THE BOTANY OF CHRISTMAS ISLAND. 259 



enclosed in it from the action of the salt water, and also aids 

 to float it, and the corky outer coat of the seed of Carapa. 



But many of the seeds often sea-dispersed have no more 

 protection than the hard seed-coat. Such are the beans 

 Canavalia, Erythrina, Strongylodon, Entada, Guilandina etc. 

 It is essential of course that these seeds should float uninjured 

 and it is necessary also that the plant should be able to grow 

 on the sea shore when it arrives ; so that the greater number 

 of Sea-borne plants are always to be found on the shores or 

 close to the sea. But there are some, such as Terminaha 

 Catappa and Eugenia grandis which also can grow for some 

 way at least inland, and their fruits are carried by bats or birds 

 to some distance from the sea, whence they originally landed. 

 Probably a good many plants travel by sea occasionally and 

 arrive in safety at distant islands which one would not imagine 

 to be able to travel so. I have seen plants of Dendrobium 

 crumenatum a widely distributed plant floating apparently 

 quite uninjured by sea water in the Banka Strait far from 

 land, and I have been informed by Mr. Ross, that a clump of 

 sugarcane had once drifted up upon Cocos Island where it 

 began to grow and was eventually propagated. Many small 

 seeded plants which commonly occur on sea beaches and shores 

 are almost certainly sea dispersed, but owing to the smallness 

 of their seed they have not been detected in sea drift, and 

 thus one may be uncertain about them. A good deal more 

 information is wanted on this head. 



As to the direction of sea-currents in these seas, I have 

 but little information but I may remark that we found plenty 

 of pumice-stone in the eastern corner of Flying Fish Cove and 

 this had doubtless come from Krakatau, which is west of 

 Christmas Island, and in 1890 I saw, in going from the Sunda 

 Straits to Cocos and Christmas Islands, much of this pumice 

 floating in large patches. The pumice also occurred some years 

 ago in quantity on the point known as Tanjong Gol in the 

 extreme south west of Singapore. So that currents capable 

 of carrying pumice-stone run both east and west from 

 Krakatau. Seeds therefore of plants could be brought to 

 Christmas Island at least from Java and Sumatra without 



R, A, Soc, No 45, 1905 



