1. Fix small pieces in 10 per cent formol, 4 days. 2. After-harden in saturated watery picric solution 4-8 days: or combine 1 and 2 by using formol 10 cc. with 90 cc. saturated picric acid solution. 3. Place in a 5 per cent aqueous solution of ammonium bichromate, 4-7 days at 37°C., changing solution 011 second day; or 3-4 weeks at room-temperature. 4. Without washing, harden in alcohol; imbed in celloidin or paraffin; cut. 5. Place sections in ¼ per cent aqueous solution of potassium permanganate, 15-30 minutes. 6. Wash in water. 7. Immerse in 5 per cent aqueous oxalic acid, 5-30 minutes. 8. Wash in several changes of water. 9. Stain in following solution, 1-several days: Hæmatoxylin 0.1 grm., 10 per cent phosphotungstic acid 20 cc., hydrogen peroxide 0.2 cc., water 80 cc. 10. Wash rapidly in water. 11. Differentiate in freshly prepared 30 per cent alcoholic solution of ferric chloride, 5-20 minutes. 12. Wash in water. 13. Dehydrate in 95 per cent and absolute alcohol or blot with xylol. 14. Clear in xylol; balsam. When Zenker’s fixation is used, omit 2 and 3, and after cutting sections treat with Lugol’s to remove mercury and then with 95 per cent alcohol to wash out iodine; then wash in water and proceed with 5. Neuroglia, nuclei and fibrin, dark-blue; all else is pale yellow or gray. If the differentiation in 11 is omitted, the axis-cylinders and ganglion-cells are rose-pink; the connective-tissues, dark red-pink. 6. =COMBINED STAINING OF SEVERAL NERVOUS STRUCTURES.= Various methods of impregnation with silver, gold or lead are used in histologic work, the Golgi methods and their modifications in particular. They have but little application in pathologic work, and for that reason are omitted here, as is also a consideration of Ehrlich’s vital methylene-blue method and its modifications. Full details of these methods can be found in laboratory textbooks on histology. 7. =METHODS FOR THE DEMONSTRATION OF NERVE-DEGENERATION.= A. Marchi’s Method. 1. Harden small fresh pieces of tissue in Müller’s fluid for at least 8 days. Handle tissue very carefully to prevent mechanical injury. The tissue may be placed first in formol, and then later transferred to Müller’s fluid. 2. Place in freshly prepared Marchi’s fluid (Müller’s fluid 2 parts, 1 per cent osmic acid solution 1 part) for about 8 days in the incubator at 37°C. The brain requires a longer time. When the mixture loses the osmic acid smell renew it. 3. Wash in running water, 24 hours. 4. Harden in graded alcohols. 5. Imbed in celloidin; cut; dehydrate; clear; mount. Degenerated nervous tissue (fat) is black: all else brownish gray. Contrast stain in Van Gieson’s, lithium carmine, etc. This method is good for the demonstration of early degenerations.