The sense of feeling ascends upon its second stage, when its organ, having been freed from the mass of the body, surrounds the viscera as a self-substantial tegument. The feeling is then no longer one of a merely general character, but is a definite perception of external objects, a passive power of feeling.
3122. True muscles could not as yet originate in this skin, and that for obvious reasons, although fibres are present; for the former are to be brought under the signification of arterial fibres.
3123. Cilia, when furnished with fibres by whose agency they are rendered moveable and susceptible of inversion, are called tentacula, which here occur under every variety of form.
3124. Would we compare the Vascular animals with the plants, they must then represent their ducts, liber, and stalk. The heart is the stalk, the arteries liber, the veins tubes or ducts. These animals have assumed also upon the whole the cauline or cylindrical form—Cauline animals.
3125. From their having obtained in addition to the intestine only the vascular system, they are still governed by the water, and live therefore for the greatest part in this element. They have the first mode of respiration and thus an aqueo-respiratory process—possess branchiæ but not tracheal tubes.
3126. The sexual parts, which in the Germ-animals were still coalesced for the most part with the body, here become self-substantial through the separation of the teguments, make their appearance as a repetition of the digestive system under the condition of a free or separate system, and are evolved into true ovaria and even male parts—Sexual, Glandular animals.
3127. The first step towards the evolution of male parts is, however, only half achieved. Only one testis originates, while the other remains behind as ovarium—Androgynous or Bisexual animals.
3128. These animals, which are characterized by the vascular system, and by the first self-substantial or external sexual parts, which indicate organs of sense, are the Conchozoa, such as the Mussels, Snails, and Kracken.
Circle III. Respiratory Animals.
3129. When once the intestinal and vascular system, through perfection of their individual parts, such as the liver and branchia, and through separation of the sexual parts, are completed; then the individualization of the tegument steps into view, and it becomes an independent respiratory system.