. Animal micrology; practical exercises in microscopical methods. Microscopy -- Technique; Microscopes -- Technique. Chapter V: The Paraffin Method 45 drawn lightly across the ball of the thumb, freely enters the moist epi- dermis. Finally the blade is wiped clean with a soft cloth, great care being taken not to injure the edge. Stropping.—A broad firm strop of finest calfskin is best. It should be affixed to a solid back so that it will not spring and thus round off the delicate edge of the knife. In stropping, the motions are the same as in honing (both sides of blade), only the knife passes
. Animal micrology; practical exercises in microscopical methods. Microscopy -- Technique; Microscopes -- Technique. Chapter V: The Paraffin Method 45 drawn lightly across the ball of the thumb, freely enters the moist epi- dermis. Finally the blade is wiped clean with a soft cloth, great care being taken not to injure the edge. Stropping.—A broad firm strop of finest calfskin is best. It should be affixed to a solid back so that it will not spring and thus round off the delicate edge of the knife. In stropping, the motions are the same as in honing (both sides of blade), only the knife passes back foremost and from heel to point. The blade must move lightly over the surface of the strop with very slight pressure on the part of the operator. The stropping is ordinarily consid- ered sufficient when the blade will cut a loose hair freely along every part of the edge. An examination under a low power of the microscope should reveal no nicks in the edge. 12. To Remove Pigments and to Bleach Osmic and Chromic Acid Materials a 3 per cent, solution of peroxide of hydrogen frequently is sufficient. Tissues left too long in this liquid macerate. Mayer's chlorine method is one of the best for bleaching. To several crystals of chlorate of potash in a glass tube a few drops of hydrochloric acid is added. When the greenish fumes of chlorine appear, add from 5 to 10 of 50 per cent, alcohol. The object, which in the meantime has been standing in 70 per cent, alcohol, is transferred to the tube. From 15 min- utes to 24 hours are required for bleach- ing, depending upon the nature of the material. It is well to suspend the ob- ject from the mouth of the bottle. Sec- i tl-,o dirlA mav Vilpnolipf] in n FlG- 30.—Metal Ls for molding tions on tne slide may I i a imbedding masses. few minutes. This method is especially recommended for removing natural pigments and for bleaching osmic material. 13. Large Objects May Be Cut in Paraffin better with a slanting knife than with a
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