For the development of melancholia a predisposition seems to be necessary. Most people can suffer the reverses of fortune, the accidents of life, and the griefs of loss of friends and relatives, without mental disequilibration. Certain predisposing factors are well known. Heredity, for instance, is extremely important. Melancholic conditions are frequently found in successive generations of the same family. While heredity is not as prominent a feature in melancholia as in other forms of insanity, the direct descent of a special form of melancholic mental disturbance from one generation to another is noted more frequently than in any other form of insanity. Women are more often the subjects of melancholia than are men. This is especially true in the earlier and in the later periods of life. In the years between twenty and thirty-five the proportion of cases in each sex is more nearly equal. The two conditions, the establishment of the sexual functions, that is, the important systemic changes incident to puberty, and the obliteration of the sexual function at the menopause, with its consequent physical disturbances, are especially important in predisposing to the occurrence of {217} melancholia in women. Their mental functions are less stable naturally, and are subject to greater physical strains and stresses. Childbirth and lactation are also important factors in the causation of the condition. Long-continued lactation--that is, beyond the physiological limit of about nine months--is especially a frequent cause. The development of the mental disturbance in this case is always preceded by a state of intense anaemia, in which the skin assumes a pasty paleness, and other physical signs give warning of the danger. Lactation is sometimes prolonged for no better reason than the hope to avoid pregnancy. Usually we may say this method fails of its purpose and pregnancy and lactation together work serious harm. In young people particularly, homesickness is a not uncommon cause of melancholia. It is especially liable to produce the condition if young people at a distance from home are subjected to serious mental and physical strain at a time when the food provided for them is either insufficient or unsuitable, or when disturbances of their digestive systems make it impossible for them properly to assimilate it. A number of instructive examples of this condition have occurred in the last few years among our young soldiers in the Philippines. To the physical strain necessarily incident to campaigning, especially in young men unaccustomed to the life of the soldier, there was added the serious trial of the tropical climate and the unusual and not over-abundant or varied diet provided by the army rations.