FOREIGN DRIFT OF THE TURKS ISLANDS 125 



The ripe fruit, which usually contains about ten seeds, floats 

 when it falls into the water. In course of time it breaks down 

 whilst still at the surface, the seeds escaping and floating away; 

 its buoyancy being due not only to the seeds but also to the floating 

 power of the pericarp. The seeds are flat and round and about 

 two inches across. They are as buoyant in the moist fresh condition 

 when just freed from the fruit as they are in the dry condition. 

 The embryo which forms the kernel has no buoyancy, the seed 

 owing its floating power to the coverings. On first examining it, 

 the seed would seem to be structurally well equipped for transport 

 by marine currents. In the moist fresh state, when the embryo or 

 kernel fills its cavity, the cotyledons are closely appressed; but the 

 embryo is imbedded in spongy cellular tissue, especially aeriferous in 

 its outer part and very buoyant. Outside this tissue is a thin crus- 

 taceous shell, which is non-buoyant, but the seed possesses an outer 

 border or edging, 4 to 5 mm. thick, of a brownish suber-like material 

 which is very buoyant. Thus it is that when, as often happens, an 

 empty seed splits into two halves in the manner below described, the 

 two portions float away and occur loose in the drift. In the older seeds 

 found afloat in the river the inner spongy tissue is drier, brownish, 

 and increased in buoyancy; whilst the floating power of the seed 

 is sometimes augmented through an empty space in its interior due to 

 the shrinkage of the embryo. 



But there is a weak place in the seed's structure as far as buoyancy 

 is concerned, since water is apt to penetrate the suture between the 

 two halves of the crustaceous shell. This might favour the germina- 

 tion of a seed floating in a river; but it would be fatal to the ger- 

 minative capacity of a seed floating in the sea. This explains the 

 condition of the seeds found afloat in the Black River drift, many of 

 which must have been a long while out of the influence of the current 

 and doubtless belonged to the previous fruiting season. They were 

 very frequent in the river-drift in January, and I examined a 

 considerable number of them from my canoe, with the following 

 results — 



Sound seeds (one or two germinating) 50 per cent. 

 Seeds injured by boring animals or by 



the nibbling of fish . . . 15 ., ,, 

 Seeds empty or with decaying embryo 30 ,, ,, 

 Seeds represented by the two separated 



halves of the shell . . 5 „ 



100 



Thus, excellent as the provision for long flotation at first sight 

 seems to be, it is really very faulty, and it is doubtful whether 

 effectual over-sea transport is possible for any distance. 



Reference will now be made to the testimony of these seeds as 

 they lie stranded on the Jamaican beaches after being brought 

 down by the rivers. I especially studied their condition on the 

 beaches stretching four or five miles on either side of the mouth of 



