LG GEORGE E. NICHOLLS 
That the fiber was broken just prior to the experiment, in 
no. 49, also, appears extremely probable. In the trunk region 
the central canal of the spinal cord is found empty of fiber, 
while in the hinder part of the spinal cord and the filum terminale 
the fiber is seen much coiled and swollen throughout the entire 
length of two pieces of the tail region which were sectioned. 
Here, too, as in no. 3, there was practically no retraction for- 
ward from the lesion (fig. 22) so that the whole of the retraction 
observed must have resulted from the backward withdrawal of 
the fiber towards the tail. Behind the incision the fiber extends 
to the severed end of the terminal filament but is loose and un- 
dulating, shows some spiral winding and, near the terminal 
sinus, is distinctly swollen. As in the previous case, therefore, 
we have the evidence of a retraction which has started prior to 
the operation and was the result of an accidental breakage of the 
fiber far forward in the trunk region. In this case the speci- 
men recovered from the anaesthetic and manifested a marked 
reaction, not to be attributed to the experimental incision. The 
experiment, however, was of much shorter duration than was the 
case in no. 3 and the less intricately coiled condition of the fiber 
in this specimen is clearly related to the shorter period during 
which the fiber was free to withdraw. In nos. 9 and 39, in 
which the accidental cutting of the fiber took place after death, 
the fiber was free to retract only for the much shorter period 
which was required for the penetration of the fixing fluids. In 
both of these specimens the fiber has simply undergone a fairly 
regular twisting but has not produced the more complicated 
secondary spirals seen in no. 49 and, still better developed, in 
no. 3. 
In both of the two experiments which remain to be considered 
(nos. 46 and 55) the fiber appears as an extraordinary delicate 
filament lying somewhat slackly but not apparently withdrawn 
from the injured place. In neither case was the experiment of 
long duration and in both the reaction observed took on a some- 
what unusual character, there being manifested a distinct de- 
parture from the normal pose but no appreciable deviation of the 
long axis from the regular straight line. While this reaction 
