Professor Betz, of Kiew, has lately produced brain sections, which have attracted very considerable attention in Vienna. His specimens are of vast extent. He appears to be able to produce thin sections of an entire hemisphere. We append his method of hardening and cutting as it is stated in the “Correspondentze Blatt der deutschen Gesellschaft für Psychiatrie und Gerichtlich Psychologie, Jan., 1873.” The method of hardening which we wish to bring into notice is as follows:—observing that differences exist in the treatment of the spinal-cord, cerebrum and cerebellum. The spinal-cord—after tbe careful removal of the dura mater, it is placed in spirit of from 75 to 80 per cent., which is tinged a clear brown colour by the addition of Iodine. After from one to three days, during which the preparation must stand in a cool temperature, the Pia Mater and the Arachnoid are also removed; the specimen remaining in the spirit, to which a few drops of Iodine must be added daily for three days, maintaining an ordinary temperature. It is then transferred to a three per cent. solution of Chromate of Potass, and back again to the cool temperature. Here it hardens thoroughly, which is known by the fluid becoming turbid, and by the formation of a brown deposit upon the preparation. When this occurs, it must be immediately thoroughly washed with water, and immersed in a solution of Chromate of Potass, from a half to one per cent. strength, in which it will not become too hard or brittle.