_Lesions._ In _fermentation fever_ no tissue lesions are known. In _septicæmia_ gross lesions are usually lacking unless the case has been prolonged to allow of secondary abscesses (septico-pyæmia). The blood however is dark and coagulates feebly if at all. The spleen is enlarged, softened, dark in color and gorged with blood. There are petechial hæmorrhages into the serosæ and mucosæ, and the solid organs; cloudy swelling of internal organs from coagulation necrosis; a parboiled appearance of heart, liver, kidneys and voluntary muscles; congestion of the lymph glands and usually the presence of the specific microbes in the blood and local lesions. The kidneys are always congested, and their epithelia granular and swollen, and there may be exudation between the glomeruli and their capsules. _Symptoms._ Septic intoxication or septic infection may be ushered in by a staring coat or slight chill, but it rarely shows a violent rigor, such as inaugurates pyæmia. There is a rapid rise of temperature (102° to 104°), which persists for three to seven days without the marked remissions of pyæmia; weak, compressible pulse; great muscular debility; hurried, shallow breathing, usually without cough; anorexia; emesis in vomiting animals; dusky or yellow mucosæ from dissolved hæmoglobin; scanty, high colored urine, rarely albuminous; dulness, sometimes nervous twitching, delirium, apathy, stupor or paraplegia; and either constipation or, later, diarrhœa. When such symptoms supervene on a gangrenous sore, septic abscess or fistula, retained placenta, blood clot in the uterus or elsewhere, suppurating tubercle, or other morbid product, gangrenous lung or other internal organ, purulent pericarditis, pleuritis or peritonitis, or any febrile affection which is complicated by necrosis, septicæmia is to be suspected. “Septicæmia should always be suspected during the course of any disorder the lesions of which afford an opportunity for the growth and development of septic microörganisms, when the symptoms of that disorder depart from the usual type and an elevated temperature continues beyond the usual duration.” (Atkinson). “The final diagnosis of septic infection must be based on the existence of an infection atrium, through which pus microbes have entered the tissues, and from which they have reached the general circulation.” (Senn). _Prognosis_ is always grave. A slight infection, overcome by the leucocytes or a simple septic intoxication may get well in two or three days, but an _acute progressive septic infection_ will usually prove fatal in from one to seven days. _Prevention_ does not differ from that recommended for pyæmia.