224 



STUDY OF PIG EMBRYOS. 



have the small notochord, Nch, and the large median dorsal aorta, Ao. In the 

 ventral portion of the embryo appears the large body-eavity into which protrude 

 the Wolffian bodies and the intestine. The ccelom also has a downward prolon- 



m.pl. G 



Nch. 



V.U.S 



Fig. 132. — Pig, 9.0 mm. Frontal Series 54, Section 194. 

 Ao, Aorta, card, Cardinal vein. F, Ectodermal fold at the border of the limb-bud. G, Ganglion, gen. 

 Genital ridge. Glo, Glomerulus. In, Small intestine (jejunum), mes. Splanchnic mesoderm (of the 

 intestinal wall), m.pl, Dorsal growing edge of the muscle plate. My, Muscle plate of secondary 

 segment. Nch, Notochord. P.L, Posterior limb. Rid, Large intestine. Sow, Somatopleure. Sp.c, 

 Spinal cord. V.U.D, Right umbilical vein. V.U.S, Left umbilical vein. U'.b, Wolffian body. 

 IV. D, Wolffian duct. X 35 diams. 



gation into the beginning of the umbilical cord, and in this prolongation lies the 

 loop of the intestine, In. The coelom is bounded everywhere by the layer of 



