142 PLANTS, SEEDS, AND CURRENTS 



on the Pacific side of tropical America, and in that respect the com- 

 parison with Rhizophora mangle is incomplete. 



With the two species of Carapa that between them cover the tropics 

 of the globe the writer is familiar, having studied the trees together 

 with their fruits and seeds in Fiji and in Trinidad, and having gathered 

 their seeds from the floating river-drift and the stranded beach-drift 

 of various parts of the world, as on the south coast of Java, in the 

 Keeling Islands, in Fiji, and in the West Indies. Though it does 

 not seem that Treub found stranded Carapa seeds on the beaches 

 of the devastated island of Krakatau, when he visited it in 1886, 

 nearly three years after the great eruption, those of C. moluccensis 

 were observed by Penzig in 1897 ; and when Ernst and other botanists 

 examined this locality in 1906 they found Carapa trees established. 

 The species was referred by them to C. obovata ; but there can be 

 little doubt that the trees grew from such stranded seeds as were 

 previously observed by Penzig, the two forms not being distinguish- 

 able by their seeds (vide Treub and Penzig in Annates du jardin 

 botanique de Buitenzorg, 1888 and 1902, and Ernst's New Flora of 

 Krakatau, 1908). 



Carapa seeds were frequently noticed by me in the floating drift 

 of the Rewa estuary in Fiji, and often in a germinating condition. 

 They must form a feature in the drift of the estuary of the Orinoco, 

 since many more drift seeds are piled up on the southern coasts of 

 Trinidad than could have been derived from the trees in the coast 

 districts of that island. We cannot doubt that they are equally 

 abundant in the floating drift of the Amazon and of the rivers of 

 the Guianas. 



But the grave perils that threaten the floating and the stranded 

 Carapa seeds lessen their effective value for oceanic dispersal. In 

 the first place, there is the tendency to germinate when afloat in an 

 estuary before the sea passage begins. Then there is the tendency 

 to germinate prematurely after being stranded on the beach at the 

 completion of a long sea traverse. This, I especially noticed, in the 

 Keeling Islands, where after a drifting passage of at least 700 miles 

 the seeds often sprouted on the beach, the protruding portions either 

 falling a prey to the crabs or being withered up in the sun. Then 

 there is the danger from the attack of boring molluscs and other 

 marine creatures during the ocean passage. This presented itself as 

 a very real risk in the case of seeds of Carapa moluccensis that I 

 found stranded in the Keeling Islands and on the south coast of 

 West Java. Here the empty cavity was often occupied by the tubes 

 of the Teredo. As a result of these repressive influences Carapa 

 moluccensis seems never to have been able to establish itself on the 

 Keeling Islands. Yet it may be remarked that the tendency to rapid 

 germination on the part of a stranded seed, whilst usually leading 

 to fatal results on an exposed sandy beach, would be a direct advan- 

 tage on the muddy shores of a mangrove-fringed coast, where the 

 germinating seed could at once strike into the mud in the shade of 

 the trees. 



With respect to the occurrence of the seeds of Carapa guianensis 

 in the beach-drift of the West Indian region, the following remarks 



