118 MANUAL OF ANIMAL BIOLOGY 



1. Nutritive System 



The mouth lies underneath the mandibles, and from it the 

 small esophagus runs dorsally for a short distance, then makes 

 a right angle turn and runs posteriorly into the enlarged crop 

 which functions as a temporary storage place for food. Branch- 

 ing salivary glands lie beside the esophagus. They extend 

 anteriorly and finally open into the mouth cavity. 



Posterior to the crop is a muscular grinding apparatus, the giz- 

 zard, or proventriculus, and behind that the thinner-walled 

 stomach, or ventriculus. The anterior end of the stomach is 

 surrounded by a number of pouch-like structures, the gastric 

 caeca, which are responsible for the formation and secretion into 

 the alimentary tract of essential digestive fluids. 



Continuing posteriorly from the stomach to the anal opening 

 at the extreme posterior end of the body is the intestine. It 

 appears, for the most part, as an undifferentiated tube except near 

 the posterior end where it enlarges to form the rectum, just before 

 opening to the exterior. Mention should also be made of the 

 numerous thread-like malpighian turules which form a coiled 

 mass surrounding the intestine for some distance and open into it. 

 These tubules are excretory organs, and they will be described 

 below. 



Functional. The food of the Grasshopper, consisting almost 

 entirely of plant tissues, is torn from the plant by the mouth 

 parts and after considerable shredding is passed into the mouth 

 cavity. Here the salivary juice, which contains a starch-digesting 

 enzyme, is added, and then the food material is passed on through 

 the esophagus and into the crop for temporary storage. The 

 gizzard is the next step, and after the food is sufficiently ground, 

 it is in a suitable condition to be digested in the stomach and 

 in the anterior portion of the intestine. Very important in this 

 connection are the enzymes in the digestive fluids secreted into the 

 anterior end of the stomach by the large gastric caeca. 



Food materials, after being rendered soluble by the digestive 

 processes, are absorbed by certain of the cells lining the stomach 

 and intestine, while the indigestible materials are passed on through 

 the remainder of the intestine and egested through the anal opening. 

 It is important to note that the alimentary canal is, for the most 

 part, surrounded by a large blood cavity, or hemocoel, and it is 



