350 VEGETABLE SUBSTANCES. 



extends, with but few interruptions, from the shores 

 of the Atlantic to the contines of Persia, an extent of 

 nearly four thousand miles. The shores, the banks 

 of the rivers, and ever)- part of this region in which 

 there is humidity, are exceedingly fertile ; and with 

 but unskilful culture produce the most abundant crops 

 and the choicest fruits. But along the verge of the 

 desert, and in the smaller oases or isles which here 

 and there spot that wilderness of sand, the date palm 

 is the only vegetable upon which man can subsist. 

 The lofty summits of the mountains of Atlas form an 

 effectual barrier to the humid winds from the sea. 

 Accordingly, the richer vegetation extends only as 

 far to the south of them as the courses of the streams 

 that are fed by the mountain snows ; and these 

 streams are soon evaporated by the air, or absorbed 

 by the thirsty soil. The more lowly vegetables on 

 that soil are chiefly of a saline and succulent descrip- 

 tion, such as euphorbias, salsolas, and cactuses, 

 which retain their own humidity in consequence of 

 their smooth and close rinds, without much aid from 

 external moisture ; but their juices are in general too 

 acrid, or too much impregnated with soda, for being 

 of any use as food. Over these, the date-palm raises 

 its trunk and sf)reads its leaves, and is the sole vege- 

 table monarch of the thirsty land. It is so abundant, 

 and so unmixed with any thing else that can be con- 

 sidered as a tree in the country between the states 

 of Barbary and the desert, that this region is de- 

 signated as the Land of Dates (Biledulgerid ;) and 

 upon the last plain, as the desert is approached, the 

 only objects that break the dull outhne of the land- 

 scape are the date-palm and the tent of the Arab. 

 The same tree accompanies the margin of the desert 

 in all its sinuosities ; in Tripoli, in Barca, along the 

 valley of the Nile, in the north of Arabia, and in the 

 south-east of Turkey. 



