Another method is to stain for about ten minutes, and then leave for a minute in Gram’s iodide solution. The sections are then washed in alcohol, dehydrated, clarified in oil of cloves, and mounted in balsam. By these methods the stain is withdrawn except from certain elements, _e.g._, those undergoing colloid or calcareous degeneration. A quarter per cent. watery solution is sometimes employed as it stains nucleoli and actively dividing nuclei very brightly, while the rest of the cell is stained faintly. It may be employed to study karyokinesis in the cells of a rapidly growing cancer. *Ehrlich-Biondi stain.*--This stain has been much employed for staining specimens of blood, for studying karyokinesis, and for investigations on the supposed parasitic bodies found in cancer cells. It is prepared by mixing saturated aqueous solutions of the following aniline dyes, slowly and with constant agitation:-- Solution of Orange G 100 parts " Rubin S 20 " " Methyl Green OO 50 " finally add Distilled water 70 " Filter from the copious precipitate which forms. The solution must be made up frequently as it does not keep well. Sections may be stained rapidly for half an hour or an hour, but better results are obtained by diluting the fluid with twenty volumes of water, and staining all night. Sections should be washed in water and then passed rapidly through absolute alcohol and xylol and mounted in Canada balsam. CHAPTER VI. SPECIAL STAINING METHODS.--SPECIAL METHODS FOR STAINING THE NERVE CENTRES. 1. For staining *nerve fibres*. Three methods (two of which are modifications of the first) are employed far more often than any others. By these methods the myelin coating is stained. Tissues must have been hardened previously for many weeks in Müller’s fluid, or some other bichromate solution. They are then overstained in a solution of hæmatoxyline, and the section treated with a suitable bleaching reagent, when the colour is discharged from all the tissue elements except the nerve fibres. This method displays not merely the nerve fibres in the white matter, but also the fine network in the grey matter of the brain and spinal cord. Degenerated fibres are left unstained and so degenerated tracts shew up as unstained spots on a dark background. The sections may be subsequently stained with alum carmine or eosine to shew the cells and neuroglia. *Weigert’s method.*--The piece of cord to be cut after prolonged hardening in Müller’s fluid is transferred without washing to absolute alcohol and dehydrated preparatory to embedding in celloidin (p. 30). When sections are cut they are transferred at once to Weigert’s hæmatoxyline solution:-- Hæmatoxyline 1 4 grains. Alcohol 10 45 minims. Distilled water 100 1 ounce. They are stained in this for twenty-four hours or longer, until they are quite black.