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 tracheae 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 oesophagus, 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 coeca, 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. 



