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TEXTBOOK OF ZOOLOGY 



emulsification of fats and the conversion of albuminoids into pep- 

 tones. Much of the food is absorbed into the hemolymph from the 

 stomach. Between the stomach and the intestines is a pyloric valve 

 which permits the contents of the system to pass in only one direc- 

 tion. In the intestine, which is divided into the ileum, colon, and 

 rectum, absorption of food continues, especially in the ileum. Just 

 back of the stomach many threadlike tubes enter the intestine. These 

 tubes are the excretory organs, known as Malpighian tulules, and 

 perform a similar function to the kidneys of higher animals. The 

 rectum has thick muscular walls with six-surface rectal glands. The 

 feces are expelled from the rectum to the outside of the body through 

 the anus. 



Fig-. 204. — Anterior aspect of brain (supraesopliageal ganglia) of Rhomaeha 

 microptera. (Magnified.) 1, nerve to paired ocellus; 2, nerve to eye, showing 

 fibers to ommatidia ; S, nerve to antenna; 4 and 5, nerves to mouth parts; 6, nerve 

 to unpaired ocellus; 7, circumesophageal commissure. (From White, General 

 Biology. The C. V. Mosby Co.) 



The nervous system consists of a series of ganglia or nerve cells 

 connected by a double set of commissures or connecting nerve fibers 

 lying along the ventral body wall. Five ganglia are located in the 

 abdomen. Since there are at least eleven segments in the abdomen 

 of the adult grasshopper, it is apparent that the ganglia of some of 

 the segments have fused together. In the larvae of insects there is 

 usually a ganglion to each segment. Three large, well-developed 

 ganglia are found in the thorax ; the anterior one is connected with 

 the subesophageal ganglia which in turn are connected with the 

 brain or supraesophageal ganglia by nerve fibers which pass on 

 each side of the esophagus. Nerves pass from the brain to the eyes, 

 antennae, and palpi of the head. The subesophageal ganglia supply 

 the mouth parts with nerves. The legs and wings are coordinated 

 in their movements by the thoracic ganglia. In the vertebrates the 



