ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 823 



embryo remains permanently exceedingly rudimentary, consisting, in 

 perfectly ripe seeds, of at most four, sometimes of only two or three 

 cells, and often of only one. The seeds will frequently attain their 

 full sizo without developing any embryo-sac. 



Fall of Branches of the White Poplar.* — When a large number 

 of trees grow in close proximity, they in general lose their lower 

 branches, the upper branches only growing and flourishing. M. Leclerc 

 du Sablon has observed that, in the case of the white poplar, this 

 loss of the lower branches is brought about by a process somewhat 

 similar to that which causes the fall of leaves. A layer of tissue in 

 close proximity to the trunk becomes strongly lignified. There is, 

 however, no generating layer formed in the bark, as in the case of 

 leaves ; but simply lignification of the walls in the layers of cells 

 above the corky layer. 



First Vessels in the Leaves of Crucifers.f — M. A. Trecul 

 describes the order of appearance of the vessels in the leaves of tho 

 cabbage and of some other crucifers, which is of tho kind that he terms 

 mixed, i.e. in basipetal succession in tho lower, basifugal in tho 

 upper part of the leaf. 



Structure of the Leaves of Water-lilies.]: — M. J. Costantin finds 

 in Nymphsea rubra two kinds of leaves, one entirely submerged, which 

 possess no stomata at all, the other floating, which have stomata on 

 their upper surface only. The former kind are thin,' transparent, 

 arrow-shaped, and well adapted to be swayed by currents of water. 

 In Nupkar lutea there are also two kinds of leaves, but they grow 

 on different plants. When the yellow water-lily grows in very 

 deep water, its leaves are all thin, transparent, with very flexible 

 petioles, and entirely destitute of stomata. Tho difference between 

 the two kinds of leaves is manifested very early, the stomata being 

 developed on those which tire destined ultimately to float, while they 

 are still rolled up and entirely submerged. 



Tendrils of Cuciirbitaceae.§ — M. P. Duchartre points out that in 

 tho Cucurbitaceaa there are tendrils of two kinds as respects their 

 development, viz. (1) tendrils which are coiled from the very earliest 

 period of their formation, and which complete their coiling while still 

 in the bud-condition ; and (2) tendrils which arc straight while in 

 the bud-condition. This distinction does not correspond in any way 

 to any natural system of classification of the members of the order 

 into sub-orders or even into genera. 



Glands of Bunias Erucago.|| — Sig. P. Pichi has examined the red 

 spots on the stem of this plant, which he finds to be composed of 

 glandular structures of the nature of emergences. They produce a 

 colourless fluid with an acid reaction, but the author was unable to 

 ascertain that they were visited by insects. 



* Bull. Soc. Bot. France, xxxiii. (1S86) pp. 25-7. 



t Comptes Rendus, cii. (1SSG) pp. 575-81. 



\ Bull. Soc. Bot. France, xxxii (18S5) Scss. Extraoid., pp. xv.-xix. 



§ Ibid., xxxiii. (18S6) pp. 10-19 (1 fig.). 



|| Nuov. Giorn. Uot. Ital., xviii. (1886) pp. 5-9 (1 pi.). 



