I390 



HUMAN ANATOMY. 



prepuce and of the nymphae and the glans penis and ditoridis. With the exception of 

 those regions in which the growth is sufficiently long to constitute a complete cover- 

 ing — the scalp, bearded parts of the face in the male, axillae and mons pubis — the 

 hairs are for the most part short and scattered, although subject to great individual 

 variation and sometimes to remarkable redundance. 



The hairs in various locations are known by special names ; those of the scalp 

 being capilli ; of the eyebrows, supercilia ; of the eyelashes, cilia; of the nostrils, 

 vibrisscs ; of the external ear, tragi ; of the beard, barba ; of the axillae, hirci ; of 

 the pubes, pubes ; while the fine downy hairs that cover other parts of the body are 

 designated laiiiigo. 



The closest set hairs are on the scalp, where, according to Brunn, on the vertex 

 they number from 300-320, and in the occipital and frontal regions from 200-240 

 per square centimeter. On the chin 44 were counted, on the mons pubis 30-35, 



Erector muscle 



Sweat gland 



Hair-papill 



Paniculus 

 adiposus 



Section of scalp, showing longitudinally cut hair-follicles. X 14. 



on the extensor surface of the forearm 24 and on the back of the hand 18 for like 

 areas. Even where their distribution is seemingly uniform, close inspection shows 

 the hairs to be arranged in groups of from two to five. 



The length of the hairs includes the extremes presented by the lanugo, only a 

 few millimeters long, on the one hand, and by the scalp-growth, sometimes meas- 

 uring 150 cm. (59 in.) or more, on the other. Their thickness, likewise, shows 

 much variation, not only in different races, individuals and regions, but also in the 

 same person and part of the body, as on the scalp where fine and coarse hairs may 

 lie side by side. The thickest scalp-hairs have a diameter of .162 mm. and the 

 finest one of .011 mm., with all intermediate sizes. The hairs of the beard vary 

 from .101-203 mm. and those on the pubes from .054-. 135mm. (Falck). In a 

 general way hairs of light color are finer than dark ones, the respective diameters of 

 blond, brown and black hairs being .047, .054 and .067 mm. (Wilson). On 

 attaining their full growth without mutilation, hairs do not possess a uniform thick- 

 ness throughout their length, since they diminish not only towards the tip, where the 

 shaft ends in a point, but also towards the root. This feature is most evident in 

 short hairs, as in those of the eyebrows. 



The color of the hair, which varies from the lightest straw to raven black, is 

 closely associated with racial and individual characteristics, being usually, but by no 



