THE MOPANE-TREE. 151 



some centuries of being as old as the Christian era (1400). 

 Though it possesses amazing vitality, it is difficult to 

 believe that this great baby-looking bulb or tree is as old 

 as the pyramids. 



The Mopane-tree (Bauhinia) is remarkable for the little 

 shade its leaves afford. They fold together and stand 

 nearly perpendicular during the heat of the day, so that 

 only the shadow of their edges comes to the ground On 

 these leaves the small larvae of a winged insect appear 

 covered over with a sweet gummy substance. The people 

 collect this in great quantities, and use it as food ;* and 

 the lopane — large caterpillars three inches long, which 

 feed on the leaves, and are seen strung together — share 

 the same fate. 



In passing along we see everywhere the power of vege- 

 tation in breaking up the outer crust of tufa. A mopane- 

 tree, growing in a small chink, as it increases in size rends 

 and lifts up large fragments of the rock all around it, 

 subjecting them to the disintegrating influence of the 

 atmosphere. The wood is hard, and of a fine red colour, 

 and is named iron- wood by the Portuguese. The inhabi- 

 tants, observing that the mopane is more frequently 



* I am favoured with Mr. Westwood's remarks on this insect as 

 follows : — 



" Taylor Institution, Oxford, [uly 9, 1857. 



" The insect (and its secretion) on the leaves of the Bauhinia, and 

 which is eaten by the Africans, proves to be a species of Psylla, a 

 genus of small very active Homoptera, of which we have one very 

 common species in the box ; but our species, P. buxi, emits its secre- 

 tion in the shape of very long white cotton-like filaments ; but there 

 is a species in New Holland, found on the leaves of the Eucalyptus, 

 which emits a secretion very similar to that of Dr. Livingstone's 

 species. This Australian secretion (and its insect originator) is known 

 by the name of Wo-me-la, and, like Dr. Livingstone's, it is scraped 

 off the leaves and eaten by the aborigines as a saccharine dainty. The 

 insects found beneath the secretion, brought home by Dr. Livingstone, 

 are in the pupa state, being flattened, with large scales at the sides of 

 the body, enclosing the future wings of the insect. The body is pale 

 yellowish coloured, with dark -brown spots. It will be impossible to 

 describe the species technically until we receive the perfect insect. 

 The secretion itself is flat and circular, apparently deposited in concen- 

 tric rings, gradually increasing in size till the patches are about a 

 quarter or a third of an inch in diameter. 



" Jno. O. Westwood." 



