400 THE ORGANS 



layer of the follicle. From these are given off branches which form 

 a rich plexus of small arterioles and capillaries in the vascular layer 

 of the foUicle. Capillaries from this plexus also pass to the seba- 

 ceous glands, the arrectores pilorum muscles, and the papillae. 



The lymphatics of the skin. These begin as clefts in the papillae, 

 which open into a horizontal network of lymph capillaries in the 

 pars papillaris. This communicates with a network of larger lymph 

 capillaries with wider meshes in the subcutaneous tissue. The latter 

 also receives lymph capillaries from plexuses which surround the seba 

 ceous glands, the sweat glands, and the hair follicles. 



The nerves of the skin. These are mainly sensory. Efferent sym- 

 pathetic axones supply the smooth muscle of the walls of the blood- 

 vessels, the arrectores pilorum, and secretory fibres to the sweat glands. 

 The medullated sensory nerves are peripheral processes of spinal gang- 

 lion cells. The larger trunks lie in the subcutis, giving off branches 

 which pass to the corium, where they form a rich subpapillary plexus 

 of both medullated and non-medullated fibres. From the subcuta- 

 neous nerve trunks and from the subpapillary plexus are given off 

 fibres which terminate in more or less elaborate special nerve end- 

 ings (see page 430). Their location is as follows: (i) In the subcutis: 

 Vater-Pacinian corpuscles, the corpuscles of Ruffini, and the Golgi- 

 Mazzoni corpuscles of the finger-tip. The first two forms are most 

 numerous in the palms and soles. (2) In the derma: Tactile corpuscles 

 of Meissner and Wagner. These are found in the papillae, especially 

 of the finger tip, palm, and sole. Krause's end bulbs — usually in the 

 derma just beneath the papillas, more rarely in the papillae themselves. 

 (3) In the epithelium: Free nerve endings among the epithelial cells. 



Branches of the cutaneous nerves supply the hair follicles. As a 

 rule but one nerve passes to each follicle, entering it just below the 

 entrance of the duct of the sebaceous gland. As it enters the follicle 

 the nerve fibre loses its medullary sheath and divides into two 

 branches, which further subdivide to form a ring-like plexus of fine 

 fibres encircling the follicle. From this ring, small varicose fibrils 

 run for a short distance up the follicle, terminating mainly in slight 

 expansions on the vitreous membrane. 



TECHNIC 



For the study of the blood-vessels of the skin inject (technic, p. 25) the 

 entire hand or foot of a new-born child. Examine rather thick sections 

 either mounted unstained or stained onlj' with eosin. 



