. Contributions to embryology. Embryology. ORIGIN OF BLOOD-VESSELS IN BLASTODERM OF CHICK. 247 figure 08 B (1908) from a cliick of 10 somites, and in Van der Stricht's figure 3 (1895, p. 210). In this specimen (fig. 25, plate 5) many of the clumps have become tiny vesicles bj^ the Hquefaction of their centers, and several show a few red blood- corpuscles. These vesicles over the somatopleure remain isolated for a long time, simpl)' because they are few and far apart. I have a specimen of the fourth day of incubation, grown on a cover-slip, which has as many as 10 or 12 of them. Some of them, I
. Contributions to embryology. Embryology. ORIGIN OF BLOOD-VESSELS IN BLASTODERM OF CHICK. 247 figure 08 B (1908) from a cliick of 10 somites, and in Van der Stricht's figure 3 (1895, p. 210). In this specimen (fig. 25, plate 5) many of the clumps have become tiny vesicles bj^ the Hquefaction of their centers, and several show a few red blood- corpuscles. These vesicles over the somatopleure remain isolated for a long time, simpl)' because they are few and far apart. I have a specimen of the fourth day of incubation, grown on a cover-slip, which has as many as 10 or 12 of them. Some of them, I think, are degenerate, but it soon becomes difficult to follow them in the living specimens on account of the increasing thickness of the blastoderms. Their especial interest Ues in noting the early appearance of vessels in the somatopleure in the chick. In the middle or venous zone of the area pellucida the angioblasts of this specimen have become vessels. They form a delicate plexus and the vessels are consequently small and inconsjMcuous in the photograph. In the living chick, how- ever, the process of hquefaction can be easily followed. Most of the vessels of this area are emjity, that is as far as cells are concerned, but here and there are a few small clumps of red-blood cells, showing that the angioblasts have the potentiaUty to produce cells bearing hemoglobin. The posterior zone of the area pellucida is especially interesting in this specimen, as it happens to be one in which all of the angioblasts exist in the form of isolated masses of cells. There are numerous deh- cate sprouts from these masses, but for the most part these have not yet joined similar masses of Text-figi'RE 1.—Diagram showing the position of the angioblasts which are the forerunners of the endocardium in a chick (No. 206) with 6 somites, incubated for 24 hours and .SO minutes and then grown in Locke-Lewis solution in which there was per cent XaCl. The diagram shows the actual masses
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Keywords: ., bookauthorcarn, bookpublisherwashingtondc, booksubjectembryology
