ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
63 
and then put out lateral branches of a higher order which display similar 
properties. 
Epinasty and Hyponasty.^ — From observations made on a number 
of plants growing either naturally in the soil or in a clinostat, Prof. 
S. H. Vines has arrived at the conclusion that the changes in the 
position of the leaves of growing plants are due entirely neither to the 
action of light nor to that of gravitation, but are epinastic and hypo- 
nastic, i. e. are the result of an inherent tendency of one or the other 
surface of dorsiventral organs to grow faster than the other surface. 
The tendency of epinasty, or the more rapid growth of the upper surface, 
in leaves, is to bring the lamina into the vertical plane, the apex being 
directed downwards ; while the tendency of hyponasty, or the more 
rapid growth of the under surface, is to raise the member so that its 
long axis approaches the vertical. The changes in the position of the 
leaves of Mimosa, and that of the petals of flowers on variations in 
temperature, he attributes in the same way to the action of epinasty and 
hyponasty acting in conjunction with light 
Ascent of Sap in Woody Stems.f — Dr. F. Fankhauser gives fresh 
proof of the accepted theory that the ascent of sap takes place chiefly 
in the xylem of the vascular bundles, and principally in its vessels, from 
which it is distributed to the parenchyme ; to a less extent through the 
epiderm and supporting tissue. He adopts Sachs’s imbibition-theory, 
and considers that neither root-pressure nor transpiration is necessary 
to account for the elevation of the sap. 
The same principles are further applied t to explain the large quantity 
of water found in the endosperm of grasses, especially of barley. 
Conduction of Water. § — After a resume of the results of the most 
recent investigations by others, Herr T. Bokorny describes a fresh series 
of experiments with a view to determine the tissue through which the 
ascent of sap takes place in woody plants. The general conclusion 
arrived at is that this is by no means constant, though the conduction 
takes place chiefly through the vascular bundles, both in woody plants 
with a closed woody mass, and in those in which the vascular bundles 
are distributed over a transverse section. In certain plants the collen- 
chyme and the sclerenchyme and even the epiderm, may take part in 
this function. In the bundles themselves, the chief part is played by 
the xylem, though the movement takes place also, to a certain extent, 
through the thin-walled bast. In plants which have no true vascular 
bundles, such as mosses, the ascent takes place through the central 
bundle of the stem. 
Conduction of Water in Wood.|| — Keplying to Hartig’s criticisms,^ 
Herr A. Wider adduces fresh arguments in favour of his view that the 
conduction of water does not take place indiflerently through the whole 
* Ann. of Bot., iii, (1889) pp- 415-37 (2 figs.). 
t ‘Beitr. z. Erklarimg d. Saftleitung,’ 14 pp. and 1 pi., Bern, 1889. See Bot 
Centralbl., xl. (1889) p. 114. 
X Allg. Zeitschr. f. Biei-hrauerei u. Malzfabrikation, 1889,4 pp. and 2 pis. See 
t. c., p. 115. § Biol. Centralbl., ix. (1889) pp. 289-303, 321-7. 
11 Ber. Deutscb. Bot. Gesell., vii. (1889) pp. 204-12. Cf. this Journal, 1889, 
p. 251. ^ Cf. this Journal, 1889, p. 90. 
