The adage, “Prevention is better than cure,” is one of the most truthful sayings in the English language, and, if persons would profit from the admonitions of a “_slight cold_,” many a fatal pneumonia or bronchitis could be averted. What is true of the mucous membrane that is common to both sexes is true of that which is peculiar to the female organs alone. There is no mucous membrane that is more liable to catarrhal inflammations than that lining the uterus. There never was a woman who was not some time in her life afflicted with a transient uterine catarrh. It may have been of so mild a form that the symptoms which it occasioned were hardly noticed, or, perhaps, ascribed to some other ailment. There are several varieties of endometritis; some of these are based upon the length of time that the affection has lasted, while others owe their classification to the anatomical division of the uterus into body and cervix. Those that relate to the duration of the disease are either acute or chronic. Acute endometritis is the most common form; it has also been described under the names of acute uterine leucorrhœa, acute uterine catarrh, and acute internal metritis. It usually runs a rapid course, ending in recovery or in the chronic form. It undoubtedly passes unrecognized in many instances, and in this way many cases of painful menstruation or suppressed menstruation are explainable. It can be said that at each and every menstrual period there is a _physiological catarrh_, which belongs to the natural process of the menstrual function. During each menstruation there is a hyperæmia, or congestion of the mucous membrane, so that the turgent blood vessels rupture, and this constitutes the menstrual flow. Before this congestion reaches the point of bursting the capillaries, and about the time that the sanguineous flow ceases, there is an increased and altered mucous secretion of the mucous membrane. If this secretion is prolonged beyond the normal period that constitutes healthy menstruation, or if it continues to be present at any time between the menstrual periods, it constitutes a disease or a catarrh. Now when we consider the close relation that the normal functions of the womb have to those that are _abnormal_, and that the one may be the stepping-stone to the other, we need not be surprised that endometritis, or catarrh of the womb, is one of the most common affections to which women are liable. Chronic endometritis is where the disease has lasted for a long time; some authorities consider it a rare affection, but this is a great error. Any disease so frequent as acute endometritis must, in the very nature of inflammatory processes, become chronic, in a large proportion of cases.