. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FORM OF NEPHKIDIA IN AREN1COLID/E. 247 nephridium, divides, one branch going to the setal sac and gill, if present, one to the integumentary vessels and one to the nephridium. The latter enters the nephrostome and forks, one branch traversing each lip. After reuniting, the vessel, reformed, runs out onto the wall of the nephridium as the gonadial vessel. Each of the three main branches of the afferent vessel gives off smaller vessels which, with more or less anastomosing with ad- jacent vessels, form capillary net-works in t
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FORM OF NEPHKIDIA IN AREN1COLID/E. 247 nephridium, divides, one branch going to the setal sac and gill, if present, one to the integumentary vessels and one to the nephridium. The latter enters the nephrostome and forks, one branch traversing each lip. After reuniting, the vessel, reformed, runs out onto the wall of the nephridium as the gonadial vessel. Each of the three main branches of the afferent vessel gives off smaller vessels which, with more or less anastomosing with ad- jacent vessels, form capillary net-works in the organs FlG. I. Partly diagrammatic cross-section of Arenicola cristata at about the level of the first nephridium. , dorsal blood vessel. H., heart. , lateral gastric blood vessel. N., neural blood vessel. V., nephridial longitudinal blood vessel. P., parietal blood vessel. S. V., sub-intestinal blood vessel. ventral blood vessel. The efferent vessels are formed by the union of capillaries in these same regions. The afferent vessel, as a rule, comes from the ventral vessel. This is true for all except the first two nephridia of A. Grnbii and of A. ecaudata, which nephridia are supplied, the first by a branch of the dorsal, the second by a branch of the parietal vessel (Fig. 2, c/). In addition to the afferent vessel from the ventral vessel, the following nephridia also receive branches from the dorsal vessel: the first of A. cristata, the first two of A. Claparedii and the first three of A. marina (Fig. 2). The following nephridia return blood directly to the subintes- tinal vessels through efferent vessels whose numerous branches are adjacent to theirfunnels : the fourth, fifth and sixth of A. cristata, the fourth and fifth of A. Claparedii and the fifth and sixth of A. marina. All others must pour the blood into the parietal and nephridial longitudinal vessels which, in turn, pass it to some of the more posterior efferent vessels (Fig. 2).. Pl
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
