With the formation of pus the skin becomes soft and boggy at several points, and eventually breaks, giving exit to a quantity of thick grumous discharge. Sometimes several small collections under the skin fuse, and an abscess is formed in which fluctuation can be detected. Occasionally gases are evolved in the tissues, giving rise to emphysema. It is common for portions of fascia, ligaments, or tendons to slough, and this may often be recognised clinically by a peculiar crunching or grating sensation transmitted to the fingers on making firm pressure on the part. If it is not let out by incision, the pus, travelling along the lines of least resistance, tends to point at several places on the surface, or to open into joints or other cavities. _Prognosis._--The occurrence of _septicæmia_ is the most serious risk, and it is in cases of diffuse suppurative cellulitis that this form of blood-poisoning assumes its most aggravated forms. The toxins of the streptococci are exceedingly virulent, and induce local death of tissue so rapidly that the protective emigration of leucocytes fails to take place. In some cases the passage of masses of free cocci in the lymphatics, or of infective emboli in the blood vessels, leads to the formation of _pyogenic abscesses_ in vital organs, such as the brain, lungs, liver, kidneys, or other viscera. _Hæmorrhage_ from erosion of arterial or venous trunks may take place and endanger life. _Treatment._--The treatment of diffuse cellulitis depends to a large extent on the situation and extent of the affected area, and on the stage of the process. _In the limbs_, for example, where the application of a constricting band is practicable, Bier's method of inducing passive hyperæmia yields excellent results. If pus is formed, one or more small incisions are made and a light moist dressing placed over the wounds to absorb the discharge, but no drain is inserted. The whole of the inflamed area should be covered with gauze wrung out of a 1 in 10 solution of ichthyol in glycerine. The dressing is changed as often as necessary, and in the intervals when the band is off, gentle active and passive movements should be carried out to prevent the formation of adhesions. After incisions have been made, we have found the _immersion_ of the limb, for a few hours at a time, in a water-bath containing warm boracic lotion or eusol a useful adjuvant to the passive hyperæmia. _Continuous irrigation_ of the part by a slow, steady stream of lotion, at the body temperature, such as eusol, or Dakin's solution, or boracic acid, or frequent washing with peroxide of hydrogen, has been found of value.