. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 406 SISTER FLORENCE MARIE SCOTT appearance, and over-all expansion of tissues from their contracted state enables the body to occupy more fully the tunic cavity of the host (Figs. 20, 21, 22, 23, 24). The oesophageal stub of each branchial sac extends farther in the direction of the homologous oesophageal stub of the abdominal member. In the composites that effect a Y-shaped union, the branchial sacs unite either separately or jointly with the stomach; that is. the two funnels may fuse and then combine with the single oesoph
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 406 SISTER FLORENCE MARIE SCOTT appearance, and over-all expansion of tissues from their contracted state enables the body to occupy more fully the tunic cavity of the host (Figs. 20, 21, 22, 23, 24). The oesophageal stub of each branchial sac extends farther in the direction of the homologous oesophageal stub of the abdominal member. In the composites that effect a Y-shaped union, the branchial sacs unite either separately or jointly with the stomach; that is. the two funnels may fuse and then combine with the single oesophagus of the stomach (Figs. 26, 27, 28, 29) or one funnel may engage the gastric stub and the second funnel reconstitute an independent oseophageal con- nection with the stomach (Fig. 22). Since the chance union of the branchial baskets in these forms ranges from a Y with widely diverging limbs through parallel alignment of pharynges to partial fusion of them, with two sets of siphons pro- jecting at various angles from the fused mass, the paths followed by the oesophageal stumps also vary in accordance with the relative positions of the homologous parts. FIGURE 31. Diagram outlining the channel of traffic in a form with two stomachs and one intestine. Each dissociation depending, as it does, on the delicate conditions of the zooid's sensitive response to cutting and the critical control of a micro-knife, within the distance of mm., it is evident that parts of the stomach may be included in the branchial member along with the other usual constituents of that member. In such cases the partial stomach reconstitutes itself and the secondary product associates itself, at its posterior end, with the intestinal loop beyond the primary stomach. The end product in this composite possesses two stomachs, two oesophagi and one intestine. Figures 32, 33, 35 and 36 show the systemic organization of twins with two stomachs and a single intestine. Stomach 1 is the primary one, that is
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
