The production of the most perfect coat or covering is the second step, whereby the tegument ascends.
3444. Hitherto the outer covering of animals was pretty inorganic, consisting either of hollow tracheæ, feathers, or semicavernous scales, coat of mail, or lastly, only mucus. All these organs were only constructed after the type of individual vegetable systems, in greatest part only after the respiratory organ, and were therefore partial in aspect or deficient.
The highest covering must also bear the highest meaning. This is that, which grows out of the sanguinary system collectively, out of the capillary vessels. The capillary vessels of the covering are, however, the hairs. The hair is the most perfect covering of the animal.
3445. These animals are the Thricozoa.
Already the highest birds, e. g. the Ostrich and Cassowary, exhibit feathers which merge over into hairs.
3446. An integument clothed with hair, and self-substantially moveable is the perfection of this organ, it is a fur—Furred animals.
3447. The fur is the peripheric combination of the Vegetable and Animal. The hairs are the highest Vegetable, as being the vascular system grown out of or above the animal, and constituting the fundamental or basi-system of the whole body. The tegumental muscles are the lowest Animal. In the fur consequently the whole animal has been represented, but as a limit set between animal and world.
3448. The tegumental covering also varies. The hairs become scanty in respect of number; instead of them spines, horny rings or scales occur, yet there are always hairs on the belly. In many Whales they seem to dwindle into bristles. In some they have coalesced to form a kind of bark, as in the Stellerian Walrus or Sea-cow.
Thorax.
3449. In all the respiration is aerial; in all there is a true costal structure, and a respiration effected through the motion of the ribs or a pumping action; in all the lungs are filled with cells; in all there is a diaphragm, a larynx, a trachea with cartilaginous rings, and a thyroid gland. But the air no longer penetrates from out the lungs into all the cavities of the body, as in Birds.