v SOCIAL HOMES 201 



last being the leafy envelope. The spheres are 

 more perfect than those of Myrapetra, but they are 

 not always literally concentric* circles, and in reality 

 they are incomplete towards the summit of the nest. 

 This irregularity is unavoidable, for if the combs 

 were only united at the top they could not be kept 

 fixed firmly in their relative positions ; no pillars of 

 union between them exist, as in Vespa. Nature sub- 

 stitutes an excellent contrivance, which is at once a 

 means of communication and a prop to the edifice. 

 A veritable flight of stairs extends throughout the 

 nest from the centre to the lower surface. The 

 Nectarines, like other cardboard wasps, pierce 

 holes through their successive stages as a means 

 of traffic ; the combs being of immense breadth, 

 the holes are numerous to save time and fatigue 

 in gaining the exits, and the overcrowding of 

 the passages that would otherwise result in the 

 populous communities. But these routes are 

 not deemed adequate for comfort and conveni- 

 ence. To the underside of the great orifice with 

 which each comb-tier is perforated, material is added, 

 and prolonged obliquely downwards, so as to meet 

 the platform of the comb lower. Tier after tier, from 

 the top to the bottom of the nest, bears the same 

 arrangement ; the hole in each tier is situated below 

 that of its immediate predecessor. It will be per- 

 ceived that the wasps in descending or ascending by 

 these stairs and through these holes, pass in spiral* 

 fashion from the centre to the circumference of the 

 nest. The envelope itself is penetrated with a hole, 

 and the ladder leads out into the open air. These 



