88 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
temperature be lowered ; or, in case the temperature be raised, pro- 
ducing an elongation. Following this mechanical action, a period of 
depressed growth usually follows. The duration of the depression- 
period depends upon the position of the lower temperature-limit and on 
the length of time of exposure to this temperature. The depression is 
regarded as the irritable response to the stimulus furnished by the 
exposure to the low temperature followed by the sudden change to the 
higher degree. The duration of the depression may be increased by 
lowering the minimum temperature-limit and by lengthening the period 
of exposure. An exposure to the lower temperature for less than a 
certain period of time is followed by no noticeable depression. Changes 
of temperature between 18° and 80° C. as extremes seem to be followed 
by turgor-changes only. 
Growth in the Tropics.* * * § — Herr G. Kraus gives measurements of 
the extraordinarily rapid growth of the bamboo in Java. He also shows 
that the same law of growth holds good in the Tropics as in temperate 
climates, that, with regard to the trunks of trees, the increase in diameter 
takes place in the night, an actual decrease being sometimes recorded in 
the day-time. 
Germination of Lodoicea Seychellarum.f — Prof. G. Cuboni records 
an example of the very rare occurrence of the germination of the double 
cocoa-nut of the Seychelles. The hypocotyl ( peziulo cotiledonare ) attained 
the extraordinary length of 70 cm., growing in a perfectly horizontal 
direction. The first foliage-leaf was altogether destitute of lamina. 
Path of the Transpiration Current.^: — Pursuing their investigations 
on this subject, Mr. H. H. Dixon and Dr. J. Joly have endeavoured to 
follow the course of the current by means of precipitates, and also by 
choking the cell-cavity by the introduction of foreign substances. The 
result of the experiments was that the stoppage of the cavity and the 
freedom of the cell-wall were preserved by the use both of gelatin and 
of paraffin. The flagging of the leaves appears to be the more rapid the 
more completely the closure of the cavity is effected. The freedom of the 
cell-cavity seems to be necessary for the rapid transmission of water, 
although a slow current may pass through the wood even when the 
cavities are completely blocked. 
Movement of Gases in Rhizomes.§ — Miss K. E. Golden has investi- 
gated the phenomena connected with the movements of gases in rhizomes, 
which they must enter by diffusion through the epiderm, there being no 
stomates or lenticels through which they can pass. In the cases examined 
there were found to be two sets of movements, a molecular one, when 
the gases are passing through the imperforate epiderm, diffusing through 
the cell-sap or permeating the protoplasm ; and a movement of the masses 
of gases, when they fill the intercellular spaces, vessels, and air-cavities. 
The factor of greatest importance in determining these movements is the 
specific character of the membrane of the epiderm, which varies greatly 
in different plants. 
* Ann. Jard. Bot. Buitenzorg, xii. (1895) pp. 196-21G (2 pis.). 
f Bull. Soc. Bot. Ital., 1895, pp. 123-4. 
t Ann. Bot., ix. (1895) pp. 403-20 (7 figs.). Cf. this Journal, 1895, p. 335. 
§ Proc. Amer. Ass. Adv. Sci., 1894 (1895) pp. 275-82. 
