G08 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Tubercles on the Roots of Leguminosae. — M. P. Van Tieghcra * 

 tliscussos tlio origin, structure, and morphological nature of the radical 

 tubercles of Leguminosre. Like the rootlets, they originate in tho 

 pericycle of the mother-root, oi)posite the woody bundles if there are 

 more than two, and on each side of them if there are less tJian two. At 

 the same time the endoderm, and sometimes also several of tho internal 

 cortical layers, increase, and their cells divide so as to envelope tho 

 rootlet. By their origin, and by their disposition, radical tubercles 

 may be said to be only rootlets that have enlarged. Sometimes the 

 tubercles possess two, three, or four distinct central cylinders inserted 

 the one above tho other on i)oints on the central cylinder of the mother- 

 root, opposite the same woody bundle. In this case tho tubercle may 

 be said to be formed from a compound rootlet. 



Sig. P. Pichi t regards tho Y-shaped bodies found in the tubercles 

 of the roots of MeUlotus alba as probably si^ores. He describes also tho 

 occui-rence of hyphas in the corresponding structures of a large number 

 of species belonging to the LeguminosfC. 



Leaves of Bupleurum.:]: — Herr P. Klausch classifies the leaves of the 

 various species of this genus of Umbellifera) under three heads : — grass ■ 

 like ; elliiitic ; and those with reticulate venation ; in addition to the 

 monotypic B, di [forme : the special form of leaf being adai^ted to the 

 external conditions of climate and habitat of the species. In many cases 

 the epidermis of the two surfaces of the leaf is quite alike, the internal 

 structure of the leaf bearing a striking resemblance to those of Mono- 

 cotyledons. 



Anatomical Structure of the Leaves of Orchide8e.§ — Dr. M. Mobius 

 discusses the structure of the leaves in difterent genera of Orchidea), and 

 the bearing of the characters thus obtained on the division of the order 

 into tribes as proposed by Pfitzer. He finds in his observations a 

 support in the general way for the classification proposed. The charac- 

 ters to which his observations chiefly refer are : the degree of cuticu- 

 larization of the epidermis, and the presence or absence of trichomic 

 structures ; the presence or absence of hypoderma and of scleren- 

 chymatous bundles or fibres ; the degree of development of the bast in 

 the vascular bundles ; the differentiation of the epidermis ; and the 

 presence or absence of stomata on the two sides of the leaf, &c. 



Influence of Climate on the Cuticularization and Thickening- of the 

 Leaves of some Coniferae. II — Herr F. Noack finds, from observations 

 on the leaves of a number of Conifers, chiefly species of Pinus and 

 Picea, that they owe their great power of resistance to the eflfects of 

 climate, partly, like those of other evergreen plants, to the extraordinarily 

 strong cuticularization and thickening of the walls of the epidermis ; 

 partly also to the lignification of larger or smaller portions of the cell- 

 ■walls. In Picea various degrees of this lignification are exhibited, 

 increasing with the increase of latitude in which the trees grow, or with 

 the height above the sea-level. 



* Bull. Soc. Bot. France, xxxv. (1888) pp. 105-9, 



t Atti Soc. Tosc. Sci. Nat., vi. (1888) pp. 45-7. Cf. this Journal, ante, p. 251. 

 X Klausch, P., ' Ueb. d. Morphol. u. Anat. d. Blatter v. Bupleurum,' 30 pp. and 

 2 pis., Leipzig, 1887. See Bot. Centralbl., xxxiv. (1888) p. 169. 



§ Pringsheiin's Jahrb. f. Wiss, Bot., xviii. (1887) pp. 530-607 (4 pis.). 

 II Ibid., pp. 519-29 (1 pi.). 



