506 



HAIR 



in a large proportion of the hairs of the scalp. In 

 structure it consists of two or three rows of rectan- 

 gular cells, which contain a certain amount of air. 



The structure of human hair is such that it can 

 almost always be distinguished from hair drawn 

 from other sources. At the same time it should be 

 noted that the hair of certain of the anthropoid 

 apes ( more especially the Chimpanzee and Gorilla ) 

 resembles it so closely, both in structure and in 

 microscopical appearance, that the differentiation 

 would be matter of extreme difficulty if indeed 

 it were possible. Waldeyer, in his Atlas der 

 Menschlichen und Thierischen Haare (1884), gives a 

 series of beautiful illustrations in which the hair of 

 man may be compared with that of certain of the 

 lower animals. 



In connection with each hair there is a remark- 

 able contrivance by means of which it is kept 

 smooth, glossy, and pliant. It is furnished with 

 two or more oil-glands, which secrete a greasy fluid. 

 Each of these glands consists of a little sacculated 

 pouch which opens into the hair-follicle near its 

 orifice by a short duct or channel of exit. The 

 oily matter which is formed in the gland is dis- 

 charged into the hair-follicle, and thus upon the 

 surface of the hair. 



Hairs are likewise provided with minute muscles. 

 These consist of slender bands of contractile tissue, 

 which cross the obtuse angle which is formed by the 

 hair-follicle and the surface of the skin. On the 

 one hand this little muscle is attached to the super- 

 ficial part of the true skin, and on the other 

 to the lower end of the hair-follicle. They are not 

 under the control of the will, but cold and certain 

 emotions, such as horror and fear, will bring them 

 into play. In such cases the hair-muscles contract ; 

 they straighten the hair-follicles and erect the hairs. 

 The condition known as ' goose-skin ' is the result. 



The hair-follicle is the laboratory in which the 

 manufacture and continued growth of the hair is 

 effected. At the bottom of the follicle is the little 

 papilla upon which the hair-bulb is moulded. The 

 blood-vessels of the papilla supply the material 

 necessary for the growth of the hair. Additions are 

 made to its base, and as it rises up in the follicle 

 its upwardly-directed scaly covering sweeps before 

 it the scales lining the follicle. The scales which 

 are thus carried to the surface constitute a part of 

 the scurf of the head. The rate at which the hair 

 grows differs very much in different parts of the 

 body, and it is also said to be affected by the age 

 of the individual, the age of the particular hair 

 under investigation, the season of the year, and 

 even the hour of the day. The average growth of 

 the beard has been computed to be 6 inches each 

 year. In the growth of the head-hair the greatest 

 discrepancies exist in the results obtained by differ- 

 ent observers. In young females who have lost 

 their hair by fevers it has been noticed to grow at 

 the rate of 7 inches each year. 



When the growth is good the average length of 

 hair on the female head will be found to vary 

 from 22 to 28 inches. Anything beyond this must 

 be regarded as exceptional. Cases, it is true, are 

 recorded in which it has measured from 5 to 6 

 feet ; but these are very rare. In the ' Hair Court ' 

 of the 1862 international exhibition there was a 

 specimen of jet-black hair measuring 74 inches. 

 But most extraordinary instances are recorded of 

 the power of hair-growth possessed by certain of 

 the North American Indians. A chief of the Crow 

 tribe is mentioned by Catlin as having hair of the 

 almost incredible length of 10 feet 7 inches. 



The duration of hair-life is limited, and sooner or 

 later it is shed. Indeed it is stated that the hairs 

 of an infant are completely shed within a year 

 after birth ; those on the body and limbs go first, 

 whilst the hairs of the head and the eyelashes 



follow. This change is carried on almost im- 

 perceptibly, seeing that the place of the falling 

 hairs is taken by a second crop. The process of 

 loss and renewal is very simple. The old hair is 

 detached from the papilla, and soon another hair 

 makes its appearance at the bottom of the same 

 follicle, and grows towards its orifice. The detached 

 hair is thus thrust out and shed. The whole process 

 is not unlike the replacement of the milk teeth in 

 the child by the permanent teeth. The second crop 

 of hair which appears is perennial. An eyelash 

 has been calculated to remain attached for 110 

 days. A head-hair has a longer period of life. It 

 lives from two to four years. Before it dies 

 provision is made for its successor, and so the 

 process of shedding and renewal goes on continually. 

 During its life a hair is only capable of growing a 

 certain determinate length. The circumstance 

 which determines this length is the amount of 

 nutritive material which can be drawn from the 

 blood-vessels of the papilla. Thus when a hair has 

 attained its full length it will resume growth for a 

 second time on being cut short. It is only when 

 the loss exceeds the powers of renewal that a 

 tendency to baldness results. In the case of the 

 female head the daily loss may contain a quarter 

 of the hairs shed of a length under 6 inches without 

 giving rise to apprehension. Should the number of 

 fallen short hairs exceed this proportion the hair- 

 loss is abnormal, and baldness is likely to ensue. 



As age advances the hair becomes gray. This is 

 a natural and physiological process ; but it may be 

 hastened by severe trouble or other causes. In 

 many cases the premature blanching of the hair is 

 hereditary. When the change is taking place 

 party-coloured hairs may be frequently found ; of 

 these it is the basal portion which is white, while 

 the terminal part retains its colour. Brown- 

 Sequard made some interesting experiments on his 

 own beard whilst it was turning gray. He marked 

 certain of the coloured hairs, and kept a constant 

 watch on them. He states that in some cases an 

 entire hair would turn gray in the course of a 

 night. Two factors would seem to be at work in 

 producing this condition of hair viz. a loss of the 

 power to produce pigment, and an increase of air 

 in the shaft of the hair. Sometimes the change 

 occurs rapidly in the course, perhaps, of a few 

 hours. Well-authenticated cases of this are on 

 record. It is said that the auburn hair of Marie 

 Antoinette turned gray in a single night. Surgeon 

 Parry asserts that he actually saw the jet-black 

 hair of a rebel sepoy whilst under examination and 

 the fear of a horrible death turn gray in the course 

 of half an hour. Baron Alphonse de Rothschild 

 during the Commune is another instance. It is 

 difficult to give any reasonable explanation of these 

 sudden cases of hair-blanching. 



The hair is regarded by anthropologists as being 

 of high importance as a race character. Although 

 there is no one special colour of hair peculiar to 

 any one race, this character must not be dis- 

 regarded. In our own country we may see every 

 hue from the fairest flaxen to the blackest jet. 

 Without doubt this points to a diversity of origin. 

 Independently of colour, however, there are char- 

 acters present in the hair which separate many of 

 the races of man widely from each other. In the 

 American Indians, Chinese, Japanese, and natives 

 of High Asia the hair is long, straight, and harsh like 

 a horse's mane. Amongst the negroes, Hottentots, 

 and Papuans it is crisp and woolly. Between these 

 extremes we may place the European, in whom the 

 hair is wavy and flowing. The close curling of the 

 negroes' hair has been shown by several observers 

 to be largely due to the fact that the hair-follicles 

 are curved. A spiral twist is thus given to the hair. 

 It has been held that the straight harsh hair of 



