726 



OF THE ORGANS OP THE SENSES, AND THEIR FUNCTIONS. 



single medullated nerve-fibre. The nerve runs without division sometimes 

 only as far as the lower pole, sometimes as far as the middle, and sometimes 

 even to the extremity of the corpuscle, frequently winding around it once or 



FIG. 250. 



Fir,. 251. 



Tactile Papillae from the Skin of the palmar surface of the forefinger, showing the tactile corpuscles 

 or "axile bodies:" A, in the natural state; B, treated with acetic acid. 



twice, and constricting it at these points. The nerve at length suddenly loses 

 its medulla and can no longer be traced, so that the termination of the axis- 

 cylinder is unknown. The corpuscle further presents certain transverse ele- 

 ments (Fig. 250 B), which are the nuclei of oblong cells, and anastomose 

 with each other by means of prolongations of elastic tissue fibres. The cap- 

 sule of the corpuscle is formed by a circular layer of elastic tissue formed 

 by the anastomosing processes of cells. 1 That the axile corpuscles of Wag- 

 ner are intimately associated with proper nervous tissue, is clearly shown by 

 the fatty degeneration they undergo on section of the nerves supplying them. 

 In a majority of so-called uerve-papillrc one or more capillary loops may 

 easily be demonstrated. A very simple form of the axile bodies has been 

 described by Krause as occasionally occurring in the conjunctiva, lips, and 



soft palate, in the tongue, and in the glans penis 

 and glaus clitoridis. Here the nerve forms a 

 " terminal button or knob," consisting of a deli- 

 cate sheath dotted with nuclei and filled with 

 granular plasma, into which the cylinder-axis of 

 the nerve enters terminating by a simple blunt 

 extremity. In the Pacinian bodies, the number 

 <>t' which in Man is estimated by Rauber to be 

 2142,- a more complex structure is met. with 

 than in either of those just mentioned, the chief 



y loops in Cutaneous papilla difference being that instead of a single sheath, 

 HI margin of lips. there are many investing capsules; a space 



1 Dr. Beale appears t<> doubt the termination in any instance of sensory nerve- by 

 froo extremities; Cor be has everywhere obtained demonstrative evidence of a net- 

 work, the fibres beini: oft, MI of extraordinary tenuity. He believes that in the papilhe 

 of the Skin, and even in the Pacinian bodies, after becoming connected with nuclei or 

 corpuscles the nerve-lihres turn or loop buck to the cell from whence they originate. 



! Untersuch. Miinchen, 1867. 



