PACINIAN BODIES. 



879 



Fia. 485. 



Portion of a Pacinian corpuscle, from the mesentery 

 of a cat. 



a a, the internal capsules ; b b, capsules of the 

 external system, with intervening fluid. Corpuscles, 

 as at c, are seen in all the capsules. The outer 

 capsules show a double layer, d ; e, occasional form 

 of corpuscle in the intercapsular spaces; n n, con- 

 necting membrane between two capsules ; o, capil- 

 lary vessel containing corpuscles or nuclei in its 

 wall, and lying with^i, a tubular nerve-fibre in q, 

 the channel of the stalk, the fibrous tissue sur- 

 rounding them not being represented. The vessel 

 divides into two branches, one of which perforates 

 the wall of the channel of the stalk and enters an 

 intercapsular space, and the other advances as far 

 as the central capsule. The nerve has the double 

 contour as far as r, where it enters the central cap- 

 sule ; from that point it is pale and faint. This 

 specimen represents an offset of the central cavity, 

 and of the pale nerve at s. The stem continues its 

 course, t, towards the further end of the central 

 cavity, while the offset follows the curved axis of 

 the subordinate cavity as far as v, where it ends in 

 a bulb by which it is fixed. Several of the cap- 

 sules are united together at x. Magnified about 300 

 diameters. 



surface exhibits very faintly marked elongated 

 nuclei, which most probably belong to the wall 

 of the inner capsule. 



There is little to add to the description of 

 the nerve-tube, already given. It is faintly 

 granular in texture, and occasionally regains, at 



one or more points of its course within the 

 central capsule, the dark contour which it had 

 lost on entering it. This is particularly the 

 case when it follows a bend of the cavity, and 

 certainly seems to indicate the presence there of 

 a material elsewhere deficient. It is rare, how- 

 ever, to see this re-assumption of the dark 

 border in any very well-marked degree. The 

 mode of attachment of the end of the nerve- 

 fibre varies, being generally by a single tubercle 

 or conical swelling, sometimes by two, and 

 sometimes even by three such. Whatever the 

 number of branches, however, their aggregate 

 thickness is about the same as that of the simple 

 fibre from which they spring. Where the cen- 

 tral cavity exhibits the offsets above-mentioned 

 the pale nerve-fibre is also invariably branched, 

 its subordinate branch always traversing the 

 axis of the subordinate cavity, and being regu- 

 larly fixed at its extremity. It is interesting to 

 observe how accurately the nerve-fibre preserves 

 its place in the axis of the central cavity, how- 

 ever abruptly that may be bent or branched, a 

 fact which might be supposed to indicate some 

 degree of viscidity in the clear substance through 

 which it runs. 



Respecting the function or use of the Paci- 

 nian corpuscles no satisfactory account has yet 

 been given, nor even a plausible explanation 

 offered. Their presence in so great abundance 

 on the nerves of the palm and sole, and their 

 absence from motor nerves, suggests the ob- 

 vious enquiry, whether they may not be con- 

 nected in some way with the sense of touch, or 

 at least with the function of sensation, to which 

 the fact of their concentration in such numbers 

 in the splanchnic nerves of some animals as 

 obviously answers in the negative. Undoubt- 

 edly, however, we may anticipate much from a 

 more extended research into their connections 

 with the several parts of the nervous system in 

 man and animals, than the very recent date of 

 their disvovery has yet allowed. The specu- 

 lation that they may be concerned in the pheno- 

 mena of what is called animal magnetism is 

 not to be passed over with contempt, if only 

 because it has been hazarded by their distin- 

 guished discoverer, Pacini, who, in common 

 with many other unprejudiced and not inca- 

 pable observers, is inclined to believe in the 

 reality of some of the less marvellous effects 

 which popularly pass under that title, such, in 

 particular, as the mesmeric somnolence and 

 catalepsy. Yet so vague an hypothesis, per- 

 haps, barely deserves to be placed in juxta- 

 position with the descriptive anatomy of the 

 corpuscles. 



It will be more to the purpose to institute a 

 brief comparison between these bodies and the 

 electrical organs of the torpedo, a description of 

 which will be found under the head of ANIMAL 

 ELECTUICITY. Since that article was written, 

 however, further researches, and especially 

 those of Savi,* have added some points of im- 

 portance which it will first be necessary to no- 



* Savi, Etudes Anatomiques sur le systeme ner- 

 veux et sur 1'organe electrique de la Torpille. Vide 

 Matteucci, Traite des phenomenes electro-physiolo- 

 giques. Paris, 1844. 



