THE CATERPILLAR. 



entire body, which fairly rests upon the sur- 

 face of motion. 



Another peculiarity of the body is a series of 

 breathing-pores upon the sides, through which 



the air enters certain 

 tubes ramifying within 

 for the aeration of the 

 blood ; there is but one 

 of these spiracles or 

 stigmata upon either 

 side of any segment, 

 and they are absent 

 from the second and 

 third thoracic and from 

 the last two abdominal 

 segments ; it would ap- 

 pear therefore that the narrowing hinder por- 

 tion of the body can be supplied with air from 

 the segments in advance ; but the absence of 

 spiracles from what is ordinarily the stoutest 

 part of the body, the centre, too, of the great- 

 est variety and largest development of internal 

 organs, requires another explanation ; and it is 

 to be found only in the fact that the spiracles 

 are absent from these same segments in the per- 

 fect insect, where they would interfere with the 

 special purpose of this part of the body, viz., the 

 support of the wings and of the apparatus 

 for their vigorous movement. Here we have a 



: 



FIG. 25. Caterpillar of Heodes 

 Hypophlaeas, nat. size. 



