PACINIAN CORPUSCLES. 



343 



perineurium of a nerve. Each lamella (fig. 404) consists of a connective tissue 

 layer formed both of white fibres, which have mostly a transverse direction and are 

 placed near its surfaces (b), and of elastic fibres, which pass in various directions, 

 and (with occasional bands of white fibres) stretch across the thickness of the 

 lamella from one surface to the other (c). The surfaces of the lamellae are covered 



Fig. 403. MAGNIFIED VIEW 

 OP A PACINIAN BODY FROM 

 THE CAT'S MESENTERY. 

 (Ranvier. ) 



., stalk with nerve-fibre en- 

 closed in sheath of Henle passing 

 to the corpuscle ; n', its continu- 

 ation through the core, m, as a 

 pale fibre ; a, termination of the 

 nerve in the distal end of the 

 core. In the corpuscle here 

 figured the termination is arbor- 

 escent, d, lines separating the 

 tunics of the corpuscle, often 

 taken for the tunics themselves ; 

 f, channel through the tunics, 

 traversed by the nerve-fibre ; c, 

 external tunics of the corpuscle. 



with a layer of endothelial 

 cells (a), which can be 

 brought to view with 

 nitrate of silver, and then 

 their continuity with the 

 similar cells in the perineu- 

 rium is made manifest (fig. 

 405). The tissue of each 

 lamella is lax as compared 

 with that of the layers of 

 the perineurium, and the 

 interstices between the 

 fibres are occupied by a 

 considerable quantity of 

 watery fluid, probably of 

 the nature of lymph, and 

 containing occasionally 

 lymph - corpuscles. This 

 fluid in the fresh state 

 tends to obscure the deli- 

 cate fibres of the lamellae, 

 so that the adjacent layers 

 of endothelial cells belong- 

 ing to the successive lamellae stand out sharply when the corpuscle is viewed 

 in optical section, and were long taken to represent the actual tunics of the 

 organ. The layers are not however everywhere in such close juxtaposition, but are 

 here and there separated from one another by interlamellar spaces which are occu- 

 pied by lymph, and represent tha lymphatic clefts between the layers of the peri- 

 neurium of a nerve. 



The nerve-fibre, the disposition of which may now be noticed, is conducted 

 along the centre of the stalk, enters the corpuscle, and passes straight into the core, 

 at the further end of which it terminates. As shown by Pacini, the layers of the 



