em; less frequently those
of the small saphena system. Sometimes both systems are involved, and
large communicating branches may develop between the two.

The essential lesion is the absence or deficiency of valves, so that
they are incompetent and fail to support the column of blood which bears
back upon them. Normally the valves in the femoral and iliac veins and
in the inferior vena cava are imperfectly developed, so that in the
erect posture the great saphena receives a large share of the backward
pressure of the column of venous blood.

The whole length of the vein may be affected, but as a rule the disease
is confined to one or more segments, which are not only dilated, but are
also increased in length, so that they become convoluted. The adjacent
loops of the convoluted vein are often bound together by fibrous tissue.
All the coats are thickened, chiefly by an increased development of
connective tissue, and in some cases changes similar to those of
arterio-sclerosis occur. The walls of varicose veins are often
exceedingly brittle. In some cases the thickening is uniform, and in
others it is irregular, so that here and there thin-walled sacs or
pouches project from the side of the vein. These pouches vary in size
from a bean to a hen's egg, the larger forms being called _venous
cysts_, and being most commonly met with in the region of the saphenous
opening and of the opening in the popliteal fascia. Such pouches, being
exposed to injury, are frequently the seat of thrombosis (Fig. 66).

[Illustration: FIG. 66.--Thrombosis in Tortuous and Pouched Great
Saphena Vein, in longitudinal section.]

_Clinical Features._--Varix is most frequently met with between puberty
and the age of thirty, and the sexes appear to suffer about equally.

The amount of discomfort bears no direct proportion to the extent of
the varicosity. It depends rather upon the degree of pressure in the
veins, as is shown by the fact that it is relieved by elevation of the
limb. When the whole length of the main trunk of the great saphena is
implicated, the pressure in the vein is high and the patient suffers a
good deal of pain and discomfort. When, on the contrary, the upper part
of the saphena and its valves are intact, and only the more distal veins
are involved, the pressure is not so high and there is comparatively
little suffering. The usual complaint is of a sense of weight and
fulness in the limb after standing or walking, sometimes accom