THE BOOK OF NATURE STUDY 



inside the tube, or projects its head to procure food, or waves its 

 tail about so as to change the water around it and so assist respira- 

 tion. At times the larva quits its tube and swims through the 

 water with a peculiar lashing movement, re- 

 peatedly bending the body into the shape of 

 the letter S. The red colour of the blood- worm 

 is due to the presence of a colouring matter 

 called haemoglobin the same as occurs in the 

 red corpuscles of our own blood. This substance 

 has an especial power of combin- 

 ing with oxygen and of giving it 

 up to the tissues of the body. 

 It is only found in those species 

 of chironomus which do not live 

 ij|| at the surface, and is doubtless 

 of great importance in enabling 

 the deeper dwellers to make full 



(M/H use ^ ^ e scan ^ er supplies of 

 oxygen in their neighbourhood. 

 The little worm Tubifex possesses 

 the same substance, and has the 

 same habit of waving its tail to 

 and fro in the water above its 

 burrow. 



The larva has twelve segments 

 behind the head. The head bears 

 a pair of short antennae, two 

 pairs of black eye-spots, a pair of 



, J r ,., , FIG. 16. Side view 



strong, ]agged mandibles, very of pupa of chiro . 

 rudimentary maxillae, and a flat nomus. (After 

 crescentic labium or lower lip MialL ) 

 (second maxillae), whose edge is provided with 

 FIG. 15. Larva of teeth of several different and peculiar shapes. 



wings and legs remarkable array of hooks and bristles, which 



of the imago are are thought to be of service in directing the silk 



tTe^trva^Tin threads used in the construction of the tube. 



(After Miaii.) The appendages of the body are few ; the pro- 



