Sheet 24.
-The Development of the Fowl_.
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Figure 1. Chick about the -fifth- [third] day. At this stage the chick lies on its left side in the yolk. [For lettering of blood vessels, see (7) below.] i., the intestine. u.v., the yolk sac. v.v., the vitelline veins. al., the allantois. Figure 2. Chick about sixth day. Figure 3. Development of heart. Figure 4. Development of the eye. Figure 5. Chick about the sixteenth day. A.M. is the amnion surrounding the embryo. Note particularly how the allantois (al.) has spread over surface of shell and how the yolk sac is shrivelled. Figure 6. Figures to illustrate the relative function and importance of allantois and yolk sac in bird and mammal. In the fowl, however, the blood-vessels of the allantois also probably absorb the albumen of the egg, and may excrete urea into the egg-space. Figure 7. Simplified figure of the embryonic circulation, for comparison with the similar figures annexed to Dog-Fish and Rabbit. {Lines from Second Edition only.} [A.C., anterior cardinal. Ao., Aorta. Br4, sixth aortic arch (fourth branchial). C.S. Cuvierian sinus. H., the heart. I.C., inferior cava. P.C., posterior cardinal vein. Tr.A., truncus arteriosus. v.v., vitelline vein.] Figure 8. Chick on the nineteenth day. |
