TEANSFORIVIATION OF INSECTS. A 



Now, the upper and lower portions of these rings are cobi- 

 paratively ine'iastic, and cannot themselves expand, thougu 

 tliey can be opened wider at the sides in proportion to the 

 interior expansion of the body. IMeanwhile, the larva continues 

 busily its sole business, that of eating, and increases rapidly ir- 

 size, so that, within a certain time, its skin is stretched to the 

 utmost, and can expand no more. • SV A ' ae larva continues t(^ 

 increase, though its tight integuments, v-ause it so much un- 

 easiness that it ceases to eat, and at last the overstretched 

 skin bursts, and the larva emerges, clad with a new skin, which 

 has been forming imder 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 tlian its cast skin, that to put 

 it back again would be fatal. This process 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 larger 

 have not grown since their last change, nor will the small 

 specimens ever attain the dimensions of tlieir larger relatives. 

 In a measure, the same rule prevails among mankind, and. 

 though some may be giants and other dwarfs, the dwarf will 

 never become a giant, nor has the giant ever been a dwarf, and. 

 different as are their sizes, both ceased to grow when they 

 attained the age of manhood. 



The modes of passing through the successive changes of form 

 are exceedingly variable in the different orders of insects, and 

 are alwavs most interesting^ to careful observers. I shall not 

 mention them in this place, but shall give the descriptions of 

 the metamorphoses together with the history of the different 

 species. 



Next in order comes the statement that all true insects 

 have six legs when they have attained the perfect form, or 

 Imago. The reader will see that this definition at once ex- 

 cludes all other Annulata. The Crustacea, for example, have 

 a considerable number of legs, and the Arachnida are eight- 

 legged, while tlie Myriapoda are, as their name infers, many- 

 and tlie Annelida have no legs at all. It is true 



