138 INSECT ARCHITECTURE. 



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 sub- 

 stance, different from wax, had been employed in 

 varnishing the orifices and strengthening the in- 

 terior of the cells. M. Huber, by numerous ex- 

 periments, 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 yellov/ colour is 

 not imparted by propolis, to which it bears no ana- 

 logy. 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 pliant pencil, 

 when it appears to leave some sprinkling of a trans- 

 parent liquid. 



Beside painting and varnishing their cells in this 

 manner, they take care to strengthen the weaker parts 

 of their edifice by means of a mortar composed of 

 propolis and wax, and named pissocci'os* by the an- 

 cients, who first observed it, though Reaumur was 

 somewhat doubtful respecting the existence of such 

 a composition. We are indebted to the shrewd ob- 

 servations of Huber for a reconcilement of the Roman 

 and the French naturalists. The details which he 

 has given of his discovery are perhaps the most in- 

 teresting in his dehghtful book. 



'^ Soon," he says, '' after some new combs had been 



* From two Greek words, slgmfy'wg pitch and wax. 



