Bramble-bees and Others 



portion to the number of those partitions, in 

 whatever manner the exit be effected. 



But there is another task which we must 

 take seriously into consideration, because it is 

 often more troublesome than the boring of 

 the partition: 1 mean the work of clearing a 

 road through the wreckage. Let us suppose 

 the partitions pierced and the several cham- 

 bers blocked by the resulting rubbish and by 

 that rubbish only, since the horizontal position 

 precludes any mixing of the contents of differ- 

 ent chambers. To open a passage for itself 

 through these rubbish-heaps, each insect will 

 have the smallest effort to make if it passes 

 through the smallest possible number of cells, 

 in short, if It makes for the opening nearest 

 to It. These smallest individual efforts 

 amount, In the aggregate, to the smallest total 

 effort. Therefore, by proceeding as they did 

 in my experiment, the Osmiae effect their exit 

 with the least expenditure of energy. It Is 

 curious to see an insect apply the "principle of 

 least action," so often postulated In mechanics. 



An arrangement which satisfies this prin- 

 ciple, which conforms to the law of symmetry 

 and which possess but one chance In 5 I2 Is cer- 

 tainly no fortuitous result. It is determined 



45 



