A LARGE GRASSHOPPER ii 



called the fat body, which covers the viscera. Remove this care- 

 fully. The alimentary canal will be disclosed, a large tube running 

 through the median axis of the body ; above its abdominal por- 

 tion 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, 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 11. Make a sketch of the animal on a scale of 5, showing 

 the internal organs, 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 sur- 

 rounding tissues with a needle. Identify the following divisions 

 of the alimentary canal : (i) the pharynx, the space just back of 

 the mouth ; (2) the oesophagus, the narrow tube which runs up- 

 ward from the pharynx and, bending back, enters the thorax, 

 where it enlarges to form a pouch called the crop ; (3) 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 ; (4) the 

 gastric caeca, eight elongated sacs which encircle the base of the 

 crop; (5) the stomach, a large tube which extends back to the point 

 where the delicate urinary, or Malpighian, tubules join the alimen- 

 tary canal ; (6) the intestine, the hinder portion of the alimentary 

 canal, which ends at the anus and is made up of three divisions. 



The Excretory System. The kidney of the insect consists of 

 the Malpighian tubules. These are delicate, tubular glands, 

 about fifty in number in the grasshopper, which unite with the 

 alimentary canal and discharge their products into it at the point 

 of juncture of the stomach and the intestine. They extend freely 

 into the body cavity and excrete urinary wastes from the blood, 

 in which they lie immersed. 



Exercise 12. Make a drawing of the alimentary canal and the Mal- 

 pighian tubules on a scale of 7 and label all of the parts. 



