28 Journal of Comparative Nmrology and Psychology. 



General characters of the spinal ganglion cells. — The 

 spinal ganglion cells in embryos of the white rat, lo to 13 mm. 

 long, present a bipolar shape in most cases ; one of the pro- 

 cesses contains a large amount of the cytoplasm and is recog- 

 nized easily because it stains more deeply than the other. The 

 second process arises from the opposite side of the cell-body 

 and stains faintly. It contains a very small amount of cyto- 

 plasm and is hard to distinguish from the surrounding struc- 

 tures. Only the former process is shown in the figures. The 

 relation of these processes to the spinal cord will be described 

 in a future paper. Hereafter, in this paper, the term process 

 means the former branch, rich in cytoplasm. 



The nucleus is very large compared with the cell-body and 

 presents a more or less oval shape. It contains a large number 

 ,of the minute granules among which two different forms may 

 ,be distinguished, not only by their size but also by their stain- 

 ing reactions with iron-haematoxylin ; one form of the granules 

 stains deep black while the other presents a grey tint. The 

 granules which stain an intense black are very much larger in 

 size and occur most abundantly along the nuclear wall and its 

 vicinity; the faintly staining granules, on the other hand, are 

 'Very small in size and appear to form a fine network in the 

 inucleus. This network is most condensed around the larger 

 granules of the former group. The large granules are identi- 

 fied with the basophile substance and the small granules with 

 linin or oxyphile substance. This grouping is by no means 

 satisfactory, for by using the Biondi-Ehrlich stain, as well as 

 by applying the microchemical tests, it has been noticed that 

 among basophile granules (larger form) there are several differ- 

 ent kinds which stain with different intensities and similarly 

 there are several different kinds of the oxyphile granules. So 

 far, therefore, as color reactions are concerned, the oxyphile 

 and basophile granules grade into one another and no sharp 

 distinction can be drawn between the two. This fact is ex- 

 tremely important in connection with the present investigation 

 and will be discussed more fully later on. 



Among the large granules, sometimes one and in some 



