264 
MR. NEWPORT ON THE NERVOUS AND CIRCULATORY SYSTEMS 
tenor (b), which passes forwards to join with it, and these two approximated nerves, 
forming one trunk, have between their roots and the margin of the ganglion a very 
minute interspace, which is filled up with cellular tissue. Each of these approximated 
nerves contains distinct commissural fibres. Those of the anterior nerves are on the 
front of the ganglion, and are distinctly traced from side to side. Those of the pos- 
terior traverse the posterior part of the ganglion, and passing forwards on each side 
join with the lateral or rejiex fibres of the cord, which ascend along the sides of the 
cord at the posterior part of the ganglion, or, as before described, if traced from the 
peripheral surface of the segment, pass inwards from the nerve to form part of the 
sides of the cord. The existence of the longitudinal tracts of the cord is also distinct. 
The fibres of the inferior series have a large proportion of gray nucleated cells inter- 
spersed between them in each ganglion, and these are more especially abundant and 
distinct at its sides. The caudal ganglia exhibit the different structures of the cord 
better than the abdominal ones, above which the superior aganglionic tract of the 
cord is less distinct, and is less easily observed in consequence of the greater 
opacity and thickness of the ganglia. I ought also to state that the structure of the 
cord and ganglia of the Scorpion, owing to their greater thickness and more compact 
and united condition, can only be satisfactorily seen in the very small specimens, or 
in the very early condition of the animal, and after being preserved for some time in 
strong spirit. This remark also applies to the Myriapoda and other Articulata. 
Functions of the Brain and Nervous Cord. 
Although I have now pointed out the existence of fibres in the nervous cord of 
Myriapoda and Arachnida, which lead us to the conclusion that the doctrine of the 
individuality, or special function, of each fibre is correct ; that there are fibres in 
every nerve derived from two distinct portions of the cord, which from their direct 
communication with the brain, from one end of the body to the other, are believed 
to minister to volition and to sensation ; and that other fibres also exist in the same 
nerves, that have no communication whatever with that organ; — and further, that 
some of these, which are extended transversely across the body, influence both sides 
of those individual segments to which they are distributed, and those only ; while 
others combine in action two or more contiguous segments, but only by direct in- 
fluence on one side of the body; — it yet remains to be shown by experiment, whether 
the assignment of certain functions to these parts of the nervous system, in these in- 
ferior animals, is correct ; — whether the results of experiments on these worm-like 
beings agree in principle with the experiments already made by many physiologists 
on the vertebrated classes, and with those which the pathology of disease has afforded 
in Man himself; — whether, as leading to these important results, they coincide with 
the first experiment made on one of the Crustacea, conjointly by Dr. Marshall Hall 
and myself*, in the spring of 1834, and with others subsequently performed by 
* Lectures, Lancet, Feb. 3, 1838, p. 650. Memoirs on the Nervous System, p. 67. 
