638 PHYSIOLOGY 



connected. Other end-organs which are supposed to be stimulated by 

 changes of pressure and therefore to be tactile, are the organs of Ruffini 

 which occur in the papillae of the palm and fingers and, lying more deeply, 

 the elastic tissue spindles as well as the Golgi corpuscles and the Pacinian 

 corpuscles in the subcutaneous tissue. 



As regards pain, we know that in the cornea, which possesses only 

 the pain sense, the sensory nerve-endings are in the form of branches of 

 axis cylinders among the epithelial cells. Similar free nerve endings occur 

 in the epidermis all over the body, and it is therefore imagined that these 

 have the special function of subserving the pain sense. We have at present 

 no evidence as to the histological character of the organs by which the 

 sensations of heat and cold are aroused. 



