248 
MR NEWPORT ON THE NERVOUS AND CIRCULATORY SYSTEMS 
that separate as principal trunks at the inner side of the great longitudinal series of 
abdominal muscles. The anterior of these trunks (e) is the analogue of the respiratory 
nerves of insects, and passes across the upper layer of these muscles, on their visceral 
surface, giving off to them many minute branches. The first of these branches turns 
backwards and inwards, in the direction of the spiracles and principal tracheae, on the 
under surface of the segment behind the legs, while the main trunk of the nerve, 
greatly reduced in size, passes upwards to the muscular appendages of the heart. 
The other set of nerves is divided into two main trunks, which pass between the 
layers of longitudinal muscles, the first of them (f) giving off branches to the mus- 
cles of the inferior and lateral parts of the body, to which it is almost entirely distri- 
buted ; and the other (g), the larger of the two, passing round the sides of the body, 
is distributed to the dorsal muscles. Besides these regular branches each alternate 
pair of nerves gives off a branch from its posterior surface (h), near its origin from 
the cord. This branch is given to the muscles that connect the two segments. The 
second pair of trunks ( d ) from the ganglion, as in lulus, is given directly to the legs, 
and send off only one small branch to the coxae before entering them. 
Structure of the cord. — The formation of the great abdominal cord in the lulidse, 
by the lateral approximation of two distinct portions, is indicated on its upper surface 
by a slight median sulcus, and on its under surface by a slight longitudinal division 
between the two approximated ganglia that form each of its enlargements. Each of 
these lateral divisions of the cord in lulus, as formerly shown in the Scolopendra and 
other Articulata, is a compound structure, formed of two distinct longitudinal series 
or columns of fibres, which, notwithstanding the different explanation that has been 
given of their function, since I had the honour of first describing them to the Royal 
Society*, are quite distinct from each other, although closely approximated together. 
By the aid of means superior to those formerly employed in my investigations, I now 
find that the abdominal cord contains other structures besides those already described. 
In my former communication to the Royal Society, I indicated the existence of fibres 
that run transversely through the ganglia of the cord in the larva of the common 
butterfly and similar structures have since been shown by Dr. Carpenter J in other 
Articulata, and applied to explain some of the reflex phenomena of the nervous system, 
in accordance with the theory promulgated by Dr. Marshall Hall. But besides 
these two sets of longitudinal fibres, and the series that passes transversely through 
the ganglia, there are other structures in the cord that have hitherto been entirely 
overlooked. These are fibres that run longitudinally, in part of their course, at the 
sides of the cord, and enter into the composition of all the nerves from the ganglia. 
These fibres I shall designate the fibres of reinforcement of the cord. 
The superior longitudinal set of fibres of the cord (fig. 4. e), which I formerly 
* Philosophical Transactions, 1834, Part II. p. 408. f Op. cit., p. 412, Plate XVI. fig. 37. 
+ Inaugural Dissertation on the Physiological Inferences to be deduced from the Structure of the Nervous 
System in the Invertebrated Classes of Animals, by William B. Carpenter, M.D., 1839. 
