A method has been employed for deepening the colour of the stain, but the writer has no experience of it. Kallus (_Zeitsch. f. Wiss. Mikr._, 1893, 477) dilutes an ordinary hydrokinone developing solution (prepared as for developing an ordinary photographic plate) with about ten times its volume of distilled water. Just before using a third part of absolute alcohol is added. Sections which have been through the silver process when placed in it become grey or black in a few minutes, and, after washing in methylated spirit, are transferred to a 20 per cent. aqueous solution of hyposulphite of soda for a couple of minutes and then washed very thoroughly in distilled water for twenty-four hours. They are then dehydrated and mounted in balsam. *Buckley’s modification of the silver method.*--Described in _Brain_, Winter number, 1895. The method is applicable to specimens that have been hardened in Müller’s fluid. Thin slices are cut in the usual way, and then immersed in Bichromate of potassium, 3 per cent. solution 5 parts Osmic acid, 1 per cent. solution 1 part for three to five days. Excess of bichromate is removed from the sections by blotting paper, and they are transferred to the _freshly prepared_ staining mixture:-- Phospho-molybdic acid (10 per cent.) 1 minim 2 drops. Nitrate of silver (1 per cent.) 1 ounce 60 c.c. which must not be filtered. Stain for several days. The sections should be cut at once after removal from the staining solution. It is claimed that the minute details of structure of the cell processes are better shewn by this method. *Corrosive sublimate* method.--This method is similar in its mode of action to the last, mercury being deposited in the cell instead of silver. It is rather less certain and requires more practice. It seldom stains uniformly. One cell will be found exquisitely stained while those in its vicinity are unaffected. Small pieces of cortex are hardened for several weeks in Müller’s fluid, or other bichromate solution, and are then transferred direct to a one-half per cent. aqueous solution of corrosive sublimate, in which they should be left from three to six weeks. Shorter periods will only give disappointing and inconstant results. Sections should be cut, if possible, in gum. They may be mounted in Farrant, or dehydrated and mounted in balsam. Tal has proposed to render the effect sharper by transforming the deposit of mercury into mercuric sulphide, by treating the sections with a solution of sulphide of sodium, which he prepares by saturating a ten per cent. solution of caustic soda with sulphuretted hydrogen and then adding an equal quantity of fresh soda solution. They are stained in this for a few minutes and then thoroughly washed. By this method the pyramidal cells and their delicate processes appear as black opaque objects on a light ground. The neuroglia cells with their fine delicate processes are often also beautifully stained.