I02 The H tinting IVasps 



ing the insect's chromatic evolution is easily 

 gathered from this brief sketch. We see that, 

 with the exception of the eyes and the ocelli, 

 whose early development recalls what takes 

 place in the higher animals, the starting-point 

 of the coloration is a central spot, the meso- 

 thorax, whence it gradually invades, by centri- 

 fugal progression, first the rest of the thorax, 

 then the head and abdomen, lastly the different 

 appendages, the legs and antennae. The tarsi 

 and the mouth-parts colour later still ; and the 

 wings do not assume their hue until after they 

 are taken from their cases. 



We now have the Sphex arrayed in her 

 livery. She has yet to cast her nymphal 

 wrapper. This is a very fine tunic, moulded 

 exactly in accordance with the smallest struc- 

 tural details and scarcely veiling the shape and 

 colours of the perfect insect. As a prelude to 

 the last act of the metamorphosis, the Sphex, 

 suddenly shaking off her torpor, begins to move 

 about violently, as though to call her long- 

 numbed limbs to life. The abdomen is alter- 

 nately lengthened and shortened ; the legs are 

 abruptly extended, then bent, then extended 

 again ; and their different joints are stiffened 

 with an effort. The insect, using its head and 

 the tip of its abdomen as a lever, with the 

 ventral surface underneath, repeatedly distends 



