102 Transactions of the South African Philosophical Society. 



well hidden among the fragments of yellow and brown shale that 

 they are most difficult to detect. Yet this is also not true mimicry, 

 for if these plants are cultivated in a moistar climate, e.g., at Cape- 

 town, they produce green leaves. This shows that the yellow and 

 brown colourings were the effect of the karroo climate and not 

 acquired protective adaptations, although the plants do obtain 

 efficient protection from them in their natural surroundings. 



3. There are, however, some species of Mesembrianthemum, viz., 

 M. bolusii and M. nobile, which retain their remarkable surface 

 structure even in cultivation, although the leaves become somewhat 

 less dull under these modified conditions and lose consequently 

 something of their desert character. This, I think, may be 

 mimicry, or if one prefers the word, homoplasy. 



It is possible that M. truncation Thunb. and M. trnncatellum 

 Haw. are some more examples of this group. 



