the delicate filamentous processes which constitute the covering of the skin in mammals generally; and which likewise appear in animals of the lower orders, indeed in all animals that have a true epidermis. It is distinctly developed in the soft-skinned insects, such as butterflies and caterpillars, spiders, bees, &c.; and occurs in tufts in certain parts of the crustacean animals, as on the feet, jaws, &c. Hair, in its mechanical nature, may be regarded as a condensed form of cuticle. The feathers of birds may be considered as analogous to hair; while the only two classes of animals that are wholly devoid of any kind of hair are the fishes and reptiles. The variety in the conformation of hair is very great, ranging from the finest wool to the quills of the porcupine, or the horn of the rhinoceros, which last is nothing more than an assemblage of many hairs in one compact mass.

But it is to hair, commonly so called, and more particularly to that of man, that we would now direct attention. The human skin is entirely covered with hairs of different degrees of fineness, except on the palms of the hands and the soles of the feet. Each hair originates in the cellular membrane of the skin, from a small bulbous root, which, by the intervention of its vessels, connects it with the corium in which it is imbedded. A small portion of the lower end of the hair is hollow, and contains a pulpy matter which is intended for its nutrition; but this cavity never, in common hairs, extends as far as the external surface of the skin. The hair, in a healthy state, is insensible; the pain which is felt on its extraction arising from the nerves which surround the root; yet when in the abnormal condition of what is called plica polonica, it becomes sensitive to a high degree, and even bleeds when cut. Among many of the lower animals the hair (though insensible in itself) serves as a very delicate medium of sensation. The slightest touch, even that produced by a human hair, is sufficient to make such animals as cats contract their skin, and by a tremulous motion of their bodies rid themselves of anything adhering to it.

The form of the human hair is rarely cylindrical. It appears to be so only in the straight hairs. In curled hair the transverse section is elliptical; and occasionally it exhibits a bean-like form, arising from a furrow that passes lengthwise down one side of the hair. The flattened form seems in general to be necessary to the curling of the hairs, while the cylindrical figure is opposed to it. In the crisp woolly hair of the negro a very marked flattening is observed, the hairs being sometimes as much as two-thirds broader in one direction than in the other. In the wool of the sheep, which appears to approach the cylindrical form, the phenomenon of curling is probably due to the transverse inequalities with which the surface of the hairs is furrowed. Human hair possesses a very remarkable degree of strength, compared with its small diameter, is considerably extensible, and highly elastic. Saussure found that a human hair, when freed from grease by maceration in an alkaline solution, formed a very delicate hygrometer, from its property of elongating on absorbing moisture. The colouring matter of the hair appears to reside in an oily fluid, analogous in its nature to that which is contained in the rete mucosum of the skin; and according to its colour arises the diversity of black, brown, fair, and red hair, and their several shades. Grayness is induced by a deficiency of this fluid, whether arising from age, sickness, or excessive mental emotion, such as grief, or sudden terror. The hair of the head, in particular instances, has been known to attain a length of seven or eight feet. Though hair, in a healthy state, grows only on the external parts of the body, instances have occurred in which it has been formed inside the body in diseased parts. It is also a curious fact that hair will sometimes continue to grow for a certain period after death.

As the hair is a very conspicuous object, and susceptible of much graceful adornment, its arrangement has always been one of the most important duties of the toilet. In scarcely anything has the caprice of fashion been more strikingly displayed than in the various forms which the tastes of different nations and ages have prescribed for disposing this natural covering of the head. The ancient Greeks allowed their hair to grow to a great length; and their natural fondness for this attribute of beauty has been perpetuated by their poets and sculptors alike. The early Egyptians again, who were proverbial for their habits of cleanliness, removed the hair as an incumbrance. All classes among that people, including the foreign slaves, were required to submit to this custom (Gen. xlii.14); and in place of nature's covering they made use of wigs, the reticulated texture of the ground-work on which the hair was fastened allowing free ventilation, while the hair effectively protected the head from the sun (Wilkinson, Anc. Egyptians, iii.354). The Hebrews, on the other hand, esteemed fine hair as a great beauty, and particularly deprecated baldness. Though among the males it was usually kept short, the Hebrew women gloried in their luxuriant tresses, plaiting them and adorning their heads with ornaments of gold and silver and precious stones (Isaiah iii.). The misfortune of Absalom shows that men sometimes indulged in the effeminacy of long hair; and Josephus relates (Antiq. viii.7), that Solomon's horse-guards daily strewed their heads with gold dust, which glittered in the sun. Artificial hair was used not only by the Egyptians, but also by the Greeks, the Carthaginians, and especially by the Romans, among whom the sale of human hair, particularly the blond hair of Germany, was an ordinary species of traffic. Dyeing the hair, too, was much practised by the Romans; and a kind of gold dust was used by ladies who did not adopt borrowed locks. The Roman ladies (as inferior in this respect to the Greeks as in all matters of taste) delighted to pile up the hair tower-like on the top of the head, while they had several rows of curls arranged formally round the sides, and sometimes pendant curls in addition. Fashion also regulated the style of wearing the hair among men in the later times of Rome. A boy's hair, for instance, was cut for the first time at seven years of age, and again at fourteen. On the introduction of Christianity, the apostles and fathers of the church launched severe invectives against the vanity and extravagance displayed in the dressing of the hair, upon which all the resources of ingenuity and art were exhausted. Hair to set it off to advantage, and load it with the most dazzling finery. The mimic skill of the friseur was frequently called into requisition to represent fanciful devices, such as diadems, harps, wreaths, emblems of public temples and conquered cities, or to plait it into an incredible number of tresses, which were often lengthened by ribands so as to reach to the feet, and loaded with pearls and clasps of gold.

