So A NATURALIST IN Til 1C 1'ACIHC CHAf 



as if they mivhi :..ii< l\ he transported by the currents round .m<l 

 round the globe; and De Candolle very ri-htlv placed tin's species 



in hi-, scanty list >! plants dispersed hy currents. Yet lew seeds 



are more treacherous when their Imovam y in sea-water is tested in 

 a warm place, as in a hot-house. They may take up water, swell, 

 and sink in a week, or they may float unharmed for ;i year, 



The seeds most exposed to this risk are those <>r the 



l.e : ;nminons ; ;i.ml climber,, the lianes o| th- , o.i-.i .ind inl.ind 



forests of the islands of the tropical Pacific. They belong to the 

 genera Mucuna, Strongylodon, &c, ; and thus several of the plant 

 that constitute for the student of plant-dispersal the enigmas of 



the Pacific are here included. The seeds of Miieiina are especially 



liable when afloat in sea-water under warm conditions to display 

 the early signs of germination, swelling up and sinking to the 

 bottom of the vessel, a process, however, soon arrested and 

 followed by the death of the embryo unless the seed is removed in 

 time. Yet the seeds of this genus are notably long "floaters," 

 Those of an American species, variously designated as Mucima 

 pruriens D.C. and M. urens D.C., have long been known to be 

 washed ashore together with the seeds of Entada scandi n <>n tin- 

 western shores of Europe, and particularly on the Scandinavian 

 coast, where they form regular constituents of what the Scan- 

 dinavian botanists correctly term the Gulf-stream Drift. 



Mucuna urens D.C. occurs with other American shore plan! 

 that are dispersed by the currents on the African West Coast ; and 

 there is no reason to doubt that its seeds perform the trans- 

 Atlantic voyage. It is found in Polynesia, in Hawaii, in tin- 

 Marquesas, and according to Reinecke also in Samoa; and 

 probably it occurs in other groups. The specific determinations of 

 the genus, however, need thorough overhauling, so that it is not 



possible to deal more than in -encral terms with the distribution 



of a species. The distribution of Mucuna urens in the Pacific i ,, 

 however, irregular, and no doubt this is to be connected with tin- 

 uncertain behaviour of its seeds when transported by tropical 

 currents. The seeds would, I venture to think, often sink through 

 abortive germination in the warm areas of equatorial seas. 



When in Hawaii I kept ten of the seeds of this spe. 

 (M. urens D.C.) in sea-water for four and a half months, none of 

 them sinking in that period, the temperature of the water rarely 

 reaching over So K, the average daily temperature bcini; 76 -/; . 

 However, when four years afterwards in England I placed five .i 



the seeds obtained at the same time in sea-water under conditions 



