THE BEHAVIOUR OF INSECTS 125 



she must needs build, even if her labour be superfluous 

 and contrary to her interests. The cell I give her is 

 certainly quite complete in the opinion of its own con- 

 structor, since the bee from whom I subtracted it was 

 finishing the store of honey. To touch it up, and, above 

 all, to add to it is useless and absurd. All the same the 

 bee which is building will build. On the orifice of the 

 honey store she lays another layer of mortar, then another 

 and another, until the cell is actually a third beyond its 

 usual height. Now the task is done — not as well indeed 

 as if the bee had continued the cell whose foundations 

 she was laying when the nests were exchanged, but cer- 

 tainly in a way more than enough to demonstrate the 

 irresistible impulse which drove the builder on. Then 

 came the storing, likewise abridged, for otherwise the 

 honey would overflow by the union of the stores of two 

 bees. Thus the mason bee, which is beginning to build, 

 and to which one gives a cell completed and filled with 

 honey, alters nothing in the order of her work. First she 

 builds and then she stores ; only she shortens her labours 

 — instinct warning her that the height of the cell and 

 quantity of honey are beginning to assume proportions 

 too great." 



The concluding words of this passage introduce us to 

 another aspect of insect behaviour. We perceive that 

 the instincts of an insect, inflexible in the main, may 

 nevertheless prove capable of some adjustment. They 

 are not, as is sometimes stated, absolutely " blind." In- 

 deed, an action can be regarded as purely instinctive in 

 its initial performance only. Thereafter, the factor of 

 experience must be taken into account ; and it is by no 

 means easy to determine what part of a given action may 

 be due to instinct and what to memory. One point, 

 however, is clear. Instinct does not grow into intelli- 



