PACINIAN BODIES. 877 
process of the fibrous neurilemma, advances 
right into the centre of a series of concentric 
-ovoidal capsules of fibrous membrane, through 
a channel which perforates them all, and which 
has its proper wall, to which every capsule is 
attached. All the capsules, except from five to 
_ twenty of the inner ones, have spaces between 
them containing a clear watery fluid. These 
spaces do not communicate with one another 
or with the channel in which the nerve runs, 
Each one is distended by its own fluid, and in 
the natural state is more or less tense, offering 
Pacinian corpuscle, from the mesentery of a cat ; in- 
tended to shew the general construction of these 
bodies. The stalk and body, the outer and the inner 
system of capsules, with the central cavity, are seen, 
a; Arterial twig, ending in capillaries, which 
form loops in some of the intercapsular spaces, 
and one penetrates to the central capsule. b. 
The fibrous tissue of the stalk, prolonged from 
the neurilemma. 2x. Nerve-tube advancing to the 
central capsule, there losing its white substance, 
and stretching along the axis to the opposite end, 
where it is fixed by a tubercular enlargement.— 
From -Todd and Bowman. 
resistance to external pressure. The innermost 
capsule of all is an elongated nearly cylindrical 
cavity, somewhat larger at the further end, and 
always contains a clear fluid, which distends it 
and prevents its sides from falling together. 
The nerve-tube has the ordinary double dark 
contour as well as every other character of 
those found in the ordinary cerebro-spinal 
fibres until its entry into the central capsule. 
At that point it becomes less bulky, somewhat 
flattened (so that.its section is oval instead of 
round), and in particular much paler. The 
dark border which has distinguishes it hitherto 
now disappears, and if it were not for the trans- 
parency of the contents of the capsules its fur- 
ther course would be untraceable. It is, how- 
ever, when fresh, and with a good light, dis- 
tinctly seen to proceed along the very axis of 
the central capsule from one end to the other, 
and finally to be implanted by more or less of 
a swelling (fig. 483) into the further extremity 
Fig. 483. 
Extremity of the pale nerve-fibre in the inner capsule 
of a Pacinian body from the mesentery of a cat, 
n, pale fibre advancing into the further end of 
the central capsule; a, conical swelling by which 
the nerve is fixed; 6, corpuscle of the inner cap- 
sule; c, capsules of the internal system. Magni- 
fied 300 diameters. From Henle and Kolliker. 
of this central compartment. The originally 
dark border of the nerve-tube does not cease 
with absolute abruptness, but the two lines of 
the border coalesce in a somewhat sloping 
manner, and the pale continuation has merely 
a single bounding line, and that so exceedingly 
thin as not to allow of being described as an 
investment distinct from the rest of the fibre. 
This line, as Henle and Kolliker have re- 
marked, is more evident when the edge of the 
flattened fibre is towards the observer than 
when the flat surface is upwards, in which 
latter position it is sometimes altogether absent. 
Such is the general plan of the structure of 
these bodies. Their usual length is from 1-20th 
to 1-10th of an inch, and their stalk is often 
1-10th of an inch long. Though usually oval, 
they are often more or less elongated and bent 
on themselves. Sometimes the internal cap- 
sules only are bent, while the outermost are 
simply oval. In the human subject they are 
found in large numbers, detached or in clus- 
ters, in the subcutaneous areolar and adipose 
tissues of the palm and sole, in connection 
with the cutaneous nerves, as well as more 
sparingly in the same connection at other parts 
of the extremities. A few are also met with in 
the sympathetic plexuses ; and in the catin par- 
ticular they are usually so abundant in the 
mesentery and omentum, as instantly to arrest 
the eye when these parts are spread before it. 
They are here indeed most favourably situated 
for examination. They are included merely 
between the duplicature of the transparent peri- 
toneum, can be obtained in great numbers per- 
fectly fresh, and admit of being inspected with- 
out the addition of any water or other medium. 
