2261. The nose is the cephalic thorax; but it has also the thoracic contents, or the very lung repeated in itself. 2262. The multicavernous ethmoid bone is the lung in the nose, the two nostrils being the stigmata or foremost openings of the trachea. The nasal muscles are homologous to the cartilages of the trachea, and especially to those of the larynx. 2263. The velum palati is the diaphragm between nose and mouth, or between the cephalic thorax and the cephalic abdomen. _Coverings._ 2264. The animal coverings are desiccated respiratory organs appertaining to the integument. _Capillary Vessels._ 2265. The principal function of the vessel is that of secretion, whereby nutrition is imparted. This secretion must take place in the whole body, in so far as it is opposed to the lung. The vessels then pass over into the finest canals, and are called _capillary vessels_. 2266. The capillary system of vessels is an organ in antagonism to the lung; what enters the latter organ, passes out through the former. 2267. The capillary system of vessels is the property of the tegumentary system. It may almost be said that wherever there is integument, there capillary vessels are present. The most perfect evolution of capillaries is the integument. It is the proper exsecernent, in opposition to the intestine, which is the absorbent organ. 2268. Evaporation is the essential tegumentary process. 2269. The product of the evaporation is mucus. 2270. In the evaporation, however, the mucus becomes analyzed by the influence of the air and light. _Epidermis._ 2271. The external mucus exuding from the skin becomes oxydized, the inferior on the contrary reduced; the oxydized becomes vitreous and transparent. It is the _Epidermis_. 2272. With the maximum of oxydation the epidermis passes over into a vitreous transparent horn, e. g. _scales_. 2273. The scales, which invest the toes and digits are called claws, and finally become nails. The finger-nail is nothing but a scale, which in this situation has become particularly large and strong. 2274. That which is reduced beneath the vitrified epidermis determines the colour of the skin. With a demi-oxydation it is uncoloured, appears white. Where the integument is thin, the red colour of the blood appears through it; such integument is therefore white upon the whole, but red in individual places. 2275. With the most complete reduction effected by the highest operation of light, its substratum or under-layer becomes black. The mucus passes over into reduced carbon. Beneath the vitreous epidermis there is thus a metallic _pigmentary membrane_. _Hairs._ 2276. Capillary vessels, which simply convey mucus, but are elongated singly above and from out the cutis, are _Hairs_. The idea of the hair is a _capillary vessel_, the contents of which are no longer blood, but reduced mucus. It is an indifferent capillary vessel. The hair is hollow and contains an oil, which determines the colour.