3 88 



THE SKIN AND ITS APPENDAGES. 



In the distal phalanx of the index-finger every fourth papilla is 

 a tactile papilla, containing one or sometimes two corpuscles of 

 Meissner. They are, however, not nearly so numerous in other 

 parts of the hand or in the foot. These corpuscles are further 

 found on the dorsal surface of the hand and volar surface of the 

 forearm, in the nipple and external genitals, in the eyelids (border), 

 and in the lips. In figures 310 and 311 are shown two Meissner's 

 corpuscles, giving the appearance presented by these end-organs 

 when not stained with special reference to nerve terminations. For 

 the latter see figure 137. 



The Krause's end-bulbs, both spheric and cylindric, are, as a 

 rule, situated a short distance below the papillary layer, although 

 they are frequently found in the papillae. They occur in man in the 

 conjunctiva, lips, and external genitals, and in the mucous mem- 

 branes previously mentioned (p. 170). See page 170 and figure 

 136 for their structure. 



In the palm of the hand and sole of the foot, the subcutaneous 

 connective tissue contains numerous Pacinian corpuscles. They 

 occur also along the nerve-fibers of the joints and in the periosteum 

 of the extremities. 



Very recently Ruffini demonstrated in the human corium the 

 existence of peculiar nerve end-organs, which consist of a connec- 

 tive-tissue framework supporting a rich arborization of telodendria. 

 They occur side by side with the Pacinian corpuscles and in appar- 

 ently equal numbers. These nerve terminations resemble in many 

 respects the neurotendinous spindles (see Fig. 145), although they 



present certain structural differences. 

 Instead of intrafusal tendon fasciculi, 

 the Ruffini end-organ is composed 

 of white fibrous and elastic tissue. 

 In this end-organ the medullated 

 nerves make long and tortuous 

 turns before becoming nonmedul- 

 lated, and the terminations of these 

 nerve-fibers occupy the whole of the 

 cross-section. 



The Golgi-Mazzoni corpuscle re- 

 sembles in structure the Pacinian 

 corpuscle, although it possesses fewer 

 lamellae and a relatively larger core, 

 and the nerve - fibers terminating 

 therein are more extensively branched 

 than in the Pacinian corpuscle. Ruf- 

 fini has found these nerve-endings in 

 the subcutaneous tissue of the finger- 

 tips. 



The blood-vessels of the skin are richly supplied with the vaso- 

 rnotor nerves, which terminate in the nonstriated muscle of the 



Terminal disc of 

 nerve-fibers. 



Epithelial cell. 



Connective-tissue 

 capsule. 



- Nerve-fiber. 



.Fig. 312. Grandry's corpuscles from 

 bill of duck ; X 5- 



