292 HABITS AND INSTINCTS OF ANIMALS. CHAP. X. 



was not sufficient to satisfy me, by ocular proof, that 

 they added to their nest as they annually increased in 

 numbers, still, from the many trees which I have seen 

 borne down by the weight, and others which I have 

 observed with their boughs completely covered over, it 

 would appear that this really was the case. When 

 the tree, which is the support of this aerial city, is 

 obliged to give way to the increase of weight, it is 

 obvious they are no longer protected, and are under the 

 necessity of rebuilding in other trees. One of these 

 deserted nests I had the curiosity to break down, so as 

 to inform myself of its internal structure, and I found 

 it equally ingenious with that of the external. There 

 are many entrances, each of which forms a separate 

 street, with nests on both sides, at about two inches 

 distant from each other. The grass with which they 

 are built is called the Boshman's grass, and I believe 

 the seed of it to be their principal food ; though, on 

 examining their nests, I found the wings and legs of 

 different insects. From every appearance, the nest 

 which I dissected had been inhabited for many years, 



and some parts of it were much more complete than 



others. This, therefore, I conceive nearly to amount 

 to a proof that they added to it at different times, as 

 they found necessary, from the increase of the family 

 or rather, I should say, of the nation or com- 

 munity."* Our author further observes, that these 

 little republicans select a particular species of acacia 

 tree as the site of their city, the structure of which 

 they are led, by instinct, to perceive is peculiarly adapted 

 for the purpose. The stem of this tree shoots up to 

 the height of near thirty feet from the ground before 

 it sends out any branches ; while the stem, being covered 

 with a smooth and polished bark, effectually secures 

 the birds from the attacks and injuries of all the snakes, 

 lizards, and other reptiles which swarm around their 

 habitations, many of which, could they but ascend the 

 glassy surface of the stem, would suck the eggs and 



* Trav. in Africa, p. 133. 



