LENGTH OF THE INTERNODES 31 



We can test this conclusion still another way; since the per- 

 centage increase in the internodal length when the mean length 

 in group 1 is compared with that of group 5, is approximately 

 150 per cent, while the gain in the length of nerve runs as high as 

 200 per cent, thus the length of the nerve increases faster than 

 that of the internode. 



In this connection it is a matter of interest to note that the 

 average number of the internodes is 33.8 in the present case, 

 while Boycott has obtained 34.5. Although the present method 

 of obtaining the mean values was entirely different from that used 

 by Boycott, nevertheless the results show a difference of less 

 than 1.5 per cent, indicating a close agreement between the 

 simpler and more complicated treatment. Therefore we are 

 forced to conclude as Boycott did, that so far as our present data 

 are concerned, the number of the internodes increases with the 

 advancing ages of the frogs. 



It is however extremely important before drawing any final 

 conclusions from these data to consider at least the two follow- 

 ing points: 



1. Technical difficulty in measuring the longer internodes as 

 often as the shorter. This has been already discussed. 



2. Number of newly added fibers. 



This is certainly an important point to be considered. 

 Takahashi commented on this point thus: 



It follows from the foregoing result that so long as the nerve receives 

 new (young) fibers, there will always be internodes which are relatively 

 short, since they belong to fibers which have been subjected to the 

 lengtheniilg process for only a short time. The presence of these fibers 

 reduces the average length of the internodes, and hence accounts in 

 part at least for Boycott's observation that on the average the lengthen- 

 ing of the internodes in the sciatic nerve is slightly less than that of the 

 nerve itself. 



Both these points require further study. 



