522 STRUCTURE OF THE DERMIS. 



eyelids, the penis, and the scrotum it is peculiarly delicate. It 

 is connected by its under surface with the common superficial fascia 

 of the body. 



The Papillary layer of the dermis is raised in the form of conical 

 prominences or papillae. Upon the general surface of the body the 

 papillae are short and exceedingly minute ; but in other situations, as 

 on the palmar surface of the hands and fingers, and on the plantar 

 9 surface of the feet and toes, they 



are long and of large size. They 

 also differ in arrangement; for on 

 the general surface they are distri- 

 buted at equal distances and with- 

 out order ; whereas on the palms 

 and soles, and on the corresponding 

 surfaces of the fingers and toes, 

 they are collected into little square 

 clumps containing from ten to twen- 

 ty papillae ; and these little clumps 

 are disposed in parallel rows. It 

 is this arrangement in rows that 

 gives rise to the characteristic pa- 

 rallel ridges and furrows which are 

 met with on the hands and feet. 

 The papillae in these little square 

 clumps are for the most part uniform in size and length, but every 

 here and there one papilla may be observed which is longer than the 

 rest. The largest papillae of the dermis are those which produce the 

 nail ; in the dermic follicle of the nail they are long and filiform, 

 while beneath its concave surface they form longitudinal and parallel 

 plications which extend for nearly the entire length of that organ. In 

 structure each papilla is composed of a more or less convoluted capil- 

 lary and a more or less convoluted nervous loop. 



The EPIDERMIS or cuticle (scarf-skin) is a product of the dermis, 



* Anatomy of a portion of skin taken from the palm of the hand. 1,1. The 

 papillary layer, in which the longitudinal furrows (2) marking the arrange- 

 ment of the papillae into ridges is shown. Each ridge is moreover divided by 

 transverse furrows (3) into small quadrangular clumps. The quadrangular 

 clumps consist of a tuft of minute conical papillae, of which one or two are 

 frequently longer and larger than the rest. In this figure the long papillae are 

 alone seen, the rest being too numerous to introduce into a wood-engraving. 

 4. The rete mucosum raised from the papillary layer and turned back; the 

 under surface of this stratum presents an accurate impression of the papillary 

 layer ; on which are seen longitudinal ridges corresponding with the longi- 

 tudinal furrows, transverse ridges corresponding with the transverse furrows, 

 and quadrangular depressions corresponding with the quadrangular clumps of 

 papillae. Moreover, wherever one of the long papillae exists, a distinct conical 

 sheath will be found in the rete mucosum. 5, 5. Perspiratory ducts drawn 

 out straight by the separation of the rete mucosum from the papillary layer ; 

 the point at which each perspiratory duct issues from the papillary layer, and 

 pierces the rete mucosum, is the middle of the transverse furrow between the 

 quadrangular masses. 



