INSECTS 



283 



by a series of moults, acquiring at each certain of the 

 ... „ . adult organs. This occurs in the cockroach 



Life-Histories. , . & . , . , T 



and insects related to it, in bugs, etc. In 

 other cases the young differ considerably from the adult, 



and the change from one to the other takes place at a 

 definite stage in the life-history. A young animal which 



19 



