LARVAL GROWTH. 



of skin is evident. The larva, like the perfect insect, 

 is made of a series of flattened rings, or rather, of a 

 double series of half rings, connected along the sides 

 by an elastic membrane, so as to permit the creature 

 to breathe and eat. 



Now, the upper and lower portions of these rings 

 are comparatively inelastic, and cannot themselves 

 expand, though they can be opened wider at the sides 

 in proportion to the interior expansion of the body. 

 Meanwhile, the larva continues busily its sole business, 

 that of eating, and increases rapidly in size, so that, 

 within a certain time, its skin is stretched to the 

 utmost, and can expand no more. Still the larva 

 continues to increase, though its tight integuments 

 cause it so much uneasiness that it ceases to eat, and 

 at last the overstretched skin bursts, and the larva 

 emerges, clad with a new skin, which has been form- 

 ing under the old one. As soon as it is free, it takes 

 a number of deep respirations, and in half an hour, or 

 thereabouts, is so much larger than its cast skin, that 

 to put it back again would be impossible. This pro- 

 cess is repeated until the larva is about to assume the 

 third or pupal state. 



In consequence of this mode of development, the 

 whole of the growth is completed during the larval 

 state, and, however long an insect may live, it never 

 grows after it has attained its perfect form ; and, 

 though it is common enough to find insects though of 

 the same species yet of very different sizes, the largest 

 have not grown since their last change, nor will the 

 small specimens ever attain the dimensions of their 

 larger relatives. In a measure, the same rule prevails 



