110 PHYSIOLOGY FOB THE LABORATOBY. 



e. The axon, or axis cylinder, is in the centre. Add a 

 drop of chloroform and look for this along the centre of 

 the fibres. These are called medullated or white fibres. 

 Distinguish from them the non-medullated or gray fibres; 

 where are the latter found? 



/. Look for nuclei along the nerve fibre. 



g. Sketch a single fibre and show all these parts. 



F. A Nerve Ganglion. 



Material. A prepared section of a nerve ganglion. 

 Apparatus. A compound microscope. 



Examine a section of a nerve ganglion. 

 Notice : 



a. The size and general shape. 



b. The outer coat, its thickness and structure. 



c. The nerve cells. 



1. What is their size and shape ? 



2. Have they any nucleus ? 



3. Compare them with those seen in the brain. 



d. The fibres. Do any of them join the cells ? Are 

 they nerve fibres? 



e. Sketch. 



G. The Functions of the Spinal Cord. (Reflex Action.) 

 I. THE KNEE-JERK. 



Sit with one knee crossed over the other. With the 

 tips of the fingers strike the crossed knee just below the 

 knee pan. Notice the motion of the foot. Was the action 

 voluntarjr ? Trace the course of the nerve impulse. 



