N 



THE SKIN. 559 



its own arteriole, which branches into looped capillaries, empty- 

 ing into the common venous retictilum of the hair follicle. The 

 vascular district of the papillary layer also furnishes the supply 

 for the muscles, the ducts of the sweat-glands, and the larger 

 nerves. The muscle-layer of the scrotum only has an independent 

 vascular supply. 



(4) Lymph-vessels. Successful injections of the lymphatics of 

 the skin with colored liquids have proved that these vessels con- 

 stitute a closed reticular system, in two layers, interconnected 

 by oblique branches. The superficial layer of capillary lymph- 

 atics is situated in the papillary portion of the skin, beneath the 

 superficial layer of blood-vessels. It is composed of ramules, 

 closer and narrower than those of the deep layer j from it the 

 larger papillae receive blind offshoots or shallow loops. I. Neu- 

 mann describes lymphatic reticula around the hair follicles, the 

 sebaceous and the sweat glands. The wide lymphatic branches 

 which spring from the deep layer are destitute of valves, and 

 accompany the arteries producing capillaries twined around the 

 arteries. After having received the lymphatics of the subcuta- 

 neous tissue they are furnished with valves, and take their course 

 in this tissue in large numbers, especially in the flexor aspects of 

 the extremities. 



(5) Nerves. The skin is abundantly provided with both medul- 

 lated and non-medullated nerve-fibers, more especially in the palms 

 of the hands and the soles of the feet, particularly in the skin cov- 

 ering the last phalanges of the fingers and toes. The nerves 

 usually penetrate the derma together with the blood-vessels. 

 Some of the medullated nerve-fibers terminate in the subcutane- 

 ous tissue as Pacinian corpuscles ; others reach the upper por- 

 tions of the derma in bundles, where they produce a plexus. 

 From this plexus arise branches for the nervous supply of the 

 papillae and the epithelial layer, some of which are medullated 

 and some non-medullated. The medullated nerve-fibers run to 

 the larger papillae, which, as a rule, are destitute of blood-vessels, 

 and terminate as a tactile corpuscle either in the papilla or at its 

 base, or even below its level. (See Fig. 233.) 



The corpuscles of Pacini or Vater are ovoid bodies, discernible to the 

 naked eye, some of them attaining a longitudinal diameter of two mm. or 

 more. According to Genersich, they increase in size with advancing age. 

 They are attached to medullated nerve-fibers, and are composed of a number 

 of concentric, nucleated layers, more closely arranged at the periphery of the 

 corpuscle than toward its center, and freely supplied with capillary vessels 



