480 SUMMARY OF CURRENT RESEARCHES RELATING TO 



bably all the various forms of crystal in Datura stramonium belong to 

 the monoclinic system. 



Lithium in Plants.* — Herr E. Tschermak finds lithium to be a much 

 more widely diffused substance in the vegetable kingdom than has hither- 

 to been supposed. He detected it only in the leaves, the finer portions 

 of the stem, the flower, and the fruit. 



(3) Structure of Tissues. 



Vascular System in Ricinus.t — Miss Edith Chick has undertaken 



an examination of the vascular system of the hypocotyl and embryo of 



the castor-oil plant, with a view to determine the origin of the (eight) 



bundles in the young hypocotyl which are ultimately united by a band 



of interfascicular cambium. They were found always to result from 



the splitting of four original stem-bundles. Further details are given 



with regard to the branching and distribution of the bundles in the 



embryo, hypocotyl, and epicotyl ; and the authoress emphasises the 



primary importance of the bundle as an anatomical unit in the stem of 



typical Angiosperms, and the dependence of the stele on the close lateral 



approximation of the bundles for continuity of the tissues of external 



conjunctive, since the latter are primarily arranged in relation to the 



separate bundles. 



C4J Structure of Organs. 



Structure of Flower of Dicentra.J — Prof. E. Martel discusses in 

 detail the floral structure of Dicentra spectabilis, and comes to the con- 

 clusion that the carpels of Hypecoum do not correspond to those of the 

 Furnariaceae and the Cruciferae, but that, on the contrary, the antero- 

 posterior stamens of Hypecoum are homologous to the antero-posterior 

 carpels in those two orders. 



Style and Stigma of Compositae.§ — M. F. Guegen has studied the 

 structure of these organs in a large number of specie6 belonging to the 

 different tribes of Composite. As a general conclusion he states that 

 their variations are not of systematic value in characterising the tribes 

 or genera. The conducting tissue of the style presents great uniformity 

 of structure. It is always composed of collenchymatous tissue, which 

 guides the pollen-tube in its course to the ovary. The arrangement of 

 the xylem of the fibrovascular system is also very uniform ; that of the 

 phloem is subject to great variation, except in the Cynareae and Labia- 

 tiflorae. The style is the organ which, in Composite, least frequently 

 contains a secreting system ; but when laticiferous cells or tubes occur 

 in it, they are more fully developed than in any other organ of the plant. 

 The styles of the central and of the peripheral parls of the capitule 

 often display a dimorphism in this respect, as in the Anthemideaa and 

 Calendulese. 



Heterocarpy of the Composite. || — Sig. L. Nicotra describes in great 

 detail the size, colour, form, &c, of the fruit, and the development of 



* Zeit. Laudw. Vers.-Wesen Oesterreich, ii. pp. 560-72. See Journ. Cheui. Soc, 

 1900, Abstr. ii. p. 235. 



t Proc. Eoy. Soc. Edinburgh, xxii. (1900) pp. 652-72 (3 pis.). 



X Mem. Accad. Soi. Torino, xlix.'(1900) pp. 55-72 (3 pis.). Cf. this Journal, 

 1899, p. 504. § Bull. Soc. Bot. Fiance, xlvii. (1900) pp. 51-70 (41 figs.). 



|| 'Delia eteroenrpia, segnatameute nelle Sinauteree,' Sassari, 1899. See Bot. 

 Centralbl., lxxxii (1900) p. 33]. 



