Elements of Physiophilosophy

by Lorenz Oken

3332. Fishes swallow the air and drive it into the pulmonic cyst, where it is analysed or decomposed.

3333. This lung, so soon as it stands opposite to and enters into conflict with a branchia, is what serves to direct or control the action of the heart. It is only when the swim-bladder is allowed to hold good as lung, that the circulation in Fishes admits of being understood. For otherwise venous blood must flow into the heart, from this into the branchiæ, from these directly into the aorta, and so to the different organs without again entering a cardiac cavity, a structure which occurs in no other class of animals, but rather in every instance its reverse. The first heart is arteriose, not venous in all animals, even in the Mussels and Snails and in the embryos. Now, the Fish is still such an embryo, and has only an arteriose heart.

3334. Thus, the following is the "modus operandi" of the parts in question; the swim-bladder is the lung, in which, seeing that it contains air, the blood is oxydized; this oxydized blood flows into the heart and renders it arteriose in character, despite the concomitant influx of venous blood into that organ. Upon this, the blood passes out of the heart through a true aorta, which is called the branchial artery. Instead then of this aorta giving off only some twigs as bronchial vessels to the gills, and next proceeding to pursue its course as a main trunk through the body and along the back, it passes wholly to the branchiæ, i. e. it entirely becomes a bronchial vessel, is slightly oxydized, and then returns upon itself to form the aorta, which should have taken its course directly from the heart.

Senses.

3335. In accordance with the thorax, the corium or true skin is developed. It is mucous in character and muco-secernent like the intestine, from its being constantly in the water. The whole skin is undermined by mucous canals and perforated by their excretory apertures. These foramina of the lateral line are arrested, and metamorphosed branchial foramina, which have only retained the evaporative function of respiration.

3336. The remnants of the tegument's annulation are the scales. They are desiccated air-branchiæ, alary opercula or elytra, and consequently indicate that feature of the Insect, which has continued to work its way into the class of Fishes.

3337. Like the skin, so are the limbs—tegumental members. What is flesh and bone upon them, has kept quite close to the body, and that only which is designed for splitting into digits projects, constituting tegumental digits with cartilages—fins. These fins are something better than the lateral papillæ of the Worms, are furnished at their base with joints, and are in number only four, but crippled or stunted in every possible way.

3338. The fin-rays do not correspond to the digits, but to the nails. They are fibrillated nails, like the wing-feathers of Birds.

3339. Lastly, the head possesses all the organs of sense which belong to a head, but they are still far removed from their perfect condition.

3340. As the nervous system is the first mass, from which the remaining ones have been set free, so also is the nervous sense the first after that of the tegument, which appears as a whole, and serves as a pattern for the subsequent senses. The eye is the sense which is first developed most perfectly, not directly as regards its own completeness, but when considered in reference to the others.