PAR VAGUM. 
( Fig. 486.) 
One of the follicular nervous organs of the electrica 
_ torpedo. 
a, branch of fifth pair of nerves; 6, twigs going 
to the organ and passing through cc, the fibrous 
band; d, the nerve as it lies on e, the granular 
mass ; f and g, the inner and the outer capsules 
containing fluid ; &, anastomosing filament from the 
preceding follicle ; /, anastomosing filament to the 
succeeding follicle. Much magnified and slightly 
compressed. From Savi. 
twig is derived from the fifth pair and passes 
first through a slit in the tendinous band. After 
passing this aperture it bends underneath the 
granular mass, and again emerges at the base 
of the follicle, but at the opposite side from 
that at which it entered. It is remarkable that 
the nerve is much thinner at its exit, and re- 
duced to an exceedingly delicate filament (/), 
which proceeds along the tendinous band to 
the next follicle, penetrating its wall and join- 
ing its nerve at the point of its flexion under 
the granular mass (k). 
“* On examining under the microscope the 
rounded granular mass, made flat by the com- 
pressor, and after the removal of the membranes 
of the follicle, we see the nerve running length- 
wise over it from end to end, the anastomosing 
branch coming from the preceding follicle (k) 
and the very delicate filament which proceeds 
to that next in order (/). We further remark 
that the nerve of the follicle, in its course along 
the granular mass, gives off a great number of 
elementary fibres, which disseminate themselves 
through the mass and thus reduce the nerve to 
so small a size. Sometimes I have fancied that 
these fibres formed loops and returned; but I 
_ have never obtained a clear view of their termi- 
nation. I am no less doubtful regarding the 
course of the elementary fibres of the anasto- 
mosing branch coming from the preceding 
follicle. Sometimes I have seen these fibres 
return towards the slit in the tendinous band 
and rejoin the nerve in order to regain the 
centre. In other cases I have seen these fibres 
_ pursue their primitive direction, and ,pass on 
with the rest towards the opposite end of the 
granular mass. Hence I imagine that the fibres 
_ of the anastomosing bundle do not all follow 
_ the same course, and that while some advance 
_ into the granular mass, others turn back towards 
| Vou. 111. 
t 
~ 
881 
the centre through the slit in the fibrous band.” 
“ It occasionally happens that two nervous 
twigs pass from the main branch to the same 
follicle. When this happens, there are always 
two distinct granular masses.” M. Savi then 
describes accurately the arrangement of the 
several series of these follicles in the torpedos 
which he examined, an account of which is not 
necessary for our present purpose. In one 
example he found that the follicles amounted in 
all to two hundred and fourteen. 
We cannot adduce these remarkable and 
peculiar structures as at present throwing any 
light on the function of the Pacinian corpuscles, 
since we must confess with M. Savi that as yet 
we are entirely ignorant both of their real nature 
and use. Nevertheless the resemblance is such 
as, it is hoped, will warrant the introduction of 
the preceding account, which is new in this 
country, and very interesting in itself. It is 
unnecessary to recapitulate the several points of 
similarity and difference, which, after the de- 
tailed description of each now offered, may be 
readily apprehended by the reader himself. 
It only remains that we should direct atten- 
tion to the very admirable memoir of Henle 
and Kolliker on this subject. They corrobo- 
rated the principal results of Pacini, and added 
many most valuable observations which the use 
of higher powers of the microscope and perhaps 
greater experience in research had enabled them 
to make. These observations M. Pacini has 
recently informed me he has himself almost 
entirely confirmed. An excellent abstract of 
their labours appeared in the British and Foreign 
Medical Review for January, 1845, and in the 
following April Dr. Todd and myself gave an 
account of these structures, drawn up from origi- 
nal observations and containing some new results, 
though on the whole confirmatory of those 
previously published. See the PuysrotocicaL 
Anatomy aND Puysrotocy or May, vol. i. 
p. 395. 
It is right to add that MM. A. G. Andral, 
Camus, and Lacroix, met with these bodies in 
1833, and that they were noticed subsequently 
by Cruveilhier and Blandin in their respective 
works on descriptive anatomy, but without any 
real light being thrown on their nature or 
internal structure. 
( William Bowman. ) 
PAR VAGUM NERVE. (Human Ana- 
tomy.) —(Nervus Vagus; Pneumogastric ; 
part of the sixth pair of nerves of the older 
anatomists; one of the three divisions of the 
eighth pair in the classification of Willis; the 
ninth pair of Andersch; the tenth pair of 
Sommerring ; the moyen sympathique of Win- 
slow.) The par vagum, like the other cerebro- 
spinal nerves, consists of two nerves exactly 
similar at their origin, and placed on different 
sides of the mesial line of the body. It has a 
very long course,—passing down the neck, and 
through the thorax to the upper part of the 
abdomen,—is distributed upon numerous and 
dissimilar organs, and anastomoses very freely 
and extensively with the sympathetic and vari- 
ous cerebro-spinal nerves. It is the chief nerve 
3 L 
