Economy of Energy 



rear-wall of another chamber, which Is first 

 victualled and then closed; and so on until the 

 cylinder is sufficiently colonized and receives a 

 thick terminal stopper at its orifice. In a 

 word, the chief characteristic of this method 

 of nest-building, the roughest of all, is that the 

 partition in front is not undertaken so long as 

 the victualling is still incomplete, or, in other 

 words, that the provisions and the egg are 

 deposited before the Bee sets to work on the 

 partition. 



At first sight, this latter detail hardly de- 

 serves attention: Is it not right to fill the pot 

 before we put a lid on? The Osmla who 

 owns a medium-sized reed is not at all of this 

 opinion; and other plasterers share her views, 

 as we shall see when we watch the Odynerus^ 

 building her nest. Here we have an excellent 

 illustration of one of those latent powers held 

 in reserve for exceptional occasions and sud- 

 denly brought into play, although often very 

 far removed from the insect's regular 

 methods. If the reed, without being of inor- 

 dinate width, from the point of view of the 

 cocoon, is nevertheless too spacious to afford 



^A genus of Mason-wasps, the essays on which have 

 not yet been translated into Englhh.— Translator's Note. 



215 



