v SOCIAL HOMES 189 



the Chartergus go to work on precisely the opposite 

 plan, first forming new cells and covering them after- 

 wards. Taking the bottom of the nest as starting- 

 point they set cells over its exterior surface, 

 being careful to extend the circumference by a row 

 or two to 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 addition is visible on the outside of the 

 envelope, which would seem constructed at one 

 stroke. 



The nest of C. apicalis is uneclipsed for grace of 

 design ; it is one of the most wonderful examples of 

 intelligent workmanship among insects. Exteriorly 

 the form is a more or less fusiform* or spindle-shaped 

 sac, terminating at its inferior extremity in a prolong- 

 ation or narrow neck, which is open and constitutes 

 the entrance. The sac surrounds and impastes the 

 branches of trees, which piercing it almost from end 

 to end act as its support. To the branches, in the 

 interior a number of combs, one above the other much 

 as in Vespa, are affixed ; as a rule the largest and 

 straightest among them becomes the axis to the 

 whole edifice. When the axes are multiplied, the 

 regularity of disposition of the combs is destroyed ; 

 numerous small cell-groups are commenced on the 

 different branches, and at different levels, and do not 

 unite to form perfect and complete tiers. Due to the 

 shape of the spindle, the higher and lower combs are 



