FOREIGN DRIFT OF THE TURKS ISLANDS 133 



the rivers and deposited on beaches in Fiji, and my experiments 

 showed that they can float for a year and more unharmed in sea- 

 water. There is, however, a difficulty connected with the distribution 

 of this species. It seems from Hemsley's reference to it (Bot. Chall. 

 Exped., IV., 291) to have been first described from Brazil. Yet if 

 it is so widely distributed by currents in the Pacific, having been 

 recorded from Hawaii, Fiji, Tahiti, etc., it is strange that it should 

 only be confined to Brazil in the New World and that its seeds do 

 not figure in West Indian beach-drift. 



Interesting as the genus Dioclea is to the student of distribution, 

 it only repeats the problems displayed by two other genera of legumi- 

 nous tree-climbers, Mucuna and Entada, all three of them holding 

 species possessing seeds capable of wide dispersal by currents, species 

 that range over the tropics of the globe, and all three of them con- 

 taining species of more limited range that, certainly in Entada and 

 probably also in the other two genera, are not adapted for this 

 mode of dispersal. These three genera thus behave like other 

 leguminous tropical genera, such as Canavalia, Guilandina, Sophora, 

 etc., that hold littoral species, found round the tropical zone, plants 

 possessing buoyant seeds known to be distributed by currents far 

 and wide over the oceans; whilst they own other species restricted 

 to smaller areas and not capable of dispersal by the currents. In 

 neither case could the agency of the current be appealed to in explana- 

 tion of the distribution of the genera round the tropics. It is only 

 the species of the estuary and of the beach that offer in the buoyancy 

 of their seeds the opportunity for the currents. Species that habitu- 

 ally grow away from the sea-beach on the river-bank as a rule possess 

 seeds that sink, a fact brought out in my book on Plant Dispersal. 

 These inland species with their limited range largely make up the 

 genus, the distribution of which around the world opens up very 

 different issues. 



Sacoglottis amazonica, Mart. (Humiriacew) 



This is one of the most interesting of the West Indian drift fruits 

 that have been found on European beaches. Though characteristic 

 of West Indian beach-drift, this fruit can scarcely be said to 

 belong to a West Indian plant, since the small tree to which it belongs 

 has its home in the Amazon estuary, and is otherwise only known 

 from the island of Trinidad, where it is of very rare occurrence. It 

 is, however, highly probable that the tree will be found in the estuary 

 of the Orinoco, if it has not already there been found. There is 

 no other fruit or seed amongst the West Indian drift of European 

 beaches, about which it may be assumed with such confidence that 

 the original source was one of the great estuaries of the South 

 American mainland between the Equator and the Gulf of Paria, 

 most probably the Lower Amazon. 



The story of the mystery that long surrounded the parentage of 

 these drift fruits was told in Nature many years ago (January 31, 

 1889; November 21, 1895) by Mr. Morris (now Sir Daniel Morris). 

 Although they had been known for two centuries and more, not only 



