222 The Anatomy of a 12-mm. Pig 
vein. The fusion of azygos and hemiazygos is described by Parker and 
Tozier, 98. 
The subeardinal veins, Lewis, 02, are formed by an anastomosis of 
Wolffian sinusoids. The cephalad portion of the right subcardinal con- 
veys the blood from posterior cardinal to the liver, and is a part of the 
inferior vena cava. That on the left disappears. 
The wmbilical veins, which in the cord of series 518 are fusing with 
one another, separate in the embryo and extend through the body wall 
to the liver. Here the left umbilical vein is broken into sinusoids 
except for a quite open passage to the portal vein. The larger right 
umbilical vein passes through the liver as the ductus venosus Aranti 
which joins with the portal vein and inferior vena cava to form the 
vena hepatica communis. 
It remains to describe the portal vein, the hepatic relations of which 
appear in Plate IV. It is a continuation of the omphalo-mesenteric 
vein as shown in Plate IiJ. That vein, beginning with branches from 
the yolk sac, crosses the abdominal cavity in a detached bit of mesen- 
tery and passes along the left side of the duodenum where it receives the 
superior mesenteric vein. The mesenteric vein begins in the intestinal 
loop, not in the yolk sac. Similar conditions have been found in the 
cat by Dexter, 02, from whose work it appears that the mesenteric vein 
is a new branch, and not one of the omphalo-mesenteric vessels, as has 
generally heen supposed. 
Prof. Minot has shown in his laboratory text-book that the thorough 
study of a few embryos is for students the shortest way to a compre- 
hensive knowledge of embryology. As a means for correlating special 
embryological investigations, the complete description of single embryos 
is a promising but almost untried experiment. 
Notre.—It should be understood that though the results here presented 
have been drawn upon in part in the making of a text-book, the present 
study is complete in itself and independent of the text-book. This paper 
accepted for publication in No. 1, Vol. 2, was unavoidably delayed till 
now by circumstances beyond the control of the author.—EDITor. 
PUBLICATIONS CITED. 
BRACHET, A., 96.—Le développement du pancréas et du foie. Journ. de 
Anat. et de la Physiol., Vol. 32, pp. 620-696. 
BreMER, J. L., 02-—On the origin of the pulmonary arteries in mammals. 
Amer. Journ. of Anat., Vol. 1, pp. 137-144. 
Born, G., 89.—Beitrage zur Entwicklungsgeschichte des Saugethierherzens. 
Arch. f. mikros. Anat., Bd. 33, pp. 283-378. 
DEXTER, F., 02.—On the vitelline vein of the cat. Amer. Journ. of Anat., Vol. 
1, pp. 261-267. 
= =a i ee et ea 
— 
