TOUCH. TEMPERATURE SENSATIONS. 577 



part of the rectum, all of which possess tactile sensibility. 

 Very similar bodies are found in the synovial membranes of 

 some joints. In man they are spheroidal and vary in diameter 

 from .03 to 0.1 m.m. (-g^-^ inch). Each has an external 

 capsule of connective tissue within which is a core consisting 

 of polygonal nucleated ill-defined cells. The nerve-fibre 

 loses its medullary sheath close to the end bulb and the axis 

 cylinder enters the core and there usually breaks up into fila- 

 ments which ramify between the cells of the core and end in 

 little knobs: sometimes the axis cylinder does not branch. 

 The tactile corpuscles (Fig. 170) are found especially in the 



Fife. 170. Section of skin showing two papillae of the dermis and some of the 

 deeper cells of the epidermis ; a, papilla containing blood vessels; 6, papilla con- 

 taining a tactile corpuscle, t ; d, niedullated nerve-fibres going to the corpuscle; 

 at/, optical cross-sections of the fibres are seen as they wind round the outside of 

 the corpuscle; the general transverse direction of the connective-tissue bundles of 

 the capsule of the corpuscle is shown. 



skin of the hands and feet, but also on the inner surface of 

 the forearm, on the nipple, the lips, and mucous membrane 

 of the tip of the tongue. They lie in dermic papillae and are 

 oval in form, measuring about 0.8 m.m. (^fa inch) in the long 

 and 0.3 m.m. ( J T inch) in the transverse diameter. Each 

 has an outer capsule of connective tissue from which many 

 transverse or oblique dissepiments enter and divide the in- 

 terior into many small chambers. Two or three medullated 

 nerve-fibres go to each corpuscle, and after winding around ifc 

 obliquely several times penetrate the capsule at various levels, 

 at the same time becoming non-medullated. The axis cylin- 

 ders run in the clefts between the connective-tissue dissepi- 

 ments and after branching many times end in pear-shaped or 

 spherical enlargements, which are always placed near the out- 

 side of the corpuscle. 



