284 



ELEMENTS OF PHYSIOLOGY 



ing the food ; the dry food would stick to the esophagus 

 and have to be washed down with water; the gastric juice 



would not be secreted at just 

 the right time; the food would 

 ferment in the stomach, and 

 the person would soon be ill. 

 516. Nerve Cells (Fig. 193). 

 -You learned when studying 

 the master tissues that the ner- 

 vous system consists of nerve 

 cells with their branches, called 

 nerve fibers. Nerve cells are 

 microscopic bits of protoplasm, 

 like other cells, yet they are 

 remarkable among animal cells 

 for their large size. Some of 

 the cell bodies in the spinal 

 *cord are so large as to be almost 

 visible to the unaided eye, and 

 have branches leading from 

 the cord to the hand or foot. 

 Each cell contains a nucleus, 

 within which is a nucleolus 

 (Fig. 193). Nerve cells are 

 the most remarkable in the 

 body for irregularity of shape ; 

 some of them have so many 

 branches that they have a star- 

 like appearance. 



. Branched Nerve Cell from 



Spinal Cord. 517. The Dendrons of a nerve 



a, axis cylinder or axon; b t dendrons; c, cell are the treelike branches 



which bring impulses to the 



cell (Fig. 193). Through the dendrons the cell may be in 

 communication with numerous other cells. 'A branch of 

 one cell does not join the branch of another cell. It has 



