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CHAPTER V. 
ANATOMY AND PHYSIOLOGY. 
ABDOMEN. EXTERNAL SKELETON. MUSCLES. RESPIRATORY SYSTEM. 
SOUNDS PRODUCED BY INSECTS. ORGANS OF CIRCULATION. NERVOUS 
SYSTEM. 
WE turn next to the abdomen, the third great divi- 
sion of the insect body. The external conformation 
of this part in the Vespz is very characteristic of the 
family. It is cylindrical, tapermg towards each end. 
At the caudal extremity it runs on to a point, but 
forwards the abdomen suddenly contracts into a 
narrow stalk called the pedicle. The wasp is not 
more proverbial for the quickness of her temper than 
for the slenderness of her waist. In some of the 
solitary species, this pedicle is longer, and scarcely 
thicker, than the tibie of the imsect, swelling out 
gradually into the first rmg of the abdomen. In the 
Vespe it is short, and does not gradually expand into 
the first abdominal ring, but springs out almost at a 
right angle; the square truncated end of the abdomen 
being one of their typical characters. 
Four of the thirteen segments of the larva have 
been already accounted for; namely, one in the con- 
struction of the head, and three in that of the thorax. 
The fifth segment makes the pedicle which unites the 
thorax to the abdomen. This tube, so slight in 
