FOURTH WEEK] May 121 



however, are found out upon the ocean, where the tiny 

 creatures row themselves cheerfully along. It is thought 

 that they attach their eggs to the floating sargassum sea- 

 weed. If only we knew the whole life of one of these 

 ocean water striders and all the strange sights it must see, 

 a fairy story indeed would be unfolded to us. 



However, all the Lilliputian craft of our brooks are not 

 galleys ; there are submarines, which, in excellence of action 

 and control, put to shame all human efforts along the 

 same line. These are the water boatmen, stout boat- 

 shaped insects whose hind legs are long, projecting outward 

 like the oars of a rowboat. They feather their oars, too, 

 or rather the oars are feathered for them, a fringe of long 

 hairs growing out on each side of the blade. Some of the 

 boatmen swim upside down, and these have the back 

 keeled instead of the breast. Like real submarine boats, 

 these insects have to come up for air occasionally; and, 

 again like similar craft of human handiwork, their principal 

 mission in life seems to be warfare upon the weaker 

 creatures about them. 



Upon their bodies are many short hairs that have the 

 power of enclosing and retaining a good-sized bubble of 

 air. Thus the little boatman is well supplied for each 

 submarine trip, and he does not have to return to the 

 surface until all this storage air has been exhausted. In 

 perfectly pure water, however, these boatmen can remain 

 almost indefinitely below the surface, although it is not 

 known how they obtain from the water the oxygen which 

 they usually take from the air. 



All of these skaters and boatmen thrive in small aqua- 



