282 H. B. GUPPY, M.B., 
Probably enough they were brought here in the crevices of 
a drifting log. Why is it, however, that these insignificant 
seeds have not germinated here successfully before ? 
Many of the trees that originally took a prominent place 
in the flora of these islands have been long known to be 
distributed by the ocean currents. Thus, the drifting fruits 
of Barringtonia speciosa, Calophyllum inophyllum, and Ter- 
minalia catappa are very commonly stranded on these islands, 
and I have already referred to the fact that those of the two 
first-named trees have been found germinating on the beaches. 
The Ironwood tree (Cordia subcordata), which is widely dis- 
persed in the Indian and Pacific Oceans, is evidently 
- distributed by ocean currents. Its fruits, which are fre- 
quently transported by the sea to these islands, float for 
‘long periods on its surface, their corky or suberous outer 
covering eminently adapting them to withstand immersion.* 
It is necessary, however, before they are fitted for flotation, 
that they should first lie on the ground for some time, in 
order that they may become dry and lose their thin green 
skin. Such fruits I have found to float buoyantly after 
remaining 40 days in sea-water; and after the experiment 
7 fruits were sown out at Buitenzorg; 10 out of a total of 28 
seeds germinating. If, however, the experiment is made 
with ripe fruits, freshly picked from the tree and still bearing 
their outer skin, most of them will become rotten and sink in 
from two to four weeks, and only a small proportion will 
survive. Pemphis acidula is often associated with Cordia 
subcordata at the borders of the lagoon. Its small seed- 
vessels sink when freshly picked, but after a fortnight’s 
drying they will float between two and five days, a period, 
however, quite insufficient to explain the wide distribution of 
this small tree or bush over the coral islands of the Pacific 
and Indian Oceans. Its seeds, also, are very small and ill 
suited for drifting on the sea, although they float, whilst the 
seed-vessel, when freshly picked, sinks. Probably, sea birds 
are the agents mainly engaged in its distribution. It is on 
the bushes of Pemphis acidula, bordering the lagoon of North 
Keeling Island, that the frigate-birds and boobies nest in 
thousands, and it is of the small sticks and twigs of this bush 
. * A corky covering is commonly found to invest fruits and seeds that 
occur in numbers in vegetable drift, as in the case of those of Termznalia 
Catappa, Scevola Kenigii, Guettarda speciosa, Cerbera odollam, Ochrosia 
parviflora, and other trees. It is this covering that adapts the seeds of 
the Teak tree for transportal by the ocean currents. 
