ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 917 



Epidermal Tissue of the Root.* — 0. Juel finds, iu several water 

 plants, in addition to the ordinary elongated cells of the epidermis of 

 the germinating root, other nearly cubical cells, from which spring 

 root-hairs. The hypodermal layer of cells of the root may have the 

 side walls of the elongated cells either parallel or convex with respect 

 to one another. The short cells vary in width, and may be narrower 

 or broader than the elongated cells ; and looked at from the surface 

 their outline may be circular, elliptical, square, or rectangular. The 

 walls of the two kinds of cells appear to be of about equal thickness. 



Lenticels.f— H. Klebahn does not find the absolute distinction, 

 previously J insisted on, between the closing layer and the intermediate 

 layer in lenticels. The whole tissue outside the renewing layer he 

 includes under the term intermediate substance ; and this may occur 

 in two modifications : — (1) It consists only of cork-cells, which leave 

 intercellular spaces between them, which Klebahn terms pore-corh ; 

 (2) it consists of alternate suberized and non-suberized layers, while 

 he calls the separate unsuberized layers cTioriplielloid. The cells of 

 this tissue proceed centripetally from the renewing layer, and the 

 cell-walls are either lignified or consist of pure cellulose ; their 

 thickness varies. All lenticels belong to one or other of these types. 



Klebahn finds lenticels on the aerial roots of PMlodendron per- 

 tusum, resembling those of the Marattiaceae, and consisting of dense 

 layers without intercellular spaces, the loose intermediate cells being 

 suberized. He also finds lenticels on the medullary rays in Vitis and 

 Cleviatts. 



The chief function of lenticels is undoubtedly to facilitate the 

 entrance of gases through the otherwise almost impermeable outer 

 layers of the cortex. 



Torsion of Twining Stems.§— F. G. Kohl believes he has esta- 

 blished the fact, stated by Mohl, but doubted by Darwin and de Vries 

 of the sensitiveness of a twining stem to permanent lateral contact. He 

 does not agree with Schwcndcner in regarding antidromous torsion 

 only as normal, homodromous torsion occurring normally with thin 

 supports, and then changing to antidromous when the support 

 exceeds a certain thickness, or when the friction between the climbing 

 stem and the su])port is increased. 



Structure and Growth of Palms. || — Branner gives some interesting 

 results of original and apparently careful studies of the mode of 

 growth of many palms. 



The essential points of difference between these results and those 

 obtained by other observers relate to the development of the fronds. 



• SB. Bot. Gesell. Stockholm, Feb. 27, 1884. See Bot. Ceutralbl xviii 

 (1884) p. 282. ■' 



t JenaJBch. Zeitschr. f. Naturwiss., x. (1884). See Bot. Centralbl xviii 

 (1884) p. 28*;. ' 



X See ill 18 Journal, ante, p. 78. 



§ Pririgflheim's .Jaliib. f. Wiss. Bot,, xv. (1884) pp. 327-CO (1 pi.). 



II Proc. Amer. Phil. Soc., 18th April, 18-S4. Amer. Journ. Sci., xxviii 0884) 

 pj). 230-40. ^ 



