198 ROMANCE OF THE INSECT WORLD CHAP. 



is strange that the inferior surface of the nest is pro- 

 vided with tubercles, a circumstance that must put the 

 insects to the trouble of gnawing them away each 

 time they add a stage. Probably the same material 

 is again employed in establishing fresh cells, and in 

 building the new platform. 



A longitudinal section shows the peculiar disposi- 

 tion of the combs. Just as in the spherical nests of 

 Polybia, the highest ones are perfect, or almost 

 perfect, spheres; but this method of construction is 

 soon found to be too laborious. A nearly globular 

 mass of the brown paper-like substance exists at the 

 top, the nucleus so to speak. The first combs closely 

 surround this, so that they form the best parts of hollow 

 spheres, then come great arcs of circles, followed in 

 regular order by other tiers, their rotundity becoming 

 gradually reduced until the curve of the lower ones is 

 extremely shallow, exactly like the tiers of Tatua, 

 except that they exhibit a trifling convexity on their 

 lower surfaces. They are carried to the common 

 wall, and thereto affixed, small spaces being left open 

 here and *here between their edges and the envelope. 

 The solid wall at the top is of great thickness (see 



Fig. 34)- 



In the nest in the British Museum already described, 

 a quantity of brownish-red honey was found in the 

 upper combs, but hard and dry. Even so long ago 

 as the beginning of the century, Azara, a Spanish 

 officer, who was sent out by his government to 

 Paraguay to make certain investigations in that 

 country, mentions that a South American wasp which 

 he calls Chiguana has the strange habit of hoarding 



