180 GEORGE E. NICHOLLS 
2. The spiral winding of the fiber and the occurrence of ‘snarls’ 
Examples of the peculiar spiral contraction of the fiber have 
been seen in a number of the experiments. Thus numbers 3, 4, 
9, 19, 34, 35, 37, 41, 49 and 56 all show the fiber twisted to a 
greater or less extent. That the list is not more lengthy is to 
be explained by the fact that in a number of cases I have not 
cut sections of the spinal cord sufficiently far forward to find the 
retracted end. 
There is distinct evidence that, in the case of no. 3, this re- 
traction (though not the result of the experimental incision) 
must have taken place, for the most part, during the three hours 
or so which elapsed between the operation and the fixation of the 
material. The similar but less extensive coiling which occurred 
in no. 49 (again not the result of the experimental incision) 
must, likewise, have been produced almost wholly after the fiber 
was severed by the operation, for the severed portion of the fiber 
behind the incision is but little affected. This specimen was 
allowed to live but an hour and a half after the beginning of the 
experiment and there is doubtless a connection between the less 
intricately coiled condition of the fiber in this specimen and the 
shorter period which elapsed between the breaking of the fiber 
and fixation. 
The case of no. 9 differs from that of the two preceding speci- 
mens in that the cut which started the backward recoil was 
made after the death of the specimen just as the material was 
about to be plunged into the fixing fluid. The simple and con- 
tinuous spiral winding which is found in this specimen can have 
been produced, therefore, only during the time which was neces- 
sary for the fixing fluid to thoroughly penetrate and harden the 
material. 
In the case of experiments 34 and 56 (both of which were of 
short duration) the fiber has retracted (spirally) away from the 
lesion and the recoil, therefore, was definitely a consequence of 
the experimental incision. The character of the spiral winding 
in the fiber in the case of four other experiments (4, 35, 37, 41) 
is somewhat different. It is found at the free end but does not 
