WHAT AN INSECT IS LIKE: INSIDE 27 



1. The foregut, extending from the mouth to the stomach. 

 This is the chitin-lined front portion. Its lining layer 

 is shed at every moult and hangs attached to the head, 

 as already noted. It is usually differentiated into 

 mouth, esophagus, crop and gizzard, as described on 

 page 8. 



2. The thick-walled stomach, ventriculus, or mid gut. 



3. The hind gut, consisting of intestine and rectum. This 

 portion, also, is lined with thin chitin and is moulted 

 with the skeleton. At its front end arise the Malpighian 

 or renal tubules. 



II. In dissections of one side, showing food tube and 

 nervous system in place, study the latter, noting: 



1. The large brain, occupying the top of the head with 

 some fine white nerves extending forward from it into 

 antennae and mouthparts. This lies above the esopha- 

 gus. 



2. The smaller, subesophageal ganglion, placed ventrally 

 in the head and connected to the brain by a pair of 

 nerve trunks that surround the esophagus. 



3. The chain of ganglia, lying on the floor of the body 

 cavity, one ganglion for each segment (excepting the 

 rearmost ones), all connected by a double nerve cord, 

 and all giving off nerve fibers to adjacent parts of the 

 body. 



