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THE POPULAR SCIENCE MONTHLY 



crease of the envelope to admit of extension, of the tiers, the CJiar- 

 tergi go to work on precisely the opposite plan, first forming new 

 cells and covering them afterward. Taking the bottom of the 

 nest as a starting point, they set cells over its exterior surface, 

 being careful to extend the circumference by a row or two to 



Fig. 3. Wasp's Nest (Chartergus apicalis), Interior and Exterior. 



augment the diameter in proportion to the length, so that the 

 symmetry of the building may not be lost. The walls are then 

 lengthened to include the fresh stage, and the end is closed with 

 a new floor, in its turn to become the ceiling of the next tier of 

 cells when further enlargement is desired. No trace of the addi- 

 tion is visible on the outside of the envelope, which would seem 

 constructed at one stroke. 



The other kind of nest of Chartergus is constructed on a 

 straight and upright branch, having no lateral twigs. Its ele- 

 gance can not be sufficiently admired. 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, separated by considerable intervals, and so 

 admirably upheld by the petioles that the aid of all pillars or col- 

 umns is dispensed with. The envelope is a spindle of a single leaf 

 of ligneous paper, most artistic in appearance, being marked with 



