R ANSON, Degeneration in Spinal Nerves. 279 



the spinal ganglion; the extent and constancy of the degeneration 

 is expressed in Table V. 



TABLE V. 

 Showing the Decrease in the Number of Cells in the Spinal GangHon Sixty 

 Days After the Division of the Ramus Posterior of the II C. Nerve in Rats 

 Tv\^elve Days Old. 



Normal. Operated. 



7>72i 3.845 



8,116 3,896 



9.343 3.764 



8,624 4,193 



4.497 



4133,804 5)20,195 



Average 8,451 4.039 



Average loss 4.4'^ 



Per cent, average loss 52 



From Table V we see that two months after the second cervical 

 nerve had been cut in a rat twelve days old the corresponding 

 spinal ganglion had lost about one-half its cells, and that this 

 occurred with striking unif(>rmity in five different specimens. In- 

 deed, we find that the smallest number of cells in the operated 

 ganglia, 3764, differs from the largest number 4497 by only 19 per 

 cent, of the smaller number, while in the normal ganglia the great- 

 est variation amounts to 21 per cent. Hence there can be little 

 doubt but that the numerical differences which the operated gan- 

 glia show among themselves are due to normal individual variation 

 present in the ganglia before the operation. We repeat, there- 

 fore, that this table shows an altogether striking uniformity in the 

 number of cells in the operated ganglia, and that the number of 

 cells dropping out of a ganglion must represent a certain constant 

 percentage of the cells it originally contained. There must be 

 some very definite reason for this constant reaction; but our knowl- 

 edge of the architecture of the spinal ganglion is at present so 

 vague that it is not possible to say what are the responsible factors. 



If it is desired to know the percentage of cells that disappear, 

 this may be determined by taking the average normal number of 

 cells, 8451, as the base number, of which 4412, the average num- 

 ber of cells destroyed, constitutes 52 per cent. Here again we 

 are totally at a loss for an explanation. We know of no anatomical 

 relations which would justify the expectation of such a result. 



