_Morbid anatomy._—On examining a well-marked hallux valgus it is seen that the facetted surface of the head of the metatarsal bone has been extended considerably over the external aspect, the prominent inner side of the head lies beneath the stretched joint capsule, the sesamoid bones are displaced outwards from their normal grooves, the internal lateral ligament is greatly elongated and considerably thickened, the external ligament undergoes an inversely proportionate shortening and opposes the reposition of the displaced phalanx (Fig. 14); and the cartilage over the portion of the joint surface, removed from its normal contact with the opposed bones, presents marked degenerative changes. The integumentary structures over the projecting head of the metatarsal bone are affected in the same way as those over the angle of flexion in hammer toe, as a consequence of friction by contact with the shoe leather; callosities and bursal formations, often of great size, are found, and inflammation of the abnormal bursa may give rise to great suffering. [Illustration: FIG. 14. Hallux valgus. From a preparation at St. Thomas’s Hospital. A. _Dorsal aspect._—1. Metatarsal bone; 2. Elongated and thickened internal lateral ligament, a large bursa lay over this; 3. First phalanx; 4. Shortened external lateral ligament; 5. Displaced external sesamoid bone. B. _Plantar aspect._—1. Metatarsal bone; 2. Degenerating cartilage over disused sesamoid furrow; 3. Displaced internal sesamoid bone; 4. Section of thickened capsule (the structure had here assumed the character of a glenoid ligament); 5. First phalanx; 6. Displaced external sesamoid bone.] Although the great majority of cases of hallux valgus are undoubtedly provoked by ill-shaped boots, it is probable that some, and especially those of a very aggravated type, are, like hallux flexus and hammer toe, dependent essentially upon causes not obviously connected with any vice in the foot covering. It is at least certain that some examples of extreme deformity are confined to one foot, the opposite member being of normal shape—a fact that strongly negatives the boot theory; and there are also bilateral cases in which the form of the distortion and the history given by the patients and friends make it equally difficult to accept the common explanation. In one instance recently under my notice the first, second, and third toes of the left foot were carried outwards over the fourth, producing a deformity of a strongly marked kind, while the right foot was perfectly well formed, and the patient, an intelligent woman, insisted that “the toes went wrong by themselves while she was growing up,” and that her shoes had nothing to do with it. In some cases the conditions may be traced to paralytic or spastic affections, and if we accept the developmental theory with respect to hammer toe and hallux flexus, we may assume that hallux valgus occasionally arises in the same way.