124 



NERVOUS TISSUES 



apyknomorphous condition. The Nissl granules are apparently used up 

 during functional activity of the nerve cell. 



The brain-cells show a strong affinity for adrenalin, the secretion of 

 the suprarenal glands; this fact leads Crile (1914) to strongly suspect 

 that the Nissl substance is a volatile, extremely unstable combination of 

 certain elements of the brain-cells and adrenalin because the suprarenal 



FIG. 137. ISOLATED NERVE CELLS FROM THE SPINAL CORD OF MAN. 

 x, axon. Carmin. X 160. (After Sobotta.) 



glands alone do not take the Nissl stain, and the brain deprived of 

 adrenalin does not take Nissl stain. 



Nissl substance disappears in case of lesion of the neuron, but re- 

 appears in abundance after temporary injury and recovery of the cell. 

 Such disappearance after section of the axon (axonal reaction) is accom- 

 panied by a swelling of the neuroplasm and the peripheral migration of 

 the nucleus, after from ten to fifteen days. 



Concerning the finer structure of the unstainable substance of Nissl, 

 comparatively little is known. With varying methods of fixation this 

 portion of the cytoplasm has been found to show very fine fibrils (neuro- 



