knowledge to a certain class of surgical cases in a most
revolutionary and satisfactory manner.

What led to Hunter's far-reaching discovery was his investigation
as to the cause of the growth of the antlers of the deer. Wishing
to ascertain just what part the blood-supply on the opposite
sides of the neck played in the process of development, or,
perhaps more correctly, to see what effect cutting off the main
blood-supply would have, Hunter had one of the deer of Richmond
Park caught and tied, while he placed a ligature around one of
the carotid arteries--one of the two principal arteries that
supply the head with blood. He observed that shortly after this
the antler (which was only half grown and consequently very
vascular) on the side of the obliterated artery became cold to
the touch--from the lack of warmth-giving blood. There was
nothing unexpected in this, and Hunter thought nothing of it
until a few days later, when he found, to his surprise, that the
antler had become as warm as its fellow, and was apparently
increasing in size. Puzzled as to how this could be, and
suspecting that in some way his ligature around the artery had
not been effective, he ordered the deer killed, and on
examination was astonished to find that while his ligature had
completely shut off the blood-supply from the source of that
carotid artery, the smaller arteries had become enlarged so as to
supply the antler with blood as well as ever, only by a different
route.

Hunter soon had a chance to make a practical application of the
knowledge thus acquired. This was a case of popliteal aneurism,
operations for which had heretofore proved pretty uniformly