of the European hazel (Corylus avellana), 

 which, for the first time in several years, had perfected themselves 

 contemporaneously. The past winter had been distinguished by a 

 uniform low temperature the entire season. In other years a few 

 warm days in winter would advance the male flowers so that they 

 would mature weeks before the female flowers opened : hence the 

 females were generally unfertilized, and there were few or no nuts. 

 Under this law, it was evident, amentaceous plants could not abound 

 to any great extent in countries or in localities favourable to bringing 

 forward the male flowers before there was steady warmth enough to 

 advance the female. He thought this was likely to be the reason 

 why so many coniferous trees under culture in the vicinity of 

 Philadelphia bore scarcely any fertile seed in their cones — a fact 

 which had often been remarked in connection especially with the 

 Norway spruce. The male flowers would mature before the female 

 bad advanced far enough to be receptive of the pollen. 



Influence of Light on the Structure of the Leaves of Allium 

 ursinum.J — C. Musset has investigated the truth of the statement 

 that light has an influence on the leaves of certain plants, and finds 

 that, in Allium ursinum, at any rate, there is no change in structure 

 which can be ascribed to the action of light. 



. Effect of Light and Shade on Pine-leaves.§ — E. Mer describes 

 at length the difference in the development of the " needles " of Abies 

 excelsa, according to their position on the tree or the branch, and 

 according to whether the tree stands alone or is closely surrounded 

 by others, depending therefore on the amovmt and the direction of the 

 light which falls on the leaves. 



Movement of Water in Plants.|l — As a contribution towards our 

 knowledge of the causes of the movement of water in plants, 

 J. Dufour has made a series of observations of the relation between 

 the size of the cell-cavity and the thickness of the cell-walls in a 



number of woody plants, with the following approximate results : • 



Sambucus nigra, cell-cavities (without vessels) 16-18-8 per cent., 

 walls of wood-cells, 81 • 2-84 per cent. ; Fagus sylvatica, diameter of 

 vessels 7 '4, cell-cavities 7 "5, xylem-parenchyma 17 "0, cell-walls 

 68*1 per cent.; Hcematoxylon carnpecManwrn, cell-cavities 4 • 8-23 • 0, 

 cell-walls 77-95*2 percent.; Ccesalpinia echinata, cell-cavities 4*2- 

 14-0, cell- walls 86-95-8 per cent.; Alnus incana, cell-cavities 43-5- 



♦ Proc. Acad. Nat. Sci. Philad., 1884, pp. 116-7. 

 t Bee this Journal, iii. (1883) p. 5.32. 

 X Comptes Rendus, xcviii. (1884) pp. 1297-8. 

 § Bnll. Soc. Bot. France, xxx. (1883) pp. 40-50. 



II Arbeit. Bot. Inst. Warzburg, iii. (1884) pp. 36-51 and Arch. Sci. Plivs. et 

 Nat, xi. (1884) p. 15. Cf. tljia Journal, ante, p. 414. 



