ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
439 
remains rudimentary. If tlie former one is encased so as to hinder 
growth, or is destroyed, then the smaller usually fugacious cotyledon 
takes its place and performs its functions. 
Protrophy.* * * § — Dr. A. Minx claims to have noted for the first time a 
peculiar relationship of growth between the different elements of a lichen, 
to which he gives the name protrophy. It is best exhibited in Biatora 
intumescens. The protroph is at first a lodger but not a guest; even- 
tually it obtains its nourishment through the medium of another lodger, 
viz. a different lichen ; and the protrophy becomes thus an example of a 
very remarkable “ wet-nurse relationship ” ( Ammenverhaltniss ). 
Plasmolysis and Growth of Medullary Tissues.f — According to 
Herr R. Kolkwitz the chemical composition of the solution used for 
plasmolysis influences the intensity of the phenomenon. Temperature 
has a sensible, though very small, effect on the elasticity of membranes. 
The author also shows that superficial growth has no connection with 
turgor, but may in fact take place in opposition to it. 
(3) Irritability. 
Movements of the Leaves of the Marantacese.t — Herr B. Debski 
describes the structure of the motor cushions of the leaves of various 
species of this order, especially belonging to the genera Maranta , 
Ctenanthe, and Calaihea. The movements are nyctitropic, heliotropic, 
and paraheliotropic. They occur not only in the cushions themselves, 
but also in the similar parts of the mid-rib. The lieliotropic movements 
are not connected with growth, since no lengthening, or only a slight 
one, of the cushion could be detected, but are caused by changes in 
turgor, which result in the shortening of the concave side of the cushion. 
The active tissue in this phenomenon is the parenchyme of the concave 
side. 
Irritability of Drosera.§ — From a series of experiments on Drosera 
rotundifolia , Herr C. Correns draws the conclusions that the tentacles 
exhibit no perceptible sensitiveness to changes of temperature, and that 
various salts of calcium possess the property of rendering the leaves 
insensitive to chemical irritation. 
C4) Chemical Changes (including Respiration and Fermentation). 
Action of Carbon Dioxide on the Protoplasm of the Living Cell, t! 
— Herr G. Lopriore describes in detail an apparatus for the purpose of 
testing the action of carbon dioxide on living protoplasm. The material 
experimented on consisted of the staminal hairs of Tradescantia , spores of 
Mucorini, yeast-cells, and the pollen-grains of Angiosperms. The retard- 
* Oesterr. Bot. Zeitschr., xlvi. (1896) pp. 50-2, 88-91. Cf. this Journal. 1893, 
p. 665. 
t Beitr. z. wiss. Bot. (Fiinfstuck), i, (1896). See Bot. Ztg., liv. (1896) 2 t9 Abt., 
p. 151. 
i Anz. Akad. Wiss. Krakau, 1895, pp. 244-59 (34 figs.) (German). 
§ Bot. Ztg., liv. (1896) l te Abt., pp. 21-8. 
|| Jahrb. f. wiss. Bot. (Pfeffer u. Strasburger), xxviii. (1895) pp. 531-626 (2 pis. 
and 3 figs.). 
2 h 2 
