If now in addition to such a condition, we have a goodly tone in the abdominal musculature and a firm, well-developed rectus sheath which resists dilatation of the umbilical ring, the resulting hernia is pedunculated. (Fig. 6.) Generally, however, the omentum drags the transverse colon along after it into the sac. This sequence of events is entirely in accord with, and adequately explains, the operative findings as to the contents of Omentum is invariably present; most frequently associated with the large intestine. The small intestine is added later on. Occasionally, in a continuation of this same process, the traction of the colon on the gastro-colic omentum brings the greater curvature of the stomach into the sac. That this is not at all the rule is due in large measure to the uniformly firm and constantly placed meso-colic attachment in the left flank anchoring the splenic flexure.

The intra-abdominal pressure, acting on the sac contents in conformity with the same law applying to fluids, "that pressure exerted on a fluid is transmitted equally in all directions" produces gradual enlargement of the hernial ring. In so doing it not only pushes to one side and stretches the aponeurotic fibres of the transversalis fascia and the linea alba, but pushes the innermost decussating fibres outward toward the surface as well. Thus there is formed an aponeurotic funiculus which extends up the sac proper for a distance of from one to three cm. diminishing in density and terminating in a few stray fibres which seem to have been actually torn loose from their tendon.

This displacement process is, in reality, in the nature of a rolling back of these tendons, resulting in a constant increase in the ability of the ring to withstand further stretching as it increases in size.

The same forces which are gradually displacing the aponeurotic fibres are at the same time acting against the resisting powers of the coverings of the sac, and were it not for the pronounced tendency to the early formation of adhesions, the growth of an umbilical hernia would be much more rapid than is in fact the case, and its ring would be smaller. Just in so far as the sac can resist pressure, that pressure can operate to enlarge the

ring. When, however, the ability of the ring to withstand pressure equals and slightly exceeds the holding powers of the sac, from then on, the sac and not the ring must give. This marks a definite stage in the development of an umbilical hernia, and explains why a small hernia may, and in fact so frequently does, remain practically unchanged in size for years, and then, without obvious reason, suddenly increases in size. From this time on there is very little, if any, increase in the size of the ring, but the growth of the hernia is continuous. That is why the size of the hernia itself is no criterion of the size of the ring to be closed. That is also why strangulation is more frequent in small than in large umbilical herniae.

The early formation of adhesions and subsequent growth of the sac leads to the presence of trabeculae sometimes several inches in length and well vascularized. These trabeculae extend from one visceral element in the sac to another or to the wall of the sac. Again, the sac wall may be closely united to the contents over considerable areas with adhesions varying in degree from slight filmy veils to the most intimate consolidation.

In the large herniae, diverticulae from the main sac are common, and may equal or even exceed the original sac in size. Such sacculations in obese patients are prone to burrow well underneath the panniculus, and are to be constantly borne in mind when making the first incision. (Fig. 7.)

The enormous stretching to which the skin is subjected in the large herniae gives rise to superficial ulcerations, which are of the utmost importance as portals of entry of infection. The cutaneous veins are dilated-sometimes varicosed, from the stretching of their walls and cicatricial areas surrounded by zones of pigmentation, particularly about the summits of the sac, mark the site of healed ulcers and indicate the lowered circulatory efficiency of the sac wall. They are to be interpreted precisely as similar manifestations are interpreted in the lower leg. Chafing or maceration of the skin folds underneath the tumor, between it and the abdominal wall is almost invariably present in obese patients, particularly in the hot seasons, and,

FIG. 8.-Very early stage of umbilical hernia. Note that hernia comes through upper portion of umbilicus and tends to spread upward over linea alba, obliterating upper margin only of umbilicus. Shows also large post operative ventral hernia.