BLOOD AND VITELLINE VESSELS IN AMPHIBIA 377 
In Amblystoma and Desmognathus both a right and a left 
vitelline vessel develop; in later stages the left becomes the larger 
and persists as the vitelline vein. As the liver develops, branches 
from the vitelline vein are formed in connection with it and these 
become the hepatic veins. As the yolk sac becomes somewhat 
reduced and as the intestine begins to differentiate, the anterior 
vitelline vessel becomes changed and the posterior portion, which 
remains about the same, may now be called the subintestinal. The 
anterior part of the left vitelline of early stages comes to be a more 
dorsal vessel which develops more and more with the develop- 
ment of the intestine ‘and this, with the subintestinal vein or 
posterior portion of the early vitelline, forms the hepatic-portal. 
This posterior part of the hepatic-portal is not a new structure in 
the strict sense. 
The development of the first blood vessels in the body-wall of 
the embryo which form the lateral cutaneous, may be due to the 
penetration of yolk vessels at an early stage, but later the two sys- 
tems develop practically independently of each other. The lat- 
eral cutaneous vessels in Amblystoma are formed a little differ- 
ently from those of Desmognathus, probably largely because of 
the differences in yolk, but from the later developed vessels of 
these, the ventral abdominal is formed. 
In both species there seems to be some indication that the first 
vessels formed after the lateral cutaneous, have some communica- 
tion with the liver or thesinus. It may be that the ventral abdomi- 
nal retains its connection with the liver through the modification 
of some of these early vessels. However this may come in much 
later, for as set after set of lateral vessels is formed, each one makes 
different connections forward and the third set has no relation at 
first to the liver. The position of the anterior ends of the last, 
just under the liver, would bring it into the proper position to 
join the hepatic capillaries as somatic and visceral vessels would be 
in contact. 
The development of the ventral abdominal vein is, as Hoch- 
stetter (’94) pointed out, from paired somatic vessels. These are 
not early vessels or transformed parts of such, but correspond to 
