344 EXCEETION BY THE SKIN AND KIDNEYS. 



much thicker than the papillary layer and is dense, resisting, quite elastic 

 and slightly contractile. It is composed of bundles of fibrous tissue, inter- 

 lacing with each other in every direction, generally at acute angles. Distrib- 

 uted throughout this layer, are found anastomosing elastic fibres of the small 

 variety, and with them a number of non-striated muscular fibres. This por- 

 tion of the skin contains, in addition, a considerable quantity of amorphous 

 matter, which serves to hold the fibres together. The muscular fibres are 

 particularly abundant about the hair-follicles and the sebaceous glands con- 

 nected with them, and their arrangement is such that when they are excited 

 to contraction by cold or by electricity, the follicles are drawn up, projecting 

 upon the general surface and producing the appearance known as " goose- 

 flesh." Contraction of these fibres is particularly marked about the nipple, 

 producing the so-called erection of this organ, and about the scrotum and 

 penis, wrinkling the skin of these parts. The peculiar arrangement of the 

 little muscles around the hair-follicles, forming little bands attached to the 

 surface of the true skin and the base of the follicles, explains fully the man- 

 ner in which the " goose-flesh " is produced. (See Fig. 107, page 349.) Con- 

 traction of the skin, under the stimulus of electricity, has been repeatedly 

 demonstrated, both in the living subject and in executed criminals immedi- 

 ately after death. 



The papillary layer of the skin passes insensibly into the subjacent struct- 

 ure without any marked line of division. It is composed chiefly of amor- 

 phous matter like that which exists in the reticulated layer. The papilla? 

 themselves appear to be simple elevations of this amorphous matter, although 

 they contain a few fibres, connective-tissue nuclei and little corpuscular 

 bodies called cytoblastions (Robin). 



As regards their form, the papillae may be divided into two varieties ; the 

 simple and the compound. The simple papillae are conical, rounded or 

 club-shaped elevations of the amorphous matter and are irregularly distrib- 

 uted on the general surface. The smallest are T^ to ^-g- of an inch (36 to 

 62 /A) in length and are found chiefly upon the face. The largest are on the 

 palms of the hands, the soles of the feet, and the nipple. These measure 

 ^io- to -gfa of an inch (100 to 125 ft). Large papillae, regularly arranged in 

 a longitudinal direction, are found beneath the nails. The regular, curved 

 lines observed upon the palms of the hands and the soles of the feet, particu- 

 larly the palmar surfaces of the last phalanges, are formed by double rows of 

 compound papillae, which present two, three or four elevations attached to a 

 single base. In the centre of each of these double rows of papillae, is a fine 

 and shallow groove, in which are found the orifices of the sudoriferous ducts. 



The papillae are abundantly supplied with blood-vessels terminating in 

 looped capillary plexuses and with nerves. The termination of the nerves is 

 peculiar and will be fully described in connection with the organs of touch. 

 The arrangement of the lymphatics, which are very abundant in the skin, 

 has already been indicated in the general description of the lymphatic system. 



The Epidermis and its Appendages. The epidermis, or external layer of 

 the skin, is composed of cells. It has neither blood-vessels, nerves nor lym- 



