FOREIGN DRIFT OF THE TURKS ISLANDS 123 



to Miss Knowles. The only Irish seed inspected by me came nearest 

 to the true urens type. 



On the beaches of the South of England Mucuna seeds are occa- 

 sionally found. In the Kew Museum there is a specimen named 

 M. urens from Cornwall, and another specimen from the Isle of 

 Wight is named u near M. wrews." I found a sound seed of the kind 

 last mentioned on the south coast of Devonshire, and Hemsley names 

 Mucuna seeds (doubtless of one or other of these two sorts) as picked 

 up near Portsmouth (Chall. Bot., IV., 291). Many of these seeds found 

 on European beaches are quite sound. Lindman procured the 

 germination at Upsala of seeds of M. urens obtained from the Scan- 

 dinavian beaches (Sernander, p. 7); and in this connection it is 

 important to note that seeds gathered by me from the plant in the 

 Hawaiian islands germinated and gave rise to healthy plants, after 

 being kept afloat in sea-wa f er for a year (Plant Dispersal, p. 80). 



With regard to the buoyancy of the seeds of these two kinds of 

 Mucuna, their frequent occurrence in beach-drift and their ability to 

 cross the Atlantic unharmed are facts of observation above recorded. 

 In my woik on Plant Dispersal (pp. 80, 81, 531, etc.) I deal more 

 especially with the seeds of M. urens as found in the Pacific islands. 

 Though, as above observed, seeds remained afloat after a year in sea- 

 water and subsequently germinated, it was indicated in my experi- 

 ments that on account of the liability of the seeds to absorb sea- water 

 and swell in the warmer parts of the ocean, a large proportion, at 

 least 50 per cent., would sink in the early part of the transatlantic 

 passage. 



As concerns the station of the plants of Mucuna that are most 

 frequently represented in West Indian beach- drift, I have only 

 data for M. urens proper ; but doubtless the plants yielding the seeds 

 of the other kind are similar in their habits. If, as is not unlikely, 

 the last mentioned prove to be the seeds of M. altissima, DC, then 

 we are concerned with a species that grows in mountain-woods in 

 the West Indies and on the tropical American mainland. This 

 species came under my notice as a tree- climber around the lake of 

 the Grand Etang in Grenada, but not in seed. M. urens came under 

 my notice in Jamaica climbing on the trees of the wooded slopes of 

 the Black River above Lacovia, and also in the " pen " district 

 around Moneague in the centre of the island, growing on trees by 

 the side of ditches. I also found it hanging from the trees on the 

 banks of Les Coteaux River in Tobago. In such stations the seeds 

 are very likely to fall into streams and rivers, and they may be 

 observed amongst the drift stranded at the mouths of rivers, as in 

 the case of the Black River and of the White River in Jamaica. It 

 is in this manner that the seeds of this plant are generally brought 

 within the influence of the ocean currents, being first carried down 

 by rivers from inland regions to the sea. 



However, not all the seeds of Mucuna urens that fall into the rivers 

 reach the sea, since a number of them sink in fresh-water. I did 

 not test the relative buoyancy in fresh-water of seeds gathered 

 directly from the plant ; but the seeds of the beach-drift, though they 

 all float in sea-water, not infrequently sink in fresh-water. Ten 



