440 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
ing effect on growth of pure C0 2 appears to be positive, not merely 
negative from the absence of oxygen. The turgor-pressure of growing 
pollen-tubes is decreased, while the extensibility of the cell-wall is 
increased ; but if the action lasts only for a limited time there is no 
permanently injurious effect. In other cases the cell-wall is ruptured. 
A small proportion of C0 2 — 1-10 per cent. — promotes growth, but 
does not increase the turgor-pressure. The different parts of plants 
exhibit a very different degree of sensitiveness to the action of C0 2 , and 
the living cell can, to a certain extent, adapt itself to resist its injurious 
effects. 
Physiology of Woody Plants.* — Experiments made by Herr K. G. 
Lutz on the beech showed that, between October 10th and November 10th, 
a large transference of starch takes place from the interior of the trunk 
to the last annual ring and to the bark, and that this starch is then 
transformed into a fatty oil and glucose. If the leaves were removed, 
the succeeding growth was entirely destitute of vessels, the tree used up 
its reserve food-material for the formation of new buds. When pines 
were stripped of their leaves, very few buds were produced ; if this was 
done in the spring or early summer, the reserve-materials were used up 
until the close of the growing period; no increase in thickness took 
place if no buds were formed. 
y General. 
Hornell’s Microscopical Studies in Botany. f — The most recent part 
of this publication contains photomicrographs, with descriptive letter- 
press, of the following preparations : — Longitudinal and transverse 
sections through underground bud of Equisetum maximum; transverse 
sections through leaf-bud of ash and elm ; cuticle of Araucaria imbricata ; 
longitudinal section through node of sycamore; longitudinal section 
through flower- bud of peony ; transverse section through fruit of date- 
palm ; transverse sections through flower-bud of Iris germanica and 
Lilium croceum. 
Mimicry of Pebbles by Beans.j' — Mr. W. K. Sherzer describes 
the remarkable resemblance of the seeds of the £< Philippine Island 
Bean ” to the pebbles among which they fall. It is exceedingly difficult 
to distinguish them, the resemblance extending to their shape, size, 
colour, lustre, hardness, and stratification. They appear also to be 
uninjured by soaking in sea-water. 
B. CRYPTO G AMI A. 
Cryptogamia Vascularia. 
Embryogeny of Angiopteris and Marattia.§ — Dr. H. F. Jonkman 
has followed out the formation and development of the embryo in these 
two genera, which he considers establishes a closer relationship of the 
Marattiace® than of the other Pteridophyta to the Hepatic®, while 
exhibiting some remarkable points of affinity with Phanerogams. 
* Beitr. z. wiss. Bot. (Fiinfstuck), i. (1895) pp.1-80. _ 
f Yol. i. pt. 2, 14 pp. and 5 pis., Jersej 7 , Hornell. 
j Bot. Gazette, sxi. (1896) pp. 235-6. 
§ Bot. Centralbl., lxvi. (1896) pp. 49-52. Cf. this Journal, 1894, p. 481. 
