2810. The wings also support the body.
2811. Feet and hands define man. Through the two only does he become free.
Tegumental Covering.
2812. The skin, as being originally a branchia, is provided also with its branchial operculum. This is the epidermis.
2813. Scales are plications or folds of the epidermis, which accord with the situation of the branchial vessels; they are therefore arranged generally in a circular form around the body, and are more definitely varied upon the dorsal than ventral aspect of the body. Large scales, or those which may be regarded as formed by the confluence of several scales, are called scutes.
2814. It is merely the epidermis which is concerned in the production of the squamous covering; but if the former branchial vessels emerge themselves so as to project above the integument and become dried, then hairs originate.
2815. If these hairs ramify, then there are feathers.
2816. It is only therefore the Mammalia and Birds who possess a proper external covering or garment.
2817. The claws or nails are scales upon the extremity of the branchial arches, which have become animal in character, or in other words, are digital scales; they are animal branchial opercula.
2818. The nails are demi-claws, and therefore leave the points of the digits free. Free digital apices or points constitute the most perfect organ of touch, because this is then divided into two parts and because the nail increases the amount of resistance.