Hatat, Spinal Ganglion Cells in the Rat. 9 
To the second variety belongs a coarse granular cell (grob- 
scholligen Zellen), the appearance of which depends on the 
appearance of the stainable substance, and most of the cells 
belong to this variety. These cells are of medium size, but 
sometimes small and rarely very large. 
The third variety contains the spinal ganglion cells which 
have a peculiar internal structure. These cells stain darkly be- 
cause of the density of the ground substance. 
Cox! describes in the rabbit two main varieties of spinal 
ganglion cells: 
One variety contains larger or smaller irregular masses of 
stainable substance, which do not show a distinct concentric 
arrangement. The cells of this variety may be either large or 
small. 
The other variety contains large, irregular masses of stain- 
able substance arranged concentrically. 
From these citations it is clear that the above authors 
classified the spinal ganglion cells in accordance with the three 
following characters: (1) Size of the cell body; (2) The ar- 
rangement of stainable substance; (3) Chemical reactions of 
the ground substance. Using the characters just named we 
shall in this paper make still another classification which will be 
presented in detail below. 
The smaller cells in the white rat measure only 25 to 
18 , in diameters, and the nucleus 12 to 10 , in diameter. Such 
small cells are more nnmerous than the larger cells and stain 
more deeply. One group of these smaller cells stains so deeply 
with erythrosin and eosin that one can easily distinguish them 
from the larger ones. A careful study of these smaller cells 
which stain next deeply shows that the stainable substance is 
thickly massed around the peripheral portion of the cell. Near 
the nucleus, the stainable substance is very scanty. The stain- 
able masses are of large size only at the extreme periphery of 
the cell and the remaining part is filled up with fine powdered 
1 Cox, W, H.—Der feinere Bau der Spinal Ganglienzelle des Kaninchens. 
Anatomische Hefte, Abth. 1, Bd. 10, 98, 
