THE BEETLE. 



143 



The functions of 

 circulation and of 

 respiration are ac- 

 complished in in- 

 sects in the most 

 simple manner. Ex- 

 cepting a movement 

 that is visible in a 

 vessel located in the 

 region of the back, 

 called the dorsal ves- 

 sel, there is, so to say, 

 no circulation ; the 

 blood penetrates into 

 the organs .as water 

 soaks into a sponge, 

 and appears to be 

 stagnant in the la- 

 cunae of the tissues. 

 Nevertheless, this 

 blood, like that of 

 man and other higher 

 animals, must be 

 aerated by contact 



DIGESTIVE APPARATUS OF THE 

 MAY-BUG. a, antennae; p, 

 maxillary palps ; te, cesoph- 

 agus and craw ; e, stomach ; 

 t, intestine ; r, rectum ; m t 

 Malpighian tubes. One of 

 these tubes is in its natu- 

 ral position, close to the 

 digestive apparatus; the 

 other has been removed to 

 show its structure. 



FIG. 77. 



