THE NERVE CELL 



105 



other tissues. The nuclear 

 membrane is distinct and high- 

 ly chromatic. The contents of 

 the nucleus, however, except 

 for the large spherical nucleolus which 

 is quite constantly present, is noticeably 

 deficient in chromatin. Those few small 

 karyosomes which are present are mostly 

 adherent to the inner surface of the nu- 

 clear membrane. The achromatic nucleo- 

 plasm forms the greater portion of the 

 nucleus. Occasionally the chromatin 

 forms still finer granules, and is more 

 equally distributed throughout the nucle- 

 us. A large, chromatic, centrally situ- 

 ated nucleolus is nearly always present. 

 Cytoplasm. The finer structure of 

 the cytoplasm of the nerve cell is the 



FIG. 102. ISOLATED NERVE CELLS FKOM THE 

 SPINAL CORD OF MAN. 



.r, m-uraxis. ('aniiin. x 160. (After Sobotta.) 



b a 



FlG. 101. A UNIPOLAR GANGLION 

 CELL OF A FROG. 



a, cell body ; 6, neuraxis ; c, 

 dendrite. Methylen blue. High- 

 ly magnified. (After von Smir- 

 now.) 



subject of considerable 

 difference of opinion. 

 The studies of Xissl have 

 shown that it is divisible 

 into a substance which 

 is readily stained by 

 methylen blue, thionin, 

 etc. (the stainable sub- 

 stance of Nissl,tigroid of 

 von Lenhossek), and an 

 apparently homogeneous 

 substance which is not 

 so readily stained (the 

 unstainable substance of 

 Nissl). 



