Deformities of this kind may be met with in association with various diseases of the nervous system. The most common condition is a hammer deformity of the lesser toes, with retraction at the metatarso-phalangeal joint, and an exaggeration of the plantar arch (paralytic cavus). This is probably due to paralysis of the interossei in nearly all cases. Occasionally a single toe is affected. In the great toe it may arise from paralysis either of the short flexors or of the tibialis anticus (as pointed out by Mr. Davies-Colley), and is associated with retraction of the first phalanx and flexion of the second. In the smaller toes the digits assume a position like that of the clawed finger in ulnar paralysis, with extension of the proximal and flexion of the middle and distal phalanges, but, unlike in true hammer toe, there is distinct evidence of paralysis, and the capacity of the flexed joints for passive extension is usually retained for long periods. In these cases where the unopposed extensor leads to very inconvenient retraction of the first phalanx the tendon may be divided, and Mr. Davies-Colley suggests that the proximal cut end should be fixed to the metatarsal bone in order to preserve its utility as a dorsal flexor of the ankle. The return of the deformity must be prevented by the subsequent use of splints and manipulation. SECTION III CONGENITAL DEFORMITIES OF THE HANDS AND FEET The congenital deformities of the hands and feet are very numerous. They include excessive growth, a variety of other irregularities and deficiencies of nutrition, numerical increase of parts and abnormal union of digits. These defects are often hereditary, they may co-exist in various combinations, and may be associated with faults of evolution in other parts of the body. In most cases the _rôle_ of the surgeon is limited to the removal of useless or unsightly parts, but occasionally a higher function is open to him. The most interesting of the congenital defects of the digits is the curious and often complex condition known as makrodactyly. [Illustration: FIG. 17. Various congenital defects of the hands and feet (from Förster, Missbildungen des Menschen). 1 to 4 and 15.—Numerical defects of fingers. 5 to 14.—Hands and feet with combination of hypertrophy and defective development of fingers and toes, all from the same individual. 10 to 14 show the crab-like deformity described in the text (p. 147). 16, 17, 18, 19.—Syndactyly. In 16 and 19 the united fingers are larger than their neighbours. In 17 and 18 the union involves all the fingers except the first, and on one hand the number of digits is reduced to four. 20, 21.—Hand and foot with suppression of first four digits. In 20 there is a rudiment of the index or middle finger.] MAKRODACTYLY.