PLATE 9 



EXPLANATION OF FIGURE 



20 Drawn from a reconstruction of a chick embryo of 6 days and 10 liOLirs, 13.5 

 mm. (series no. 426). Ventral view. 



1, aorta 



2, dorsal aortic roots 



3, aortic arch VI 



3(1, pulmonary artery 



4, aortic arch IV 



5, celiac artery 



10, precardinal vein 



11, subclavian vein 



12, duct of Cuvier 



13, vertebral vein 



15, jugular lymph sac 



16, groups of developing blood cells 



17, first rudiments of thoracic duct 



180 



