254 
TlMEHRI. 
to attain the same end. The courida when contrasted 
with the mangrove is a grand example of this. Living 
under similar conditions these two have taken distin6l 
paths. Rarely does the courida develop anything like 
flying buttresses, but here and there a puny aerial root 
finds its way from the lowest branches down into the 
mud. Like useless encumbrances these are often un- 
developed and withered. Here is a much taller tree 
than the mangrove, but instead of being stiff and un- 
yielding like its neighbour, it is to a certain extent 
flexible. It takes care however not to have a dense 
canopy of foliage ; like those of the Lombardy poplar, its 
narrow leaves offer little resistance. It would be im- 
possible to overturn the mangrove, but the courida could 
not stand an hour without some contrivance for an 
anchorage. It has overcome the difficulty in a most 
curious manner. Walking between the trees you come 
upon thousands of short prongs or blunt spikes, all 
pointing upright from a dense mat of roots extending in 
every direction. At first sight you wonder what is the 
meaning of these, but look a little closer and bits of 
grass, twigs, and other things entangled in them hint that 
they are here for a purpose. Further along you 
come to a space where a layer of silt almost covers 
them and shows unmistakably that they collect mud 
and sand and help to keep the roots at anchor. Care- 
fully scrape everything above and below and some- 
thing like a double harrow is disclosed. Prong-like 
roots descend into the mud and hold down a mat of 
fibres while finger-like spikes above colle6t material to 
cover it. Engineers make similar contrivances by 
driving small piles and interlacing them with fascines, 
