n6 



ELEMENTS OF HISTOLOGY. [Chap. xv. 



and which consists of a single medullated nerve-fibre 

 (Fig. 71), differing from an ordinary medullated 

 nerve-fibre merely in the fact that outside its 



neurileruma there is pre- 

 sent a thick laminated 

 connective tissue sheath. 

 This is the sheath of 

 Henle continuous with 

 the perineural sheath of 

 the nerve branch with 

 which the nerve-fibre is in 

 connection. This medul- 

 lated nerve-fibre within its 

 sheath possesses generally 

 a very wavy outline. The 

 corpuscle itself is com- 

 posed of a large number of 

 lamellae, or capsules, more 

 or less concentrically ar- 

 ranged around a central 

 elongated or cylindrical 

 clear space. This space 

 contains in its axis from 

 the proximal end, i.e., the 

 one nearest to the stalk, to 

 near the opposite or distal 

 end, a continuation of the nerve-fibre in the shape 

 of a simple axis cylinder. But this axis cylinder 

 does not fill out the central space, since there is 

 all round it a space left filled with a transparent 

 substance, in which, in some instances, rows of sphe- 

 rical nuclei may be perceived along the margin of 

 the axis cylinder. At or near the distal end of the 

 central space the axis cylinder divides in two or 

 more branches, and these terminate in pear-shaped, 

 oblong, spherical, or irregularly-shaped granular- 

 looking enlargements. 



Fig. 71. A Pacinian Corpuscle, 

 from the Mesentery of the Cat. 



a, The inedullated nerve-fibre ; 6, the 

 concentric capsules. 



