SECT 



39-] 



CUTIS. 



81 



determined) real bifurcations of the primitive fibres of the nerves ; 

 and. from the plexus itself, at least in certain places (particularly 

 on the palm of the hand, the sole of the foot, and the margins of 

 the lips), one to four, but, in general, two, nerve-fibres finally pass 

 into the base of certain papillae, and, running towards their apices, 

 there unite in form of a loop, or end free. 



According to the observations of Meissner and R. Wagner, nerves are not 



to be found in ;ill the papilla? of the palm and sole, but only in certain of them 

 which contain a peculiar central structure, called eorpusculwm tactus, and 

 are. for the most part, also destitute of vessels. This assertion is, upon the 

 whole, right ; and the papillae may be divided into vascular and nervous. 

 With regard to the nature of the tactile corpuscles (fig. 37), microscopists 

 entertain different views. I am of opinion that they are composed of an 

 axial tract of homogeneous connective tissue and an external layer of fusiform 

 plasm-cells, and 1 cannot, therefore, recognise a special structure in them. 

 Nerves pass into the papillae containing tactile corpuscles to the number of 

 one, two, or four, run on the external surface of the corpuscles, either straight 

 or in a spiral manner, to the summit, and end sometimes apparently free, 

 sometimes in loops, although it cannot be affirmed that these loops are the 

 true terminations. Papilla, with the so-called tactile corpuscles, have been 

 hitherto found, in addition to the places mentioned above, more sparingly 

 and less developed on the red border of the lip, on the tip of the tongue, on 

 the nipple, the glans penis, and the clitoris. 



In the hand, these so-named tactile corpuscles are almost wholly con- 

 fined to the palmar surface ; they are found especially on the fingers, par- 

 ticularly the third segment. On 

 the foot, they are likewise seated, 

 for the most part, on the ex- 

 tremities of the third phalanges 

 of the toes ; still they are not 

 entirely wanting in the middle 

 of the sole, or even on the 

 heel. On the dorsal surface of 

 the hands and feet a few such 

 bodies are often found ; some- 

 times they are wanting. With 

 regard to their number, Meissner 

 counted, on the terminal pha- 

 lanx of the index-finger of a man, 

 400 papillae in a square line, of 

 which 108, or one-fourth, pos- 

 sessed tactile bodies. In a square 

 line of the second phalanx 40 

 bodies were found ; on the me- 

 tacarpal phalanx, 15 ; on the 

 skin over the metacarpal bone 

 of the little finger, 8 ; on the 



plantar surface of the terminal phalanx of the great toe, 34 



(; 





l Wk 





,: 



A. Side view of a papilla (if the band. ". Cortical layer, 

 with plasm-cells ami tine elastic fibres ; 6. tactile corpuscle, 

 with transverse nuclei; c. small nerve of the papilla, with 

 neurilemma ; d. its two nervous fibres running witli spiral 

 coils around the tactile corpuscle ; e. apparent termination 

 of one of these fibres. D. A tactile papilla seen from 

 above, so as to show its transverse section a. Cortical 

 layer, with plasm-cells; b. a nerve-fibre; c. outer layer of 

 the tactile body, with nuclei ; d. clear interior substance, 

 from the human subject; treated with acetic acid. Mag- 

 nifled .')50 times. 



in the centre of 



