. The Cambridge natural history. Zoology. 320 FISHES CHAP. 1 .^^.z; forwards along the outer border of the kidney of its side, it re- ceives a number of segmental veins, and, at the same time, gives off branches to the renal capillaries. In addition, each renal portal vein is connected with the hepatic portal vein by a series of singular arch-like vessels into which the ovarian or spermatic veins open. It is obvious, therefore, that in both Amiurus and Anguilla the primitive direct continuity of the caudal and posterior cardinal veins has been interrupted by the formation of a well - developed
. The Cambridge natural history. Zoology. 320 FISHES CHAP. 1 .^^.z; forwards along the outer border of the kidney of its side, it re- ceives a number of segmental veins, and, at the same time, gives off branches to the renal capillaries. In addition, each renal portal vein is connected with the hepatic portal vein by a series of singular arch-like vessels into which the ovarian or spermatic veins open. It is obvious, therefore, that in both Amiurus and Anguilla the primitive direct continuity of the caudal and posterior cardinal veins has been interrupted by the formation of a well - developed renal portal system, and further, that tlie residue of the caudal venous blood finds its way to the liver through the hepatic portal vein; hence it follows that, as in so many of the lower air- breathing Vertebrates, the whole of the venous blood from the tail is distributed either to the kidneys or liver in the course of its return journey to the heart. Tig. 188.âRenal portal circulation in the The Tench (Tinca vulgaris) ^A [Anguilla vidgaris). c.^, Caudal exhibits the interesting anomalv vein ; , intestinal vein ; , , ^ . a j left and right posterior cardinal of poSSCSSing twO Caudal VeinS, veins; ^..,>, hepatic portal vein; ij g, dorsal and a Ventral (Fig. 189). luduey ; , , renal portal , ^^uiiij. ^^ â '&⢠j-^^j. veins ; , segmental veins ; x, arch- The dorsal vein is directly COn- like anastomoses between the renal f;â,-.^,-,r. x,,;*-!, j-T, ⢠i,j- j. â portal and hepatic portal veins; y, tmUOUS With the right posterior vein from the urinary bladder. (From cardinal, while the Ventral One divides into three branches, two forming right and left renal portal veins and receiving numerous segmental veins, and the third becoming one of the affluents of the hepatic portal vein. In this Teleost it is clear that a portion of the caudal blood passes directly to the heart through the right posterior cardinal without traversing either the
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
