The evidence as to the hereditary character of neuralgia assumes a yet higher importance when supplemented by the facts respecting the alternations of neuralgia with other neuroses as the same individuals. Every practitioner must be aware how frequent is the latter occurrence. Nothing is more common, for example, than to see insanity developed as the climax of minor nervous troubles, especially of neuralgia. And there is one form of neuralgia, the true epileptiform tic, which is intimately bound up with a mental condition of the nature of melancholia, and even with the markedly suicidal form of the latter affection. I have lately had under my care a lady in whom the prodromata of a severe facial neuralgia were mental; the disturbance commenced with frightful dreams, and there was great mental agitation even before the pain broke out; this disturbance of mind, however, continued during the whole period of the neuralgia, and was relieved simultaneously with the cessation of the attacks of pain. This is contrary to what happens in some cases; thus, Dr. Maudsley quotes the case of an able divine who was liable to alternations of neuralgia and insanity, the one affection disappearing when the other prevailed. Dr. Blandford has met with several instances in which neuralgia has been followed by insanity, the pain vanishing during the mental disturbance, and reappearing as the latter passed away. And he remarks that, in the transition of a neuralgia (to mental affection), we may well believe that the neurotic affection is merely changed from one centre to another, from the centres of sensation to those of mind. He says that the ultimate prognosis of such cases is bad; a point to which we shall have to refer again. The prominent place which quasi-neuralgic pains hold in the earlier history of locomotor ataxy is a fact that cannot but engage attention. In this volume we have not treated these pains as belonging to the truly neuralgic class, for the very practical reason that they are but incidents in a most important organic disease, and that in a diagnostic and prognostic point of view it is necessary to dwell on their connection with that disease. But, in considering the pathological relations of neuralgia, it would be improper to omit the consideration of the pains of locomotor ataxy, which bear a striking semblance to neuralgic pains. The fact that they are an almost if not quite constant feature of a disease which is from first to last an atrophic affection (mainly of the posterior columns of the cord), in which the posterior roots of the nerves are almost always deeply involved, has a bearing on our present inquiry too obvious to need further remark.