Sections from a very old anæsthetic macule showed only very slight infiltration along the vessels; the cells were mostly spindle-shaped; only a few were round or epithelioid. In most of the sections no bacilli were found; in some, one or two distinct bacilli and some granules, taking the same stain. The maculæ are therefore like the nodules, leprous infiltrations of the cutis, consisting of round epithelioid and spindle cells, the latter being more numerous the greater the age of the macule. These infiltrations appear to proceed from the vessels. Lepra bacilli are always present, but are most numerous in the younger macules. In young, not as yet anæsthetic, macules, the nerve twigs appear unchanged; in the older ones they are usually affected. Langerhans’ cells are, according to our view, wandering cells, and their number is probably dependant on the inflammation. We have only had the opportunity of examining the nerves in this form of the disease in old cases, and have not found bacilli in them, but merely great increase of the interstitial connective tissue and disappearance of the nerve fibres. Dr. Arning has, however, as is well known, found bacilli in a piece of ulnar nerve which he removed during life from an anæsthetic patient. Our results, therefore, correspond with the proposition put forward above, that the leprous affection disappears, and that the anæsthesia is a result of the atrophy of the nerves caused by secondary shrinking. We found on a mutilated finger the collateral nerve almost completely transformed into fibrous tissue, not a single medullary fibre being evident. In a case where on account of joint disease (which proved to be tubercular) we amputated, the small periosteal nerve twigs were much degenerated; in another, where the foot was amputated for gangrene, the small peri-articular nerves also showed degeneration. Danielssen found, in some cases, changes in the spinal cord which, using the methods of investigation then at his disposal, he regarded as degenerations and inflammations of leprous origin. Armauer Hansen, Neisser and Leloir have not been able to find any leprous affection of the cord. The cases with changes in the cord, described by Langerhans and Steudener, were, in our view, _not_ leprosy. Tschiriew’s case, _Lepra tubero-anæsthetica_, presented no marked changes. Looft has found, in two cases of maculo-anæsthetic leprosy, degeneration of the posterior columns, atrophy of the posterior roots and fibrous degeneration of the spinal ganglia, with disappearance of the medullary fibres, and changes in the nerve cells. In these two cases the affection appeared to be primary in the ganglia, and secondary in the cord. Lepra bacilli were not found in either case, but Chariotti found them once in the cord, and Suderkowitsch in the spinal ganglia.