TOUGH. 523 



of both fingers and toes are ridged internally by very beautiful 

 lines rnore or less spiral * ; and are shielded externally by nails. 



" These scutiform nails 11 are bestowed upon man and a few- 

 other genera of mammalia only (we allude to the quadrumana 

 which excel in the sense of touch) 1 , for the purpose of resisting 

 pressure, and thus assisting the action of the fingers, while exa- 

 mining objects* 



" They are of a horny nature, but on the whole very similar to 

 the epidermis. For under them lies the reticulum, which in 

 negroes is black m ; and under this again is found the corium, 

 adhering firmly to the periosteum of the last phalanx. These 

 constituent parts of the nails are striated lengthwise. The pos- 

 terior edge, which, in the hands, is remarkable for a little lunated 

 appearance, is fixed in a furrow of the skin ; and the nails, grow- 

 ing constantly from this, are protruded forwards, so as to be per- 

 fectly renewed about every six months." 



Dr. Breschet considers that the organ of touch is not a mere 

 nerve, but that an apparatus exists as in the eye and ear : that, 

 like the optic nerve entering the sclerotic, the nerves of touch 

 lose their neurilema on entering the cutis and derive a new 

 covering from its outer part, and then, terminating in a round 

 extremity or projecting papilla, are covered by a thin layer of 

 epidermis indispensable to the sense of touch." 



Weber has shown that the tactile power of the skin is not pro- 

 portionate to its sensibility. Thus the mammae are easily tickled, 



"Grew, Phil Tram. No. 159." 



k " B. S. Albinus, Ann^at. Academ* 1. iu tab. vii. fig. 4, 5, 6." 

 1 <f Namely* simiafc, papiones> cercopitheci, and lemures, the apices of whose 

 fingers in their four hands are very soft, and marked, as in the human subject, 

 with spiral lines. 



" Physiologists have disputed whether the sense of touch is bestowed on any 

 besides man and the quadrumana." " On one side, I would grant to both parties 

 that the snowy hands of a delicate girl must enjoy a milch more exquisite sense 

 of touch than what I call the fingers of brutes-. But, on the other, I have 

 frequently seen simias and papiones possessing much softer fingers, and using 

 these fingers to explore surfaces much more dexterously, than many barbarous 

 nations and innumerable persons among the lower orders of Europeans whose 

 hands have been hardened by labour." 



m " B. S. Albinus, De Habitu el Colore ^thiopum, fig. 3." 

 " Nouvdles Recherches sur la Structure de la Pcau, par M. G. Breschet. 

 Paris, 1835. 



