136 



INTRODUCTION TO NEUROLOGY 



cribed. Neurons whose peripheral fibers have been severed, 

 thus cutting the cell body off from its usual avenue of functional 

 discharge, within a few days thereafter undergo structural 

 changes, chief of which is chromatolysis, or the solution and dis- 

 appearance of the Nissl bodies (see p. 49). Thus, after cutting 



m ** 



Fig. 62. Four sketches to illustrate the degenerations of somatic sensory 

 and motor fibers which follow section of spinal nerve-roots indifferent places. 

 Fibers separated from their cells of origin will degenerate, as shown in black 

 (see the text, p. 135). 



a ventral spinal root (Fig. 62, II), a microscopic examination of 

 the spinal cord will show the chromatolysis effect (see Fig. 13, 

 p. 48) in every neuron in the ventral gray column which gives 

 rise to a fiber of this root, while all of the other neurons will 

 remain normal. 



Physiological experiments upon men and other animals where 



