222 



THE INDUSTRIES OF ANIMALS. 



prepare a very thick terrace on the external surface 

 of the dwelling which has become too small. They 

 carry to it small balls of earth ground very fine by 

 their jaws, and then lightly piled up so as to pulverise 

 afresh ; these are then spread over the construction 



with the anterior 

 legs. Then, by 

 hollowing out, 

 the ants trace 

 the plan of the 

 new storey, 

 leavingthewalls, 

 partitions, and 

 columns in re- 

 lief After hav- 

 ing raised these 

 parts to a suffi- 

 cient height, all 

 work together to 

 cover them with 

 a general ceil- 

 ing, each ant 

 applyingitselfto 

 one small corner 

 of the work. 



Thevaultingis 

 executed by the 

 method already 

 described; horizontal ledges, slanting from the summit 

 of pillar or wall, are formed to meet one another. The 

 insects are intelligent enough to begin their labour at 

 the spots best fitted to give strong support to the over- 

 hanging materials, as for instance, at the angle of two 

 walls. There is so much activity among the workers, 



Fig. 40. 



