This is a method to which considerable importance has been and is attached in Germany. Nissl's original description appeared in 1885, and in this magenta is recommended as the staining agent. In 1890 he described a modification which has superseded the older process. In this country but little seems to be known of the method, of which the following is a brief description:—Have ready (1) a 0·5 % aq. sol. methylene blue (methylenblau patent B, from C. Buchner and Sohn, Fabrik pharmaceut. chem. Producte, Munich); (2) a mixture of anilin oil 20, alcohol 96 % 200 parts (this must not be too old); (3) origanum oil; (4) benzine; (5) a balsam made by dissolving colophonium in benzine, and of the consistence of ordinary chloroform-balsam. Portions of tissue as fresh as possible, in size 1-2 ccm., are placed for fixation and hardening in alcohol 96-98 %, for 24 hours. Remove, fix on cork by gum (caused to set by placing the whole in methylated spirit), and cut sections by the sliding microtome into spirit. The sections are placed, from pure alcohol or distilled water, in the methylene-blue solution, and this is heated until bubbles form—“until the crackle of bursting bubbles is heard.” After cooling, transfer the sections to the anilin-alcohol, and agitate them about until no more clouds of colour are given off. An appreciable differentiation takes place. Transfer a section to a slide, dry it well with filter-paper by pressure, apply a few drops of origanum oil (which is quickly allowed to run off), dry again with filter-paper. Run some benzine over the section to drive off the remains of the origanum, and place a drop of the colophonium solution on the section. The slide is now drawn through the flame of a spirit-lamp and the benzine set alight. When it has all been burnt off adjust the cover-slip. Warm the under surface of the slide, pressing down the cover gently; the colophonium is rendered fluid. Allow to cool.