384 NATURE'S TEACHINGS. 



The Water-spider is really a remarkable being. Itself a 

 denizen of air, breathing our earthly atmosphere just as we do, 

 and as capable of being drowned as ourselves, it nevertheless 

 passes nearly the whole of its existence under water, and in that 

 strange locality lays its eggs and rears its young. How this 

 wonderful feat is performed we shall now see. 



When the female Water-spider wishes to deposit her eggs, 

 she looks out for a suitable locality, and, being a good diver, 

 tests the various aquatic herbage until she has found a favour- 

 able spot, and then sets to work on her remarkable nest, which 

 I believe is quite original in zoology. 



After stretching a few stout threads by way of a scaffolding, 

 she attaches to the plant a small silken cell, shaped very much 

 like an acorn, but not so large. Ascending to the surface of the 

 water, she contrives to clasp a bubble of air between her last 

 pair of legs, and, laden with this airy treasure, dives below. 



As soon as she has reached the entrance to the cell, which is 

 always below, she loosens her hold of the air-bubble. It at once 

 rises into the cell, and expels a proportionate amount of water. 

 Not many of these journeys are required before the nest is 

 filled with air, and then the diminutive architect spends the 

 greater part of its time in holding on to the mouth of the little 

 diving-bell, and supporting life by means of the air within it. 



This nest, as the reader will see, is an exact representation 

 of the various diving schemes in which air-bells are the chief 

 portions of the machinery, although the air is conducted into 

 them after a different fashion. 



WE now come to another mode of diving, in which the bell 

 is practically superseded by the flexible tube, which allows to 

 the diver far more range than can be obtained by the bell. In 

 this case the diver wears a peculiar dress, the chief part of 

 which is a helmet so constructed that air can be introduced to it 

 from above the surface of the water, and, after respiration, can 

 escape by means of a valve. 



Air is pumped into the tube by assistants above water, and, 

 as the tube is long and elastic, the diver can move about with 

 considerable freedom. As is the case with the diving-bell, the 

 diver's tube is strengthened by an internal spiral wire, so that 

 it is always open, however it may be bent or twisted. 



