164 GEORGE E. NICHOLLS 
D. Raia microcellata 
61. The incision was made at 7.15 p.m., August 21. At 10.30 p.m 
the tail was distinctly raised and remained so until the specimen was 
killed at 11 p.m. Duration of experiment 3% hours. 
Sections prepared through the tail were useless. The brain was 
sectioned, sagittally, and showed the fiber lying in normal position, of 
usual size and apparently tautly stretched, so that if retraction of the 
fiber took place in the tail region, it had not extended forward to the 
head. 
In all, serial sections were prepared of sixty-two specimens.’ 
Of these, the microscopical examinacion showed that in one case 
(16) the hinder part of the spinal cord was in an advanced stage 
of degeneration due to an accident which must have occurred 
at some time prior to the experiment. The sections through 
the region including the point of injury were, in five cases (30, 
50, 61, 63, 69), absolutely worthless and two others (82, 48) 
were somewhat fragmentary and of value only in establishing 
that the experimental incision had severed the filum terminale 
(and therefore Reissner’s fiber), while in another instance (70) 
the sections are, for the most part, very thick and Reissner’s 
fiber can be but doubtfully distinguished. In this case the 
experimental incision did not penetrate the filum terminale. 
Sufficiently satisfactory sections were obtained, therefore, in 
fifty-three examples. Of these Reissner’s fiber shows a most 
remarkable coiling in two cases (3, 49) which must be attributed 
to the breaking of the fiber very shortly before the experiment. 
In the former of these, moreover, the specimen never recovered 
from the anaesthetic and afforded, therefore, no reaction. Two 
experiments (9, 39) were vitiated by an accidental cutting of the 
spinal cord very far forward, while the fixation was incomplete 
and in both of these cases, also, an interesting spirally wound 
condition of the fiber was produced. Apart from these four 
experiments, in which there was definite evidence of an interfer- 
ence with the condition of the fiber before or after the experi- 
2 Four specimens (1, 25, 27, 31) which died during the progress of the experi- 
ment had been so long dead, apparently, as to be worthless for the purpose of 
this investigation. A fifth specimen (33) was unaccountably mislaid. 
