252 
MR. NEWPORT ON THE NERVOUS AND CIRCULATORY SYSTEMS 
rejlex ; entirely independent of sensation, but capable of being excited into action by 
external causes. 
The existence of these lateral fibres in the cord may now fully explain the reflected 
movement of parts anterior or posterior to an irritated limb on the same side of the 
body, as the commissural ones do the movement of parts on the side opposite to that 
which is irritated. The presence of these fibres in the cord of insects I had long 
suspected, from the curved direction of the fibres that bound the ganglia, and from 
that of the origins of the nerves from the aganglionic tract, as figured in my former 
paper* ; and although I had communicated this opinion to a friend several years ago, 
I have never until recently been able to satisfy myself of its correctness. 
This uncertainty of the existence of any structure in the cord that seemed sufficient 
to explain the reflected movements on the same side of the body, independent of the 
brain and the nerves of volition and sensation, long obliged me to withhold my assent 
to the doctrines now received respecting these phenomena. Although the fibres that 
pass transversely through ganglia might explain the effect produced on one side of 
the body, by the irritation of a corresponding part on the other, there seemed no ana- 
tomical structure to account for the movements of distant parts, anterior or posterior 
to a given point, on the same side, if the doctrine long received, that each fibre is en- 
dowed with but one special function, were correct. Now, therefore, that we find an 
anatomical structure in the cord that seems to account for these phenomena, I ought, 
in justice, to state, that Dr. Hall, to whom is due the high credit of collecting, com- 
paring and arranging in one system numerous facts connected with the reflected 
movements of animals, as observed by Whytt, Blane and others, and also by him- 
self, — adopting the principle established by our distinguished physiologist. Sir Charles 
Bell, that every nervous fibre is continued unbroken from its origin to its termi- 
nation, and is capable of ministering only to one special function, — conceived the ne- 
cessity for the existence of special nerves for the reflected movements ; and that, at 
the period when I was engaged with Dr. Hall in his experiments on this subject, in 
1833, he requested me to examine the cord in the Hedgehog to ascertain the correct- 
ness of his opinions. This examination was not made, because at that period I differed 
from him in attributing the reflected movements to the agency of another part of 
the nervous system. Now that the views of Dr. Hall seem proved to be correct, 
I am desirous of adding this testimony of the acuteness and perception of one who 
has done much for physiological science. 
In the Poli/desmidce (Plate XI. fig. 6.) the nervous system corresponds with that of 
lulus in regard to the nerves given to the generative outlets, but the ganglia of the 
cord are larger and situated at much greater distances. Those of the first two pairs 
of legs have united with the first suboesophageal ganglion ( d ), and the whole form 
one elongated large nervous mass, similar to the short nervous cord of the Ostracion 
and some other fishes. This great elongated ganglion is situated anterior to the 
* Philosophical Transactions, 1834, Plate XVII. fig. 40-42, g. 
