FOREIGN DRIFT OF THE TURKS ISLANDS 113 



on the beaches that line the coast in the neighbourhood of estuaries 

 that the " stones " of these fruits are most abundant. 



On the Pacific shores of tropical America they would seem to be 

 equally abundant, whether afloat in the estuaries or cast up on the 

 beaches. Thus, I found them in the Guayaquil River in Ecuador 

 and on the beaches of the Ecuadorian coast towards the Peruvian 

 border. They came under my notice on the beaches at Panama 

 and afloat in a neighbouring estuary, and it may be added that they 

 were gathered by me from the beach at Colon on the Atlantic side 

 of the isthmus. 



The distribution of the tree over the greater part of the West 

 Indian region, as well as on the Pacific and Atlantic borders of tropical 

 America, derives new interest from the circumstance that the tree 

 occurs on the tropical coast of West Africa. As before remarked, 

 the " stones " are fitted for carriage in the Main Equatorial Current 

 from West Africa to Brazil, and the seeds would probably preserve 

 their capacity for germination. The difficulty, however, is that this 

 tree is not a truly littoral plant. It may grow amongst the trees 

 bordering a beach ; but it is more at home in an inland station on a 

 hillside or near a river bank. It is, in fact, the river that as a rule 

 brings the floating " stones " down to the coast before giving them 

 over to the agency of the currents. 



Although I have gathered a large number of the stranded " stones " 

 on beaches, I have never found one showing germinating seeds. In 

 such an event, however, the young plant would certainly fail to 

 establish itself. The " stones " are so extremely light that, as I have 

 observed in the Turks Islands, the strong winds are able to blow them 

 off the beach into the bush behind, where more favourable conditions 

 might be found, though not in this particular group. Land crabs, 

 also, that frequent the beach, might often carry them off and bury 

 them in their burrows. 



It is likely that the spread of this tree within the same land area 

 is assisted by the facility with which it roots when stakes are placed 

 in the ground. The wood is very light, and it is possible that the 

 trunk or a branch floating in a river may on stranding be able to 

 establish itself on the bank. Sloane observes that it " grows easily 

 by the branch " (II., 127). Under the head of Growing Stakes or Live 

 Fences in Jamaica, this tree is mentioned in association with several 

 others in Note 31 of the Appendix to my book on Seeds and Fruits. 



Hippomane mancinella, L. (Manchineei) 



Few plants seem to be better fitted for dispersal by currents than 

 this littoral tree, which is widely spread over the tropics of the New 

 World, occurring not only throughout the West Indies and on the 

 Atlantic coasts of the mainland from Mexico to Venezuela, but also 

 on the Pacific side. 



Pax, in his recent memoir on the section of the Euphorbiacea?, to 

 which this plant belongs (Euphorbiaceo3-Hippomaneo3, Das Pflan- 

 zenreich, IV., 147, V., 1912), only implies its occurrence on the Pacific 

 side in the case of Costa Rica ; but doubtless he includes both coasts 

 i 



