CHANGES IN FETAL VESSELS OF THE LIVER 



487 



tissue and there was an entire absence of non-striated muscle 

 even within a half centimeter of the left portal. Nevertheless, 

 that this vein was the original umbilical vein is shown by the 

 entire absence of any remnant or vein in the caudal border of 

 the suspensory ligament. Moreover, the total disappearance 

 of the umbilical vein at so early a day in cats is, of course, very 

 unlikely. 



Apparently then, in these animals the retraction and de- 

 generation of the suspensory ligament takes place -pari passu 



Fig. 4 Round and suspensory ligaments of the cat. o, remnant of the umbil- 

 ical vein ; 6, a large lymphatic. X97. 



Fig. 5 A section of the suspensory and round ligaments of the cat. a, rem- 

 nant of the umbilical vein; b, lymphatic. X79. 



with that of the umbilical vein and is dependent upon and de- 

 termined by the retrogressive changes in the vein to a certain 

 extent at least. That these processes are more or less inde- 

 pendent of each other, however, is well illustrated by two dogs 

 over a year old in which the suspensory ligaments were well- 

 preserved while the umbilical vein had disappeared completely. 

 A similar condition is also not uncommonly found in old rabbits, 

 cats and guinea-pigs. On the other hand, in the dog and sheep 

 in which the umbilical vein becomes totally isolated and never 

 has any permanent connections with the peripheral veins it de- 



