354 



THE SENSES 



often closely associated with the Pacinian corpuscles. They consist of 

 a connective-tissue frame-work on which a plexus of teleodendria is 

 arranged about the elastic fibers. Another organ bearing Ruffini's name 

 is the plume-organ so-called. This von Frey suggests may be the end- 

 organ of heat. Nerve-rings of the hair-follicles (Bonnet) (Fig. 206) 

 have been recently described. These for the first time suggest a use- 

 ful function of the lanugo hairs found on nearly all parts of the body, 

 the hand-palms and the foot-soles being marked exceptions. These 

 end-organs consist essentially of a ring of nerve-fibrils forming a narrow 



FIG. 204 



FIG. 205 



The afferent nerves and Pacinian 

 corpuscles of the third finger. (Henle 

 and Kolliker.) 



Tactile corpuscles of three degrees of complex- 

 ity (diagrammatic): A, corpuscle of Grandry with 

 one tactile disk, dt, and two tactile cells, ct; B, 

 corpuscle with two disks and three cells; C, Meiss- 

 ner's corpuscle; 1, 2, 3, its component parts 

 (Grandry's corpuscles); n, nuclei of the tactile 

 cells; a, nerve-fiber; si, interannular segment. 

 (Duval via Morat.) 



cylindrical plexus in the wall of the hair-follicle just below the ducts of 

 the sebaceous glands. When the hair is bent, as by a touch on the skin, 

 its shaft acts as a lever and compresses on one side this ring of nerve- 

 fibrils. The tactile menisci or disks are the most superficial of the 

 cutaneous sense-organs of touch. They each consist of an epithelial 

 cell placed upon a delicate meniscus, each disk being connected below 

 with a nerve-fiber (Fig. 207) . These are placed in the lowest portions 

 of the epidermis. In addition to the foregoing, it is likely enough that a 

 certain free nerve-ending in the cornea (Fig. 219) and possibly also an 

 encapsulated end-organ figured by Longworth represent touch. 



