2118. As the intestinal system reappears in what is animal under the condition of a vertebral column, so also does the aggregate of the vascular system ascend, and the vessels become animal.
2119. The animal vessels are the muscles, or filled-up vessels. The polar process enters the body through the vessels; thereby the tubes obtain two strong poles, and are drawn out lengthways. They are fibres, and consist of a series of strongly oxydized blood-globules.
2120. The fibre is chiefly apparent in those vessels, such as the arteries, in which the influence of air operates more forcibly. Now an artery has, in addition to the external cellular coat, two coats, like the first animal body, or one wall turned towards the mucus, and one towards the air. The internal arterial wall is enteroid, the external dermoid in character; the one being simply granular, the other fibrous membrane. The two membranes separate into two cysts or tubes, which likewise adhere within each other like intestine and skin. The external will become fibre, the internal bone.
2121. There is a vegetative and an animal fibre-or muscle-system. The one is associated with the tegumentary formations, the other with the bones and nerves.
a. Vegetative Muscles.
2122. The muscles of vegetative life are simply fibrous tunics, as in the arteries, and are found in the skin, in the intestine, and in the vessels.
2123. The tegumentary muscles lie under the skin, and are inserted into it, or into the dermo-osteous system, when such an one is present. If the fibrous membrane be strongly developed under the skin, then it receives the name of a Panniculus carnosus.
2124. The intestine has also its fibrous coat, which, upon the stomach, anus, and pharynx, is frequently developed as a panniculus carnosus.
2125. The same holds good of the vessels, especially of the arteries and trachea.
2126. The fibres are either elongated or else annular fibres. The latter obtain the preponderance at the extremities of the tubular formations, as on the pharynx, anus, lips, and eyelids.