154 Insect Architecture. 



structed. But afterwards, when those on the edge are 

 deepened like the cells of the rest of the surface, the bees 

 no longer preserve the decreasing gradation which is seen in 

 the new combs." * 



THE FINISHING OP THE CELLS. 



While the cells are building they appear to be of a dull 

 white colour, soft, even, though not smooth, and translucent ; 

 but in a few days they become tinged with yellow, particu- 

 larly on the interior surface ; and their edges, from being 

 thin, uniform, and yielding, become thicker, less regular, 

 more heavy, and so firm that they will bend rather than 

 break. New combs break on the slightest touch. There 

 is also a glutinous substance observable around the orifices 

 of the yellow cells, of reddish colour, unctuous, and odori- 

 ferous. Threads of the same substance are applied all around 

 the interior of the cells, and at the summit of their angles, 

 as if it were for the purpose of binding and strengthening 

 the walls. These yellow cells also require a much higher 

 temperature of water to melt them than the white ones. 



It appeared evident, therefore, that another substance, 

 different from wax, had been employed in varnishing the 

 orifices, and strengthening the interior of the cells. M. 

 Huber, by numerous experiments, ascertained the resinous 

 threads lining the cells, as well as the resinous substance 

 around their orifice, to be propolis ; for he traced them, as 

 we mentioned in our account of propolis, from the poplar buds 

 where they collected it, and saw them apply it to the cells ; 

 but the yellow colour is not imparted by propolis, to which 

 it bears no analogy. "We are, indeed, by no means certain 

 what it is, though it was proved by experiment not to arise 

 from the heat of the hives, nor from emanations of honey, 

 nor from particles of pollen. Perhaps it may be ascribed to 

 the bees rubbing their teeth, feet, and other parts of their 

 body, on the surfaces where they seem to rest ; or to their 

 tongue (haustellum) sweeping from right to left like a fine 



* Huber on Bees, p. 391. 



