B. Donaggio’s Methods for Early Degeneration. Method I— 1. Fix in Müller’s fluid or in 4 per cent potassium-bichromate solution. The tissue may remain in the fluid for any length of time. 2. Transfer directly, without washing, to alcohol. Dehydrate; imbed in celloidin; cut sections 20-30 microns. Place sections in distilled water for a few seconds. 3. Transfer to the following mixture for 10-20 minutes: To 20 per cent solution of ammoniated chloride of tin add an equal amount of 1 per cent aqueous hæmatoxylin. Allow to stand for five days. Keep in the dark, and in a cool place. 4. Wash rapidly in distilled water. 5. Differentiate in Pal’s solution (oxalic acid 0.5 grm., potassium sulphite 0.5 grm., water 100 cc.) until the normal fibres are entirely decolorized. 6. Dehydrate; xylol; neutral balsam. Degenerated fibres blue; normal, decolorized. Method II— 1. Fix in Müller’s fluid: imbed as in Method I. 2. Place sections in 0.5-1 per cent aqueous hæmatoxylin solution, 10-20 minutes. 3. Transfer directly to a saturated aqueous solution of neutral acetate of copper, 30 minutes. Renew copper solution once. 4. Decolorize as in Method I. 5. Wash rapidly in distilled water. 6. Dehydrate in graded alcohols; xylol; balsam. Degenerated fibres black; normal fibres unstained, except for a narrow circle at periphery. Method III— 1. Fix and imbed as in Method I. 2. Stain in 0.5-1 per cent aqueous hæmaloxylin solution, 10-20 minutes. 3. Transfer directly to 10-20 per cent solution of perchloride of iron. The section becomes black. After a few seconds they lose their color. If washed in water, they regain their color. 4. Without washing, differentiate in acid alcohol (0.75 cc. HCl in 100 cc. alcohol). 5. Dehydrate in absolute alcohol; xylol; balsam. Degenerated fibres appear as small black streaks or circular areas. C. Staining of Fat-granule Cells. Fix in Flemming’s or Marchi’s mixtures; or in formol, staining with sudan III or scharlach R. The tissues may be examined also in the fresh condition. D. Old Degenerations. Use Weigert’s myelin method to show absence of myelinated fibres. Van Gieson’s method stains the neuroglia of degenerated areas a deep red; it is very useful combined with Weigert’s myelin stain. Weigert’s neuroglia stain may be used to demonstrate the relative parts played by neuroglia and connective-tissue in the formation of sclerotic patches. When Weigert’s iron-hæmatoxylin is used with Van Gieson’s the neuroglia remains unstained, while the connective-tissue stains red. With other hæmatoxylins the neuroglia cannot be sharply differentiated from connective-tissue when stained with Van Gieson’s. 8. =PERIPHERAL NERVES.=