58 POND LIFE 



each little worm is able to store up some of the oxygen it 

 obtains by means of the red substance Haemoglobin to 

 which its colour is due. Life among these little worms is one 

 of activity, for some of the members are always either making 

 or leaving a home. It often happens that a larva settles near 

 to a burrow tenanted by another member of its family. Then 

 a most amusing incident occurs, the new comer gradually 

 makes its way in, whilst the owner most unwillingly makes its 

 way out, and probably fearing that the visitor is purely on 

 business bent, hesitates not but swims away to a fresh spot, 

 where it either plays the same game on some other unfortunate 

 larva, or else rapidly weaves a few pieces of mud and decaying 

 leaves together to form a fresh home. If a large number 

 of these larvae are present in a small pool they will gradually 

 arrange the mud in so many little heaps, that gives a most 

 curious effect. Whilst at home they are by no means sleeping, 

 but are continually undulating so as to produce a constant 

 stream of water through their habitat, and at times they vary 

 the monotony by pushing their tail-end out and waving it 

 to and fro, in order to obtain any free oxygen that is present 

 in the surrounding water. Every now and again the head end 

 makes its appearance, and after making a quiet survey of the 

 neighbourhood and having collected any mud that it may 

 require, by means of its clawed feet, withdraws again. Its feet, 

 which are furnished with several claws, are well suited for 

 collecting debris. The head is supplied with a most complex 

 set of hooks, spines, teeth, &c., some of which are probably used 

 whilst engaged in the weaving operations. The Chironomous 

 larva, like all other larva, not only lives, but lives well, until it 

 changes into the pupa, which remains in the mud at the bottom 

 of the pond. The pupa of Chironomous bears a slight super- 

 ficial resemblance to the pupa of Culex (gnat)and Corethra, but 

 is black in colour, and has curious tufts of " hair " on the head 

 portion. These tufts, which take the place of the pair of 

 " horns " in Culex, are respiratory tubes. The changing from 

 the pupa to the imago is a thing of surprising rapidity. Firstly 

 the pupa rises without effort to the surface, owing to the fact 

 that its skin has become well filled with air, which it extracted 

 from the water towards the end of the pupa stage. In fact so 

 low is its specific gravity, owing to the collected air, that the 

 pupa is totally unable to sink, even if it wishes to. Within a 

 few seconds from the moment it reaches the surface the case 

 begins to split, and the adult fly gradually comes farther and 

 farther out. There is no hitch of any kind, no struggle, but 

 simply a continual movement. No sooner are the head and 



