386 



TERMINATION OF SENSORY NERVES. 



form of imperfect membranous septa (figs. 392, 393 A), between which are supported 

 the convolutions and ramifications of the nerves, and the enlargements in which the 

 branches of the axis-cylinder eventually end (small tactile cells according toMerkel). 

 These terminal enlargements, which are either pyriform or globular in shape, are 

 always placed near the capsule, and in small tactile corpuscles may occasionally 

 project beyond it. On entering the corpuscle the nerve-fibres for the most part lose 



Fig. 391. TACTILE CORPUSCLE 

 WITHIN A PAPILLA OP THE 

 SKIN OF THE HAND, STAINED 

 WITH CHLORIDE OP GOLD. 

 HIGHLY MAGNIFIED. 

 (Ranvier.) 



n, n, two nerve-fibres passing 

 to the corpuscle ; a, a, terminal, 

 varicose ramifications of the axis- 

 cylinder within the corpuscle. 



Fig. 392. ANOTHER CORPUSCLE, TREATED WITH OSMIC ACID, SEEN IN LONGITUDINAL SECTION. 



(Flemming, from a preparation by Fischer.) 



1, entering nerve-fibre, medullated ; 2, 2, the same cut variously within the corpuscle ; 3, 3, clear 

 spaces around the fibre (perhaps homologous with the core of the cylindrical end bulbs) ; 4, 4, nuclei of 

 the transverse and spirally-disposed cells of the corpuscle. 



Fig. 393. TACTILE CORPUSCLES FROM THE PALM OF THE HAND, SEEN IN SECTION (Merkel). 



A, Longitudinal section showing the interior traversed by connective tissue septa derived from the 

 capsule ; the nerve-fibres are cut across. B, transverse section at the point of entrance of a nerve-fibre, 

 showing the axis-cylinder branching. Other nerve-fibres are cut obliquely. 



their medullary sheath, but some retain it for a short while, or it may reappear here 

 and there in the course of the fibres. The axis-cylinders, which are often varicose, 

 have, as before intimated, a convoluted course before ending in their terminal 

 enlargements (fig. 391). 



The absence of a central core such as is found in the Pacinian corpuscles, and in some 

 end-bulbs, was first pointed out by Langerhans and afterwards by Thin. The latter observer 

 stated as the result of his observations, that tactile corpuscles could be divided into simple or 

 compound, according as they receive one or a greater number of nerve-fibres ; each nerve-fibre 

 passing to one distinct corpuscle, and the larger corpuscles being compounded of two or more 

 simple ones. On the other hand, even in the same papilla, several small corpuscles may occur 

 near to but distinct from one another. 



