298 NATURAL HISTORY. [CH. XXIII, 



ments of which are, of course, completely hollow. 

 There is still another variation in the nature of the 

 transformations of the insects of this order, which 

 occurs not in the changes themselves, but in the 

 situations in which they are undergone. Thus 

 some species of flies, as the blowfly, hatch their 

 eggs previous to their exclusion from the body; 

 while others, as the forest-flies, retain the larva, not 

 only until they are full grown, but until they have 

 assumed the pupa state, at which period, from their 

 large size, one only is capable of being produced at 

 a time. 



CHAPTER XXIII. 



HINTS FOR STUDENTS. 



Collection of Insects — Charge of Cruelty considered — Advantages 

 of the Study of Entomology — Number of Species — Means of 

 obtaining a Knowledge of Forms and Classification — Number of 

 Generic Divisions — Terms — Instruments for collecting — Easiest 

 Modes of putting to Death, <^c. — Localities of Insects — Store- 

 Boxes. 



Having given a series of the histories of various 

 insects, some of our readers might, after their peru- 

 sal, from the singularity of the facts therein stated, 

 be induced to pursue further the interesting and 

 healthy science of entomology — a science which 

 cannot but cause the most lively interest, as it opens 

 the road to a still higher and more advantageous 

 result than the mere study itself, by the expansion 

 of the mind to the contemplation of the wisdom 

 and power of Him who caused all created beings to 

 exist. 



Many objections have been raised against this at- 

 tainment of a knowledge of the habits and economy 



