Hatai, Spinal Ganglion Cells. 29 



cases more than one, can be distinguished as exclusively com- 

 posed of the basophile substance, but in many cases, the large 

 granules contain both basophile and oxyphile substances. When 

 this occurs and the basophile surrounds the oxyphile substance 

 then such a granule may be regarded as a nucleolus of the adult 

 nerve cells. 



Enlarged granules of this nucleolar type are shown in 

 Figs. I and 2. The position of these granules is not constant 

 but they lie in some cases along the nuclear membrane and in 

 others they occupy the center of the nucleus (Fig. i). 



Shape of nncleiis. — Changes in the shape of the nucleus 

 and the alterations of its position in the cell have been noted 

 by a number of observers. The phenomena have been observed 

 especially under experimental and pathological conditions. In 

 the normal condition, however, they have been reported by 

 only a few investigators. Several investigators observed a 

 pocket formation along the nuclear surface in the spinal gang- 

 lion cells of fish. These invaginations are repeated several 

 times in one nucleus, some of them being deeper than the 

 others, and thus the nucleus presents pseudopodia-like pro- 

 cesses. Such an appearance is rather common in the nuclei of 

 the nerve cells m spinal ganglia and ventral horn of lower ver- 

 tebrates (Holmgken), but on the other hand, it is rarely visible 

 in the cells of the higher mammalia, and when it occurs it is 

 not so conspicuous as in the lower forms. The present writer 

 had the opportunity to examine a large number of the prepa- 

 rations of the nerve cells of the white rat at different ages, but 

 failed to find the pseudopodia-like processes of the nuclei in ani- 

 mals of one day or older. As a rule, after the age of one day 

 the shape of the nuclei is constantly ovoid or spherical and does 

 not show pseudopodia-like processes. 



By examining the nuclei of spinal ganglion cells of em- 

 bryos (10 to 13 mm.), the following appearances have been ob- 

 served : 



As is shown in the figures, the nucleus of the embryonic 

 spinal ganglion cells lies, as a rule, at one side of the cell body ; 

 that is it lies eccentrically. Such an eccentric location of the 



