A GRASSHOPPER 15 
which hold it to the body-wall. Immediately beneath the heart 
is a loose network of yellowish fatty tissue, called the fat-body, 
which covers the viscera. Remove this carefully. The alimen- 
tary canal will be disclosed, a large tube running through the 
median axis of the body; above the abdominal portion are the 
paired reproductive glands, from which a duct passes on each 
side around the alimentary canal to the ventral side of the 
animal. Notice the silvery air-tubes or trachee and the air-sacs 
on each side of the alimentary canal ; also observe the tangled 
mass of delicate brown threads, the urinary or Malpighian 
tubules, between the reproductive glands and the alimentary 
canal. 
Exercise 13. Make a sketch of the animal on a scale of 5, show- 
ing the internal organs in situ, and label them all. 
The digestive system. With fine scissors sever the alimentary 
canal at its extreme posterior end, where it joins the anus. 
With great care draw it forward between the ducts of the 
reproductive organs and from beneath those organs, loosening 
it from the surrounding tissues with a needle. Identify the 
following divisions of the alimentary canal: the pharynx, the 
space just back of the mouth; the esophagus, the narrow tube 
which runs upward from the pharynx and, bending back, 
enters the thorax, where it enlarges to form a pouch called the 
crop; the salivary glands, a pair of delicate, branched organs, one 
on each side of the crop, the ducts of which run forward to the 
pharynx; the gastric ceca, eight elongated sacs which encircle 
the base of the crop; the stomach-intestine, a large tube which 
extends back to the point where the delicate urinary or 
Malpighian tubules join the alimentary canal; the ileum, a 
thick tube the diameter of which is the same as that of the 
stomach; the colon, a narrow, slightly coiled tube; and the 
rectum, which has six ridge-like rectal glands along its sides and 
opens into the anus. 
