206 PLANTS, SEEDS, AND CURRENTS 



tinguished by their soft coverings. The floating pods are much 

 less frequent. 



Quite 80 per cent, of the seeds afloat in the Black River drift were 

 in a germinating condition, a result not to be surprised at when we 

 reflect on the unprotected state of the seed. The germinating seeds 

 when carried down to the sea would soon be destroyed by the salt 

 water; whilst the few that had not begun to germinate would, on 

 account of their unprotected character, meet the same fate. The 

 buoyant capacity would, of course, be limited under any condition, 

 and the tendency of the seeds to germinate afloat would render them 

 quite ineffective for purposes of dispersal by currents. I did not 

 learn how the seeds liberated themselves from the pod, whether 

 on the tree or in the river. But it seems probable that in the last 

 case the pod takes up water, and that this leads to its rupture through 

 the swelling of the seeds. This appears to be indicated by the fact 

 that the seeds afloat in the river are too large for the pod as it grows 

 on the tree. The germinating seeds are thrown up in numbers on 

 the beaches near the Black River estuary, and shrivel up in the sun. 

 The pods were not to be found in the beach-drift, and evidently they 

 do not reach the sea. 



Seeds of a species of Crudya are brought down by the Orinoco and 

 deposited in the germinating state with much other drift on the south 

 shore of Trinidad. 



Some matters have still to be investigated relating to Crudya 

 spicata; but enough has been said to show that it possesses no 

 effective means for overseas dispersal. We cannot look there for 

 an explanation of its range. 



DODONiEA VISCOSA, L. 



This plant is discussed at length in my work on Plant Dispersal 

 (p. 338, etc.). Here, as there, Bentham is followed in the inclusion 

 within this species of nearly all the extra- Australian forms. In the 

 West Indies I renewed my acquaintance with this cosmopolitan plant, 

 more especially in Jamaica and the Turks Islands. The form that 

 I experimented on in Jamaica was Dodoncea burmanni, DC; but, 

 as Grisebach observes, both this form and that of D. viscosa proper 

 grow on the seashore in that island. Since they occupy the same 

 stations and accompany each other over most of the warm portions 

 of the globe, both as littoral and inland plants, the facts of distribu- 

 tion would in this respect go to support Bentham' s view of the com- 

 prehensive nature of the species. 



The form above named grows in Jamaica among the vegetation 

 bordering the beach and on the drier mud-flats and behind the 

 mangrove fringe of the salt-water lagoons in the Black River district, 

 where it is associated with Conocarpus erectus, Coccoloba uvifera, 

 etc. Millspaugh speaks of Dodoncea viscosa growing on the sandy 

 beach at Grand Cayman (Plantce Utowance), and Harshberger mentions 

 it as a dune plant in Bermuda (p. 703). 



The dark round seeds, 2-5 to 3 mm. in diameter, float in sea- 

 water, their buoyancy being due to the unfilled space in the seed- 



