oint with regard to the cervical vascular cleft.
Examples of the tendency to spread in the anatomical direction of least
resistance are also offered by the cases of aneurism at the root of the
neck, where extension was into the posterior triangle.

The further clinical history and signs are as follows. A local swelling
is found, usually at first diffuse, often commencing to develop with
cessation of the external haemorrhage. It increases, for the first few
days maintaining its diffuse character. If near the surface, it may be
superficially ecchymosed. At the end of this time a tendency to
localisation, as evidenced by increasing firmness and more definite
margination, takes place, and this is followed by general contraction
and rounding off of the tumour. The latter process may be continuous,
and eventually the sac may become small and stationary or ultimately
disappear and a pure varix be the result. The latter is only likely to
be the case under the most satisfactory of the conditions enumerated
above. Occasionally an opposite course may be followed, and fresh
extension take place, as evidenced by enlargement of the tumour,
disappearance of sharp definition, softening, and pain. The natural
termination of such cases in the absence of interference would no doubt
be rupture, and possibly death in some positions, loss of the limb in
others. The former I never saw.

_Purring thrill._--This, the pathognomonic sign of either condition, was
always present in the fully developed stage, and is probably present
from the first unless a temporary thrombosis obstructs the vascular
openings. It was noted as early as the third day in case 13. In many of
the other patients it was palpable only with the subsidence of the
primary swelling attendant on the injury. In some of the forearm and
calf aneurisms, and in some of the popliteal, it was only discovered by
accident some weeks even after the injury, but this often because no
serious vascular lesion had been suspected. The thrill was widely
conducted, often apparently superficial on palpation, and much more
pronounced with light than with forcible digital pressure.

In case 10 the _visible_ vibration in consonance with the thrill when
the vein was exposed during the operation of ligature of the carotid was
a novel experience to me.

_Murmur._--The typical 'bee in the bag,' or 'machinery' murmur was
present in every case, and was often very widely distributed, especially
over the