Some Remarks on the Central Nervous 
System of the Starfish 
WILLIAM A. HILTON 
There are several questions in connection with the central nervous 
system of star fish which, so far as I know, are not answered by 
older or more recent investigations. They are as follows: 
1. Is there any special center in the radial or circum-oral nervous 
system? 
If there are true nerve cells how are they related? 
Are there true neurofibrille ? 
Is there any tigroid substance? 
Is there any connection between the superficial and the deep 
radial systems ? 
6. Are all the elements in the central nervous system nerve cells? 
7. Do different species differ from each other materially? 
Six species of starfish were collected at Laguna Beach. Two 
methods were used for fixation; hot mercuric cloride or Flemming’s 
fluid were used upon the whole animal. ‘The first reagent was 
especially useful in extending the animals and whitening the radial 
and circum-oral nerves. Borax carmine was used with good results 
in staining after the first fixation and iron hematoxylin after the 
second. By both methods cells and fibers were clearly shown. 
In all the specimens examined just after killing, the central por- 
tion of the radial or circum-oral nerves seemed like a definite line 
of nervous tissue. Sections showed in some cases a thicker epithel- 
ium in the mid-ventral line of the nerves. The radial nerve was 
often less thick than the central part of the nerve ring. The chief 
structural difference between the radial and circum-oral nerves in 
their central portions was in the arrangement of the cells and fibers. 
In these regions the nerve fibers seem to cross more and run in 
towards the middle line. This was very marked in some specimens. 
Some indication of this is given by Cuenot, 1890. 
In the central nervous system there are unipolar and bipolar cells 
with long slender processes reaching through the whole thickness of 
wm & W dO 
