88 DESERT PLANTS. 



Kalahari Desert, another family of plants, the mesem- 

 bryanthemums, stood ready to neutralize the aridity which 

 must otherwise have followed. This family of plants 

 possesses seed-vessels which remain firmly shut on their 

 contents while the soil is hot and dry, and thus preserve 

 the vegetative power intact during the highest heat of the 

 torrid sun ; but when rain falls, the seed-vessel opens and 

 sheds its contents just when there is the greatest proba- 

 bility of their vegetating. In other plants heat and 

 drought causes the seed-vessels to burst, and shed their 

 charge. 



One of this family is edible {Mesembryanthemum edule) ; 

 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 from 

 a very dry atmosphere and soil, so that, if a leaf is broken 

 during a period of the greatest drought, it shows abundant 

 circulating sap. The plants of this family are found much 

 further north, but the great abundance of the grasses 

 prevents them from making any show. There, however, 

 they stand, ready to fill up any gap which may occur in 

 the present prevailing vegetation ; and should the grasses 

 disappear, animal life would not necessarily be destroyed, 

 because a reserve supply, equivalent to a fresh act of 

 creative power, has been provided. 



One of this family, M. turbinifovme, is so coloured as to 

 blend in well with the hue of the soil and stones around 

 it ; and a gvyllus of the same colour feeds on it. In the 

 ca.se of the insect, the peculiar colour is given as com- 

 pensation for the deficiency of the powers of motion, to 

 enable it to elude the notice of birds. The continuation 

 of the species is here the end in view. In the case of the 

 plant the same device is adopted for a sort of double end, 

 viz. perpetuation of the plant by hiding it from animals, 

 with the view that ultimately its extensive appearance 

 will sustain that race. 



As this new vegetation is better adapted for sheep and 

 goats in a dry country than grass, ike Boers supplant the 

 latter by imitating the process by which graminivorous 

 antelopes have so abundantly disseminated the seed of 

 grasses. A few waggon-loads of mesembryanthemum- 

 plants, in seed, are brought to a farm covered with a scanty 

 crop of coarse grass, and placed on a spot to which the 

 sheep have access in the evenings. As they eat a little 



