PAPILLAE AND VESSELS. 



ccv 



thus named, which seem chiefly intended to contribute to the perfection of 

 the skin as an organ of touch, seeing that they are highly developed where 

 the sense of touch is exquisite, and vice versa. They serve also to extend the 

 surface for the production of the cuticular tissue, and hence are large-sized 

 and numerous under the nail. The papillae are large, and in close array on 

 the palm and palmar surface of the fingers, and on the corresponding parts 

 of the foot (fig. ex. ). There they are ranged in lines forming the curvilinear 

 ridges seen when the skin is still covered with its thick epidermis. They are 

 of a conical figure, rounded or blunt at the top, and sometimes cleft into 

 two or more points, when they are named compound papillae. They are 

 received into corresponding pits on the under surface of the cuticle. In 

 structure they resemble the superficial layer of the corium generally, and 

 consist of a homogeneous tissue, presenting only faint traces of fibrillation, 

 together with a few fine elastic fibres. On the palm, sole, and nipple, 

 where they are mostly of the compound variety, they measure from ^^ ff 

 to -j^* of an inch in height. In the ridges, the larger papilla} are placed 

 sometimes in single but more commonly in double rows, with smaller ones 

 between them (rig. cxxm.), that is, also on the ridges, for there are none in 

 the intervening grooves. These ridges are marked at short and tolerably 

 regular intervals with notches, or short transverse furrows, in each of which, 

 about its middle, is the minute funnel-shaped orifice of the duct of a sweat 

 gland (fig. cxi.). In other parts of the skin endowed with less sensibility, 

 the papillae are smaller, shorter, fewer in number, and irregularly scattered. 

 On the face they are reduced to from -g^ to 3-^ of an inch ; and here 

 they at parts disappear altogether, or are replaced by slightly elevated reti- 

 cular ridges. In parts where they are naturally small, they often become 

 enlarged by chronic inflammation round the margin 

 of sores and ulcers of long standing, and are 

 then much more conspicuous. Fine blood- 

 vessels enter most of the papillae, forming either 

 simple capillary loops in each, or dividing into two 

 or more capillary branches, according to the size 

 of the papilla and its simple or composite form, 

 which turn round in form of loops and return to 

 the veins. Other papillae receive nerves, to be 

 presently noticed. 



Blood-vessels and lymphatics. The blood-vessels 

 divide into branches in the subcutaneous tissue, 

 and, as they enter the skin, supply capillary plex- 

 uses to the fat-clusters, sweat-glands, and hair- 

 follicles. They divide and anastomose still further 

 as they approach the surface, and at length, on 

 reaching it, form a dense network of capillaries, 

 with rounded polygonal meshes. Fine branches are 

 sent into the papillie, as already mentioned. The 

 lymphatics are abundant in some parts of the skin, 

 as on the scrotum and round the nipple ; whether 

 they are equally so in all parts may be doubted. 

 They form networks, which become finer as they 

 approach the surface, and communicate underneath 

 with straight vessels, and these, after a longer or a 



shorter course, join larger ones or enter lymphatic glands. The finest and 

 most superficial network, although close to the surface of the corium, is 



Fig. CXI. 



g. CXI. MAGNIFIED 



VlKW OF FOUR OF THE 



RIDGES OF THE EPIDER- 

 MIS, CAUSED BY ROWS OF 



PAPILLAE BENEATH, WITH 

 SHORT FURROWS OR 

 NOTCHES ACROSS THEM ; 

 ALSO THE OPENINGS 

 OF THE SUDORIFEROUS 

 DUCTS (after Brescia et). 



