109 
In the Spinal Cord we wish to direct attention to two 
pecuharities only. The first is the giant ganglion cells 
that are found in the dorsal fissure. Transverse sections 
of the cord will demonstrate these quite easily. They 
have been studied especially by J. B. Johnston,* Sargentt 
and Dahlgren.t The latter author, who has devoted his 
attention particularly to the Pleuronectide, states that 
these very peculiar cells are the first ganglion cells to be 
differentiated in the embryo flat-fish, and that they become 
an important and permanent apparatus in the adult. In 
an adult fish they are seen to form a row of very large 
nerve cells in the median dorsal fissure, and their neurites 
pass backwards to form an isolated fibre tract on the 
median side of each dorsal horn. Their exact distribution 
and function are unknown, but Dahlgren suggests that 
the neurites pass out with the dorsal roots of the spinal 
nerves and are connected with the sensory supply of the 
unpaired fins. Sargent finds in Ctenolabrus that the giant 
cells are connected with a fibre bundle passing forwards 
through the cord and medulla, and emerging by the 
ventral root of the trigeminus nerve. If this be true then 
the fifth nerve of this fish possesses a nerve component not 
hitherto recognised, and it would be interesting to study 
the giant cell apparatus from the point of view of the 
component theory. 
The second peculiarity of the cord is one which it 
shares with all Teleosts, and that is in the presence of the 
very interesting rod or fibre within the lumen of the 
central canal known as Reissner’s fibre. This fibre has 
been investigated recently by Sargent,§ who finds that it 
“extends through the whole length of the canalis centralis 
* Jour. Comp. Neurol., x., p. 375. t Anat. Anz., xv., p. 212. 
+ Anat. Anz., xili., p. 281. 
§ Anat. Anz,, xvii., p. 33, and Proc. American Acad. Arts and Science, 
xxxvi., No. 25, 
