1^4 THE TROPICAL WORLD. 



The pulp of the melocacti, which remains juicy during the 

 driest season of the year, is one of the vegetable sources of the 

 wilderness, and refreshes the traveller after he has carefully 

 removed the thorns. Almost all of them bear an agreeable acid 

 fruit, which, under the name of the Indian fig, is consumed in 

 large quantities in the West Indies and Mexico. The light and 

 incorruptible wood is admirably adapted for the construction of 

 oars and many other implements. The farmer fences his garden 

 with the prickly opuntias ; but the services wliich they render, 

 aa the plants on which the valuable cochineal insect feeds and 

 multiplies, are far more important. 



The cactuses prefer the most arid situation, naked plains, or 

 slopes, where they are fully exposed to the burning rays of the 

 sun, and impart a peculiar physiognomy to a great part of 

 tropical America. 



None of the plants belong-ing to this family existed in the 

 Old World previously to the discovery of America ; but some 

 species have since then rapidly spread over the warmer regions 

 of our hemisphere. The Nopal {Cactus Opuntia) skirts the 

 Mediterranean along with the American agave, and from the 

 coasts has even penetrated far into the interior of Africa, every- 

 where maintaining its ground, and conspicuously figuring along 

 with the primitive vegetation of the land. 



Although chiefly tropical, the cactuses have a perpendicular 

 range, which but few other families enjoy. From the low sand- 

 coasts of Peru and Bolivia they ascend through vales and 

 ravines to the highest ridges of the Andes. Magnificent dark- 

 brown Peireskias (the only cactus genus bearing leaves instead 

 of prickles) bloom on the banks of the Lake of Titicaca, 

 12,700 feet above the level of the sea ; and in the bleak Puna,* 

 even at the very limits of vegetation, the traveller is astonished 

 at meeting witli low bushes of cactuses thickly beset with 

 yellow prickles. 



What a contrast between these deformities and the delicately 

 feathered mimosas, unrivalled among the loveliest children of 

 Flora in the matchless elegance of their foliage I Our common 

 acacias give but a faint idea of the beauty which these plants 

 attain under the fostering rays of a tropical sun. In most species 



* See Chapter III. 



