ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 821 



gives birtli to the bark, while the lower layers are more or less 

 thickened in a collenchymatous manner. Its uniform function is to 

 form a parenchymatous layer of sufficient thickness between the 

 endoderm and tho bundles. The lignification and formation of col- 

 lcnchynia in this layer are characters of no taxonomic value, since 

 they depend on the action of external and internal media, and may 

 vary even in different parts of the same stem. 



Fibrovascular Bundles of Piperaceae.* — M. F. Debray givos an 

 exhaustive description of the anatomical structure and course of tho 

 fibrovascular bundles in tho Piperaceaa, which ho divides into three 

 groups, viz. (1) Saururea), with 5 genera and 7 species; (2) Pipereaa, 

 with 2 genera, Chavica with 5, and Piper (including Artanthe) with 

 about 600 species, and (3) Peperomiea3, with 2 genera, Peperomia 

 and Verhuellia, and about 400 species. The fibrovascular bundles in 

 both stem and leaves of each division are treated of; also the axillary 

 buds, the " apposifoliar " stipulos, and the scape. 



Fibrovascular Bundles and Secreting Apparatus of the Nym- 

 phaeacese.j — From the point of view of tho structure of the fibro- 

 vascular bundles, M. P. Van Tieghem distributes the genera of 

 Nymphaeacea3 into four groups, as follows, viz. : — 1. Cabombese. 

 Bundles of the stem and petiole all direct and coalescent in pairs 

 by their xylem ; those of the pedicel all direct and free (Brasenia, 

 Cabomba). 2. Nupharese. Bundles of the stem, petiole^ and pedicel 

 all direct and frco (Nuphar, Barclaya). 3. Nymplieeese. Bundles of 

 the stem all direct and free ; those of the petiole and pedicel of 

 two kinds ; somo direct and free, others double, formed of one direct 

 and one inverse bundle united by their xylem (Nymplisea, Euryale, 

 Victoria). 4. Nelumbese. Bundles of the stem, petiole and pedicel 

 of two kinds, some direct, others inverse, all free (Nelumbo). 



All the Nympha3acea3 are provided with laticiferous cells with thin 

 and suberous membrane, and which arc coloured by fuchsinc. Their 

 character varies as follows in the four groups: — 1. Cabombese, of 

 ordinary form, superposed in long threads; no oxaliferous cells. 



2. Nupharese, of ordinary form, isolated ; no oxaliferous cells. 



3. Nymplisecse. Fusiform and very long, isolated ; no oxaliferous 

 cells. 4. Nelumbese. Of ordinary form, isolated; oxaliforous cells 

 in spheroidal groups. 



The difference exhibited in these points by the Nclumbea), as con- 

 trasted with the other three tribes, is accompanied also by the presence 

 of a sclcrenchymatous sheath to the bundles, absent from the others, 

 by the absence of both endosperm and perisperm, and the entire sup- 

 pression of the radicle in germination. Contrary to the opinion of 

 Bcntham and Hooker, M. Van Tieghem considers that these differ- 

 ences represent a wide genetic separation of the Nclumbea) from the 

 typical Nymphasaceai. 



* Debray, F., ' Etude comparative dea caracterea anatomiques ct du parcoura 

 dea faisceaux fibro-vaaculairea dea Piperaeees,' 107 pp. and 6 pis., Paris, 188G. 

 See Bot, Centralbl., xxvi (1886) p. 136. 



t Bull. Soc. Lot. Fiance, xxxiii. (1886) pp. 72-6. Cf. this Journal, iv. (1881) 

 pp. 767, 770 ; v. (1885) p. 823 



