CHARACTERISTICS OF INSECTS. 31 



spiders, scorpions, etc., etc.; the Ilyriapoda, con- 

 taining scolopenclres, centipedes, etc. ; and, lastly, 

 Insects. 



With the exception of the Annelids, these tribes 

 might all he included within the realm of Entomo- 

 logy — the lobster and spider sections having both 

 the well marked character of the insection, while 

 the Myriapods show a repetition of a similar 

 method of structure throughout the whole length of 

 their bodies, which are, in fact, formed of a series of 

 such intersections. There are, however, certain 

 characteristics, especially those connected with the 

 metamorphosis which place true insects in a very 

 distinct class. 



All true insects, with a few insignificant ex- 

 ceptions, undergo, after coming from the egg, meta- 

 morphoses or changes analogous to those which, in 

 other classes of animal life, take place in the egg 

 state, or a corresponding epoch. This difference is 

 so striking, that Swammerdam, one of the most 

 illustrious anatomists and physiologists of any 

 age, founded his system of insect classification 

 entirely on the kind of metamorphosis to which 

 they were subject, almost without reference to the 

 anatomical structure ; and so strong was his con- 

 viction on this point, that he committed the ridi- 



