PLATE 3 
EXPLANATION OF FIGURES 
16 Raia blanda (4). Part of a sagittal section through the filum terminale 
showing the free end of Reissner’s fiber in front of the lesion (the posterior end 
to the left, in the figure). > 240. 
17 Part of a transverse section through the spinal cord of the cat, showing 
a much swollen Reissner’s fiber, nearly 10 in diameter, embedded in a mass 
of coagulum which almost blocks the central canal. In the center of the fiber 
ean be seen the cut end of what appears as an axial thread or core. X 240. 
18 Raia blanda (49). Part of a sagittal section through a piece of the spinal 
eord from the anterior part of the trunk, from which region Reissner’s fiber had 
wholly retracted (caudally). The middle of the canal is occupied by a filmy 
strueture (x) which is probably coagulum. XX 240. 
19 Raia clavata (XIX, not experimental). Part of a sagittal section through 
the end of the tail showing the broken end of Reissner’s fiber in the (secondary) 
sinus terminalis. The terminal neural pore is almost choked by a mass of débris 
and coagulum. X 240. 
20 Raia clavata (XXXIX, not experimental). The broken end of Reiss- 
ner’s fiber is seen loosely coiled near the end of the central canal, the anterior 
piece of fiber depicted having been added from an adjacent section. The (pri- 
mary) sinus terminalis is fairly typical and extends downwards, in normal 
fashion, behind the end of the notochord. 240. 
21 Raia blanda (11). A length of Reissner’s fiber from the fourth ven- 
tricle, to show the brittle condition of the preserved fiber, which has splintered 
upon the microtome knife. X 240. 
22 Raia blanda (49). Part of a sagittal section through the filum terminale, 
immediately in front of the lesion. Reissner’s fiber is seen entangled in a clot 
from whick there has been no apparent retraction forward. Nevertheless, the 
whole length of fiber in the piece examined is spirally coiled, this being the re- 
sult of a backward recoil from some point in the spinal cord. X 45. 
23 Raia clavata (37). Part of a sagittal section through the filum ter- 
minale, in front of the lesion. MReissner’s fiber is seen swollen and irregularly 
coiled. 240. 
ABBREVIATIONS 
c.c., central canal of the spinal cord nch., notochord 
(and terminal filament) R.f., Reissner’s fiber 
cg., coagulum, practically filling the s.t., sinus terminalis 
central canal (fig. 17) i.n.p., terminal neural pore 
cl., blood clot, in the central canal v.c., vertebral column 
e., epithelium lining the central canal ** indicate the region of the incision 
f.t., filum terminale 
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