78 
PATHOLOGY: W. S. HALSTED 
led me to investigate the results of the congenital coarctations of the aorta 
at or beyond its isthmus. I have been interested to find that in a large per- 
centage of these cases of coarcted aorta there is dilation beyond the site of the 
coarctation. The generally accepted view that this dilation is to enable the 
aorta to better carry on the anastomotic circulation must, it seems to me, be 
erroneous. When we shall have ascertained the cause of the arterial dilation 
obtained experimentally below constricting bands and of the dilation of the 
artery proximal to an arterio-venous fistula we may be able to explain the 
dilation of the aorta beyond the congenital coarctation. 
C. Plausible explanation of the presence of blood in lymph-cysts at the second 
and subsequent tappings. — A few years ago, assisted by Dr. Heuer, I ;"e- 
moved from the abdomen of a woman about forty years of age a huge congeni- 
tal hygroma or lymph-cyst. The diaphragm was pushed high up into the 
right thorax and the liver was displaced far to the right and so rotated on its 
vertical axis that its inferior border instead of being transverse was parallel 
and almost in line with the linea alba. The enucleation of the greater part 
of the cyst was easily accomplished, the few adhesions being disposed of by 
gentle, blunt dissection. Finally, when there remained only a few filamen- 
tous fibers binding the sac to the right adrenal gland^ and the inferior vena cava 
we proceeded with even more deliberation and caution. The adhesions to 
the vein were so delicate that the gentlest manipulation with the handle of 
the scalpel sufficed to break them. We had an unusually free and clear ex- 
posure of the vein and were operating without embarrassment. Suddenly 
blood gushed from a linear defect about 3 mm. long in the vena cava. The 
hemorrhage was promptly controlled and the slit in the vessel sutured. Pro- 
ceeding thereafter with perhaps even greater delicacy, we were again confronted 
with a gush of blood from the vena cava at a higher point. Here we found a 
slit from 1.5 to 2 cm. long in this vein. The edges of the slit were smooth, 
the linear defect being clearly not due to a tear or cut. The gap in the vein 
was closed by suture. Dr. Heuer and I satisfactorily assured ourselves thal^ 
there was no defect or special thinning of the wall of the cyst at the point 
contraposed to the larger of the two defects in the wall of the vena cava.^ 
The slits in the wall of the vena cava were surely not artefacts. They rep- 
resented, I believe, imperfectly closed embryonic communications between the 
vein and lymph buds or lymphatic vessels. Dr. Florence Sabin to whom we 
owe so much for our knowledge of the origin and development of the lymphatic 
system very kindly writes me in regard to this case as follows: 
Recent work on the lymphatic system serves to demonstrate that lymphatic vessels are 
modified veins. It has been shown that lymphatic vessels occur first in the neck as sacs, 
lined with endothelium and packed with blood, which lie close to the jugular veins. The 
abdominal l3miphatics begin as a sac which lies close to that part of the inferior cava which 
connects the two Wolfiian bodies. Baetjer showed in 1908 that in the pig this sac which is 
the forerunner of the retroperitoneal lymphatics communicates for a time with the inferior 
vena cava. These communications between the lymphatics and the abdominal veins which 
are transitory in the pig were then shown to be permanent in the South American monkeys 
