3 2 Journal of Comparative Neurology and Psychology. 



membrane and become directly continuous with the linin net- 

 work. This is shown in Figs, i, 2, 4, 5. As is shown in the 

 figures, the protoplasmic lines pass through the pores of the 

 nuclear membrane and run into the nucleus where they fuse 

 with the linin network. Some of the rays fuse together with 

 the linin network as soon as they enter into the nucleus, but 

 others run quite a distance without losing their original charac- 

 ter as rays. Ultimately, however, they fuse with the network 

 and no rays can be seen near the periphery of the nucleus. 

 The penetration of these rays was verified by careful examina- 

 tions, many times repeated, all precautions being taken against 

 possible mistake. Thus my observations on the spinal ganglion 

 cells of the white rat show a direct continuation of the cyto- 

 plasm and nuclear network by means of the rays of the cen- 

 trosome. In addition to these observations, Holmgren ('99) 

 noticed in adult nerve cells oi Lophius piscatoriiis that the Nissl 

 granules were hung along the astral rays and that these granules 

 could be traced with them into the nucleus. From this fact 

 Holmgren concluded that the Nissl granules are formed by 

 the migration of the chromatin out of the nucleus, and that the 

 granules thus formed are again passed back into the nucleus by 

 means of the rays. He, therefore, regards the rays as a path- 

 way by which Nissl granules re-enter the nucleus. The present 

 writer was unable to find any formed Nissl granules along the 

 line of the rays within the centrosphere. Therefore the return- 

 ing of the formed Nissl granules into the nucleus was not 

 found in the nerve cells of the white rat. I will return to this 

 point in general discussion. 



Distribution of the nuclear material. — At this stage of intra- 

 uterine life, the nucleus of the nerve cell contains a large num- 

 ber of the chromatic particles which are scattered through it. 

 The particles vary in size from minute granules to comparatively 

 large bodies. The larger granules do not exceed five in num- 

 ber and may be composed exclusively of basophile subtances. 

 Subsequent to the stage in which basophile and oxyphile gran- 

 ules are distinct, the nucleolus appears. The minute granules 

 as distinguished from large granules, mentioned above, stain 



