400 ALEXANDER S. BEGG 
predict the permanent form which it would assume in this case. 
It serves as a common starting-point for several types of the ab- 
sence of the vena cava inferior. This would of course be true of 
a normal embryo at a still earlier stage, and as the variation is 
one of arrested development, the striking resemblance to a 
younger embryo is to be expected. 
A conspicuous and more unusual anomaly is in process of de- 
velopment in connection with the portal System. ‘The common 
vitelline vein and the superior mesenteric vein are seen to be 
well formed, but the usual large portal vein is represented only 
by small capillary connections with the hepatic sinusoids. The 
main drainage from the portal system appears to be by way of 
the splenic vein into the subcardinal anastomosis. Since this 
anastomosis normally forms part of the left renal vein in the 
adult, it follows that this condition would lead to the production 
of a trunk passing from the splenic vein to the left renal. A rare 
ease of this sort has been reported in ‘the human adult by Pensa 
(08), who cites a few other cases from the literature. In order 
to be ‘compatible with continued development, however, the por- 
tal connection with the liver should be of some size. Cases in 
which the portal vein empties directly into the systemic circula- 
tion have, however, been reported, for example, by Abernathy 
(1793) in a child of ten months, by Lawrence (1814) in a person 
of some years, and by Hyrtl (739) in two anencephalic monsters. 
The anomaly of the portal system is of a radically difierent 
nature from that of the absent vena cava; in the latter case, large 
channels normally present in younger embryos have persisted in 
their earlier proportions, whereas in the portal anomaly, on the 
contrary, a large channel always found in younger embryos 
which should persist, has atrophied. The place of this channel 
has been taken by the enlargement of a normal but insignificant 
connection, which, however, has not escaped the attention of 
embryologists. Among others, Davis has particularly called at- 
tention to capillary connections between the splenic and subcar- 
dinal veins in pig embryos. These normally remain minute or 
disappear, but occasionally may enlarge and produce the extraor- 
dinary condition found in this embryo and, in the rare cases 
cited, in the adult. It is significant, in interpreting the condi- 
