Tli ! 



i into the fibular in the caucb.l border; the other, the so-called conn 



,^ins as twigs in the abdominal wall and tibial side of the extremity and 



is into the fibular just proximal to the opening of the anterior tibial (Fig. 242) . 



?r the distal part of the primitive fibular is broken ;rp by the differentiation 



; ts (toes) and disappears almost up to the point of junction with the 



:rior tibial. The latter enlarges and receives the digital branches, and 



ontin nation of the proximal part of the primitive fibular. The 



irior tibial and primitive fibular together thus constitute the sciatic vein 



Another vessel appears in embryos of fifteen days; which represents 



u'ng of the femoral vein and opens into the cardinal, cranial to the 



in 



FlG - *42- Fro. 243. 



FIG. 242. Diagram of f a ra bi,; t embryo of 14 days 



and 18 hours (14.5 mm.). Modi6ed from Lewis. 



-bryoof 17 days 

 ;ra.). Modified fn 



ming of the sciatic (Fig. 243;. From this time on the femoral, with its 

 nches, enlarges at the expense of the other veins and becomes the principal 

 - of the lower extremity. In the human embryo the femoral anastomoses 

 iciatic near the knee and the proximal portion of the sciatic theri 

 the distal portion persisting as the small saphenous vein. Th. 



and the posterior -,, possibly are derivatives of the 



noral, but this question has not been settled. 



CJIAXGES IN THE CIRCULATION AT BIRTH. During foetal life the course of 

 s adapted to th filiation the placenta is the only 



om- which the foetus deri. 



-hrough the umbilical 

 is distributed to the b me of the 



