chap, xv.] PERIPHERAL NERVE-ENDINGS. 117 



151. The concentric capsules forming the corpuscle 

 itself are disposed in a different manner at the periphery 

 and near the central space from that in which they 

 are disposed in the middle parts, viz., in the former 

 localities they are much closer together, being thinner 

 than in the latter. On looking, therefore, at a 

 Pacinian corpuscle in its longitudinal axis, or in cross 

 section, we always notice the striation (indicating the 

 capsules) to be closer in the former than in the latter 

 places. Each capsule consists of (a) a hyaline, pro- 

 bably elastic, ground substance, in which are embedded 

 here and there (b) fine bundles of connective tissue 

 fibres; (c) on the inner surface of each capsule, i.e., 

 the one directed to the central axis of the Pacinian 

 corpuscle, is a single layer of nucleated endothelial 

 plates. The oblong nuclei visible on the capsules at 

 ordinary inspection are the nuclei of these endothelial 

 plates. There is no fluid between the capsules, but 

 these are in contact with one another (Huxley). 

 Neighbouring capsules are occasionally connected with 

 one another by thin fibres. 



152. In order to reach the central space of the 

 corpuscle, the medullated nerve-fibre has to perforate 

 the capsule at 'one pole ; thus a canal is formed 

 in which is situated the medullated nerve-fibre, 

 and as such, and in a very wavy condition, it reaches 

 the proximal end of the central space. This 

 part of the nerve-fibre may be called the interme- 

 diate part. The lamella? of the sheath of Henle 

 pass directly into the peripheral capsules of the 

 corpuscle. 



Immediately before entering the central space, 

 the nerve-fibre divests itself of all parts except the 

 axis cylinder, which, as stated above, passes into 

 the central space of the Pacinian corpuscle. In some 

 cases a -minute artery enters the corpuscle at the 

 pole, opposite to the nerve- fibre ; it penetrates the 



