This is the most vigorous form of percussion massage. The fist is half closed, and either the ulnar or the palmar surface is used for beating the surface of the body. If no force is put into the movement, it may be used over bony areas, such as the sacrum, and over areas well covered by muscle, such as the gluteal region. As our only hope from its use in these regions is to secure a reflex action, it should be performed lightly. Used over the ribs, it helps to "shake up the liver," and serves generally as the most vigorous form of massage. The knuckles of the clenched fist may be used vigorously if a purely moral effect is desired. In the case of a malingerer in a military hospital the energetic performance of this movement in the presence of the other occupants of the ward may work a rapid cure. It should, of course, be applied by the surgeon in charge, and then only if his diagnosis is incontestably correct. This treatment is not massage.

It is usually stated that percussion massage produces its best effect if the muscles of the part are maintained in a state of contraction, and some masseurs appear to believe that this movement can strengthen the muscles. We know that muscle will respond by contraction to mechanical stimuli under suitable conditions, and it is thus that we witness the phenomena known as tendon reflexes. But we know equally well that one of the tests for severe nerve-lesion is the attempt to elicit contraction of certain voluntary muscles in response to direct mechanical stimulation. Unless the stimulation is sufficient to call forth a protective or irritative reflex contraction, the normal muscle will not respond by contraction to mechanical stimulation. Thus we cannot expect that healthy muscle will contract in response to any form of percussion massage which is administered with a mildness that is not sufficient to elicit one of these reflexes. There is one exception. The abdominal muscles will respond, but only on account of the ordinary abdominal reflex, which, in itself, is probably protective. Similarly, the plantar and cremasteric reflexes can be excited by any form of percussion massage. It should be noted that it is essential to avoid touching the inner surface of the upper part of the thigh during the administration of any form of massage treatment, unless it is the site of actual injury, when the nerves of the part will probably have sustained injury and the reflex arc will thus be destroyed.

If the healthy muscle will not respond, far less will a paralysed and flaccid muscle do so, though a spastic muscle will of course contract. If we are dealing with a case of flaccid paralysis, it is obviously impossible that our first law in using percussion can be respected, namely, that the muscles must be maintained by the patient in a state of contraction. It should, therefore, be abolished from all treatment for the paralysed until such a time as voluntary contraction has not only been restored, but has been sufficiently restored for the patient to be able to maintain it throughout treatment, or until spasticity has vanished. If the paralysis is of the postural variety, gentle percussion may be used when recovery is progressing and the effects of the pressure are passing off. The promiscuous use of the movement so often encountered regardless of conditions present, indicates once more lack of adequate teaching and training, and constitutes a gross error of technique.

When, however, muscular tone is present but deficient, it can doubtless be improved by percussion massage; but the restoration is so poor compared with that following the use of electrical stimulation that it is little better than waste of time, if a battery is available.

If the muscles are allowed to remain relaxed, the effect will be a more or less general "shake up." This will be obvious if we remember that a limb in which the muscles are relaxed compares not unfavourably with a rather well-filled rubber hot-water bottle.

Spinal back hacking induces a sense of warmth and invigora-tion, and is often of service if a patient has become "chilly" from any cause.

The percussion movements are described as "stimulating," and as such are frequently recommended for neurasthenia, owing, apparently, to the confusion that exists in some minds between neurasthenia and hysteria. It would be hard to find the neurasthenic who would prescribe them for a fellow-sufferer. For such they constitute a refined method of torture. In the very late stages of convalescence they might find a place, but other methods of treatment are even then to be preferred.

If used over the reflex areas, such as the gluteal region, over the great sciatic notch, or over the left lower ribs, it is possible at times to secure by percussion a marked reflex contraction of the lower bowel or of the stomach. No attempt should be made to do so in young people, especially boys.

The skin vessels contract at first in response to the movement, but there is usually a subsequent dilatation which remains for a length of time entirely proportionate to the vigour of the treatment. It is thus possible to produce a flushing of the skin.

The nerve-endings are of course stimulated by the movement; but, if it is prolonged or vigorous, an almost complete numbing effect can be produced. It is not beneficial, however, as it is due to sheer fatigue from over-stimulation; and as the fatigue passes off irritability follows.

Percussion over the ribs is performed with the idea of stimulating the liver, but whether the action in this respect is real or imaginary is a matter for speculation. By its means we can undoubtedly "shake up the liver," and it is possible this may assist the flow of bile. The question has been more fully dealt with elsewhere (see p. 25).

Percussion over the sacrum is of assistance in atony of the bladder or rectum, and is particularly useful in post-anaesthetic bladder and rectal inactivity. Unfortunately it is seldom that it can be applied as a post-operative measure. It should never be administered to children, and should always be used with caution.