B. _Abdominal vertebræ_ 5. C. _Thoracic vertebræ_. a. Pulmonary vertebræ 5, b. Brachial vertebræ 5, c. Cervical vertebræ 5. II. _Auditory vertebra_ 1. III. _Lingual vertebra_ 1. IV. _Optic vertebra_ 1. V. _Nasal vertebra_ 1. This regularity is found too only in the human skeleton. The animals are irregular men. (Vide Oken's Zahlengesetz in den Wirbeln. Isis, 1829, S. 306.) _Cavities of the Trunk._ 2115. The osseous system forms the trunk or body, because it follows the vascular system; the two other galvanic systems, the dermal and intestinal systems, form the large portions of the trunk or its cavities; to them is added the sexual cavity or pelvis. 2116. There are thus three truncal cavities, a pulmonary, an intestinal, and a sexual cavity, or thoracic, abdominal, and pelvic cavity. 2117. The osseous system will develop itself most feebly around the abdominal, because it is the indifferent cavity. Therefore there are either no ribs at all, or they are so short that they do not reach to the anterior vertebral column or the sternum. The short or false ribs are, according to their physiological sense, _abdominal_ or _splanchnic_ ribs. The thoracic ribs must be perfectly developed, i. e. abut against both vertebral columns, be entire ribs; the entire or perfect ribs are thoracic or _pulmonary_ ribs. The sexual ribs are arrested on the pedal and coccygeal vertebræ, but on the proper sexual vertebræ, namely, the sacral bone, they are still present as rudiments. 3. MUSCULAR SYSTEM. 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._