ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
449 
lateral anisophvlly. He regards the phenomenon as generally connected 
with arrangements for the supply of light to the foliage. It is especially 
. frequent in trees and shrubs with large deciduous leaves, and is, there- 
fore, less commonly met with in tropical than in temperate vegetation. 
Lateral anisophylly affords no special advantage to the plant. 
Rain-leaves, Dew-leaves, and Snow-leaves.* — Pursuing his obser- 
vations on the adaptations of leaves to excessive rainfall, Herr J. A. 
Jungner states that, in the Cameroon Mountains, these consist of a 
pendent position of the lamina, smooth surface, an apiculate apex, the 
absence of teeth on the margin, and the presence of a cushion at the base 
■of the lamina, the very short petiole being frequently entirely converted 
into a structure of this kind ; when the leaf is compound each leaflet 
has its own cushion. The object of these cushions appears to be to give 
a certain motility to the leaf or leaflet, by means of which it can 
assume the most favourable position in relation to the external con- 
ditions. 
It is not all the plants growing in rainy climates that have leaves 
■of this description, though they are by far the most common ; the author 
notes also the occurrence of what he calls “ Dew- leaves” and “ Snow- 
leaves.” The former are erect and usually obovate in shape ; this form 
is especially adapted to utilise the dew, and to protect the leaf against 
the injurious effects of excessive light. 
Hanging Foliage of Tropical Trees.f — Mr. F. W. Keeble discusses 
the purpose of the pendent position of the young leaves of many tropical 
trees, belonging almost entirely to the Cacsalpinieae, and points out the 
advantage which the foliage may thus derive in protection against ex- 
cessive insolation and transpiration. 
Leaves of Alpine Plants. £ — A study of the leaves of alpine plants 
leads M. F. Boergesen to the following general conclusions : — The 
■greater number of species have stomates on both surfaces of the leaf, 
frequently even in greater numbers on the upper surface. The 
stomates are not depressed beneath the surface. The mesophyll has 
a very lacunar structure. The palisade-tissue is but feebly developed, 
in connection with the feeble intensity of the light ; in many species 
growing in high latitudes it is entirely wanting. The development of 
the mechanical tissue is, in general, inconsiderable, and it is often almost 
■entirely absent. 
Leaves of Conifers.§ — According to Herr K. J. May, the length of 
life of the leaves of evergreen Conifers varies between 1^ and 10 ^ years, 
■differing often greatly in the same species according to the conditions of 
growth. In some conifers the fall of the leaf takes place at one period 
•only of the year, either in the spring or the autumn ; while in others it 
continues without intermission throughout the year. 
* Bot. Notiser, 1893, 94. See Bot. Centralbl., lxi. (1895) p. 434. Cf. this 
Journal, 1892, p. 62. 
t Ann. Bot., ix. (1895) pp. 59-94 (1 pi.). Cf. this Journal, ante , p. 194. 
t Journ. de Bot. (Morot), ix. (1895) pp. 1-7, 21-7 (4 figs.). Cf. this Journal, 
ante, p. 194. 
§ Zeitschr. f. Forst. u. Jagdwesen, xxvi. (1894) pp. 648-60. See Bot. Centralbl., 
1895, Beih., p. 25. 
