54 INSECTS. 



2. The esophagus dilates posteriorly to form the inglu- 

 vies (or crop), a large food reservoir, and an important 

 organ of digestion. Its interior surface is furnished with 

 many ridges and conical processes which aid in commi- 

 nuting the food. 



3. On the sides of the esophagus lie the delicate, white, 

 branching salivary glands. These communicate with the 

 mouth by means of two salivary ducts that run forward 

 along the sides of the esophagus. 



4. The proventriculus (or gizzard) is the portion of the 

 food canal next succeeding the crop. Between the two 

 there is no separating constriction, such as there is in many 

 other insects. The proventriculus has thick, muscular 

 walls, also armed within for the comminution of food. 



5. A circle of conspicuous appendages (the gastric cceca) 

 marks the posterior boundary of the proventriculus. These 

 are spindle-shaped appendages extending lengthwise of the 

 food canal, and attached laterally, having both ends free. 

 Each is, in fact, composed of two cone-shaped glands placed 

 base to base. The function of these glands is to secrete a 

 digestive fluid. 



6. Posterior to these is the ventriculus (or stomach), 

 hardly distinguished by its external appearance in the 

 grasshopper from adjacent portions of the alimentary 

 canal. 



7. At its posterior end arises a circle of long, slender, 

 inconspicuous tubes (the Malpighian vessels') which float 

 free in the body cavity. Their function is urinary. 



8. The remainder of the alimentary canal is the intestine. 

 A study of the parts here disclosed will give a general 

 idea of the digestive system for all insects. 



Let us now review the digestive process. The food is 

 first masticated by the mandibles and by the lacinise of the 

 maxillae in the mouth, is acted upon by the secretions of 

 the salivary glands as it passes from the mouth into the 



