140 CELL INTELLIGENCE THE CAUSE OF EVOLUTION 



eral times until the little house is full of air. Of course 

 the open end of this house is down and this has to act also 

 as the entrance to it. In the little water-house the spider 

 spends the winter and rears its young ones. The house 

 also acts as a lair from which the spider can jump on un- 

 suspecting prey. 



"Another peculiar thing about the Naiads is that they 

 never get wet. They have thousands of small hairs on 

 their bodies which hold and keep the air from being 

 washed off when they enter water and so the air sticks 

 and water cannot approach. 



Scientists are acquainted with many other insect engi- 

 neers, but with none that approach Naiads in intelligence 

 and skill. The Water Beetle is probably the only other 

 one in their class. It builds a water-proof nest under 

 water, but does not live in it. It merely lays its eggs in 

 the nest, seals it up and leaves. 



The Mason Bee is as his name implies a builder of 

 structures of stone and mortar. The nest is attached to 

 almost any solid structure and actually does consist of 

 small stone, cemented together with mortar. The house 

 consists of many cells of oval shape, and into each an 

 egg is laid. The cell is lined with silken web by the 

 mother who gets out of it by holding its top. Before 

 leaving, however, she hermetically seals up the cell and 

 leaves the youngster to its fate. 



"However, such are the arrangements of nature. As 

 soon as he gets to feeling his oats and consumes the food 

 left him by the mother he finds himself supplied with 

 tools hard and sharp enough to cut through the walls to 

 freedom. 



"A member of this family found in England makes his 

 own bricks, selecting brown clay for the purpose, which 

 he mixes with saliva, rolls into small balls which soon 



