THE FUNCTION OF REISSNER’S FIBER 181 
extend for a great distance along the fiber and has a much looser 
twist which suggests the uncoiling of a spirally twisted thread. 
All four of these experiments had a relatively considerable dura- 
tion, the subject being killed towards the end of the first day or 
during the second. 
Apart from experiment 9 which was vitiated subsequently (by 
an accidental cut during dissection), the only case in which even 
a slight spiral twisting was observed in an experiment of long 
duration is no. 19. The subject was a ray, which, during the 
whole time (nearly 7 days) which elapsed between the breaking 
of the fiber and the killing of the specimen, gave absolutely no 
reaction. I have already suggested that it is probable we are 
dealing, in this case, with a slipping and coiling of the fiber which 
was started during the dissection by a reopening of the wound 
made by the operation but was quickly checked by the rapid 
penetration of the fixing fluid. 
With but this single possible exception, therefore, every case 
of spiral winding of the fiber has been found in the early stages 
of the experiment or immediately following an accidental cut; 
by the second day this torsion has usually disappeared and, 
where it is found at so late a period, is almost certainly in 
process of uncoiling. 
In confirmation of the view that the spiral coiling is found as 
the result of a comparatively recent snapping of the fiber, it 
may be noted that, while it has been found frequently in material 
in which the spinal cord has been severed during or immediately 
prior to fixation, it is more rarely found in specimens of which 
the nervous system had been preserved entire. 
In many larval lampreys and in adult myxinoids, all of which 
_ were preserved entire, I found, it is true, an intricately coiled 
mass of fiber which, in some cases, almost fills the sinus termi- 
nalis? (12a, figs. 15, 17, 18). In none of these specimens had 
there been any attempt to expose the central nervous system 
‘That this terminal coiled mass, though so frequently found, is not, as Stud- 
ni¢ka (’99) supposed, the normal condition is proved by the fact that Sanders 
has seen a taut condition of the fiber in the sinus terminalis (’94, p. 11) com- 
parable to that which I have described in the lamprey and other forms (12, 
a Draye 
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THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 27, NO. 2 
