88 MORE MINOR HORRORS 



as they can be closed by floating petrol or 

 other oil on the surface of the water — and 

 ' the trick is done.' The larvae and the 

 pupae can no longer breathe, and there is thus 

 no imago to " carry on." In Culex (the gnat),, 

 these respiratory orifices are borne on a long 

 tube directing dorsalwards — a tube which is 

 larger and longer than a segment of the body, 

 and whose presence gives the larva the appear- 

 ance of a Y with slightly unequal limbs. 

 These breathing-openings are of the greatest 

 complexity, but the outstanding fact is that 

 these stigmata pierce through the watery 

 film and put the respiratory system of the 

 larva into communication with the atmosphere 

 of the whole cosmos. If anything frightens 

 the larva, certain side -pieces and flaps fold 

 suddenly backwards and over the stigmata, 

 the connexion through the surface-film is 

 broken, and the little larva, like a German 

 submarine when it sights an English battle- 

 ship, darts below, frequently carrying with 

 it the drop of air attached to the rim of the 

 respiratory recess which surrounds the open- 

 ings of the two stigmata. 



Not infrequently the larva ceases to lie 

 parallel to the surface of the water, its 

 palmate hairs are put out of action, and then 

 its body hangs down into the water, but it 

 still maintains its respiratory connexion with 



