82 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Protection of Leaves against Excessive Rainfall.* — Prof. E. Stahl 
describes the contrivances (in Java) for the protection of leaves against 
the injurious effects of excessive rainfall in the tropics. One of the most 
frequent of these — especially characteristic of trees and shrubs growing 
in a very wet climate — is the prolongation of the apex of the leaf into a 
very long acuminate point, which serves as a conduit for carrying off the 
water from the upper surface of the leaf, as in Ficus religiosa. Another 
is the velvety structure of the upper surface of the leaf caused by the 
papillose form of the epidermal cells, a contrivance which prevents 
the moistening of the upper surface of the leaf, and facilitates rapid 
evaporation. The acuminate apex is never found associated with this 
structure, nor with a coating of wax on the upper surface. Other 
contrivances for carrying off the water are deeply channelled veins and 
rows of hairs on the stem. Heterophylly of the leaf, as in Platy cerium, 
and reversal of the upper and under surfaces, are also of frequent occur- 
rence. Protection against the mechanical injury caused by very heavy 
rain is afforded by a thick and leathery texture, by the leaf being split, 
as in Musa, or very deeply divided, as in most ferns, or by its great 
flexibility or pendent position. 
Branching of Borraginacese and Apocynacese.f — Sig. A. Baldacci 
describes in detail the mode of branching in Sympliytum orientale , with 
which also other species of the genus agree in essential points. It 
presents two peculiarities : — the constant elevation of the sympodiopho- 
rous axes and of their ultimate branches in respect to their supporting 
leaves ; and the atrophied rudimentary cone of growth which indicates 
the termination of the principal axis. 
In other genera of Borraginacese the author asserts that the state- 
ment of some authors that the branching is monopodial rests on erroneous 
observation. The inflorescence is always a sympode or dichotomous 
scorpioid cyme. 
The species of Apocynacem examined exhibit, on the other hand, in 
all cases a monopodial branching. In Vinca major we find an axillary 
floriferous axis, a dormant axillary bud, and an enormously developed 
vegetative shoot. 
Haustoria of Phanerogamic Parasites.} — Mr. G. J. Peirce describes 
in detail the structure and development of four species of Cuscuta, 
C. americana, glomerata, epilinum, and epithymum, growing on different 
host-plants. In the same species of Cuscuta the growth of the haustoria 
differs in accordance with the structural peculiarities of the host. 
In C. americana , if two or more stems twine around one another at 
a distance from the host, haustoria are not developed; but if one of 
them touches the host and sends haustoria into it, the others will also 
develope haustoria. The epiderm of the stem of the parasite bears no 
trichomes, and seldom contains stomates. The haustorium originates 
in the cortical parenchyme just beyond the pericycle, in a longitudinal 
row of cells, and consists of these and their offspring only. An opening 
into the host is effected by the exudation from the epidermal cells of 
* Ann. Jard. Bot. Buitenzorg, xi. (1893) pp. 98-182 (3 pis.), 
t Bull. Soc. Bot. Ital., 1893, pp. 337-41, 393-401, 
X Ann. Bot. vii. (1893) pp. 291-326 (3 pis.). 
