ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 51 
Biology of Tropical Orchids.* — M. M. Kaciborski records the results 
of observations on the structure and mode of life of Javanese orchids. 
Out of 63 species observed, 61 were epiphytes ; of these latter 27 were 
monopodial, 34 sympodial. 
The minute seeds of the epiphytic orchids are dispersed by means of 
elaters ; and in two species of Aerides the epidermal cells of the testa 
are provided with barbed projections, by means of which the seed is 
anchored to the substratum. In a terrestrial species of Eulophia the walls 
of the epidermal cells arc furnished with lignified annular and spiral 
thickenings ; these cells eagerly absorb water, and the small embryo lies 
buried in an aquiferous tissue. 
Several species of Aerides present the peculiarity that all the indivi- 
duals in a district appear to blossom on the same day. 
In all the monopodial species examined the embryo was undifferen- 
tiated ; the first product of germination was a dorsi ventral germ-plant, 
triangular in transverse section, and attached to the substratum by 
rliizoids. From its similarity to a similar structure in Lycopodium , 
the author terms this stage the protocorm. The protocorm is here an 
assimilating organ which can propagate by budding, and subsequently 
produces a leaf-bearing growing point. It has usually only a temporary 
existence. 
Some of the epiphytic species are not propagated by seeds, but only 
in a vegetative mode. In Dendrobium mutdbile the lamina of the leaf is 
deciduous, while the sheath remains in a dried-up condition. The leafy 
lateral shoots spring from the leafless primary shoots ; some of them 
produce inflorescences, others aerial roots which grow in all directions, 
and attach the plant to the branches of the host-plant. 
A remarkable case of mimicry is recorded, in the flower-buds of 
Benanthera moscliifera , which bear a remarkable resemblance to the 
head of a serpent. 
Bhynchostelis retusa forms long thick aerial roots, the apices of 
which are covered by a thick colourless mucilage, not produced by 
special hairs, as in other epiphytic orchids, but on the outside of the 
thin walls of epidermal cells. 
The young inflorescence of Aerides virens is covered by a sweet 
syrupy fluid, which attracts large numbers of ants, and protects the 
young flower-buds. Later this fluid dries up to a collodion-like pellicle 
enveloping the whole bud, and falling off from the margins of the sepals 
when the flowers open. 
In several species there are produced in the axil of each leaf in 
basipetal succession a row of from two to eight axillary shoots, of which 
only the uppermost one usually attains full development. 
In a Triclio glottis sp. the entire surface of the leaf is covered by a 
thick cuticle, the stomates lying in a deep and narrow channel. 
In Aeriopsis javanica the roots form a dense weft, among which are 
imbedded the “ pseudo-bulbils,” each composed of two lower internodes, 
surrounded by the dry transparent leaf-sheaths, and bearing at the apex 
from two to four leaves. 
Several epiphytic orchids present contrivances for the absorption of 
water through the leaves. 
. * Flora, Ixxxv. (1898) pp. 325-55 (13 figs.) 
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