882 SUMMARY OF CURRENT RESEARCHES RELATING TO 



tissue: — (1) the sclerencliymatous strings wliicli accompany the 

 vascular bundles; (2) tissues of various kinds distinct from the 

 vascular bundles. Some of these form the hardening layer, while 

 others do not. The venation or distribution of the finer vascular 

 bundles in the fruit of Eanunculaceje also shows a number of varia- 

 tions. 



Anatomy of the Female Inflorescence of Dioon edule.* — Sig. G. 

 Cugini furnishes a useful contribution to our knowledge of the repro- 

 ductive organs of Gymnosperms. The axis of the female inflorescence 

 of Dioon edule is composed of a nearly homogeneous parenchyma 

 through which run the numerous gum-canals characteristic of the 

 Cycadefe, in a longitudinal direction, apparently without any order, and 

 branching and anastomosing abundantly. Like the vascular bundles 

 they curve to enter the ovuliferous leaves. They are full of a yellow 

 gum which dries on exposure to the air, and is completely soluble in 

 potash. 



The fibrovascular bundles are arranged in a central cylinder sur- 

 rounded by a circle of smaller bundles ; the xylem and phloem are 

 side by side ; between them is a woody parenchyma. 



The lamina of the ovuliferous leaves has an epidermis composed 

 of tabular cells, the lower surface alone being furnished with a few 

 stomata. Beneath the epidermis is a hypoderma composed of two or 

 three irregular layers of cells, and beneath this a thickish sclerenchy- 

 matous layer. The mesophyll is composed of large cells containing 

 abundance " of starch, and is penetrated by gum-canals and fibro- 

 vascular bundles. 



Each leaf bears two horizontal or pendulous ovules, with a single 

 integument prolonged into a micropylar canal; the nucellus, con- 

 sisting of a single sac, was examined only in an unfertilized condition. 

 From the arrangement of the fibrovascular bundles, the author con- 

 cludes that the ovules are equivalents of lobes of leaves. 



Influence of the Medium on the Structure of Roots.f — As the 

 result of a series of experiments, M. J. Costantin has arrived at the 

 conclusion that when a root developes in the air instead of the soil, 

 the cortex is diminished in mass, while the pith is increased ; the 

 fibrovascular system, both cortical and central, is increased, together 

 with the number of lignified vessels ; and the endoderm-cells are 

 rendered harder and less permeable. When, on the contrary, a root 

 developes in water, the number of air-cavities is increased, both in the 

 cortex and the pith, the latter is diminished in quantity, while the 

 fibrovascular system is reduced. The changes effected by a change 

 of medium of the root are in fact similar to those produced in the 

 stem. 



Structure and Dehiscence of Anthers.^ — M. Leclerc du Sablon 

 repeats in further detail, giving a large number of illustrations, the 



* Nuov. Giorn. Bot. Ital., xvii. (1885) pp. 29-43 (4 pis.). 

 t Ann. Sci. Nat.— Bot., i. (1885) pp. 135-82 (4 pis.). 

 X Ibid., pp. 97-134 (4 pis.). 



