THE FUNCTION OF REISSNER’S FIBER 183 
At the commencement of this investigation I inclined to the 
idea that such a knot would be invariably produced when the 
broken fiber retracted, and supposed that the spiral winding, 
extending more or Jess uniformly along a great length, would be 
found only in those cases where a gradual process of fixation 
prevented the more sudden recoil. The results obtained from 
a large number of experiments indicate, however, that this sud- 
den contraction may be of much less general occurrence than was 
supposed and that the withdrawal of the fiber is brought about 
usually, by the simple spiral twisting of the fiber. 
The tightly knotted tangle of fiber present in Raia XIX, just 
above mentioned, is the only example of this condition which I 
have encountered in the course of this investigation. There is 
reason to believe that in this case the fiber may have broken 
some 24 hours before the material was preserved. In another 
specimen (10) in which the fiber was broken by the experi- 
mental incision made some 10 days before the fixation of the 
material, there is found a loosely twisted skein of fiber, a small 
part of which is represented in figure 26. That this condition 
had been preceded by the tightly knotted condition is very prob- 
able, this knot having doubtless served to hold the broken end 
and thus prevent more extensive retraction, for the tangle is 
found at no great distance (about half an inch) from the point 
of injury. It must be supposed, therefore, that during the 10 
days of the experiment the spiral torsion had disappeared and 
the process of disentangling the snarl had been proceeding. 
The fiber, except at its immediate hinder end, had become 
nearly normal in size, but whether the tangle would have been 
smoothed out eventually, if the experiment had been prolonged, 
or whether a new delicate growth from the hinder free end would 
~ have followed, I have no evidence to decide. 
8. The duration of the reaction and the problem of regeneration 
It is not quite obvious why the reaction appears to be so 
variable in its duration. If the assumption of an abnormal atti- 
tude in repose is, as I believe, a consequence of the disorganiza- 
tion of the mechanism of which Reissner’s fiber forms part, we 
