resulting sinuses and ulcers are exceedingly intractable.  Secondary deposits in the subcutaneous tissue, the muscles, and other parts, are not uncommon, and the nasal mucous membrane may become involved.  The disease often runs a chronic course, extending to four or five months, or even longer.  Recovery takes place in about 50 per cent. of cases, but the convalescence is prolonged, and at any time the disease may assume the characters of the acute variety and speedily prove fatal.

The differential diagnosis is often difficult, especially in the chronic nodules, in which it may be impossible to demonstrate the bacillus.  The ulcerated lesions of farcy have to be distinguished from those of tubercle, syphilis, and other forms of infective granuloma.

Treatment.—­Limited areas of disease should be completely excised.  The general condition of the patient must be improved by tonics, good food, and favourable hygienic surroundings.  In some cases potassium iodide acts beneficially.

ACTINOMYCOSIS

Actinomycosis is a chronic disease due to the action of an organism somewhat higher in the vegetable scale than ordinary bacteria—­the streptothrix actinomyces or ray fungus.

[Illustration:  FIG. 30.—­Section of Actinomycosis Colony in Pus from Abscess of Liver, showing filaments and clubs of streptothrix actinomyces. x 400 diam.  Gram’s stain.]

Etiology and Morbid Anatomy.—­The actinomyces, which has never been met with outside the body, gives rise in oxen, horses, and other animals to tumour-like masses composed of granulation tissue; and in man to chronic suppurative processes which may result in a condition resembling chronic pyaemia.  The actinomyces is more complex in structure than other pathogenic organisms, and occurs in the tissues in the form of small, round, semi-translucent bodies, about the size of a pin-head or less, and consisting of colonies of the fungus.  On account of their yellow tint they are spoken of as “sulphur grains.”  Each colony is made up of a series of thin, interlacing, and branching filaments, some of which are broken up so as to form masses or chains of cocci; and around the periphery of the colony are elongated, pear-shaped, hyaline, club-like bodies (Fig. 30).

Infection is believed to be conveyed by the husks of cereals, especially barley; and the organism has been found adhering to particles of grain embedded in the tissues of animals suffering from the disease.  In the human subject there is often a history of exposure to infection from such sources, and the disease is said to be most common during the harvesting months.

Around each colony of actinomyces is a zone of granulation tissue in which suppuration usually occurs, so that the fungus comes to lie in a bath of greenish-yellow pus.  As the process spreads these purulent foci become confluent and form abscess cavities.  When metastasis takes place, as it occasionally does, the fungus is transmitted by the blood vessels, as in pyaemia.