The intensity of such nervous manifestations during menstruation is dependent upon the woman’s general state of nutrition, upon the degree of instability of her nervous system, and upon her occupation. Robust and powerful women, regularly employed in the open air, such as the wives and daughters of farmers and agricultural laborers, are much less affected by the nerve-weakening influences of menstruation than the sedentary and anæmic town-dwelling women, whether these latter belong to the higher classes of society and are addicted to nerve-straining enjoyments, or to the class of shop-girls, seamstresses, and factory-women, whose employment is apt to lead to nervous exhaustion. As regards the forms of neuralgia most apt to accompany menstruation, _Windscheid_ mentions trigeminal neuralgia as the commonest, especially affecting the first division of the nerve, and producing localized pains which are to be distinguished from the headaches already mentioned. They are characterized by their intensity and their persistence in spite of anti-neuralgic treatment, and by their spontaneous disappearance as soon as menstruation is over. According to the same author, the relations between hemicrania and the process of menstruation are indisputable; at the very least it must be admitted that menstruation predisposes to an attack of hemicrania. Cases also occur in which convulsions almost invariably accompany menstruation, convulsions which are to be regarded as symptoms of hysteria. The extraordinarily powerful influence which the menstrual stimulus exercises on the mind is shown by the frequency with which the slighter psychopathic states occur as an accompaniment even of normal menstruation, these manifestations being sometimes melancholic in type, sometimes maniacal or erotic, and, when of long duration, leading ultimately to pronounced mental disorder. This influence of the menstrual stimulus is yet more potent in cases in which important changes in the course of menstruation have occurred, in cases, for instance, of suppressed, painful, or irregular menstruation. In this connection, however, in order to avoid a confusion of cause and effect, we must carefully bear in mind, that it is a much commoner causal sequence for psychical disorders to disturb the normal course of menstruation, than for disorders of menstruation to evoke psychical disorders. This view has only quite recently become established, and for this reason it is necessary to regard such data when obtained from the writings of the older gynecologists in a somewhat critical spirit.