Tin: I\TI:<,I MI:MM;Y APPENDAGES. 



71*3 



Tin- derma is ni>t of the same thickness everywhere, being much thinner 

 \\liei-e, it is protected from external injury, us on the under-snrfaco of the 

 belly, the inner side of the legs, thighs, etc.; it is also thin around the 

 margin of the natural openings, to permit the transition between the two 

 membranes, and endow these apertures with their necessary dilatability. 





SECTION OF HORSE'S SKIX; FROM WING OF THE NOSTRIL. 

 .]>idermis; D, Derma; 1, Horny layer of the epidermis; 2, Rete mucosuiu ; 3, 

 Papillary lay.-r of the derma; 4, Excretory duct of a sudoriparous gland; 5, 

 Glomerule of a sudoriparous gland ; 6, Hair follicle ; 7, Sebaceous gland ; 8, 

 Internal sheath of the hair follicle; 9, Bulb of the hair; 10, Mass of adipose 

 tissue. 



STRCCTUKK. The derma is composed of fasciculi of conjunctival tissue 

 interwoven and matted in a solid manner, and in the meshes of which are some 

 Miiooth muscular fibres, which, by their contraction, produce the condition of 

 the skin known as the cutia anserina (goose-skin). Somewhat loosely woven in 

 its deepest part to form the retlcular layer (or corium), the derma contains 

 the roots of the pilous follicles, the sudoriparous (or sweat) glands, and small 

 masses of adipose tissue ; superficially, its structure is very condensed, to 

 constitute fthdjMpflZovf /"//<r, whose uppermost 

 limit forms an amorphous border. 



The papillae are of two kinds vascular 

 and nervous, and aro regularly arranged in 

 parallel series : they are most numerous in 

 those parts of the skin specially destined for 

 the exercise of touch, as at the lips, in the 

 kcratogenous membrane (of the foot), and 

 other parts where sensibility is very acute 

 such as the scrotum, sheath, and integuments 

 of the penis. The papillary prolongations of 



. *. 1 . J f . , j. CAPIl . - IN mi: 



the derma aro conical or fungiform, and ]ndi- 

 cnlatcd ; their dimensions uru very variable ; 

 measuring from , } _th to .. 1 , th <.f an inch in h-n^th, and from , | _th to 



Fig. 364. 



