Ranson, Alterations in Spinal Ganglion Cells. 131 



but, accepting DogieFs classification based on the external morphology 

 of the neuTOiies, attempt to fix upon the arrangement of the chromatic 

 bodies characteristic for each of his type of cells. This leads ns to 

 a classification which is almost identical with that of Cox and which 

 agrees in all essential points with that of Warrington and Grifiith. 

 We distinguish the following grouj)s of cells: 



1. Small cells. 



2. Large cells. 



(a) Medium sized coarsely granular cells. 

 (h) All other large cells. 



There can be little doubt as to the justification for making size 

 the prime criterion for. the separation of the spinal ganglion cells, 

 since this classification is supported by a variety of other observa- 

 tions. We find that the large and small cells differ from each other 

 in their reaction to the protoplasmic dyes ; the small cells are asso- 

 ciated with non-medullated fibers, the large cells with medullated 

 fibers (Dogiel) ; and while the latter react to electrical stimulation 

 of the nerve, the former do not (Hodge). It will also be shown 

 that they differ in their reaction to section of the nerve. All the 

 facts justify us in regarding the large and small cells as funda- 

 mentally different from one another. It should not be supposed, 

 however, that any particular diameter of cell body can be fixed 

 upon as a dividing line between the two types. There are medium 

 sized cells which in all other respects resemble the large cells, and 

 others of the same size which present all the characteristics of the 

 small cells. 



1. The Small Cells. The characteristics of the small darkly 

 staining cells have been sufficiently described in the citations already 

 given. Their, relatively large nucleus and scanty cytoplasm, staining 

 deeply with the acid dyes, separate them quite sharply from the large 

 cells. The arrangement of the ITissl granules presents nothing pecu- 

 liar. Their tigroid substance is most often in the form of very fine 

 granules, but is sometimes aggregated into masses of medium size 

 which may be most abundant either near the nucleus or at the 

 ]ieri])hery of the cell. The small clear cells described by Warrington 

 and Griffith are not present in any considerable number in the s]3ina] 



