ioo INSECT ARTIZANS AND THEIR WORK 



dust. Taking a little of this material, she mixes it 

 with a salivary secretion, and forms it into a ring 

 around the wall of her shaft about three-quarters 

 of an inch from the bottom. When this is set 

 firm she constructs a similar ring within the cir- 

 cumference of the first, and so on until she has a 

 complete floor about an eighth of an inch in thick- 

 ness, marking off her lowest cell. Upon this she 

 lays another egg and piles up another heap of 

 provisions ; makes a second floor, and repeats 

 these operations until there are about a dozen 

 separate cells one above another from the base to 

 the summit of her shaft, each with its egg and food. 



If the thickness of the post is sufficient, several 

 parallel shafts are made. Fabre has shown that if 

 she can obtain a hollow reed of the necessary 

 thickness, she has sufficient of the labour- avoiding 

 spirit to be content with it. She will also repair 

 nests of previous years to make them serve for her 

 brood. 



It will be evident that the elaboration of these 

 floors from sawdust, and the gathering of food for 

 such cell must consume some time, so that the 

 larva in the lowest cell must finish its development 

 before the one next above it in this tenement- 

 house. If the first fledged had to emerge where 

 the mother bee began her labours, at the top of 

 the shaft, it would have to pierce through all the 

 floors and incidentally, perhaps, through several 

 of its brothers and sisters before it could gain 

 its liberty. This is the reason why the Carpenter 



