100 Transactions of the South African Philosophical Society. 



when not in flower. In autumn, however, when bright yellow flowers 

 about 2 inches in diameter appear between the leaves, the plants 

 are very showy. But that does not last long, and during the dry 

 season the leaves look just like lumps of stone. [See Plate VIII.] 



A similar colour and texture of surface have the leaves of Mcsem- 

 hrianthemum nobile Haw., which is fairly common in the karroo, cjj., 

 near Laingsburg and Fraserburg Eoad. 



In the Bokkeveld karroo, between Ceres and Calvinia, occurs 

 a species of Mesembrianthemum with small leaves, the colour of 

 which harmonises with the pebbles and gravel among which they 

 are half buried to such an extent that I detected them only while 

 stooping down, although the surface of the ground was quite bare. 

 The most curious feature of the case was that the plants differed in 

 colour, some being more yellowish, leather coloured, and others 

 more brown, rust-coloured, and that these variations coincided 

 with the yellowish or brownish colour of the shaly gravel. I 

 could not help thinking of Burchell's reference to the chameleon, 

 although I am unable to understand how this apparent adaptation 

 might have come about. To make the analogy even more complete 

 I captured a member of the Gryllus tribe — I cannot say a grass- 

 hopper, for there was no grass within miles, nor did the insect bear 

 the slightest resemblance to grass — which, when at rest, looked so 

 exactly like a brown pebble that I took a few of these fragments 

 of stone with me. 



There are several other species of Mesembrianthemum which are 

 so curiously marked that in their original locality they easily escape 

 the notice of men and animals. An instance of this kind was men- 

 tioned privately by Mr. Hammond Tooke. During a stay in the 

 karroo he had often used a certain footpath which passed for some 

 distance over bare ground merely covered with pebbles. One day, 

 however, he saw some of these pebbles bearing bright yellow flowers, 

 one at the top of each stonelet. The number of these flowering 

 pebbles increased every day until there were hundreds of them on 

 the otherwise bare veld. It was Mesembrianthemum tmncatellum 

 Haw., which occurred rather plentifully in this locality. 



It may be asked whether these plants have any enemies against 

 which this protection would be useful. On that point observation 

 leaves no doubt, for goats eat all these species readily, hence it 

 may be assumed that the wild antelopes do the same. Ostriches 

 are also very fond of them and hares and tortoises eat them as 

 well. As some of these animals feed only or mostly at night time 

 it is obvious that plants which are so well hidden have more chance 

 of escaping destruction than others which can be more easily seen. 



