170 BEES AND BEE-KEEPING. 



hive roof. She has jaws with a smooth edge (a, 

 Fig. 37), for scooping and moulding, and the closed 

 maxillae, with their polished surface, for a trowel. 



As the burrowing wild bee chips out a hole circular 

 in cross section, to admit her body, so the wax-worker 

 carves into her wax, placing the material removed 

 upon the edge of the little pitting that increases 

 before her : but two points are accomplished of 

 which no good explanation can be given ; first, that 

 the workers so place themselves that the concavity 

 made by one interferes with that made by her next 

 neighbour ; and, second, that, when carving from both 

 sides, the scraping and thinning stops before an actual 

 hole is driven through. This mutual interference 

 forms into hexagons, cells that are always circular in 

 outline at the beginning. Let us try an experiment, 

 the apparatus for which is found in every home. A 

 floating soap-bubble is perfectly globular, because the 

 tension of the soap film covers the contained air by a 

 pellicle of the smallest possible area ; but if we trans- 

 fer the bubble to the surface of a saucer, its own 

 gravity flattens one side. Giving it now a companion, 

 the two will convert their films, where united, into a 

 perfectly flat wall, because the equal tension on its 

 two sides will throw the opposing curves into a path 

 between them. So two bees scooping in contiguous 

 cells, or one bee scooping alternately in two cells, 

 will, as the resultant of two opposite curves, produce 

 a straight side. Let us add to our two soap bubbles 

 five others, so that one occupies the centre, while six 

 surround it. Now, in cross section the central bubble 

 is perfectly hexagonal, while all contiguous walls are 



