Ranson, Alterations in Spmal Ganglion Cells. 141 



that one sometimes meets Avitli vacuolation in the cells from normal 

 ganglia ; but the process does not reach the same extent nor is it 

 nearly as freqnent as in the ^'operatcnr' ganglia. 



While this is all^that can he said positively concerning the dis- 

 integrative processes, it seems probable that many of the small cells 

 become so ninch swollen that the nucleus is extruded, after which the 

 cell rapidly disintegrates. Such a process as this cannot of course 

 be observed, but it may be supposed to occur, because of the extreme 

 peripheral position of the nucleus in the cells (see Fig. 3). The 

 nuclei often are so placed that they appear half outside the cell, 

 and in some more marked cases as if the nuclcTis were a separate 

 structure indenting the cell-body from without. 



In connection with the degenerative changes two other problems 

 demand attention. Is there any special })art of the ganglion in 

 which the cells seem i^articularly susceiDtible to degeneration after 

 section of the peripheral nerve ? Is there any particular type of cell 

 which is more likely to disappear than the others i The first question 

 is suggested by observations of Bumm, who worked with the second 

 cervical nerve of the cat, and of Kleist working with the same nerve 

 in cats and rabbits, both of whom found after section of the dorsal 

 root a region on the posterior aspect of the proxinuil part of the 

 ganglion in which the degenerative changes were much more marked 

 than in the rest of the ganglion. Both Bumm and Kleist believe 

 that there are situated here cells which are associated with a fiber 

 in the dorsal root but not with one in the nerve. They consider 

 these as relay neurones inserted between the sympathetic and the 

 central nervous system. It is to be borne in mind, however, that 

 these authors base their conclusion purely on the effect of cutting 

 the dorsal roots, and that they did not attem])t to determine whether 

 these supposed cells could be demonstrated l)y their failure to react 

 when the peripheral nerve was cut. The descriptions and illustra- 

 tions given in their papers indicate that the destruction in this 

 dorso-proximal quarter of the ganglion involves a large part of the 

 cells and give the impression that these cells must be quite numerous. 

 N^ow if the idea that these cells possess no fiber in the peripheral 

 nerve is correct, they should not react to a section of the nerve and 



