INSECT TRANSFORMATIONS. 141 



detaching with a knife their silken buttons of suspension, to 

 stick them by the same, with a thread girth round the body, to 

 the upper edge of a deep-sided box; then placing this 

 beside us on the table, we shall hardly fail by an occasional 

 glance to have our curiosity gratified in their emergement under 

 our own eyes. 



We must remember that, like the embryo of a plant in the 

 seed, or the rudiments of a leaf or flower in the bud, the various 

 parts of the butterfly have been pre-existent even in the cater- 

 pillar ; and when these are arrived at their full maturity within 

 heir chrysalis cover, then approaches the crisis of emergement. 

 At this period there takes place a violent agitation in the fluids 

 of the insect, 1 by which they are driven from the internal 

 vessels into all the tubes and nervures of the wings, which 

 being at the same time filled with air from the wind-pipe, in- 

 crease considerably in size. This, added to the restless motion 

 of the legs, soon enables the imprisoned creature to burst its 

 enshrouding skin, which, flying open at the back, discloses, 

 the head and shoulder of the butterfly. Being then soon re- 

 leased entirely, it stands for awhile, motionless, on the broken 

 fragments of its late prison its wings damp and drooping, 

 small and crumpled ; but distended by the fresh supply of air, 

 inhaled through the spiracles, they expand so rapidly, that in 

 the space of a few minutes their dimensions are increased 

 five-fold! 



Directly after emergement, the wings are thick, and capable 

 of great extension by stretching, but not so after full expansion ; 

 neither do butterflies or other winged insects ever grow, when 

 they have once attained their perfect form. 



Besides that of the common White, or Cabbage, 2 the coming 

 out of the small Tortoiseshell Butterfly, 3 may also now or early 

 in June be easily observed. The gilded chrysalides of this also 

 common but very beautiful insect, are now, and again in August, 

 to be found almost everywhere, suspended head downwards, 



1 Insect Transformations. 3 Pontia brassica, &c. 3 Vanessa urtica. 



