Florence E. Sabin 



383 



the renal portal system. The area between the two kidneys is so rich in 

 blood-vessels that a brief description of the veins will aid in locating 

 the lymphatics in sections. This description is taken from a specimen 

 prepared in this way. A fresh embryo of this stage, namelv, 3 cm. 

 long, was injected with carmine 

 gelatine into the liver, and by this 

 means the venous system was filled 

 with red. The lymph ducts were 

 then injected subcutaneously over 

 the scapular area with India ink. 

 The ink entered the vein and passed 

 to the heart, which, as it was still 

 beating, pumped the aorta full. A 

 little of the black ink entered the 

 vena cava, but not enough to obscure 

 the picture. The embryo was hard- 

 ened, cut in two parts in the median 

 sagittal plain, cleared in creosote and 

 mounted in balsam. In tliis speci- 

 men, the femoral and sciatic veins 

 join to make a large median vein, 

 the vena cava, which lies directh^ 

 dorsal to the aorta opposite the 

 posterior half of the Wolffian body. 

 This median vein is connected by 

 many branches with the posterior 

 cardinal vein on the left side. 

 Opposite the middle of the Wolffian 

 body the vein is deflected to the 

 right and comes to lie beside the 

 aorta instead of behind it. The 

 branch of the vena cava from the 

 left kidney passes ventral to the aorta as in the adult. At this level 

 the double receptaculum chyli is directly dorsal to the aorta. Opposite 

 the anterior end of the Wolffian body the vena cava turns ventralward 

 in the root of the mesentery and runs directly to the liver. Thus, 

 in sections of this stage, opposite the posterior part of the Wolffian 

 body it is the vena cava behind the aorta, while opposite the anterior 

 half of the Wolffian body it is the double receptaculum chyli. This 

 area .shows especially well that in studying the lymphatic system 

 either the veins or the lymphatics rnust be injected. The lymphatic 



Fig. 9. Diagram of the lymphatic sys- 

 tem in an embryo pig- 3 cm. long, x 3- 

 Alh, anterior lymph heart; h, ducts to 

 the heart ; lu, ducts to the lung ; mp, 

 ducts to the mesenteric plexus; plh, 

 posterior lymph heart; re, receptacu- 

 lum chyli. 



