— 9a 



Fig. 3 Diagram drawn from a reconstruction of the \eins and nerves in the 

 cervical and upper thoracic regions of a chick embryo of five days and ten hours 

 (13.5 mm.) Right side. 1, Precardinal vein; ^, postcardinal vein; 3, duct of Cuvier ; 



4, intersegmental (dorsal somatic) veins; 4o, vertebral (dorsal somatic) vein; 



5, lateral group of vascular islands and channels — veno-lymphatics; 9, spinal 

 (cervical) nerves; 9a, brachial ple.xus. 



479 



