Ranson, Alterations in Spina! Ganglion Cells. 147 



2. While only a part of the cells (52 per cent) undergo complete 

 degeneration, nearly all of the cells (at least 85 per cent) show 

 chromatolysis after an operation severing all branches of the nerve; 

 and this occurs in spite of the fact that not more than 33 per cent 

 of the spinal ganglion cells are associated with medullated fibers 

 that would be injured in cutting the nerve. 



3. There is no indication that the reaction in the small cells 

 is secondary to some intra-ganglionic disturbance; it possesses all 

 the characteristics of a true axonal reaction and occurs at least as 

 early, and according to Cox and Lugaro somewhat earlier, than the 

 reaction in the large cells. 



4. The . process of degeneration varies in different cells. In 

 some cases the invasion of the degenerating ganglion cells by prolif- 

 erating fibroblasts is the most striking feature, in others vacuolation 

 appears to be the cause of the cell disintegration. In the small 

 cells it is probable that the extremely excentric nuclei may, as the 

 turgescence increases, be finally extruded. 



5. There does not seem to be any part in which the reaction 

 is more marked than in the rest of the ganglion, and the dorso- 

 proximal portion shows as many altered cells as are to be found 

 elsewhere. This fact may be taken as an argument against the 

 assumption of Bumm that this portion of the ganglion is the locus 

 of cells which do not possess a fiber in the peripheral nerve. 



6. The large cells of the ganglion can be followed through the 

 various stages of repair until they again present central nuclei and 

 are filled with a very large amount of coarsely granular chromatic 

 substance. 



7. It has been shown, moreover, that it is the small neurones 

 which are most seriously injured, since it is from among this group 

 of elements that the loss of cells chiefly occurs. Since the small 

 cells show typical axonal reaction and degenerate in by far, the 

 greatest number, we are forced to conclude that they possess axons 

 in the peripheral nerves, and that their non-medullated processes 

 traced by Dogiel as far as the junction of the ventral and dorsal root, 

 extend beyond that point into the nerve. 



This conclusion has recently been confirmed by the demonstration 



