The staining will take place much more rapidly if the fluid be kept at 100° F. in the incubator. After staining they are transferred to Weigert’s differentiating solution:-- Borax 2 160 grs. Potassium ferricyanide 2·5 200 grs. Distilled water 100 1 pint. They are left in this solution for several hours, until the ground work becomes nearly decolourised. Sections will sometimes stain more satisfactorily if they are treated, according to Weigert’s original directions, for a few hours with a half saturated solution of acetate of copper. If the hardening in Müller’s fluid has been sufficiently prolonged, this step is usually superfluous. *Pal’s modification* of Weigert’s method.--By this method quicker and more complete decolouration of the neuroglia, nerve cells, &c., is obtained. Sections are prepared in exactly the same way as in Weigert’s method and then transferred to Weigert’s hæmatoxyline. Pal recommends that this solution be diluted to half the strength and a few drops of a saturated solution of lithium carbonate added. The writer finds the results equally good if the ordinary Weigert solution be employed. When the sections have been thoroughly stained they are washed in distilled water and placed in a three-quarter per cent. solution of permanganate of potassium. The time required in this solution depends on the time the specimen has been in Müller’s fluid. It should not be less than half a minute, and in very thoroughly hardened specimens, five minutes may be allowed with advantage. In this solution the sections will become of an opaque brown colour. They are washed in distilled water, and transferred to:-- *Pal’s differentiating solution.* Potassium sulphite 1 grm. 40 gr. Oxalic acid 1 grm. 40 gr. Distilled water 200 cc. 1 pint. They are kept in this for one to five minutes, according to the depth of staining, until the white and grey matter are clearly defined and the brown colour is completely discharged. If the brown stain does not readily clear up, the section should be returned to the permanganate solution for about half a minute, and again treated with “Pal’s solution.” This manœuvre may be repeated several times. As soon as the sections are thoroughly differentiated they are transferred one by one to a large vessel of water and thoroughly washed. The blue stain of the hæmatoxyline becomes brighter during the washing process. The sections may be mounted at once, but more beautiful results will be obtained if they are stained in alum carmine for 24 hours. They should then be washed, dehydrated in alcohol, clarified in oil of bergamot, and mounted in Canada balsam. The very prolonged hardening in Müller’s fluid which is a necessary preliminary for this method led to the introduction of:--