Instillation of liquid continues day and night until all microbes have disappeared from the "smears." Therefore it is inspection of the microbial curves which indicates when the irrigation can be stopped. So long as a few microbes remain, no alteration should be made either in the quantity of the liquid or in the frequency of the instillations. So long as a focus of infection, be ft ever so small, remain on the surface of the wound, total reinfection is possible. If the instillations be stopped, or their frequency lessened, when the microbial curve shows only one or two microbes per field of the microscope, rapid reinfection may be brought about. On the other hand, the presence of hypochlorite does not lessen the rapidity of repair. By suppressing microbes, it accelerates it. As the few small infected foci which still persist on the wound after some days of instillation cannot enlarge, the greater part of the wound cicatris s with the same speed as if it were aseptic.
In general, from three to ten days are needed to sterilise a wound of the soft parts, and fifteen days or more a compound fracture. These figures are those observed when the wound is sterilised before the suppurative stage. But if the treatment is commenced after the wound has already suppurated, the duration of the instillation period is usually much longer. Bacteriological examination alone can indicate the time when the instillations may be discontinued.