228 



THE NERVOUS SYSTEM 



pedicle to the nerve whose termination it is. Through this 

 pedicle passes a single (occasionally more) nerve fiber 

 which, piercing the several concentric layers constituting 

 the corpuscle, gradually loses its myeline substance and runs 

 longitudinally through the center of the body to terminate at 

 the distal end of the central cavity in a knob-like enlarge- 

 ment. These corpuscles are found in great abundance on the 

 palmar and plantar surfaces of the hands and feet, being far 

 more numerous on the first phalanx of the index finger than 

 elsewhere. About six hundred are said to be present in each 

 hand and foot. They are also to be found on the dorsal sur- 

 faces of the hands and feet, over parts of the forearm, arm 

 and neck, in the nipples, in the substance of muscles, in all 



the great plexuses of the sympa- 

 thetic system, and in numerous 

 other situations. These bodies can- 

 not be considered true tactile cor- 

 puscles because they are situated 

 beneath the skin ; neither can they 

 be positively said to have any "spe- 

 cial sensory" function such as the 

 appreciation of temperature, 

 weight, etc. 



(b) The end bulbs of Krause 

 exist in great number in the con- 

 junctiva, the glans penis and cli- 

 toris, the lips, and in other situa- 

 tions. They bear some resem- 

 blance to the corpuscles of Pacini, 

 but are much less elaborate in their arrangement; the num- 

 ber of concentric layers is much smaller, while the contained 

 mass is larger. The shape is spherical. From one to three 

 medullated fibers pass from the underlying plexus to wind 

 through the corpuscle and break up in free extremities. The 

 sheath of the fiber is continuous with the outer covering of 

 the corpuscle, and the medulla is gradually lost as the fiber 



FIG. 71. End bulb from 

 human conjunctiva, treat- 

 ed with osmic acid, show- 

 ing cells of core. (From 

 Yeo after Longivorth.) 



a, nerve fiber; b, nucleus of 

 sheath; c, nerve fiber within 

 core; d, cells of core. 



