1G 



INSECT ARCHITECTURE. 



till she has spread fifteen or sixteen layers one above 

 the other, rendering the wall altogether nearly two 

 inches thick. The several layers are not placed m 

 contact like the layers of a piece of pasteboard, but 

 with small mtervals or open spaces between, ap- 

 pearing somewhat like a grotto built with bivalve 

 shells, particularly when looked at on the outside. 

 This is probably caused by the insect working in a 

 curvilineal manner. 



Section of tht Social-Wa'ip's Ticst.—a a, the external ^Yall ; 

 h, cc, five small terracps of cells for the neuter wasps; d d, e e , 

 three rows of larger cells lor the ina!c5 aiul females. 



Having finished the ceiling, she next begins to 

 build the first terrace of her citv, which, uM(k>r its 



