300 COORDINATION AND SENSATION 



liquid which surrounds them. They are also protected 

 from jars resulting from the movements of the body by 

 the general elasticity of the skeleton. 



Summary. The nervous system establishes connections 

 between all parts of the body, and provides a stimulus by 

 means of which they are controlled. It is made up of a 

 special form of cells, called neurons. The neurons form 

 the different divisions of the nervous system, and also serve 

 as the active agents in carrying on its work. Through a 

 side-by-side method of joining they form the nerves, gan- 

 glia, spinal cord, and brain; and by a method of end-to-end 

 joining they connect places remote from each other, and 

 provide for nervous movements through the body. The 

 nervous system may in some respects be compared to a 

 complicated system of telephony, in which the chains of 

 neurons correspond to the wires, and the brain and spinal 

 cord to the central station. 



Exercises. i . Give the meaning of the term " coordination." Sup- 

 ply illustrations. 



2. What two general conditions are supplied in the body by the 

 nervous system? 



3. Compare the skeleton outline of the nervous system with the 

 bony skeleton. 



4. Sketch outlines of mon-axonic and di-axonic neurons. 



5. Give two differences between the neurons and the other cells of 

 the body. 



6. Describe the two general methods of connecting neurons in the 

 Dody. What purpose is accomplished by each method ? 



7. Name and locate the principal divisions of the nervous system. 



8. Draw an outline of the brain (side view), locating each of its 

 principal divisions. 



9. If a pencil were placed over the ear, what portions of the brain 

 would be above it and what below? 



10. Describe briefly the cerebrum, the cerebellum, the midbrain, 

 the pons, and the bulb. 



