’ THE FUNCTION OF REISSNER’S FIBER 135 
structures by means of observations made upon the living ani- 
mals in which the continuity of the fiber had been intentionally 
destroyed, but I had other objects, also, in view. 
At the time when the experiments were undertaken practically 
nothing was known concerning the mode of recoil of the fiber. 
Sargent had stated that when cut before fixation the free ends of 
the fiber retracted into a knotted mass or ‘snarl’ but he had not 
observed that this snarl was spirally wound. I had myself 
seen such snarls in several cases in material which had not been 
specially preserved for the study of this structure and in which 
the spinal cord had been cut previous to fixation (712 a, figs. 17, 
18, 19). In most of such material the fiber was ill preserved 
and, in the main, my own attention had been confined to a 
determination of the normal anatomical relations of the fiber. 
Accordingly, I had taken special precautions to thoroughly fix 
and harden my material before severing the spinal cord. Never- 
theless, I had come, in the previous year, upon a few examples 
of this spirally wound condition which had been obtained unin- 
tentionally by a premature cutting of the spinal cord (12 a, 
figs. 12, 16). These accidents, however, had yielded no in- 
formation concerning the behavior of the fiber cut in life. It was 
naturally supposed that a breaking of the fiber in the living 
animal would be followed by a sharp recoil of the severed ends 
similar to that which was known to occur when the fiber was cut 
in freshly killed material. It was desirable, however, to ascertain 
if this were so. 
It was anticipated, moreover, that the results of the experi- 
ments would throw light upon the question of the natural limits 
of this recoil. It must be remembered that beyond the mere fact 
of the occurrence of a recoil nothing had been recorded, and it 
was not even known whether the recoil started by the section 
of the living fiber would continue until both free ends had re- 
tracted to their respective points of attachment or whether, on 
the contrary, there would be formed speedily, in the living animal, 
a tangle (or tangles) which might (on reaching a size sufficient 
to block the lumen of the canalis centralis) automatically check 
further recoil in one or both directions. 
