One of the most interesting discoveries of recent times in the department of Neuropathology is indisputably Metalloscopy, of which, as is known, Burq† is the real founder. But Burq did not possess the needful scientific authority, and immediately on its first timid appearance, in 1851, Metalloscopy was banished to the region of the impossible and of fancy by scepticism on à priori grounds, and, hardly born, disappeared into complete oblivion after a very ephemeral existence. And thus it remained, till at length, two years ago, Charcot, the great French neuropathologist, resumed Burq's researches, and not only confirmed them, but gave them an important extension. The twice-repeated reports† to a commission appointed by the Société de Biologie, as well as the numerous publications of Charcot, Vigouroux, and Landolt on this topic, are already become the common property of the medical public.