The physiology of the circulation in plants : in the lower animals, and in man : being a course of lectures delivered at surgeons' hall to the president, fellows, etc of the Royal college of surgeons of Edinburgh, in the summer of 1872 . anda distinct arterial circulation; the two kinds of blood, viz., thearterial and the venous, being no longer mixed either in thevessels or in the heart (Fig. 82). In the dugong, the systemic andpulmonic hearts are very distinct—the right and left ventricles beingwidely separated from each other attheir apices, and only joined towardstheir bases, as shown at F
The physiology of the circulation in plants : in the lower animals, and in man : being a course of lectures delivered at surgeons' hall to the president, fellows, etc of the Royal college of surgeons of Edinburgh, in the summer of 1872 . anda distinct arterial circulation; the two kinds of blood, viz., thearterial and the venous, being no longer mixed either in thevessels or in the heart (Fig. 82). In the dugong, the systemic andpulmonic hearts are very distinct—the right and left ventricles beingwidely separated from each other attheir apices, and only joined towardstheir bases, as shown at Fig. virtually divides the organ intoa left or systemic, and a right orpulmonic heart. The auricles of theheart of the dugong are of equal size,and the ventricles closely resembleeach other in their general configur-ation. The heart of the whales anddolphins more closely resembles thatof the other mammals. The arteriesof the whale, as John Hunter pointedout, are remarkable for their tortu-osity and convoluted arrangement. vessels are- found under the pleura, and between the ribs andtheir muscles on each side of the spine. Similar plexuses surroundthe medulla spinalis, more especially where it comes out from the Fig. Fig. 83.—Heart of dugong- seen an-teriorly: shows bifid apex, s, Right , Right ventricle, t, Left auricle, r, hvttventricle, u, Aorta giving off innominates,left carotid and left subclavian , Pulmonary artery bifurcating and pro-ceeding to right and left lungs. (Comparewith human heart, Fig. 82.)—Owen. Vast plexuses of tortuous 1 I have had opportunities of injecting the kidneys of birds, and the degreeof vascularity is in some cases quite remarkable. 13-1 DR J. BELL PETTIGREW ON THE brain. In the porpoise, the veins, which are for the mostpart devoid of valves, display a similar tortuosity, particularlyon either side of the spine below the kidneys. When arti-ficially injected, the venous plexuses present a very unusual appear-an
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