* We see here what great importance muscles in their healthy condition have in the development and maintenance of normal form and function.

The deformity depends upon lost equilibrium between muscles and groups of muscles around a joint. This in turn depends upon the destruction of certain motor cells and paths by an acute inflammation. This destruction is absolutely irreparable, and no treatment is of any use in restoring these centres, with their corresponding paths, to their respective functions. One must be content to treat this loss of muscular equilibrium by more direct means. With the aim of correcting the lost equilibrium between the muscles acting on a joint orthopaedists have in recent years, and on the whole very successfully, tried to cope with paralytic deformities by operation.

The aim of restoring the lost equilibrium between muscles coincides with the aim of weakening muscles which are too strong, strengthening muscles which are too weak, and compensating for muscles which are quite paralysed. Muscles which are too strong can easily be made weaker by means of the old surgical methods, as, for example, by partial or total excision or lengthening of tendons; and these operations greatly facilitate, and may in some cases be absolutely necessary to make possible, the correction of a faulty position. It is much more difficult to strengthen weakened muscles. Exercises play a predominating part in such cases; but it is very seldom possible to strengthen a paralysed muscle to the extent necessary to enable it to oppose its healthy antagonists.

To compensate a completely paralysed muscle is of course much more difficult. The only method formerly employed to attain this end was the use of complicated supports with elastic bands and springs. This method involved to a great extent all the inconveniences of the fixation treatment already referred to, and was, in the long run, unsatisfactory, although in certain cases it might considerably relieve the patient. Orthopaedic surgeons have lately resorted to quite new methods for strengthening weak or compensating paralysed muscles, namely, by operative methods, such as shortening of tendons, transplantation of tendons, partial or total transplantation of muscles, thus distributing the remaining functional muscles so that the balance of power is restored with regard to the chief function of the joint. By these methods we have greatly advanced in the treatment of infantile paralysis. The complete restitution of a joint, even in slight cases, cannot be fully achieved, for the muscle power must always remain less than in the corresponding healthy joint, yet mobility can be gained in all necessary directions and correction is maintained and relapse avoided. The result depends on the extent of the paralysis. The cure is, however, not terminated by the operation; much work in the form of "after-treatment' by gymnastics and massage is required in order that the result be successful. The medical gymnast-masseur stands now in quite a new position with regard to the poliomyelitis patient; and the aims before him can be best illustrated by a concrete example. We take a case of pes valgus paralyticus due to total paralysis of Tibialis Anticus. This deformity, which causes great trouble and functional inconvenience to the patient, who is constantly found walking with the internal malleolus on the ground, the foot completely rotated outwards, is dealt with by orthopaedic means in the following manner: - Extensor Hallucis, being very considerably developed, is cut through at the tendon and its central end sewn on to Tibialis Anticus, and the peripheral end of Extensor Hallucis is sewn on to Extensor Communis Digitorum; thereby contractile muscle substance is carried to the completely paralysed Tibialis Anticus. It is obvious that the muscles do not immediately on healing begin to function in the way aimed at. Only by the help of a long period of correct exercises can this theoretically rational treatment lead to a practical result, and the medical gymnastic treatment is of a double nature. Partly, in extensive paralysis, weak and unimportant muscles or parts of muscles, which can be used to replace the lost muscle or function, may be strengthened by resistance movements in the ordinary way, i.e., by ordinary muscle gymnastics. The more interesting aim is that these partially or totally transplanted muscles must be trained to perform entirely new functions. In this supposed case the conditions immediately after operation are as follows : - When the patient wishes to extend the great toe, and for this purpose contracts Ext. Hallucis, whose tendon is cut, no effect is produced in the great toe, but an inversion of the foot takes place because the muscle acts at the insertion of Tibialis Anticus. Therefore at first the patient is not able to invert the foot unless he thinks of extending the great toe. By practice, however, this necessity soon disappears, and it is not long before the patient can produce intentional inversion of the foot. In this way then the entire motor nerve path from the extensor centre of the great toe to Ext. Hallucis has been trained to a new function, namely, an inversion centre has been formed, and the motor nerve from it has been utilised by a muscle of inversion; in other words, the patient has acquired a new Tibialis Anticus. On the other hand, the patient has lost the power to extend the great toe by itself, and can only extend it at the same time as he does the remaining toes, a very slight loss in comparison to a great gain. When it concerns more complicated and more extended paralysis the matter is not so easy. In treatment of this kind one encounters many interesting problems in muscle physiology, which, although we have no real concern with them here, it seems suitable to touch upon in a few words.

While it is obvious, and in any case not surprising, that Ext. Hallucis can be trained to perform not only the synergistic but also in most cases the simultaneous function of Tibialis Anticus, it seems less probable that it should be possible to train a transplanted muscle to perform an antagonistic function. Still more wonderful is it to consider whether a divided muscle is able to perform different functions with its different parts. All the conditions connected with these questions have not yet been fully worked out, but during the research of recent years in connection with this method of treatment of paralytic deformities we have much extended our knowledge on these questions of muscle physiology.

We now consider it proved that a muscle which has been transplanted altogether can be trained to perform even an entirely antagonistic function; on the other hand, we think it uncertain, or even improbable, that a divided muscle is able by practice to separate into two or more functional entities with widely different functions. By degrees, as a result of these experiences, we have somewhat changed the method of operation in the treatment of these deformities. Whereas formerly, according to Vulpius, even with extensive paralysis with very little area of unparalysed muscle, it was attempted by lengthy separation and partial transplantation of the muscles to make good all the lost functions of the joints, more recently we have followed Lange in attempting in severe cases only to obtain the most important functions of the joints by transplantation of the whole muscle, in doing which we must naturally choose the least important muscles, or one of two pieces of muscles with similar function (e.g., peronei), as compensation for some important lost function. As a result of these methods we have undoubtedly made a great step forward in the treatment of these unfortunate paralyses; and we have seen how the position of the gymnast-masseur in the treatment of these diseases has by this means become considerably more pleasant. Instead of wasting an unheard-of amount of work without corresponding result, he now co-operates as a particularly important and absolutely indispensable factor in treatment which, if correctly planned and energetically carried out, always results in a real gain to the patient. Above all it must be emphasised that it is an essential part of this treatment that the masseur completely understands his task; that the whole of the plan and carrying out of the treatment is known to him in detail, so that he thoroughly understands what is expected of him. If this is not the case he soon nullifies by faulty gymnastics and harmful correction the good results of even the best-planned operation. In no part of practical medicine as in this is it so harmful for the doctor to hand over his patient to the medical gymnast without getting into personal communication with him; here, if anywhere, personal intercourse between the doctor and the gymnast, and the doctor's personal supervision of the treatment, are imperative necessities in order to obtain a good result.