Chapter X.

1. This is the nature of hair and its analogues and skin. All viviparous animals, with feet, have hair; oviparous animals, with feet, have scaly plates; and those fish alone which produce friable ova are covered with scales; for the conger and muræna among long fish have not such ova, and the eel produces no ova. The hair differs in thickness, thinness, and size, according to its situation, both in the parts of the body which it occupies, and the nature of the skin, for upon thick skins the hair is generally harsh and thick, the hair is both thicker and longer in the hollow and moist parts of the body, if they are such as to be covered with hair.

2. And the case is similar in those animals which are covered with plates or scales. If animals covered with soft hair are placed in good pastures their hair will become coarser; and, on the contrary, it becomes finer and less in those that have coarse hair. Warm and cold situations also make a difference, for the hair of natives of warm climates is harsh, but it is soft in those of colder climates. Straight hair is soft, crisped hair is harsh.

3. It is the nature of hair to split; and different kinds of hair are dissimilar in excess and deficiency; some are so changed by harshness as to bear slight resemblance to hair, and are more like spines, as in the hedgehog, wherein they resemble nails. So again the nails in some animals are not different from bones in point of hardness.

4. Man has the thinnest skin in proportion to his size. There is a mucous, glutinous fluid in the skin of all animals, less in some, more in others, as in the skins of oxen, from which glue is made; and sometimes glue is made from fishes. When the skin alone is cut it is insensible, especially that upon the head, from the absence of flesh between that and the bone. Wherever the skin is without flesh it does not unite again after being cut, as the thin part of the cheek, the prepuce, and the eyelid. In all animals the skin is continuous, and it is only wanting in places where there are natural passages for exudation, and at the mouth and nails. All sanguineous animals have a skin: all, however, have not hair, but those which are described above.

5. The colour of the hair changes in men as they grow old, and the hair becomes grey. This takes place in other animals, but not so remarkably as in the horse. The hair begins to grow white from the extremity. Most white animals are white from their birth, wherefore it is plain that whiteness does not arise from dryness, as some persons suppose, for no animal is born dry. In the exanthematous disease, called whiteness, all the hair becomes hoary; and some patients, who have suffered from illness, after the hair has fallen off on recovery, have regained their dark-coloured hair. Hair which is covered up becomes white more readily than that which is exposed to the air; in man the temples are the first to grow grey, and the fore part of the head before the hind part, and last of all the hair on the pubes.

6. Some of the hair exists on the body at the period of birth, and some appears afterwards. In man alone the hair on the head, eyelashes, and eyebrows exist at birth. The hair on the pubes, in the armpits, and on the chin appear successively after birth, so that the parts on which the hair appears at birth, and those on which it grows afterwards are the same in number. In old age the hair on the head especially is the first to fail, and falls off. This is only in front, for no one ever becomes bald on the back of the head. The smoothness on the crown of the head is called baldness, that upon the eyebrows depilation; neither of these takes place before the commencement of puberty.

7. Children, women, and eunuchs never become bald. If a person be castrated before puberty, the hair which grows after birth never makes its appearance; if after puberty these alone fall off, except the hair on the pubes. Women have no hair upon the chin, excepting a few of those in whom the catamenia have ceased, and the priestesses in Caria: and this appears ominous of future events. Women also have other hair, but not much. There are some persons, both male and female, who from their birth are without the hair which grows after birth; but those persons are barren who have not hair on the pubes.

8. The rest of the hair grows proportionally, either more or less. That upon the head grows the most, then that on the chin, and thin hair most of all. The eyebrows grow so thick upon some aged persons as to be cut off, for they are placed upon the symphysis of the bone; and this being separated in old persons, a more abundant moisture exudes. Those on the eyelids do not grow, but they fall off, when persons come to puberty, and especially in those of warm sexual desires; they become grey very slowly. If the hair is plucked out during the period of growth, it comes again, but not after it has done growing.

9. Every hair has at its root a glutinous moisture, which will adhere to anything with which it comes in contact, soon after it is drawn out. In spotted animals the spots exist both in the hair and upon the skin, and upon the skin of the tongue. As for the beard, some persons have a thick one, both beneath the chin and upon it; in others, these parts are smooth, and the beard is on the cheeks. Those who have smooth chins are least likely to become bald. The hair grows in some diseases, as in phthisis especially, and in old age, and upon dead bodies, and the hair becomes harder instead of softer. The same is the case with the nails. In persons of strong passions, the hair that is born with them decreases, while that which comes after birth increases.

10. Those who suffer from enlarged veins are less likely to become bald; and if they have this disease after they are bald, the hair sometimes grows again. The hair, when cut off, does not grow again from the extremity, but increases by growth from the root. The scales of fishes become harder and thicker, and in those that are growing thin and old they become still harder. The hair and wool of old animals becomes thicker, though the quantity decreases; and the hoofs and claws enlarge as they grow old, and the beaks of birds. And the claws grow in the same way as the nails.

11. Feathered animals, like birds, do not change their colour by age, excepting the crane, for this bird is ash-coloured, and becomes black by age. But from the change of season, when it becomes cold, some of those having but one colour, black or grey, become white, as the crow, sparrow, and swallow; but none of those which are white become black. At different seasons of the year many birds change the colour of their plumage, so as to render it difficult for those who are not acquainted with them to recognise them.

12. And many animals change their colour with a change of water; for in one place they are black, and in another white; and the same thing takes place at the season of coition. There are many waters of such a nature that if sheep drink of them before sexual intercourse, they produce black lambs; as at that which is called the cold river in the Thracian Chalcis (in Astyritis). And in Antandria there are two rivers, one of which turns the sheep white, the other black; and the Scamander appears to make the sheep yellow, wherefore some people think that Homer called the Scamander the Xanthus.

13. Other animals have no hair internally, nor upon the bottom of their feet, though it is on the upper part. The hare alone has hair on the inside of its cheeks, and upon its feet, and the mysticetus[95] has no teeth in its mouth, but hairs, like hog's bristles. The hair, if it is cut off, increases below, but not above. Feathers do not grow either above or below, but fall out. The wing of the bee, if it is plucked off, does not grow again, nor that of any other creature which has an undivided wing; nor does the sting of the bee grow after it is plucked out, but the animal dies.