1068 ORGANS OF THE SENSES AND THE COMMON INTEGUMENT 



very distinct in the follicles of minute hairs ; it is limited to the deeper part of the 

 follicle. Outside this is a compact layer of fibers and spindle-shaped cells arranged 

 circularly around the follicle; this layer extends from the bottom of the follicle 

 as high as the entrance of the ducts of the sebaceous glands. Externally is a thick 

 layer of connective tissue, arranged in longitudinal bundles, forming a more 

 open texture and corresponding to the reticular part of the corium; in this are 

 contained the bloodvessels and nerves. 



I 



Dermis 



Sebaceous gland - 



Cortex of hair 



Vessel 



Dermic coat 



Inner root sheath 



Outer root sheath 



Bulb of hair 

 Papilla of hair 



f^^~-'^.A:.;-~<'-^<.:~^-^ 



^^fefe^^^r 



~ Stratum corneum 



~ Stratum lucidum 

 " Stratum granulosum 



Stratum mucosum 



Stratum 



germinativum 



Arrector pili 

 muscle 



Dermic coat 

 Medulla of hair 



FIG. 944. Section of skin, showing the epidermis and dermis; a hair in its follicle; the Arrector pili muscle; 



sebaceous glands. 



The inner or epidermic coat is closely adherent to the root of the hair, and con- 

 sists of two strata named respectively the outer and inner root sheaths ; the former 

 of these corresponds with the stratum mucosum of the epidermis, and resembles 

 it in the rounded form and soft character of its cells; at the bottom of the hair 

 follicle these cells become continuous with those of the root of the hair. The inner 

 root sheath consists of (1) a delicate cuticle next the hair, composed of a single 

 layer of imbricated scales with atrophied nuclei; (2) one or two layers of horny, 

 flattened, nucleated cells, known as Huxley's layer; and (3) a single layer of cubical 

 cells with clear flattened nuclei, called Henle's layer. 



The hair bulb is moulded over the papilla and composed of polyhedral epithelial 

 cells, which as they pass upward into the root of the hair become elongated and 

 spindle-shaped, except some in the center which remain polyhedral. Some of 

 these latter cells contain pigment granules w r hich give rise to the color of the hair. 

 It occasionally happens that these pigment granules completely fill the cells in 



