It occurs in typhoid fever, especially in the later stages of the disease, in tuberculous lesions unaccompanied by suppuration, in malaria, and in most cases of uncomplicated influenza. The occurrence of leucocytosis in any of these conditions is to be looked upon as an indication that a mixed infection has taken place, and that some suppurative process is present.

The possibility of the three high temperatures with leucocytosis being due to intercurrent infections must be considered. Charles O. had high fever only for ten days during a psychosis of several months. Annie G.’s high fever was of about the same duration. Caroline DeS. had short periods of marked pyrexia in the first and seventh months of her long psychosis.

Recognising the "beneficent intention" of the inflammatory reaction, and the protective action of the leucocytosis which accompanies the hyperæmic stages of the process, Bier was led to study the effects of increasing the hyperæmia by artificial means.

There is pain on swallowing, and often earache; and the patient speaks with a nasal accent. He becomes weak and anæmic, and loses his appetite. There is often albuminuria. Leucocytosis is usually well marked before the injection of antitoxin; after the injection there is usually a diminution in the number of leucocytes.

In children under one year of age, the normal average is from 10,000 to 20,000. Absence of Leucocytosis Leucopenia. In certain infective diseases the number of leucocytes in the circulating blood is abnormally low 3000 or 4000 and this condition is known as leucopenia.

We have found that by painting with linimentum iodi, a ring half an inch broad, about an inch in front of the peripheral tender zone not the red margin an artificial leucocytosis is produced, and the advancing streptococci are thereby arrested.

Diarrhœa is sometimes present. The urine is usually scanty, of high specific gravity, rich in nitrogenous substances, especially urea and uric acid, and in calcium salts, while sodium chloride is deficient. Albumin and hyaline casts may be present in cases of severe inflammation with high temperature. The significance of general leucocytosis has already been referred to.

In some cases the general health is not disturbed; in others the patient is feverish and out of sorts, losing appetite, becoming pale and anæmic, complaining of lassitude, incapacity for exertion, headache, and pains of a rheumatic type referred to the bones. There is a moderate degree of leucocytosis, but the increase is due not to the polymorpho-nuclear leucocytes but to lymphocytes. In isolated cases the temperature rises to 101° or 102°

As a result of explosions, particles of carbon, in the form of coal-dust or gunpowder, or portions of shale, may lodge in a wound. The embedded foreign body at first acts as an irritant, and induces a reaction in the tissues in which it lodges, in the form of hyperæmia, local leucocytosis, proliferation of fibroblasts, and the formation of granulation tissue.

In estimating the clinical importance of a leucocytosis, it is not sufficient merely to count the aggregate number of leucocytes present. A differential count must be made to determine which variety of cells is in excess.