1 92 Sir Everard Home on the coagulation by heat 
was plugged up by a small coagulum, beyond which it was 
impervious. The opening into the sac was on the posterior 
part, and was one inch in length. The coagulum formed by 
the heated needle had so unusual an appearance and texture, 
that it is shown in the annexed drawing. The upper portion 
of the sac occupied a part of the cavity of the pelvis, and 
by its pressure prevented the branches of the internal iliac 
artery from supplying the thigh with blood. 
The coagulum in contact with the sac was the same as is 
usually met with in large aneurismal tumours ; within that 
there were innumerable thin firm lamina, and the innermost 
portion was in the state of jelly. 
It is a circumstance which could not have been foreseen, 
but one highly satisfactory to myself, that had I attempted to 
tie the artery above the formation of the aneurismal sac, I 
must have failed, since the sac extended higher than the 
division of the iliac artery into the external and internal, so 
that the external branch could not be secured without wound- 
ing the sac, which would have proved fatal ; and in the space 
above, between the division into two iliacs, and the bifurca- 
tion of the aorta, there is an ossification an inch long ; so that 
if the artery had been secured there, when the ligature sepa- 
rated, the patient must have bled to death. It may be said, 
that I might have taken up the aorta above the bifurcation ; 
but I have made up my mind to let those diseases that require 
tying the aorta, which come under my care, take their 
course. 
From the ossifications met with on the arterial trunks so 
much nearer the heart than the aneurismal sac, and a similar 
ossification having been formed in the femoral artery in the 
