46 Insect Architecture. 



in her jealous caution, for she would alight on the tiles as 

 if to rest herself ; and even when she had entered the coal- 

 house, she did not go directly to her nest, but again rested 

 on a shelf, and at other times pretended to examine several 

 crevices in the wall, at some distance from the nest. But 

 when there was nothing to alarm her, she flew directly to 

 the spot, and began eagerly to add to the building. 



It is in instances such as these, which exhibit the adapta- 

 tion of instinct to circumstances, that our reason finds the 

 greatest difficulty in explaining the governing principle of 

 the minds of the inferior animals. The mason-bee makes 

 her nest by an invariable rule ; the model is in her mind, 

 as it has been in the mind of her race from their first crea- 

 tion : they have learnt nothing by experience. But the 

 mode in which they accomplish this " task varies according 

 to the situations in which they are placed. They appear to 

 have a glimmering of reason, employed as an accessary and 

 instrument of their instinct. 



The structure, when finished, consisted of a wall of clay 

 supported by two contiguous bricks, enclosing six chambers, 



Cells of Mason-Bees, built, in the first and second figures, by Osmia bicornis between 

 bricks, and in the third, by Megachile muraria in the fluting of an old pilaster. About 

 half the natural size. 



within each of which a mass of pollen, rather larger than a 

 cherry-stone, was deposited, together with an egg, from 

 which in due time a grub was hatched. Contrary to what 

 has been recorded by preceding naturalists with respect to 

 other mason-bees, we found the cells in this instance quite 