From the great value attached to a fine head of hair, there arose a variety of superstitious and emblematical observances—such as shaving parts of the head, or cropping it in a particular form; parents dedicating the hair of infants to the gods; young women theirs at their marriage; warriors after a successful campaign; sailors after deliverance from a storm; hanging it on consecrated trees, or depositing it in temples; burying it in the tombs of friends, as Achilles did at the funeral of Patroclus; besides shaving, cutting off, or plucking it out, or allowing it to grow in sordid negligence, in token of affliction or calamity.

Among the northern nations, as the Danes, Gauls, and Anglo-Saxons, long and flowing hair was held in great estimation; and the cutting it off was inflicted as a punishment for various offences. Pope Anicetus (A.D. 155) forbade the clergy to wear long hair—an injunction obeyed not without much reluctance on the part of many. Long and flowing hair was so universally esteemed that the tonsure of the clergy was regarded as an act of mortification and self-denial. Some of them who affected the reputation of superior sanctity, inveighed with great bitterness against the long hair of the laity; and this continued long to be a topic of declamation among the clergy, who even represented it as one of the greatest crimes, and a certain mark of reprobation. Anselm, archbishop of Canterbury, went so far as to pronounce sentence of excommunication against all who wore long hair. Serlo, a Norman bishop, acquired great honour by a sermon he preached before Henry I., A.D. 1104, against long and curled hair, by which the king and all his courtiers were so deeply affected that they consented to resign their flowing ringlets, of which they had been so vain. The prudent prelate gave them no time to change their minds, but immediately pulled a pair of shears out of his sleeve and performed the operation with his own hand.

When Julius Caesar vanquished the Gauls he made them cut off their hair in token of subjection, the cropped head being the badge of slavery. Among the Frankish kings it was long, says Gregory of Tours, the peculiar privilege of the blood royal to have flowing locks; while for all other persons there were gradations in the length and peculiar cut of the hair according to rank, from the noble down to the close-cropped slave. When a prince was excluded from the right of succession to the crown, his long locks were shorn to denote that he was reduced to the condition of a subject. From the time of Clovis the French nobility wore the hair short; but as they grew less martial they allowed it to grow longer. Long hair was the prevailing fashion at the court of Francis I., when that king, proud of the wound on his head, appeared with short hair, and therupon that style became general. Long hair again came into vogue in the reign of Louis XIII.; and as curling was found inconvenient, wigs became fashionable. Then followed the reign of hair-powder, periwigs, and perukes of enormous dimensions, which, together with many other things no less preposterous, were swept away in the tide of the great French Revolution.

Hair manufactures.—The various uses to which hair is applied are familiar to every one. The most valuable kind is human hair. It is procured chiefly from the north of France, Belgium, and Germany. The lighter coloured hair, which bears the highest value, is the production of Germany; the darker shades are imported from France, where a peasant girl will sell the hair off her head without any sense of degradation; whereas in England this traffic is restricted to only by females of the lowest class. Indeed so common is the practice in France, that agents are employed to traverse certain districts annually at a particular season for the purpose of collecting the crops of human hair which are assiduously cultivated for the sake of the purchase-money, or its equivalent in gewgaws. The wholesale price of human hair varies from 30s. to 60s. per lb., and occasional specimens are of much higher value. A head of hair, such as is bought of the peasant girls in the districts above named, weighs from 1½ to 2½ pounds.

The hair used for weaving consists of the long hair from horses' tails. It is procured principally from South America and from Russia. All the black and grey hair is dyed for the manufacture of black hair-cloth for covering furniture. The white is reserved for dyeing of the brighter hues, such as green, claret, crimson, &c. The quality of the cloth, as well as the brilliancy and permanency of the colours, depend in a great degree on the nature of the warp, which may be either of cotton, linen, or worsted. In the manufacture of hair-cloth, either plain or damasked, the weaver uses a sort of hook-shuttle, which he passes between the threads of the warp, or shed, towards his left hand; the assistant, or "server," places a single hair over the end of the hook, and the weaver draws it through the warp. The placing of the hairs one by one renders this a tedious operation, and one that does not admit of the application of machinery, which is so advantageously employed in fabrics where the shot or weft consists of a continuous thread.

Hair or Down of plants. See Botany, vol. v., p. 75.

Hair-Powder, a substance used to whiten the hair, consists generally of pulverised starch, with the addition of some perfume. This mode of disguising the colour of the hair has fallen into almost complete desuetude, yet the old tax of L1. 3s. 6d. a-year is still exacted from every one using hair-powder.