Ranson, Degeneration in Spnml Nerves. 



-^n 



nerve (Hardesty '05). Hatai, working on the white rat, ob- 

 tained the following results for the adult specimen of 167 gms. 

 body weight. 



table I. 

 Ratio of Spinal Ganglion Cells to Dorsal Root Fibers. (Hatai,) 



Nerve. 



Number of Cells. 



Number of Fibers. 



Ratio. 



* The figures 2. 7 and 4. 3 given in the original are obviously misprints. 



The writer in studying the normal relations in the second cervi- 

 cal nerve of the white rat has obtained results confirmatory of 

 those of the authors already mentioned. In the three cases in 

 which the dorsal root fibers and spinal ganglion cells were enumer- 

 ated in the same individual nerve, a rather constant ratio of 

 approximately i fiber to 3.2 cells was obtained. The first two 

 specimens were seventy-two days old and weighed about no gms., 

 the third was six months old and weighed 188 gms. 



TABLE II. 



Ratio of Spinal Ganglion Cells to Dorsal Root Fibers in the Second 

 Cervical Nerve of the White Rat. 



These results are corroborative of those obtained by earlier 

 observers. The number of cells in a given spinal ganglion is 

 about three times greater than the number of meduUated fibers 

 in the corresponding root. Without going into a discussion of 

 the significance of this relation, it may be said that it is the large 

 cells of the ganglion which alone are associated with medullated 

 fibers (DoGiEL '96, Hatai '02). According to this view, 70 

 per cent, of the cells in the second cervical spinal ganglion 

 of the white rat are small cells not associated with any medullated 

 fibers which would be cut in dividing the peripheral nerve. It is 

 obvious that these facts must have an important bearing on the 

 results of injury to the nerve. 



