Fig. 2.   Disappearance of the microbes of a highly infected wound, after treatment by Dakin's hypochlorite, May 31st to June 2nd, 1915. (Case 28.)

Fig. 2. - Disappearance of the microbes of a highly infected wound, after treatment by Dakin's hypochlorite, May 31st to June 2nd, 1915. (Case 28.)

The bactericidal action of Dakin's hypochlorite was next studied in infected wounds themselves. When hypochlorite of soda is applied to a wound in such a manner that its degree of concentration remains constant, and the duration of the application is prolonged, the microbes disappear (Fig. 2). This fact has been observed a very great number of times. Indeed, one might affirm that it constantly happens when intimate contact is established between the antiseptic solution and the organisms. The sterilisation of wounds treated by Dakin's solution is an established fact. But it will be well to enquire if the treatment is actually the determining cause of the sterilisation, and if this sterilisation is due to the hypochlorite of soda.

(a) It might be suggested that, in our observations, the wounds grew sterile spontaneously. In truth this is hardly likely, because one never sees a series of infected wounds become sterile in a few days. Nevertheless, this hypothesis was submitted to experimental analysis. Choosing a wound whose various regions were uniformly infected, a square of filter-paper was placed on a selected spot, and kept constantly moist with hypochlorite of soda. On another spot was placed a square of filter-paper of the same size. Then the wound was again covered with a protective dressing. At the end of twenty-four hours, below the filter-paper moistened with hypochlorite, a smooth surface of red granulations was to be seen, and the microbes had completely disappeared. Under the filter-paper which had not been wetted with hypochlorite, the granulations were irregular and pale, and the microbes as numerous as before (Fig. 3). In the portions of the wound which had not been covered with filter-paper, there was no change in the quantity of microbes.

In a case where the half of a wound was dressed with hypochlorite, and the other half with vaselin, there was complete disappearance of microbes in the region treated with hypochlorite, whilst the infection remained elsewhere.

Similar results were obtained with deep wounds. Two shell fragments had penetrated two neighbouring points in the lumbar region; the two fragments were removed at the same time. One of the wounds was treated by the continuous instillation of hypochlorite, and the other by a simple dressing. The wound treated remained painless, and the microbes disappeared completely from the smears; whilst the wound not treated became painful, was surrounded by a red aureola, and was the seat of streptococcal infection. In the seton type of wounds, we could often observe that the region where the hypochlorite penetrated was sterile, while the portion where the hypochlorite did not penetrate still held a great number of microbes. Numerous similar observations showed in a very distinct fashion that the relation of cause and effect existed between the treatment employed and the results obtained.

Fig. 3.   Superficial wound of left arm. Comparative action on an infected wound of pieces of filter paper soaked or not in hypochlorite of soda. The continuous line represents the diminution of the microbes from 20 to o per field of the microscope, and the dotted line, the condition of the control portion of the wound. (Case No. 247.)

Fig. 3. - Superficial wound of left arm. Comparative action on an infected wound of pieces of filter-paper soaked or not in hypochlorite of soda. The continuous line represents the diminution of the microbes from 20 to o per field of the microscope, and the dotted line, the condition of the "control " portion of the wound. (Case No. 247.)

Fig. 4.   Superficial wounds of the left thigh. Comparative study of the influence of Dakin's hypochlorite and of physiological saline solution. Two wounds equally infected and of the same man were treated, one by hypochlorite, the other by saline solution. These two wounds contained from 20 to 30 microbes per microscope field. The continuous line represents the diminution in number of microbes in 24 hours under the influence of hypochlorite. The dotted line represents the state of the wound treated by saline solution at the end of the same time. (Case No. 52.)

Fig. 4. - Superficial wounds of the left thigh. Comparative study of the influence of Dakin's hypochlorite and of physiological saline solution. Two wounds equally infected and of the same man were treated, one by hypochlorite, the other by saline solution. These two wounds contained from 20 to 30 microbes per microscope field. The continuous line represents the diminution in number of microbes in 24 hours under the influence of hypochlorite. The dotted line represents the state of the wound treated by saline solution at the end of the same time. (Case No. 52.)

(b) Next, it must be made clear whether the result is due to the antiseptic action of the hypochlorite, or to the mechanical action of the instilled liquid. The following experiments were devised to elucidate this point. A wounded man had upon his thigh two wounds of dimensions almost identical, and with bacteriological conditions practically the same. One was dressed with hypochlorite and the other with physiological saline solution. At the end of twenty-four hours, the surface of the wound dressed with hypochlorite did not show a single microbe per field, while the wound treated by saline solution had more than thirty microbes per field (Fig. 4). Other experiments were made by means of wounds, on the surfaces of which were applied squares of filter-paper of similar dimensions. One of the squares carried solution of hypochlorite, while the other had physiological saline solution. At the end of twenty-four hours, the region situated under the hypochlorite contained no microbes, while the region treated by saline solution had a large number. Similarly, observations were made on deep wounds with old lesions. A case of fracture of the femur with great loss of substance and extensive osteo-myelitis of the bony extremities, was observed for several months. An india-rubber tube introduced into the suppurating cavity permitted the instillation, during arranged periods, of hypochlorite, or of hypertonic saline solution. When the case was having the hypochlorite, the pus contained many microbes and had no smell. When the hypertonic saline solution was substituted for the hypochlorite, the pus immediately gave out a tainted odour, and the microbes became much more numerous. As soon as the hypochlorite was again instilled, the odour disappeared, and the number of microbes diminished. Similar experiments were made several times with like results.