362 Ridley. — On the Dispersal of Seeds by Wind. 
sidering how lightly the wind blows in the dense forest at the level at 
which these plants fruit, it is curious to what a distance they seem to drift. 
They must often float upwards above the foliage of the lofty trees beneath 
which they grow. One noticeable fact is that while all terrestrial Orchids 
have their ripe capsules erect, those of epiphytic species are always 
pendulous, so that the seed of the former have a tendency to rise in the 
wind and the latter to descend. Cryptogams, especially epiphytic ones, 
are certainly very widely and quickly disseminated by their spores. 
Dr. Treub’s well-known paper on the Flora of Krakatau illustrates this. 
He shows there that the first plants to reach an island after the whole 
flora has been destroyed are Algae, and these are followed by ferns, and 
later by phanerogams. 
The same phenomenon is seen in the case of epiphytes, as well as on 
bare rocks, or barren clay banks, or any such places where at first there 
is no vegetation. 
On trees in the Botanic Gardens, Singapore, I note that the first 
epiphytes to appear are Algae, which settle wherever the trickling of rain- 
water makes it possible for them to grow. On quite smooth-barked trees 
such as Betel-nuts, Areca , or Cocos, nothing further except lichens usually 
appears, unless there happens to be a notch in the bark, or a small portion 
of the base of a leaf-stalk remains, which forms a nidus for spores of 
mosses. The next plants which appear when the moss has grown into 
a small patch are usually ferns, and later Orchids ; occasionally Orchids 
come before ferns. On smooth cylindric trunks the first lichens that 
appear are those of thin texture, e. g. Graphidea , Opegrapha , &c. ; later 
occasionally Parmelias and Collemas develop, and from these thicker 
lichens start mosses or hepatics. 
The same order of appearance takes place on brickwork and bare 
clay banks, except that Orchids rarely appear, and often mosses do not 
come ; phanerogams, however, always come later than the Algae. On trees 
after the Algae, mosses, ferns and Orchids (if any are in the neighbour- 
hood) ; plants whose seeds are disseminated by birds come next. 
Powder-seed Plants in Oceanic Islands. 
The proportion of powder-seed plants in oceanic islands is usually 
very large, even if we exclude the cellular plants ; but oceanic islands are 
apt to be dry in the early stages of their afforestation, so that many of this 
group cannot thrive. Fernando de Noronha possessed no Orchid, only 
one fern, and very few mosses or hepatics. These plants, however, were not 
very abundant on the adjacent mainland, which was somewhat dry, and the 
island itself was in most parts unsuited for the growth of ferns and mosses. 
