ON THE DISPERSAL OF PLANTS. 285 
that nest in the branches. Hence, as he observes, “it is easy 
to perceive how widely this tree might be disserninated by 
the birds that roost on it.” (The Eastern Archipelago, p. 30.) 
There are yet a few Cocos plants that need especial refer- 
ence. Unfortunately I had no opportunity of experimenting 
- on the seeds of /pomwa pes capre ; they occur, however, com- 
monly amongst the seeds stranded on these islands. The 
seed-vessels and seeds of Jpomea grandiflora float both in the 
green and dry condition; the capsules, however, soon open 
in the water, when the seeds escape, but sink usually in six 
or seven days, only a few seeds surviving that period. I was 
surprised, however, to find two seeds out of nine still floating 
at the end of six weeks. One of these two seeds was sown 
out by Dr. Treub, but it did not germinate. .... Further 
observations are needed with reference to the dispersal of 
these two widely spread species of Jpomaa, especially of 
I. pes capree, which is one of the first plants to establish itself 
on a coral island. 
Amongst the precursors of the vegetation on such an 
island is Triumfetta procumbens. The fruits float both in the 
ereen and dry condition; but as they sink in from three to 
seven days, they evidently require some intermediary agent 
or vehicle to enable them to traverse the wide expanses of 
sea in the Indian and Pacific Oceans that they have crossed 
in past ages. We have not long, however, to look for a 
means of transport, since one of the seeds has been observed 
erowing in the crevice of a piece of stranded pumice at the 
Cocos Islands. Probably also sea-birds aid in the distribution 
of this plant, for I learn from Mr. Ross that he has sometimes 
found the seed-vessels attached to the feathers of boobies, 
the soft investing spines with recurved points well adapting 
them to this end. There is another species of Triumfetta 
(7. subpalmata) not very common in the Cocos Islands, 
which is also one of the pioneers of the vegetation. Its 
seed-vessels float; but 1 did not carry the experiment 
further: the spines investing it are not recurved. 
There is another littoral shrub, Cwsalpinia Bonducella, that 
grows near the beach on the weather coasts of these islands, 
the young plants of which may be sometimes seen growing 
amongst the vegetable drift just above the ordinary high- 
tide level. Its hard grey marble-sized seeds are often 
brought there by the ocean-currents; but, as I am informed 
by the residents, they are sometimes found in the stomachs 
of frigate-birds and boobies, so that here we have another 
means of transportal for this plant, though probably a less 
x 2 
