Elements of the comparative anatomy of the vertebrate animals : designed especially for the use of students / by Rudolph Wagner ; ed. from the German by Alfred Tulk.

  • Wagner, Rudolph, 1805-1864.
Date:
1845
Catalogue details

Licence: Public Domain Mark

Credit: Elements of the comparative anatomy of the vertebrate animals : designed especially for the use of students / by Rudolph Wagner ; ed. from the German by Alfred Tulk. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    smaller anterior carotids arise from the arterial circle ; slight varie- ties and peculiar arrangements of these vessels occur, but can not be investigated in this work. The posterior carotid supplies chiefly the opercula of the gills, the pseudobranchiBe or retia mirabilia, and mus- cles of the lower jaw, with blood. The brain receives its arteries, which are very small, from the anterior and posterior carotids. After the aorta has supplied the liver, the intestine, the organs of generation, and the swimming-bladder, it runs within the canal formed by the inferior spinous processes of the vertebrae to the tail, and there gives off branches to the kidneys, the muscles of the trunk, and the pelvic extremities. The substance of the heart receives its blood directly from the branchial vein. The blood returning from the viscera enters partly into the inferior or posterior trunk of the vena cava, which lies below the aorta, and is usually single in the Osseous Fishes, but double in the cartilaginous ; partly also into the hepatic veins, and from the two into a large sinus-like expansion or contractile sac of the vena cava that opens into the auricle (being frequently of larger size than the latter), but is situated external to the pericardium. The blood also from the head enters the same venous sinus by two anterior venae cava?, which are expanded into sinuses upon the cranium ; they also receive the blood from the branchiae and anterior extremities. Between this sac of the vena cava and the auricle are found a pair of valves. The number of hepatic veins is subject to variety. A large proportion of the venous blood of the posterior half of the body passes in Fishes from finer ramifications into trunks, that are again subdivided to form a portal system. We find, as in many Amphibia, a double portal system ; one for the liver, which obtains its blood from the stomach, spleen, intestinal canal, and sometimes from the generative organs ; the blood from these viscera usually entering by several smaller branches into different parts of the liver, but rarely uniting, before entering that gland, into a common portal vein. The second portal system belongs to the kidneys, which or- gans receive venous blood from the tail, partly also from the sexual organs and swimming-bladder; blood is also sent from this system to the venae cavae. The arrangement, however, of the two portal systems varies greatly, according to the species and genus. Lymphatic vessels appear to be generally present in Fishes, and in some number; their parietes are thin and membranous ; they are very wide, and form even large sacs and reservoirs, but are destitute of valves, and have no conglobate glands or plexuses developed in 16