THE INTERNAL ANATOMY OF THE LOCUST 291 



f . The small intestine. The small intestine is a short, muscular 

 tube running from the end of the large intestine toward the dorsal 

 part of the body and ending in segment eleven. 



g. The rectum. The rectum is a short, muscular enlargement 

 in segment eleven and ends in the anal opening. 



2. Accessory organs of digestion. In connection with the ali- 

 mentary tract are a certain number of glands or glandular structures 

 which either aid in the digestion of the food or assist in eliminating 

 the waste products. 



a. The salivary glands. These are small, white glands located 

 on either side of the esophagus in the thorax. They open out into 

 two main ducts which lead to the mouth. 



b. The gastric cceca. The gastric caeca consist of a set of eight 

 double, cone-shaped pouches which open at the union of the crop 

 and stomach. They form a complete belt around the alimentary 

 tract at this point and secrete a fluid which aids in digestion. 



c. The Malpighian tubules. The Malpighian tubules are a sys- 

 tem of very fine, hairlike tubes which arise from the most anterior 

 end of the large intestine. Their function is excretory, similar to 

 that of the kidneys. 



3. Reproductive system. The ease with which the organs of 

 this system may be distinguished depends considerably on the sex 

 and the time of year at which the specimens were collected. 



a. Female reproductive organs. In the fall, just before the eggs 

 are deposited, the entire abdomen of the female is filled with a 

 yellow, coarsely granular organ known as the ovary. There are a 

 pair of these, one located on either side of the body. Running 

 from the posterior end of the ovary are two small tubes called the 

 oviducts, which unite near the posterior end of the body to form 

 the vagina. This opens externally upon the upper surface of the 

 subgenital plate, between the ovipositor. On a median line slightly 

 dorsal to the egg guides there is a second opening, which communi- 

 cates with a long, slender tube ending in an enlarged pouch known 

 as the spermatheca. This entire structure is very difficult to locate. 



b. Male reproductive organs. The general arrangement of the 

 male reproductive organs is quite similar to that of the female, only 

 much smaller. The two pair of testes (corresponding to the ovaries) 

 lie on the dorsal side of the stomach and are inclosed in a saclike 



