True gonorrhea is the result of an infection by a specific organism universally recognized as the _gonococcus_ of Neisser, though the discharge, when studied in the clinical laboratory, may give evidence of being the product of a mixed infection and contain the ordinary pyogenic or other organisms. The common name for the disease is _clap_. The gonococcus is a diplococcus which seems to be injurious only to the tissues of the human being, as inoculations in animals have produced no definite or reliable result. Like syphilis, it is spread by direct or indirect contagion, and usually in the same way. It is generally found in the genito-urinary mucosa of both sexes, but it has been accidentally and even innocently conveyed by immediate and mediate transfer to the mucous membranes of the _eye_, the _rectum_, and even to the _mouth_, although here, as in the nose, the mucous membrane is but little susceptible to its activity. It is generally stated that 20 per cent. of the blindness occurring in the young is due to gonorrheal conjunctivitis. Those membranes covered with cylindrical epithelium are more liable to succumb to infection by this parasite than are those covered with squamous epithelium. The more the epithelial cells conform to the former type, the more difficult it is to get rid of the infection; hence the disease lingers in the cervical canal longer than in the vagina. The disease always commences as a contagious catarrhal discharge from the mucous membrane. It may spread much farther than this, invading deeper tissues by continuity, or tissues at a distance by the lymph stream, or producing even metastatic expressions of infection in distant tissues and organs. Under these circumstances the serous membranes are likely to suffer, and the peritoneum, the endocardium, the pericardium, the pleuræ, the meninges, and particularly the serous linings of some of the joints, as the elbow and knee, show unmistakable evidences of infection; while through the medium of the venous and then the arterial systems typical representations of pyemia following gonorrhea may occur.