Ranson, Degeneration in Spinal Nerves. 



281 



constant. The percentage of loss is much smaller than in the 

 case of the ganglion cells, scarcely greater than the percentage of 

 individual variation, so that the latter tends to render the former 

 less evident. But this consideration only in part explains the lack 

 of uniformity in the results; it seems that the degenerative pro- 

 cesses in the root fibers are more variable than those in the ganglion 

 cells and more directly dependent upon such conditions as reunion 

 of the central and peripheral stump of the nerve. 



TABLE VI. 



Showing the Decrease in the Number of the Medullated Nerve Fibers in the 

 Ventral and Dorsal Roots Two Months After the Section of the Ramus 

 Posterior of the II C. Nerve in Rats Twelve Days Old. 



(Normal and "Operated" Material from Different Animals.) 



Average loss I33'3 



Average (%) loss 21 



393-' 



17 



The ventral roots show a fairly uniform loss of fibers. The 

 smallest number of fibers in the normal roots (590) exceeds by 53 

 the largest number in the operated roots (537). Moreover, the 

 average of the operated roots falls 133 behind the average for the 

 normal roots, making an average loss of 21 per cent. This loss 

 is, however, by no means so uniform as that in the number of 

 spinal ganglion cells. The loss of fibers in the ventral root is in 

 harmony with the results reported by numerous investigators who 

 found, as a result of cutting the peripheral nerve, fibers present 

 in the ventral root which gave the Marchi reaction (p. 268). It 

 is also a necessary result of the degeneration of the cells of the 

 ventral cornu of the spinal cord so constantly found after the 

 section of nerves (p. 270). 



Even more variability is shown in the column of Table VI repre- 

 senting the operated dorsal roots. The first operated dorsal root 

 that was subjected to an enumeration contained 2641 nerve fibers, 



