Keep on hand a saturated aqueous solution and dilute with water as needed. The strength of the solution to be used varies somewhat with the tissue and the reagent in which it is to be fixed; but usually the strength should be between ⅒ and ½ per cent. when eosin is used after hematoxylin. The diluted solutions should contain 25 per cent. of alcohol, otherwise they will not keep well. When eosin is used before an aniline dye, such as methylene blue, a 5 per cent. or even a saturated solution should be used. =To Stain Sections of Liver for the Study of Kupffer Cells.=—To bring out this reaction Keys suggests the following technic: Fix small blocks of the fresh tissue of spleen or liver for eighteen to twenty-four hours in Müller’s fluid plus 5 per cent. mercuric sublimate. Imbed in paraffin and section to 4 microns. Fix sections to slide, and stain twenty to forty minutes with acid carmine. Wash, and transfer to equal parts of a 2 per cent. aqueous solution of potassium ferrocyanid and of a 2 per cent. aqueous solution of hydrochloric acid. Remove after three to ten minutes, wash in distilled water, and pass quickly through a 0.5 per cent. aqueous erythrosin solution. Dehydrate in alcohol, clarify in xylol, and mount in Canada balsam. =To Prepare Anatomical Specimens for a Museum.=—The Keiserling method gives the best results, since by this method the tissues retain their normal color. The three steps are as follows: 1. Place the specimen in the following solution and leave from one to seven days, the length of time depending upon the size of the specimen. Formalin 200 c.c. Potassium acetate 30 grams Potassium nitrate 15 grams Water 1000 c.c. 2. Pass the specimen through each of the following solutions, leaving it in each twenty-four hours or until the normal color is obtained. The specimen should be removed from alcohol as soon as color is attained. If it is left in the alcohol too long it will again lose some of its color. Alcohol 40 per cent. Alcohol 60 per cent. Alcohol 80 per cent. Alcohol full strength 3. Place the specimen in the following permanent solution, label, and place in museum. Glycerin 40 c.c. Potassium acetate 40 grams Distilled water 400 c.c. A small piece of thymol must be placed on the top of the liquid in each jar, or mold will develop and spoil the specimen. =To Make Specimens Transparent.=—Specimens may be rendered transparent by the method of Spalteholz. The steps are essentially as follows: