PLATE IV 



EXPLANATION OF FIGURE 



5 Reconstruction (after Born) of veins in the lumbar region of a 29-mm. 

 cat embryo. Lateral aspect, left side, showing cardinal collateral system of 

 veins (C.C.), and complete atrophy of left side of renal collar (Subc.Sprc. 

 Anast.). Note that, with the loss of the left side of the renal collar, blood in 

 the left supracardinal (C) is directed into the right supracardinal, through the 

 dorsal intersupracardinal anastomoses, present between the right and the left 

 supracardinal veins. At the present stage of development the cava in the lumbar 

 region appears to be formed through a fusion of both supracardinal veins. Coll. 

 of P. and S. Embryological Collection, no. 575. 



