232 SKIN, HAIR, AND NAILS, BY ALFRED BIESIADECKI. 



numerous, contain a larger portion of the medullated nerve 

 fibres.* 



From the primary branches a few medullated nerve fibres 

 are given off either in the subcutaneous connective tissue, or 

 in the lowermost portion of the corium, which terminate in 

 the Pacinian corpuscles. 



The remainder of the fibres extend for the most part in an 

 oblique direction towards the surface of the corium, and form 

 a nerve plexus in the stratum papillare corii that accompanies 

 the blood vascular plexus. 



A few medullated nerve fibres often lose their medulla even 

 in the upper part of the corium, or they may extend into the 

 nerve papillse, and terminate in the tactile corpuscles. 



The non-medullated nerve fibres accompany the bloodvessels 

 of the vascular papillae (Langerhans). 



PACINIAN CORPUSCLES. 



These corpuscles were first seen by A. Vater, as Langer has 

 demonstrated, and have hence been also called the corpuscles 

 of Vater. They are present, not only in Man, but in many 

 Vertebrates and Birds, and are for the most part seated in the 

 subcutaneous connective tissue, though they may be found in 

 some other parts, as, for example, in the mesentery (in the Cat). 

 In reality they are nothing but the remarkably thickened ends 

 of medullated nerve fibres. 



The sheath consists at first of a homogeneous nucleated 

 membrane, on which, by immersion in a solution of nitrate of 

 silver, indications of the presence of an epithelium can be 

 made to appear. At a certain point it breaks up into a system 

 of twenty or thirty concentric capsules, resembling the coats 

 of an onion, that constitute the principal mass of the corpuscle. 

 Of these membranes, which are clear and apparently structure- 

 less, the external are thicker, and separated from one another 

 by a clear fluid, whilst the internal are thinner, and are in 

 very close apposition. On section, especially after the action 

 of acetic acid, numerous oblong nuclei come into view, that 



* Langerhans. Virchow's Archiv, Band xliv., 2 and 3 Heft. 



