The mechanical cleansing of a wound, therefore, commences by removal of the skin which adjoins the orifices, of the sub-cutaneous cellular tissue fouled by fragments of clothing and often infiltrated with blood, and of the muscular track encrusted with foreign bodies. The muscular wall is resected to a thickness of about two millimetres over almost the whole extent of the wound. This cleaning with a cutting instrument is much to be preferred to manoeuvres which injure tissues without cleansing them. It is no use sponging a track with a gauze swab, introduced by one orifice, pushed to and fro, and then removed by the other opening. This kind of cleansing is always ineffective and harmful, for it inoculates healthy tissues throughout the whole extent of the wound, and produces lesions which may be followed by necrosis. Indispensable manipulations, such as the repeated pressure of gauze compresses on a wound-surface to check haemorrhagic oozing, or the use of metallic retractors, have already bruised the tissues. Rough handling, likely to aggravate pre-existing injuries and increase tissue-infection, must be carefully avoided.

{b) Haemostasis. - In the course of the operation, the organs, vessels, and nerves in the neighbourhood are examined and haemostasis of the track completely established. When injury to a large vessel is found in the track of a projectile, it is most necessary to see that adjoining cellular interspaces have not been opened up and infiltrated with extravasated blood. This lesion is common on the posterior aspect of the thigh and calf. In fact, in the sheath of the sciatic nerve, under the biceps, semi-membranosus, and semi-tendinosus, haema-tomata are sometimes found, infiltrated in the connective tissue which separates the different muscles. The same thing occurs in the calf, near the soleus, gastrocnemius and flexors. There must be no hesitation about laying open these spaces from one end to the other, for infection spreads there with the greatest readiness, and may become of extremely grave character. Incisions are made in such a way as not to endanger the circulation of the part.

(c) Search for and Extraction of Projectiles and Shreds of Clothing. - The difficulties of searching for projectiles are due to the dimensions, sometimes extremely small, of the foreign bodies, to the thickness of the muscular stratum in which they are embedded, and to the irregularity of the course of the projectile through the tissues.

When a wound is cleansed some hours after infliction, and the foreign body is as large as a small nut, it is generally easy to find it. The muscles which surround the track seem struck by paralysis. Eye and finger follow the route of the missile all the more readily when radiography has indicated the direction of the track. One always tries to arrive at the projectile by means of the track, because it has to be followed and the whole wound cleaned. However, if the track is too long, it is easy to make a counter-opening in the immediate neighbourhood of the projectile. This counter-opening not only allows the projectile to be extracted, but also the inspection of the wound to be completed, and this part of the track to be resected. The various apparatus for registration, and Bergonie's electrovibrator should be made use of. Sometimes the minute fragments of shell are very difficult to locate. In fact, the openings they leave when traversing fascia are very small. Often these may be identified, but directly afterwards the track through muscular fibre is lost. Hirtz's or Contremoulin's compass may prove of use. But when the shell-fragments are numerous and close together, the multiplicity of points registered on the skin is bewildering. Then is the time to call in the aid of the telephone vibrator of M. de la Baume-Pluvinel. This apparatus enables us to find the tiniest fragments.

It is much more important to remove shreds of clothing than projectiles. As a rule, the missile is wrapped up in the fabric it has carried along with it, but sometimes it has only pushed the cloth in front. By the aid of dissecting forceps, every particle of fabric which is found on the surface of the wound is removed with minute care.

The toilet is completed by washing both wound and adjoining skin with neutral oleate of soda.

id) Drainage. - Drainage of the wound should be liberally arranged, but by a procedure different from what is usually employed. Counter-openings are not made at dependent points. In fact, the antiseptic solution must come into contact with the entire surface of the tissues, and consequently fill the wound. The liquid must not be allowed to escape through the bottom. We shall even see, later on, that when a wound is being drained naturally through a dependent opening, the inferior orifice should be plugged by a tampon. Therefore we have to be contented with freely opening the wound by one or more long incisions, situate as much as possible on the anterior aspect of the limb. The openings thus made are kept gaping by means of compresses placed in the mouth of the wound, or short lengths of very large rubber drainage tube. Compresses or tampons are never placed in the interior of the wound.

When the wound has been thus prepared, and haemostasis is complete, the tissues look quite clean. However, we are never quite sure of having cleansed the wound absolutely. There is no known method of ascertaining the bacteriological condition of a fresh wound while it is still bleeding. The "smears" which would immediately inform us as to the state of wounds more than twenty-four hours old, and from a non-bleeding surface, are of no use at this stage. Cultures give no results before the end of twenty-four hours. And even a negative culture would not signify that the wound was not infected. In reality, in fresh wounds, microbes are localised at certain points, and if the specimens are not taken from these points, the tubes remain sterile. Therefore we must refuse, absolutely, immediate closure of a wound, however satisfactorily clean its appearance. As it is impossible to ascertain precisely its state as to infection, the patient would run grave risk if it were sutured. Often has disaster followed premature closing of wounds.