THE FUNCTION OF REISSNER’S FIBER 165 
ment, there are three cases (19, 46, 55) concerning which I am 
in some doubt as to the correct interpretation of the sections. 
Excluding for the present these seven experiments which, for 
one reason or another, are inconclusive, I have, I believe, very 
definite evidence concerning the condition of Reissner’s fiber in 
no fewer than forty-six specimens. The conclusions at which I 
have arrived are based solely upon the reactions in these speci- 
mens, about which there appears to be no question. 
The subjects of these forty-six experiments may be classified, 
according to the effect of the experiment upon Reissner’s fiber, 
in four groups. * 
1. Six specimens (nos. 11, 15, 21, 23, 29, 51) in which it was 
found that the experimental incision missed the filum terminale 
and thus failed to break the fiber. 
2. Nine specimens (nos. 8, 18, 26, 28, 36, 38, 42, 44, 45) in 
which the fiber, although broken by the incision, failed to re- 
tract forward, or in either direction. The severed end (or ends) 
were held, apparently, by the adpressed walls of the filum ter- 
minale or, in some cases, secured from subsequent slipping by 
the clotting of blood which had escaped into the central canal 
from the cut meningeal vessels. 
3. This, the largest group, includes thirty specimens in which 
a more or less extensive retraction of the fiber had followed upon 
the experimental incision. While in some individuals (37, 52, 
53, 64, 66) this retraction was not very great, in others (10, 17. 
20, 22, 34, 35, 40, 41, 48, 54, 56, 57, 58, 59, 60, 62, 65, 67, 68) it 
was very considerable. In at least five (4, 5, 6, 7, 24) it may 
have been very extensive, also; but, if so, it had been largely 
repaired before the termination of the experiment. 
4. A single specimen (2) in which the process of regeneration 
was apparently almost completed. 
THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 27, NO. 2 
