148 PLANTS, SEEDS, AND CURRENTS 



localities. Urban, alluding to its station in the West Indies (Ibid., 

 IV., 567), states that it grows in marshy places, both inland and 

 at the coast. 



The suitability of the fruits of these two trees for dispersal by 

 currents was especially studied during a sojourn at Black River in 

 Jamaica. That they could be thus transported across wide tracts 

 of sea soon became evident, and the point to be determined was 

 whether after being stranded on some distant shore they were likely 

 to contain germinable seeds. 



The fresh gourd of Crescentia cujete is filled with a white spongy 

 pulp containing numerous seeds. After detachment of the fruit the 

 pulp soon begins to soften and blacken; and a process almost of 

 liquefaction sets in, which seems usually to involve the vitality of 

 the embryos of the inclosed seeds, unless conditions favouring rapid 

 germination intervene. As the fruit dries on the ground, its contents 

 ultimately dry up, and all that represents the original white pulp and 

 its seeds is a loose, rounded, blackened mass, about one and a half 

 inches across, in which the seeds may be observed either empty or 

 with embryos evidently dead, if not actually decaying. This is the 

 condition in which the fruits of the Calabash tree generally are 

 found in the Jamaican beach-drift, and anything less likely to 

 assist dispersal by currents, as far as the propagation of the species 

 is concerned, could scarcely be imagined. In these gourds of the 

 shore-drift, when the embryos of the seeds have not disappeared, 

 they are usually blackened, friable, and dead; whilst only in a few 

 cases are there any signs of vitality; and even then the discoloured 

 appearance and general condition give but little promise of any 

 capacity for germination. 



The gourds of Crescentia cujete, as found in the beach-drift of the 

 Black River district, were generally small, three to four inches across, 

 globose, much weathered by exposure, and in half of them the shell was 

 cracked. They were evidently derived from the trees growing wild 

 in the Great Morass by the riverside, and had been washed up on the 

 beaches after having been carried down to the sea. They came 

 under my notice on the beaches near the mouths of rivers in other 

 parts of Jamaica, as near the White River on the north coast. On 

 the beaches of the Black River district they were four times as 

 frequent as those of the Paki tree (C. cucurbitina). Their shells also 

 are thicker (2 mm. as against 1 mm.), and the fruits generally seem 

 better fitted for withstanding the buffeting involved in sea transport. 



The fresh gourds of Crescentia cujete float in water, and in this 

 state they are not uncommon in the floating drift of the Black River ; 

 but their buoyancy is principally due to the spongy air-bearing pulp 

 and to the impermeability of the shell, the specific gravity of the 

 last being near that of fresh-water. The fruit acquires increased 

 buoyancy after the pulpy contents have broken down and dried 

 up into a small rounded mass, leaving the greater portion of its 

 cavity empty, such being its condition in the beach-drift. The fresh 

 moist seeds, 9 or 10 mm. long, have an initial buoyancy, a capacity 

 which they owe entirely to the fact that the embryo but loosely 

 fills the cavity within its horny coverings. When dry they at the 



