132 PLANTS, SEEDS, AND CURRENTS 



probable that they are cast ashore on the Norwegian coasts; but 

 the name is not included in the list of West Indian seeds and fruits 

 given by Sernander in his account of the Atlantic drift thrown up 

 on those shores. However, one may expect to find these drift 

 seeds also in the temperate latitudes of the South Atlantic. Hemsley 

 records Mr. Moseley's discovery of the seeds of Dioclea reflexa washed 

 ashore on Tristan da Cunha (Chall. Bot., IV., 291). 



In my book on Seeds and Fruits (p. 103) allusion is made to the 

 habit of this climber of growing on trees beside streams in the moun- 

 tain forests of Grenada ; and it is there shown how small would be 

 the percentage of seeds that would be fit for attempting the Atlantic 

 traverse. On this ground alone we are thus prepared to expect 

 that the seeds of this plant would not be so frequently observed 

 among the West Indian seeds thrown ashore on European coasts 

 as those of Mucuna. Judging from my results in the Turks Islands, 

 a locality which represents an early stage in the drifting of the seed 

 across the North Atlantic, the seeds of Dioclea reflexa are rather 

 less frequent than those of Mucuna urens and much less common 

 than those of the other species of Mucuna. In the drift of the Trini- 

 dad and Tobago beaches all three seem to be of equal frequency. 

 In the Turks Islands the seeds of Dioclea reflexa were generally 

 distributed in the drift, but were most frequent in the southernmost 

 island. It is interesting to note that of the seeds of this plant collected 

 in the beach-drift of this small group, 10 per cent, sank in fresh-water 

 though buoyant in sea-water. This may be compared with the 

 results of a similar experiment on the seeds of the same plant in the 

 beach-drift of Trinidad and Tobago. Here 30 per cent, sank in 

 fresh- water, though floating in sea- water. 



No reference has been made to the occurrence of Dioclea reflexa 

 on the Pacific side of tropical America, as I possess no data directly 

 bearing on that point. However, its place is well supplied there 

 by Dioclea guianensis (Benth.), an allied species mentioned by 

 Seemann, under the synonym of D. panamensis, as growing by rivers 

 on both sides of the Panama Isthmus (Bot. Voy. H.M.S. Herald, 

 p. 109). This species is stated to be a native both of the Guianas 

 and of Ecuador ; and it is not unlikely that numerous Dioclea seeds, 

 which I found afloat in the drift of the Guayaquil estuary in Ecuador 

 and stranded on the beaches near its mouth, belong to this plant. 



Doubtless there are several recorded facts illustrating the dis- 

 tribution of the seeds of Dioclea reflexa by currents in the tropics 

 of the Old World, but the following will be sufficient for the purpose. 

 Many years ago they were identified at Kew from collections of drift 

 seeds made by me on the beaches of Keeling Atoll in the Indian 

 Ocean and on the coral islets of the Solomon Group in the Pacific, 

 as well as from another collection of floating drift obtained by 

 Moseley off the coast of New Guinea (Journ. Vic. Inst., London, 1889 ; 

 Bot. Chall. Exped., IV., 291, 309, 311). 



But there is an allied species of Dioclea, D. violacea, Mart., which 

 plays a similar role in the tropical Pacific. I was familiar with its 

 seeds in Hawaii and Fiji, and frequent mention is made of them in 

 my work on Plant Dispersal. They are commonly brought down by 



