The disadvantage of the present methods for the staining of myelin sheaths—Weigert, Spielmeyer, Loyez, Fränkel and others—is that they require days or even weeks for the preparation of the material. The following method can be performed within one hour and can be applied to sections fixed in formaldehyde and frozen or embedded in either celloidin or paraffin. Celloidin sections may be stained without removing the embedding material. In paraffin sections, the paraffin should be removed before staining. Frozen sections should be brought into 70 per cent alcohol for from five to ten minutes and then put back into water. Sections should be from 20 to 30 microns thick. The agents used are: (1) 5 per cent water solution of potassium dichromate; (2) 4 per cent water solution of iron alum; (3) 1 per cent water solution of hematoxylin prepared from 10 per cent absolute alcoholic solution (at least 6