THE NECTURUS 59 



be done on the regular formaldehyde specimens, after they 

 have been used for the other parts of the study. 



To study this part of the nervous system, cut the head 

 from the body, taking about 20 mm. of the body with it. 

 Place this in a solution of 10% nitric acid for two or three 

 days to decalcify the bone. Before using, soak for a few 

 hours in running water to remove some of the acid from 

 the tissues. If the instruments used are oiled slightly, 

 they will not be seriously injured by the action of the acid. 



OUTLINE OF THE NERVOUS SYSTEM 



The nervous system consists of the following parts: 

 (1) brain and cord, (2) peripheral system consisting of 

 the nerves and the autonomic system, (3) the sense organs. 



The brain and spinal cord are enclosed in bone for the 

 most part, the brain in the skull and the cord in the neural 

 arches of the vertebrae. The brain forms the main or cen- 

 tralized part of the system with cranial nerves and the 

 spinal cord as conducting paths. 



The peripheral system consists of two parts, the 

 peripheral system proper consisting of the connecting 

 nerves that conduct sensations to, and the motor impulses 

 away from the central system. The afferent sensory 

 nerves and the efferent or motor nerves, take this part. 

 Closely associated with this system and anatomically a 

 part of it is the sympathetic system which supplies im- 

 pulses to the viscera, blood vessels, and to other parts that 

 need automatic regulation. 



END ORGANS AND SPECIAL SENSES 



The end organs of the nervous system are located in the 

 skin as special sense organs and in other parts of the body 



