12 



TRANSFORMATIONS OF INSECTS. 



branous space is to be observed on either side of the body between 

 them. Moreover, each arch is formed of two side halves, and 

 there is often a very distinct hne of separation to be noticed 

 between the portions of the arches, and also a mark which occu- 

 pies this position on the head and along every segment of the 

 body of the grub or caterpillar. This middle or median line is 

 well seen in the immature Calosoina sycophanta. {See page 15.) 



The segments of the abdomen, which are not provided with 

 true legs, appear to be at first nine in number, and there are 

 some larvae which have twelve or more of them. Now, on com- 

 paring the segments of the larva, chrysalis, and perfect insect of 

 the same species, it is noticed that the changes in the form of the 



CHRYSALIS OF Sphhix ligustri. 



insect are not brought about by an alteration in the consistence 

 of the integuments only, but by a diminution in the number of 

 the rings or segments. It is true that this diminution is rather 

 deceptive in its appearance, for there has not been any fading 

 away of the segments, but really a union and a consolidation of 

 several in one or more single and separate pieces. Thus it is not 

 uncommon for the first rings of the abdomen to become united 

 to the last segment of the thorax or body, or for several of them 

 to conjoin and leave very faint traces of their former distinctness. 



Take as an example a kind of lepidopterous insect — a moth — 

 whose metamorphosis, so far as regards the shape of the caterpillar 

 and perfect insect is less than is usual. The large Attacns pavonia 

 major is admirably adapted for our purpose. 



The abdomen of the caterpillar commences at the fourth seg- 

 ment of the body, as in all other insects, and is formed of nine nearly 

 equal rings ; the last but one is, however, shorter than the others, 



