Chap. V. DESERT VEGETATION. 6S 



shut wh.ie the soil is dry, and thus the vegetative power is 

 jDreserved during the highest heat of the torrid sun. When 

 rain falls the seed-vessel opens and sheds its contents just 

 when there is the greatest probability of their growth. In 

 other plants it is heat and drought which cause the seed-vessels 

 to burst and scatter their progeny over the soil. 



One of this family is edible (Mesembryantliemum eduh) ; another 

 possesses a tuberous root, which may be eaten raw ; and all are 

 furnished with thick fleshy leaves, having pores capable of 

 imbibing and retaining moisture. If a leaf is broken during 

 a period of the greatest drought, it shows abundant sap. The 

 plants of this family are found much further north, but the 

 excess of grass prevents them from making any show. There, 

 however, they are, ready to fill up any gap which may occur 

 in the prevailing vegetation. It is a reserve supply which 

 would answer the same end as a fresh act of creative power. 



Another of the family, M. turbinifonne, is so coloured as to 

 blend in hue with the soil and stones around it. A gryUus of 

 the same colour feeds on it, and is compensated for its de- 

 ficiency in the power of motion by thus eluding the notice of 

 birds. The continuation of the species may be presumed in 

 the case of the insect to be the end in view, and with the 

 plant the same device is perhaps adopted, that by hiding it 

 from animals at one period its extensive propagation may serve 

 at another to sustain them. 



As this plant is better adapted for sheep and goats in a dry 

 country than grass, the Boers imitate the process by which 

 graminivorous antelopes have disseminated the seeds of the 

 herbage on which they feed. A few waggon-loads of mesem- 

 bryanthemum- plants, in seed, are given to the sheep. The 

 seeds by this means get dropped over the grazing-grounds. 

 While noticing a clever imitation of one process in nature by 

 the Cape farmers, I venture to suggest another for their con- 

 sideration. The country beyond south lat. 18° abounds in 

 three varieties of grape-bearing vines ; and one of these is fur- 

 nished with oblong tubers, which are less affected than the 

 common root by the scorching sun. This increase of power 

 to withstand the effects of climate might prove of value in 

 the more arid parts of the Cape colony, grapes being an c 

 lent restorative in the debility produced by heat, anO. by 



G 



