124 PLANTS, SEEDS, AND CURRENTS 



per cent, of the seeds of the Turks Islands beach-drift and 20 per cent, 

 of the drift seeds of Trinidad and Tobago sank in fresh-water. It 

 may be added that of the seeds of the allied species (near urens) 

 found in the beach-drift of the two localities just named, all floated 

 in sea-water, but 20 per cent, of those of the Turks Islands and 

 9 per cent, of those of Trinidad and Tobago had no buoyancy in 

 fresh-water. In their buoyant behaviour the seeds of these two 

 kinds of Mucuna, so common in West Indian beach-drift, illustrate 

 the fine adjustment, referred to on pages 96 and 181 of my work 

 on Plant Dispersal, that is not infrequently to be observed with the 

 seeds of leguminous plants dispersed by currents. This principle 

 would probably be exemplified in a more marked manner by Mucuna 

 seeds taken direct from the plant, just as has been already described 

 in the case of Entada scandens. An obvious implication of the 

 results of these experiments on the relative buoyancy of such seeds 

 in salt and fresh water is that a good proportion of those found in 

 beach-drift must have grown on coast trees, since they could not 

 have been carried down to the sea from inland districts by a river. 



In this connection one may add that of the large Mucuna seeds 

 of the Trinidad and Tobago beach-drift, which are described without 

 a specific name on page 121, 50 per cent, sank in fresh- water, although 

 all floated in the sea. 



Fevillea cordifolia, SW. (Antidote Vine) 



This plant belongs to a cucurbitaceous genus holding about six 

 species, all of which are tropical American and West Indian. It is 

 a climber on high trees, and where a river traverses a wooded region 

 the fruits often fall into its stream. It has a wide distribution in 

 the West Indies (Cuba, Jamaica, Hispaniola, Porto Rico, Guadeloupe, 

 Martinique, Trinidad, etc.), and in tropical America. 



As in the case of Grias cauliflora (see p. 211) the discussion of its 

 means of dispersal raises some critical questions relating to their 

 connection with the area of distribution. Both are restricted to the 

 tropics of the New World, and both display a general unfitness for 

 dispersal by currents — an unfitness not concerned so much with 

 deficiency in the floating power of the seed (Fevillea) or of the fruit 

 (Grias) as with the loss of the germinative capacity. 



I will at first refer to the mode in which the seeds reach the coast in 

 Jamaica, and then to their condition in the beach-drift, where they occur 

 in numbers. The station of the plant as a vine on the trees bordering 

 the Black River is noticed on page 15. The fruit is heavy, rounded, 

 and four to five inches in diameter ; and since the plant often grows 

 on the tree-branches spreading over the water the fruits frequently 

 fall directly into the river. Only a few ripe fruits were to be seen 

 on the plants when I examined the Black River in January 1907; 

 but I learned from one of my boatmen, a native of the district, 

 that the " ploom-ploom," as he termed it, of the fruits as they fall 

 into the water is commonly to be heard when ascending the river 

 in March. However, during my ascents I observed both fruits and 

 seeds afloat in the drift, the last being very frequent. 



