Structure of Neurones in Nervous System of White Rat 



through 95 per cent, and 100 per cent, alcohol and xylol. In this case, however, the 

 section mu&t be restained upon the slide. These restained preparations give clearer 

 pictures than those obtained by other methods, and, in addition, show a distinction 

 betvreen the axone and the dendrites. The appearances about to be described were 

 obtained by this method. 



II. THE FINER STRUCTURE OP THE GROUND SUBSTANCE OF THE NERVE-CELLS, 

 ESPECIALLY OF THE SPINAL GANGLION CELLS 



The spinal ganglion cells in the white rat present at least two varieties differently 



characterized ; one of the varieties is larger in size and stains faintly with eosin or 



erythrosin ; while the other shows just the opposite characters, that is, the cell-bodies 



are smaller and stain deeply with these solutions. The present description of the 



spinal ganglion cells is based on the study of the larger variety which has been 



regarded by the writer as the fully matured form (1901). 



In general, the cell-body shows a circular or a somewhat oblong shape, containing 



a single nucleus which lies at or near the center of the cell. The nucleus contains a large 



number of the oxyphile particles of various sizes. These particles are most abundant 



at the periphery of the nucleus as well as around the nucleolus which lies near its 



center. These particles hang along the fine filaments of the linin substance which 



forms a very complicated network in the nucleus (Plate XIII, Fig. 1). By using 



toluidin blue and eosin, the oxyphile substance and the linin stain red, while the 



nucleolus stains an intense blue, owing to the accumulation of the basophile substance 



around the oxyphile substance which forms the nucleolus proper (1901^). 



The distinction between the oxyphile and the linin substance may be m-ade out by 



the fact that the latter stains more faintly. The nuclear membrane is distinctly 



visible, showing a somewhat reddish brown color. The cell-body proper is composed 



of at least two different substances, as is the case in all other nerve cell-bodies, namely 



(1) the stainable substance known also as tigroid, Nissl's bodies, chromatophile 



particles, etc., and (2) non-stainable or ground substance. The stainable substance 



just mentioned appears to fill up the cell- body, except in two regions, one along the 



periphery of the cell-body and the other around the nucleus, the regions being 



known respectively as the peripheral and the inner, clear zones (Lenhoss^k, 1895). In 



these two regions the non-stainable substance alone is visible. 



Under a low magnification the cell-body appears as a red homogeneous mass 



with a bluish tinge in it. A higher magnification of such a cell reveals a large number 



of minute meshes presenting a reticular arrangement. These meshes, however, are 



not similar either in shape or in size, but differ very widely according to regions in 



which they occur. They are formed by very delicate protoplasmic filaments within 



which minute granules are clearly distinguishable. These granules are known as 



"neurosomes." The nourosome seems to be a very highly differentiated cvtomicrosome 



and to form the main part of the filament. The neurosome stains much deeper 



with eosin or erythrosin than ordinary cyto-microsome, and also is much larger than it. 



180 



