THE DEVELOPMENT OF INSECTS 125 



dages ; by limbs are meant its wings, legs, horns 

 or antennae, jaws or mandibles, etc. : strip these all 

 off, and we have a limbless trunk, which many 

 would not recognize as belonging to an insect 

 at all ; still this limbless trunk possesses char- 

 acters which assert its insect nature, as it may 

 be known from other limbless trunks by being 

 divided into three parts by two great transverse 

 divisions ; in most insects these are extremely 

 well marked, and in all they have a very 

 real existence. The parts thus divided off are 

 known by the names of head, thorax, and 

 abdomen. Anybody knows how easy it is to 

 break off the head or body of a dried insect. Now 

 the head or body breaks off at one of these 

 divisions, and it is this partitioning of the body 

 into three sections which makes one of the 

 strongest characters in the definition of an insect. 

 The three parts, thus divided off, each possesses 

 special functions in the life of the creature. 

 In the head are contained the principal organs of 

 sense and brain ; in the thorax, the organs of 

 locomotion ; and in the body those of digestion, 

 reproduction, etc. 



This division into three parts does not however 



