42 HYMENOPTERA CHAP. 



appropriate stages of its labours whether the result of so doing 

 be beneficial or injurious, yet it is nevertheless to some extent 

 controlled by the circumstances, for it does not in such cases 

 complete what should have been the full measure of its own 

 individual work : it does not, for instance, raise the cell to twice 

 the natural height, but stops building when the cell is about 

 one-third larger than usual, as if at that stage the absurdity of 

 the situation became manifest to it. 



Fabre's experiments with the Chalicodoma are so extremely 

 instructive as regards the nature of instinct in some of the 

 highest Insects, that we must briefly allude to some other of his 

 observations even at the risk of wearying the reader who feels 

 but little interest in the subject of Insect intelligence. 



Having discovered that a mason-bee that was engaged in the 

 process of construction would go on building to an useless or 

 even injurious extent, Fabre tried another experiment to ascer- 

 tain whether a bee that was engaged in the process of provision- 

 ing the nest, would do so in conditions that rendered its work 

 futile. Taking away a nest with completely built cell that a bee 

 was storing with food, he substituted for it one in which the cell 

 was only commenced, and therefore incapable of containing food ; 

 when the bee with its. store of provisions reached this should-be 

 receptacle it appeared to be very perplexed, tested the im- 

 perfect cell with its antennae, left the spot and returned again ; 

 repeating this several times it finally went to the cell of 

 some stranger to deposit its treasure. In other cases the bee 

 broke open a completed cell, and having done so went on bringing 

 provisions to it, although it was already fully provisioned and an 

 egg laid therein : finally, the little creature having completed 

 the bringing of this superfluous tale of provisions, deposited 

 a second egg, and again sealed up the cell. But in no case 

 does the bee go back from the provisioning stage to the build- 

 ing stage until the cycle for one cell of building, provisioning, 

 and egg-laying is completed : but when this is the case, the 

 building of a fresh cell may be again undertaken. This is a 

 good example of the kind of consecutive necessity that seems 

 to be one of the chief features of the instinct of these industrious 

 little animals. Another equally striking illustration of these 

 peculiarities of instinct is offered by interfering with the act of 

 putting the provisions into the cell. It will be recollected that. 



