arteries in the pons were thickened, the muscular coats being hypertrophied to an enormous extent, the outer coat being also much thickened, and in and around this coat was a molecular deposit (Plate VIII. fig. 1) containing also granular masses, this deposit in many instances filling up the perivascular space. At some parts the vessels were patent, at others completely occluded, and the lumen absent, the artery presenting the appearance of concentric rings in the centre of a granular deposit. The grey matter of the convolutions was found to be degenerated, the cells being atrophied, and their spaces in many instances being occupied by a few granules (see Plate VIII. fig. 2). The spinal cord was also affected in the same way in its arteries, and in its grey and white substance. There were many microscopic apoplexies in the white substance of the cord.

No better demonstration of chronic vascular disease of syphilitic origin, and its effects of brain-starvation, degeneration, and atrophy, with the resulting mental suspicions, hallucinations of hearing, and lack of self-control, could have been afforded than this case.

I have seen some of the most extraordinary pathological effects in the brain from slow syphilitic arteritis. I have several specimens of brains in which the whole of the white substance in the inside of the anterior and middle lobes, lying between the outside convolutions and the central ganglia, had gradually and entirely disappeared, leaving a vacant space filled with fluid and a few fibrous flocculi. The grey substance of the convolutions, looked at from the inside in an antero-posterior section of at hemisphere, present the most extraordinarily defined appearance, just as much so as when looked at from the outside (see Plate V.). They looked as if the white substance had been carefully pared off them, leaving the grey matter intact. The effect was exactly what would have resulted had that portion of brain been steeped in a fluid which had the power of dissolving away the white substance and leaving the grey entire. The cause of this is no doubt the histological facts that (1) the grey substance of the convolutions has five times the amount of capillary blood

supply of the white; and (2) the source and mode of supply is different, the grey substance getting it from the already divided and anastomosing network forming the pia mater, and the white substance getting its supply from single vessels, which in dividing form only an infrequent anastomosis, and a network with large long meshes. The white substance, in fact, slowly dies, and disappears through an arteritis which only causes partial atrophy, anæmia, and lessened mental function in the grey convolutions. Looking at such a brain many questions suggest themselves. How do the convolutions act whose white fibres of communication inwards and their interconvolutional fibres have quite disappeared? Is there a general power of conduction in the convolutions from one through the next, and so on till it reaches one whose ingoing fibres are intact! Can the convolutions still act in some degree even deprived of their projection and association system of white fibres ?

Most of the vascular cases have the general course of H. R Mentally a change of character, morbid suspicions, loss of self-control and of the moral feelings, a disregard of the decencies of life, then an intense irritability often with violence and a loss of memory, then an enfeeblement of the mental power, ending in complete dementia. Bodily, an unhealthy and cachectic general state, a lack of trophic power, with no cephalalgia necessarily, then a general failure of muscular power and a tendency to partial paralysis, then occasional epileptiform fits, sometimes unilateral, but never more localised than a motor paralysis that advances and recedes in a puzzling way, then loss of power over the sphincters, loss of trophic power, and death, if that has not occurred before through an attack of convulsions. The duration is very different in different cases, but in my experience it is never less than five years, and may be twenty-five. If one was fortunate enough to be able to diag nose a case in the earliest stages, no doubt the iodide of potas sium, with nerve tonics, nutrients, and brain rest, should be prescribed, and I think I had a case where those measures saved the patient from going further than mild and manageable child

ishness, without tendency to convulsion. But if the lumen of an artery has been lessened by slow syphilitic arteritis, we have no reason to think it can, by any therapeutic means, be made more patent; and if some of the brain tissue has already been starved into atrophy, most certainly it would be a groundless hopefulness to think of its possible restoration.

Looked at purely from the pathological point of view, the arteritis may affect vessels of any and every size down to capillaries, may thicken the fibrous or the muscular parts of the arterial wall, or any of the coats. It is usually irregular and local, and often nodular. I do not know any more instructive demonstration of the visible effects of a lack of blood supply on brain cells and fibres than may be found in sections from different parts of a brain affected by syphilitic arteritis (Plate VIII. fig. 2).

The fourth or syphilomatous formis so exceedingly various in its symptoms, mental and bodily, that I really do not know where to begin. It may consist of a syphilitic meningitis attended with a temporary stupor and delirium, which is most curable by the iodide of potassium. Or it may consist of a quick-growing syphiloma within a convolution, that causes in a few weeks extensive softening, wild maniacal excitement, general convulsions and paralysis, and speedy death; the whole process being from the beginning absolutely beyond the reach of cure, or even of alleviation. Or it may consist of local gummata, causing pressure, local convulsions, mental irritability, and very slowly progressive dementia. Or it may consist of great cakes of syphilitic inflammation and gummatous or semipurulent deposit over one or both hemispheres, causing gradual dementia, and at last coma. Or it may be a membranous or bony tertiary lesion that has been quite arrested in its growth, but has set up what is practically epilepsy and ordinary epileptic insanity. I shall just give an idea of the disease by referring to a few cases. I shall first illustrate the more acute forms by the following case of syphilitic tumour of rapid growth within the substance of the brain :