As regards the relation of the syphilitic dyscrasia to neuralgia, I agree in general with Eulenburg. "Syphilis," he says, "may be the direct cause of neuralgia, either by the development of specific gummata in the nerve-trunks or in the centres, or by arousing chronic irritative processes in the nerve sheaths, the membranes of the brain and spinal cord, or, especially, in the bones and periosteum (syphilitic osteitis and periostitis)." The case of periostitis, however, is a doubtful one: it may be questioned whether this affection (which will be among the diseases discussed in Part II. of this work) ever give rise to true neuralgia. Persons who are, by inheritance, highly predisposed to neuralgia, may from the mere general lowering of their health produced by constitutional syphilis, become truly neuralgic simultaneously with, or subsequently to, the appearance of painful nodes on their bones. And as regards the whole relations of syphilis to neuralgia, I must, from my experience, conclude that the former is, after all, but rarely concerned in the production of the latter. Syphilis has a strong specialty for producing limited motor paralyses, but a much weaker one for producing limited affections of the sensory system. 7. We now come to the discussion of a group of momenta whose influence in the production of neuralgia is at once very powerful, and of the highest significance as regards the general pathology of the disease. These are the degenerative changes of the arterial and capillary systems which are a part of the normal phenomena of old age, but may occur at earlier periods of life, in consequence either of certain constitutional diseases, especially gout, or of special toxic influences on nutrition, of which persistent alcoholic excess is very far the most important.