THE MANGROVE. 143 



here, no doubt, reward the naturalist's attention ; but the man- 

 groves know well how to keep their secrets, and to repel the 

 curiosity of man. Should he attempt to invade their domains, 

 clouds of bloodthirsty insects would instantly make him repent 

 of his temerity ; for the plague of the mosquitoes is nowhere 

 more dreadful than in the thickets of the semi-aquatic Rhizo- 

 phorse. And supposing his scientific zeal intense enough to 

 bid defiance to the torture of their stings, and to scorn the 

 attacks of every other visible foe — insect or serpent, crocodile 

 or beast of prey — that may be lurking among the mangroves, 

 yet the reflection may well bid him pause, that poisonous 

 vapours, pregnant with cholera or yellow fever, are constantly 

 rising from that muddy soil. Even in the temperate regions 

 of Europe the emanations from marshy grounds are pregnant 

 with disease, but the malaria ascending from the sultry morasses 

 of the torrid zone is absolutely deadly. 



Thus there cannot possibly be a better natural bulwark for a 

 land than to be belted with mangroves ; and if Borneo, Mada- 

 gascar, Celebes, and many other tropical islands and coasts, have 

 to the present day remained free from the European yoke, they 

 are principally indebted for their independence to the miasms 

 and tangles of a Ehizophora girdle, bidding defiance alike to 

 the sharp edge of the axe or the destructive agency of fire. 



As the mangroves are found in places suited to their growth 

 throughout the whole torrid zone, it is not surprising that 

 there are many species, some rising to the height of stately 

 trees, while others are content with a shrub-like growth. Some 

 are peculiar to America, others to the Old World ; some grow 

 near the sea, others prefer a brackish water and the low swampy 

 banks of rivers. 



The Jriarteas and Screw-pines are as singular as the man- 

 groves in the formation of their roots ; but those of the Lum, 

 a large tree which Kittlitz found growing on the island of 

 Ualan, are perhaps without a parallel in the vegetable world. 

 Each of the roots, running above-ground for a considerable 

 distance, is surmounted by a perfectly vertical crest, gradually 

 diminishing in size as the root recedes from the trunk, but often 

 three, or even four, feet high near its base. These crests, whicli 

 are very thin but perfectly smooth, regularly follow all the 

 sinuosities of the root, and thus form, for a considerable dis- 



