These accidents are not uncommon in ordinary hospital experience. The effect of such a solution of continuity over the back of the hand is to leave the first phalanx in a state of flexion, while the second and third phalanges may be voluntarily straightened without difficulty, especially if the metacarpo-phalangeal joint be passively fixed in the position of extension. The reason for this of course is that the common extensor, by virtue of its ligamenta dorsalia and its connection with the aponeurotic fibres derived from the interossei, acts with peculiar advantage upon the metacarpal phalanx, although it has no direct attachment to it, while its nominal “insertion” into the middle and ungual phalanges is subservient to the interossei and lumbricales, which are the true extensors of these bones. On the other hand, if the lesion fall just on the proximal side of the first inter-phalangeal joint, the first phalanx may be susceptible of almost complete voluntary extension; but the second and third phalanges are bent by the unopposed action of the superficial and deep flexors, because the influence of the true extensors, the lumbricales and interossei, has been cut off. In like manner, a division of the tendon over the middle phalanx leaves the terminal phalanx in the position of flexion; and a similar result follows the accident first described by Segond, in which the extensor tendon is torn away with a portion of the bone during forcible flexion of the ungual phalanx. _Treatment._—If the injury be seen in the early stage and there is no loss of substance at the point of lesion, it may be treated satisfactorily by fixing the finger, hand, and wrist in full extension, to allow the passive approximation of the divided extremities of the tendon; but should the case not come under notice until a later period it will be necessary to cut down and suture the tendon. If there is loss of substance and the two ends of the tendon cannot be brought together, the treatment must vary with the position of the injury. In some cases, where the metacarpal portion of the tendon is involved, a good result may be obtained by joining the distal end to the adjacent tendon so as to bring it again within the control of the muscle, but if the digital portion be the seat of the lesion this is impracticable, and a remedy may be found by lengthening the tendon, either by splitting one or both ends and suturing the extremities of the portions detached, or by transplanting a portion of a tendon from a dog into the gap. As a last resource the traction of the flexors may be balanced by an elastic extension band replacing the destroyed tendon, and attached by one end to a little cap drawn over the finger, by the other to the dorsal aspect of a wrist gauntlet. CONTRACTIONS ARISING FROM NUTRITIVE CHANGES IN THE MOTOR APPARATUS.