THE NERVOUS SYSTEM. 



413 



Fir. 159. 



...4 



n. pudendus communis, on the glans penis (Fick) and bulb of the ure- 

 thra, on the intercostal nerves, sacral plexus, 

 cutaneous nerves of the upper- and fore- 

 arm, on the dorsum of the hand and foot, 

 and the cutaneous nerves of the neck. 



The structure of the Pacinian bodies is, 

 upon the whole, simple (Fig. 159). Each of 

 them consists of very numerous (20-60) 

 concentric layers of connective tissue, of 

 which layers the external are separated by 

 wider, and the internal by narrower inter- 

 spaces, in which is contained a clear serous 

 moisture, which is collected in larger quan- 

 tity in an elongated central cavity, bounded 

 by the innermost lamella. Each body pre- 

 sents a rounded peduncle, formed from the 

 continuation of its lamellae, and connected 

 with a nervous twig, and in which a dark 

 nerve-fibre, 0-006-0-068 of a line (in the 

 Cat, 0-0044-0-0077 of a line) thick, runs to 

 the Pacinian body. This fibre enters the 

 central cavity from the penduncle, where it 

 becomes 0-006 of a line wide and 0-004 

 of a line thick, pale, non-medullated, almost 

 like an axis-cylinder, and terminates in the 

 upper part of the cavity, in a free, slightly 

 granular tubercle, the extremity being fre- 

 quently bifid or trifid. Further observa- 

 tions, and comparative anatomical details 

 with regard to these bodies, which are also 



found in great number in many Mammalia, as well as in Birds, in the 

 skin, beak, and tongue (Herbst, Will), and with respect to which physio- 

 logy is still wholly in the dark, will be found in the works above quoted, 

 and also in Reichert (" Bindegewebe," p. 65), Herbst (" Gbtt. gel. Anz.," 

 1848, Nos. 162, 163, 1850; " Nachr. v. d. Univ.," p. 204, 1851, p. 

 161), Will ("Sitzungsber. d. Wiener Acad.," Feb., 1850), Osann ("Bericht 

 uber d. zoot. Anst. in Wurzb.," 1849), Strahl (Muller's " Arch.," 1848, 

 p. 163), and Pappenheim (" Comptes rendus," xxiii. p. 68). [Todd and 

 Bowman, " Physiol. Anatomy," Part II., p. 395, figs. 74, 75, 76; and 

 Bowman, art. "Pacinian Bodies," " Cyc. of Anat. and Phys."] 



FIG. 159. A Pacinian body in Man, magnified 350 diam. : a, its peduncle; b, nerve- 

 fibre in it ; c, external ; d, internal layer of the sheath ; e, pale nerve-fibre in the cen- 

 tral cavity ; /, divisions and terminations of the same. 



