I METAMORPHOSES OF INSECTS 21 



which regulate the removal of the old and the deposi- 

 tion of new matter in the bones and other structures 

 of vertebrates. 1 



The modifications of the outsides are not more 

 remarkable than the changes that take place in 

 the internal organs during progressive development. 

 Many persons do not think that a larva has any 

 internal organs at all. They hold the opinion of 

 the gentleman who once confessed his belief to the 

 well-known naturalist, the late Mr. Wood, that a 

 caterpillar is " nothing but skin and squash." In 

 fact, larvae live only for eating, so that their 

 inward arrangements consist almost entirely of 

 the digestive system, which in many is scarcely 

 more than an elongated tube or sac very much 

 dilated, serving as a most capacious stomach. As 

 such it exists in the apodous * larvae of some 

 of the bee family. In other members of the order 

 it is more complicated, and it would be pos- 

 sible to go through a list of larvae whose digestive 

 organs gradually rise in the scale of importance, 

 until they become fairly developed and the simple 

 tube begins to assume the intricacies that it possesses 

 in perfect insects. Turning to the latter, the form 

 of the system is not more indicatory of the habits 

 of the species than in larvae. Regarding it in a 

 general way, the alimentary canal becomes a long 

 convoluted organ, and shows certain swellings and 

 constrictions, which mark its division into several 

 compartments. Each exhibits distinct difference 

 of texture and is adapted to peculiar function, 



1 Newport. 



