Fresh material may be obtained by means of a trocar, and may be examined in the fresh state, or films may be prepared, fixed and stained, as for blood-smears. Sections of fixed tissues may be obtained by the use of the same fixing and staining methods employed in the study of the blood or bone-marrow. For the study of the reticulum Mallory’s reticulum stain or the digestion-method may be used. In ordinary work formol-fixation followed by eosin-staining is of great value in distinguishing hæmolymphnodes and lymphatic glands. II. BONE. For ordinary work decalcification is necessary except for those pathologic conditions in which the lime-salts have been lost (see Chapter XXI). Imbed in celloidin preferably. When decalcification has been carried out place sections in an alkaline solution before staining, and stain for a longer period than usual. Methylene-blue and eosin stain osteoblasts and osteoclasts very well. Van Gieson’s is an especially useful stain for ordinary work; osteoid tissue is red, calcified areas yellow. Sections of bone without decalcification can be prepared by fixing, hardening and staining in bulk; the bone is then sawn in the dried condition, and the sections ground down to the required thickness. _Schmorl’s_ methods for the preparation of bone-sections have practically superseded all other staining methods. Schmorl’s Thionin-picric-acid Method. 1. Fix in formol or formol-Müller’s preferably. 2. Decalcify in formol-nitric acid or Ebner’s alcoholic HCl acid solution. 3. Wash thoroughly in water. After-harden in increasing strengths of alcohol; freeze or imbed in celloidin (not paraffin); cut. 4. Transfer sections to water for 10 minutes. 5. Stain sections, well spread out, for 5-10 minutes in a solution of 2 cc. of a saturated solution of thionin in 50 per cent alcohol and 10 cc. of water, to which 1-2 drops of ammonia are added. 6. Wash in water. 7. Stain ½-1 minute in hot saturated and cold filtered watery-solution of picric acid. 8. Wash in water. 9. Differentiate in 70 per cent alcohol until the color ceases to come away in blue-green clouds, 5-10 minutes or more. 10. Dehydrate in 96 per cent alcohol. 11. Clear in phenol xylol; xylol; balsam. Lacunæ and canaliculi dark brown to black; bone cells red; ground substance yellow or brownish yellow. Calcified areas take a darker yellow than non-calcified. This method consists in an impregnation with a fine precipitate rather than a staining. Should the precipitate be too heavy in portions of the section it may be removed by thorough washing between 9 and 10. Schmorl’s Thionin and Phosphotungstic or Phosphomolybdic Acid Method. 1. Fix thin pieces of fresh bone in formol, then in Müller’s for 6-8 weeks, or 3-4 weeks in the incubator. Fixation is best at 37°C.