v SOCIAL HOMES 191 



adherent to the envelope, and more or less per- 

 pendicular to it, which traverse the inner space and 

 unite the borders of the combs, forming as it were 

 vertical partitions upon the interior circumference of 

 the sac. Enlargement of the nest is effected as in 

 Vespa, but with greater difficulty, since the envelope 

 is composed of a single leaf. Great cell-like papery 

 protuberances are raised on its surface, and subse- 

 quently the portions covered are eaten away by the 

 builders from the inside. The pedicels, or columns, 

 above mentioned, which unite the combs to each other, 

 arise from careful preservation of parts of the old 

 mantle, which naturally extend from the border of 

 comb to comb. In the same way the vertical sheets 

 of paper alluded to, which bind the combs to the new 

 portion of the envelope, originate in the retention of 

 the old leaf throughout its lines of meeting with the 

 fresh superimposed coat ; and when the combs are 

 extended to reach that coat, the strips form the par- 

 titions described upon the circumference of the tiers 

 adding much to their solidity. In spite of all these 

 clever precautions the nest, owing to the feeble 

 character of the envelope, is one of extreme fragility. 

 The other kind of nest of Chartergus is con- 

 structed on a straight and upright branch, having no 

 lateral twigs. Its elegance cannot be sufficiently ad- 

 mired. Composed of a few cells only, the combs 

 are attached to the branch by means of petioles, 

 or solid masses of wax, keeping the groups in a 

 horizontal and parallel position. They stand one 

 over the other, sometimes to the number of ten, separ- 

 ated by considerable intervals, and so admirably 



