1926. The earth or the nutritive mass acts also upon its formation, and destines the tegument to a peculiar structure. The result of the electric and chemical process, or of the oxydation of the mucus, is precipitation, mass-and earth-formation; it is thus a process of nutrition, since through it the Solid of the body, with even the branchial and intestinal membranes, originates. 1927. The earth-system can only be developed where the two last systems coincide, or where the intestinal and branchial processes enter into mutual contact; in short, where the mucus is oxydized, and thereby separated into what is aerial and rigid. 1928. This spot is only in the middle between the two. The process of precipitation and the formation of elemental matter occurs, consequently, between the two layers of integument, or at present between the two teguments that have become self-substantial, or between intestine and skin. 1929. A new formation must be evolved, whereby the two shall be held together; a formation, whereby the antagonism shall be conducted from one to the other; and thus whereby the mucus shall be conveyed to the skin, but the air to the intestine. 1930. Were intestine and skin entirely separated from each other, each would perish; the former would no longer be oxydized, the latter no longer nourished. 1931. With their separation they must continue to be attached to each other at certain points, and thus undergo eversion at certain points. Thereby tubes originate in the intestine, which pursue their course toward the skin; in this again tubes, which pass to the intestine. 1932. A tube, which receives mucus from the intestine, air from the skin, and includes both within itself, is a long cyst. A cyst, which conducts mucus to the skin and air to the intestine, is a _Vessel_, a _vein_. a. _Unclosed Vascular System._ 1933. The vessel has, in virtue of its essence, two extremities, an air-extremity, which is polar, and a water-extremity, which is indifferent. Every vessel has been rooted in two systems, in the intestine and skin, and is subservient to both. 1934. The vessel is no longer a something single, like the last-mentioned or preceding cysts, but double. Every vessel hath two poles. 1935. The organization necessarily produces two kinds of vessels. A vessel, which conducts the mucus to the skin, cannot also convey the air to the intestine. There is consequently a mucus-vessel and an air-vessel, or a water-and an air-vessel, an indifferent and a different. 1936. The mucus-vessel is called _absorbent_, the air-vessel _respiratory duct_ or trachea. 1937. Air-and absorbent vessel stand in antagonism like skin and intestine, like water and air. The air-vessel is the skin or the branchia, which passes to the intestine, the absorbent vessel is the intestine, which passes to the air; the one the intestinal branchia, the other the branchial intestine.