weeks; seven days later pulsation was evident, and an aneurism
the size of a pigeon's egg, with firm walls, became localised
and palpable. It gave rise to no symptoms, and patient refused
operation during the three weeks he remained in hospital. The
aneurism continued to contract, and the patient was sent home.
The aneurism has since spontaneously consolidated.

_Aneurismal varix and varicose (arterio-venous)
aneurism._--Uncomplicated cases of aneurismal varix, as might be
expected, were less common than those in which the arterio-venous
communication was accompanied by the formation of a traumatic sac. The
initial lesion accountable for each condition was, however, probably
identical, and dependent on the passage of a bullet of small calibre
across the line of large parallel arteries and veins. Thus, obliquely
coursing antero-posterior wounds of the neck produced carotid and
jugular varices; vertically coursing tracks laid the subclavian vessels
in communication; antero-posterior tracks the brachial, popliteal, and
lower part of the femoral; and transverse tracks, the vessels of the
calf and forearm. Given an arterial wound, the mode of development of
the aneurismal sac in no way differs from that of the ordinary
traumatic variety; the main point of interest, therefore, is to seek an
explanation of the causes which may restrict the ultimate result to the
formation of a pure aneurismal varix. The explanation is possibly to be
found in some of the following circumstances.

_Size, position, and symmetry of the vascular wound._--It seems scarcely
necessary to insist on the calibre of the projectile, since this alone
determined the frequency of these conditions, but it must be borne in
mind that in the diameter of the bullets, classed as of small calibre
during this war, a range of from 6.5-8 mm. existed. In the case of both
the Krag-Joergensen and Mauser, the shape of the bullet also was better
adapted to pure perforation of the vessels. I saw no case of
arterio-venous communication in which a larger bullet than one of the
four types chosen had been responsible for the primary injury, but a
difference of 1-1/2 mm. in calibre in the small projectile might well
determine the division, the pure and symmetrical perforation of the two
vessels, or the giving way of one side, so that they were deeply notched
instead of perforated.

Such positive evidence as was afforded by operation as to the exac