SENSE OF TOUCH. 



725 



FIG. 249. 



Vertical Section of the Skin of the palmar sur- 

 face of the forefinger (treated with a solution of 

 caustic soda), showing the branches of cutaneous 

 nerves, a, 6, inosculating to form a terminal 

 plexus, of which the ultimate ramifications pass 

 into the cutaneous papillte, c, c, c. 



are little elevations of the surface of the cutis, usually simply conical or 

 t-lavate in form (Fig. 249), but sometimes presenting numerous summits. 

 On the palmar surface of the hand, 

 they are arranged in rows ; and they 

 are there so numerous that (accord- 

 ing to E. H. Weber) as many as 81 

 compound, or from 150 to 200 simple 

 papilla?, are contained within the area 

 of a square (Paris) line. The papil- 

 lae are also very numerous, though 

 without any definite arrangement, on 

 the red surface of the lips, on the 

 penis of the male, on the labia rni- 

 nora and clitoris of the female, and 

 on the nipples of both sexes ; but 

 elsewhere they are scattered more 

 widt'ly apart. Each sensory papilla 

 receives one or more nerve-fibres 

 from the plexus which is formed by 

 the inosculation of the ramifications 

 of the cutaneous nerves (Fig. 249) ; 

 and these nerve-fibres seem to termi- 

 nate (at least in the papillae of the palm of the hand and of the lips, and in 

 the simple papillae of the tongue) in a peculiar " axile body," which occupies 

 the principal part of the interior of the papilla (Fig. 250). With regard 

 to the nature of this body, there has been considerable discussion between 

 Prof. Wagner, its discoverer, and Prof. Kolliker; 1 the former regarding it 

 as an organ altogether sui generis; whilst the latter maintains that it is 

 nothing else than a mass of homogeneous connective-tissue with an external 

 layer of imperfectly-developed elastic tissue, and that it is essentially similar 

 to the bundles of fibrous tissue encircled by elastic fibres, which are to be 

 found in the substance of the cutis. This last view is in the main supported 

 by Mr. Pluxley, who regards the "axile body" as formed by the continua- 

 tion and increased development of the neurilemma of the nerve-tubes which 

 enter the papilla, and as bearing a close relation to the "Paciniau bodies." 2 

 The recent observations of Rouget, Biesiadecki, and Thin seem to show that 

 the tactile corpuscles really represent the specially modified termination of a 



1 For details in regard to the structure of the corpuscula tactus and the termina- 

 tions of the tactile nerves, see Prof. Wagner in the Gottingen Gelehrte Nachrichten 

 for Feb. 1852, and Mailer's Archiv, 1852, Heft 4 ; Prof. Kolliker in Zeitsch. fur Wis- 

 sensch. Zool., June, 1852, and in his Mik Arntt., Bd. ii,p. 24; Dalzell, in Edin. 

 Monthly Journal, March, 1853 ; Ecker, Icon., Physiol., plate xvii ; Leydig, Miiller's 

 Archiv, 1856, p. 50, and Schultze's Archiv. f. Mic. Anat., 1808, p. 'l95 ; Gerlach, 

 Mikroskop. Siudien. Erlangen, 1858; Krause, Die Terminal Korperchen der einfach 

 Sensibeln Nerven, Hanover, 1860; Huxley, in Cyclop, of Anat. Physiol., Suppl., Art. 

 Tegument. Organs, 1859, p. 503; Meissner, Beitrlige, plate i, Figs. 6 and 8; Henle, 

 Handb. der System. Anat., 1862, Bd. ii, p. 13; Fick, Lehrb. der Anat. der Sinnes 

 Urg.ine, 1862, p. 22; Tomsa, Wien Med. Wochens., 1865, Bd. xv, p. 53; Rouget, 

 Arebiv. de Physiol., 1868, p. 598; Michelson, Centralblatt, 1869, p. 446 ; G. Ciaceio, 

 Moleschott's Untersuch., Bd x, p. 579 ; J. Schobl, Schultze's Archiv, Bd. vii, p. 260, 

 and viii, p. 295; Th. Eimer, Idem, Bd. vii, p. 181 ; L. Stieda, Idem., Bd. viii, p. 274 ; 

 W. Beil, Ahst. in Centralblatt, 1872, p. 692; Sertoli, Abst. in Centralblatt, 1872, p 692; 

 Budsre, C< j ntralblatt, 1873, p. 594; Langerhans, Schultze's Archiv, Bd. ix, p. 730; 

 Johert, Comptes Rendus, 1874, p 820; G. Thin, Journ. of Anat. and Phys., 1874, p. 

 30; Biesmdecki, in Strieker's Hum. and Comp. Histology, vol. ii, p. 232; Grandry, 

 Journal de 1'Anatomie, t. vi, 1870, p. 390. 



2 See his Memoir, On the Structure and Relation of the Corpuscula Tactus, in the 

 Quarterly Journal of Microscopical Science, vol. ii, p. 1. 



