Hatai, Spinal Ga)iglion Cells of Rat. 483 



and small cells. That is to say, some small cells have characters 

 possessed by large cells and therefore size is the only means of dis- 

 tinguishing two forms. There is however another group of the 

 small cells (third variety of both Lugaro and Lenhossek) which 

 exhibit still different structural characters. They are much darker 

 in appearance owing to a strong affinity for staining reagents. 

 The arrangement of the stainable substance is irregular and indis- 

 tinct. The cell-outline is irregular. Thus there is no question 

 as to the presence of the two kinds of the small cells which differ 

 in both structure and shape from each other. The entire series 

 of small cells which exhibit a resemblance to the large cells were 

 considered by Cox, Lenhossek and Lugaro as early formed cell 

 elements which persist m the spinal ganglion as such in small 

 size. I have however just shown that a considerable number of 

 the large cells are made smaller artificially by the method of sec- 

 tioning. One would therefore expect to find a number of the 

 small cells similar in structure to the large cells, except that the 

 arrangement of the stainable substance may differ slightly accord- 

 ing to plane of section. The cell-outline of the majority of the 

 "artificial" small cells should be nearly spherical, unless they are 

 distorted. Therefore the existence of small cells with the internal 

 characters of the large cells can be explained readily on the assump- 

 tion that they are in part if not entirely those large cells modi- 

 fied by the method of sectioning. I therefore conclude that a 

 majority of these cells with the characters of the large cells do not 

 preexist as such and that consequently the conclusions of Lugaro, 

 Lenhossek and Cox are to this extent misleading. 



While the writer was engaged in the study of the structure of 

 the spinal ganglion in the albino rat (Hatai '01) the following 

 groups of cells were recognized and described. The one group 

 is larger in size and stains lightly with eosin or erythrosin, while 

 another group is smaller in size and stains deeply with eosin or 

 erythrosin. Still a third group which, although it agrees in stain- 

 ing reaction as well as in an irregular outline with the small cells, 

 nevertheless differs in the arrangement of the stainable substance 

 and in size. The size is slightly larger on the average than that 

 of the small deeply staining cells but much smaller than large cells. 

 It now seems better to consider the group intermediate in size as a 

 variety of the small cells rather than as a distinct type. The fol- 

 lowing are the reasons for this conclusion: 



