The bactericidal potency of the chloramines and of hypochlorite is such that every wound should respond to the treatment by a diminution in the number of microbes and by their final disappearance. Therefore it is important to ascertain if the bacteriological condition is being modified in a progressive manner. In fact, when that condition remains stationary, it may be concluded that contact between antiseptic and microbes is not completely established, and that the technique needs alteration.

Clinical observation alone does not enable us to follow the evolution of wound infection. It gives only the probabilities. When a patient has ceased to have pyrexia, when the wound is of a healthy red, when its margins are supple and when suppuration has disappeared, then it is fair to assume that the wound is nearly aseptic. But investigation has taught us that wounds looked upon as aseptic are often highly infected, and that it is never safe to trust the favourable appearance of the tissues as evidence that they are sterile. Besides, it often happens that wounds treated by chloramines have a slightly greyish look, and are covered with purulent secretion. They have the appearance of infected wounds. However, these wounds may be sutured without the least rise of temperature following. In this case only bacteriological examination can demonstrate to the surgeon that the pus which covers the granulations is aseptic.

It is impossible, therefore, to ascertain the results of treatment with sufficient precision, without the constant aid of the microscope. Using the simple method which will be described later, bacteriological examination of a large number of wounds may be made every day. M. Gaultier1 has shown that, even in dressing-stations {ambulances, Fr.) at the front, it is possible to make use of the microscope. That examination gives warning of the existence of errors of technique as soon as they appear, and so enables the loss of time to be avoided which is the usual consequence. It points out the moment when the wound has become surgically sterile and can be sutured.

1 Gaultier, Paris Midical, July, 1916.

To sum up, knowledge of the bacteriological condition of the wound is an indispensable part of the technique of sterilisation, and it alone can give to the latter the necessary precision.