. The physiology of the Invertebrata. re two lateral main portion of the blood passes into the renal organ(the organ of Bojanus) and ultimately to the branchiee, andfrom thence is returned as arterial blood to the auricnlarportion of the heart. (2) The Gasteropoda.—In Helix the .heart (Fig. 45) is 204 PHYSIOLOGY OF THE INVERTEBRATA. close to the pulmonary sac. It consists of an auricle anda ventricle. The aorta proceeds from the ventricle, anddivides into two branches: one of these passes forward andramifies in the head and foot, while the other passes back-wards and dorsally to th
. The physiology of the Invertebrata. re two lateral main portion of the blood passes into the renal organ(the organ of Bojanus) and ultimately to the branchiee, andfrom thence is returned as arterial blood to the auricnlarportion of the heart. (2) The Gasteropoda.—In Helix the .heart (Fig. 45) is 204 PHYSIOLOGY OF THE INVERTEBRATA. close to the pulmonary sac. It consists of an auricle anda ventricle. The aorta proceeds from the ventricle, anddivides into two branches: one of these passes forward andramifies in the head and foot, while the other passes back-wards and dorsally to the viscera, where it also arterial branches terminate .by opening into lacunas;from these the blood passes through the pulmonary arteriesto the lung, and thence through the pulmonary veins, which,ultimately join to form a large pulmonary vein which leadsinto the auricle. The organ of Bojanus, or kidney, liesclose to the pulmonary sac in the course of the current of thereturning blood. Antr. venacava. Nephridium(kidney).. Post, venacava. Capillaries. TPost. aorta. Fig. 46.—Blood System and Nephridia of Sepia. (3) The Ceplictlopoda.—The circulatory system of Sepia isseen in Fig. 46. The heart is placed upon the posterior faceof the body, on the hsemal side of the intestine, and receivesthe blood by branchio-cardiac vessels, which correspond innumber with the gills ; and, as they are contractile, might beregarded as auricles. The gills themselves have no cilia, and PHYSIOLOGY OF THE INVERTEBRATA. 205 are, in some cases, if not always, contractile. The arteriesend in an extensively developed capillary system, but thevenous channels retain, to a greater or less extent, the charac-ter of sinuses. The venous blood, on its way back to theheart, is gathered into a large longitudinal sinus—^the venacava—which lies on the posterior face of the body, close tothe anterior wall of the branchial chamber, and divides intoas many afferent branchial vessels as there are gil
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectinverte, bookyear1892
