1893.] R. L. Heinig — Blind root-suckers of the Sunderbans. 159 



a few inferior species. Towards the sea coast, where the water of the 

 rivers is markedly saline, especially duinng the dry months of the 

 year, Goran and Gengwd form the predominating species, and Sundri 

 trees are comparatively few in number, and of inferior growth. The 

 Sundri- producing tract resembles that on the west in the general 

 absence of grass and other herbaceous vegetation, hut differentiates 

 from it entirely by the presence of innnmerable blind root-suckers. 



The magnificent rivers that traverse the Sunderbans, many of 

 them of considerable breadth and depth, bring down, during the mon- 

 soon months, vast quantities of silt, some of which is deposited to 

 form churs or sand-banks. 



On the subsidence of the waters at the close of the rains those 

 sand-banks, the surface of which is left exposed at low tide, are soon 

 covered by a luxuriant growth of grass which effectually binds the 

 soil, induces further accumulations of silt, and arrests floating seeds. 



It is not surprising that under the forcing conditions of a rich 

 soil, a moist warm climate, and abundance of light, seedlings on these 

 new islands should make extremely rapid growth, forming in a few 

 years an uninterrupted canopy, in the dense shade of which it is impos- 

 sible for the grass to live. 



When the grass has disappeared there is a continual danger of 

 the island wasting away by erosion, the banks being liable to be 

 undermined and swept away by the rivers, and the whole surface, 

 inundated during high spring-floods, is subject to denudation under 

 the considerable force (to be seen to be fully appreciated) with which 

 the water pours away at every point of egress after the tide has turned. 



The soil of the islands eventually consists of a thin top-layer of 

 alluvial mud overlying a thick layer of moist, black soil in which the 

 large quantities of wood debris that accumulate in these forests undergo 

 slow decomposition with the generation of gases having the odour 

 of sulphuretted and carburetted hydrogen. The top-layer of soil ex- 

 cludes atmospheric air, and imprisons the gases generated in the 

 miasmic mud beneath. Occasionally the gases find vent along river 

 banks at low tide, and during storms when the stems of the forest trees 

 sway to and fro and cause the upper layers to be disturbed. 



Bach species of tree found growing in the swamp-forests of the 

 Sunderbans has a root-system well adapted not only to anchor the 

 tree firmly in the unstable medium below, but also to protect the mud 

 from the effects of erosion. The roots do not penetrate the soil to a 

 greater depth than 8 to 10 feet, but in this shallow layer they form a 

 tangled and confused net- work in which the tap-root is not distinguish- 

 able. Some species produce adventitious roots, and others buttress 

 J. ii. 21 



