/ ■:-. in ■ /,'. ^ 



I as mi. ii :, k. Dor as it is oi E this 



-.1111. < 111!.! 



\ sing from the cardinal veins there i- a -nit- of seven 

 ental bi extending in the nervous Eystem between the 



le primitive posterior cerebral vein (Mall 143), which arches 



A ■ 



- 



Fio. i. Injected specimen to show the anterior cardinal vein and its 



branches in an embryo pin which measured 7 mm. in Its greatest diameter. 



Magnified aboui 28 times. This is a stage before the lymphatic vessels 



begun. A = aorta arches; D. C. = duel of Cuvier; V. c. p. = vena 



ci rebralis posterior; V. 5 = fifth segmental vein. 



downward over the medulla and cord and the cerebral end of the arm 

 bud. The firsl two of these branches drain the medulla, and hence 

 there are ii\'' spina] or segmental branches proper. Each of these 

 branches has n corresponding artery which lies slightly caudalward 

 and nearer the midline. Only the lower four segmental arteries are 

 injected in this specimen. The relative position of artery and vein 



