Volume 2

Health lectures for the people.

Date:
1883-1892
Catalogue details

Licence: Public Domain Mark

Credit: Health lectures for the people. Source: Wellcome Collection.

    113/600 (page 101)
    which they emit greases the margins of the lids and prevents the tears, unless copious, from trickling over the face.* In the ear passage the secretion is commonly called the wax. It is yellowish in colour and intensely bitter, so that with the hairs in this locality we have a formidable barrier interposed against the intrusion of insects. Hairs are likewise provided with 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 superficial part of the true skin, and on the other to the lower end of the hair-follicle (Fig.l). In passing between these points it partially embraces the oil-gland. And now let us see how it acts. In the first place it is not under the control of the will, but cold and certain emotions, such as horror and fear, at once call it into play. In such cases the hair muscles contract. They straighten the hair-follicles and erect the hairs. The well-known condition of goose-skin is the result. When a thrilling ghost story is told the flesh creeps, or when a sudden ghastly apparition presents itself our hair shows a tendency to stand on end. All this is due to the contraction of the hair-muscles. In illustration of this I cannot do better than show you the admirable representation, by Sir Charles Bell, of a countenance expressive of fear. In addition to their action upon the hair-follicles, the hair- muscles exert an influence upon the oil-glands. As we have seen, they partially embrace these. Consequently when they contract, they subject the glands to pressure, and help the flow of the secretion into the follicle. Hair-growth.—I have spoken of the hair-follicle as the labora- tory in which the manufacture and continued growth of the hair is effected. The building material is close at hand. At the bottom of the follicle is the little papilla upon which the bulb of the hair rests, and this papilla, as we have seen, is permeated by minute blood-vessels. In the same manner that our rivers and * In addition to these large glands the eyelashes have special glands of their own in connection with their follicles.