ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
643 
Canal-Cells in Cycas.* — Prof. S. Ikeno contests tlie statement made 
by previous observers that canal-cells are entirely wanting in the 
archegone of the Cycadeae. In Gycas revoluta the central cell of the 
archegone closely resembles that iu Coniferse, being prolonged in its 
upper part into a long beak. Some days before impregnation, the 
nucleus is found at the apex of this beak. Immediately after the di- 
vision of this nucleus, the upper and smaller canal-cell separates com- 
pletely from the larger and lower oosphere, but soon becomes completely 
disorganised. 
Action of Salts on Vegetable Tissues.-]* — M. Ch. Dassonville has 
experimented on the effect on the growth of plants (chiefly lupin), of 
Knop’s salt (1 gr. calcium nitrate, 0*25 gr. potassium jfliosphate, 0*25 gr. 
potassium nitrate, 0 * 25 gr. magnesium sulphate, a trace of iron peroxide 
phosphate, in 1 litre water). It increases the number and size of the 
vessels and retards their lignification. It determines the formation of 
a closed ring of xylem, both in the stem and in the root. It thickens 
the inner face of the pericycle, and decreases the lignification of the 
endoderm of the root. It increases the size of the cells of the pith and 
of the cortex. Similar results were obtained with rye. With regard to 
the influence of the different salts, — the magnesium sulphate appears at 
first to retard the development of the plant, but afterwards becomes 
indispensable ; the nitrates of calcium and potassium are useful in the 
early stages, but later appear to become inefficacious ; potassium 
phosphate is absolutely indispensable. 
(4) Structure of Organs. 
Euthymorphosis.J — Prof. T. Caruel applies this term to the rapid 
succession of members of different form on the same stem, such as differ- 
ent forms of leaves ; the sudden appearance of buds differing from those 
previously formed ; and the polymorphism of flowers. In opposition to 
the theory of natural selection, he attributes this law to a force inherent 
in the organism. 
Structure of Alpine Plants.§ — Herr W. von Lazniewski points out 
that it is impossible to lay down any general laws respecting the bio- 
logical adaptations of alpine plants, seeing that the conditions in which 
they grow vary so greatly, even within the same genus, as e.g. in Saxi- 
fraga. The following types may be distinguished : — (1) Plants with 
leaf-rosettes, often forming dense cushions : many Cruciferse and Caryo- 
phyllacese, species of Primula , Androsace , Saxifraga , &c. ; the position 
and direction of the palisade-cells are arranged so as to enable the light 
to penetrate the leaves as much as possible. (2) Plants whose leaves 
are rolled up at the margin : Erica carnea, Empetrum nigrum , Azalea 
procumbens. (3) Plants with deposits of mucilage in the mesophyll or 
epiderm : Primula Auricula, P. minima, Gentiana acaulis, G. imbricata ; 
the mucilage acts as a protection against excessive transpiration. (4) 
Plants with a covering of hairs : Potentilla nitida, Leontopodium alpinum, 
* Bot. Centralbl., lxvii. (1896) pp. 193-4. 
f Rev. Gen. de Bot. (Bonnier), viii. (1896) pp. 284-94, 326-36 (4 pis. and 2 figs.). 
X Bull. Soc. Bot. Ital., iii. (1896) pp. 84-5. 
§ Flora, lxxxii. (1896) pp. 224-67 (35 figs.). 
