The Mason-bees 



is kept plastic by the salivary fluid as this Is 

 gradually disgorged. In order to consolidate 

 the clay, angular bits of gravel, the size of a 

 lentil, are inserted separately, but only on the 

 outside, in the as yet soft mass. This is the 

 foundation of the structure. Fresh layers 

 follow, until the cell has attained the desired 

 height of two or three centimetres.^ 



Man's masonry Is formed of stones laid one 

 above the other and cemented together with 

 lime. The Chalicodoma's work can bear 

 comparison with ours. To economize la- 

 bour and mortar, the Bee employs coarse ma- 

 terials, big pieces of gravel, which to her 

 represent hewn stones. She chooses them 

 carefully one by one, picks out the hardest 

 bits, generally with corners, which, fitting one 

 into the other, give mutual support and con- 

 tribute to the solidity of the whole. Layers 

 of mortar, sparingly applied, hold them to- 

 gether. The outside of the cell thus assumes 

 the appearance of a piece of rustic architect- 

 ure, In which the stones project with their 

 natural Irregularities; but the inside, which 

 requires a more even surface in order not to 



^Three-quarters of an inch to one inch. — Translator's 

 Note. 



l8 



