ANATOMY AND PHYSIOLOGY OF NERVOUS SYSTEM. 



601 



The dimensions of the nerve-cells are very variable ; the smallest 

 are about 1 / 400 o i ncn i* 1 diameter, the cells of the posterior horns of 

 the spinal cord are from 1 / 25 oo to V 120 o inch, and the giant cells of 

 the anterior horns of the spinal cord are about 1 / 250 inch in diameter. 



By employing Golgi's silver-nitrate method of staining, the 

 nerve-cells, with their processes, are stained black from a deposition 

 of the silver. By means of this, the nerve-prolongations may be 



sch 



k 



a 

 234 



235 



Fig. 234. A Piece of Medullated Nerve-fibril of Man, Nucleus and Axis 

 Cylinder Stained by Carmine. (SoeoTTA.) 



a, Axis cylinder, fc, Nucleus, m, Medulla, n, Neurilemma (Schwann's sheath). 



Fig. 235. A Piece of Medullated Nerve of Man. 

 Constrictions and Lantermann's Incisures. 



It shows Ranvier's 

 ( SOBOTTA. ) 



m, Medulla, sch, Ranvier's constrictions. 



traced to their ultimate terminations. This method beautifully dem- 

 onstrates the distribution of the neurites, their branching, and man- 

 ner of contact with dendrites of contiguous cells; also, how, as a 

 le, the neuraxon does no very immediate branching. It must be 

 ited, though, that usually from the neuraxon there proceed numer- 

 is fine fibrils to which the term collaterals is applied. These are in 

 imunication with the dendrites of the neighboring cells. In nerve- 

 iters, the neuraxon, after proceeding for some distance, does really 



