20 PROFESSOR RUTHERFORD. 



a syringe, no haphazard application of pressure, as is the 

 case with tlie syringe. This invahiable method we owe to 

 Ludwig. 



IIoio to Preserve Tissues. — 1. In the dry way. Bone, 

 toolh, hair. These may also be well kept in Canada balsam 

 or Dammar. 2. In Canada balsam or Uammar. All water 

 must be removed from the tissue by drying or by immer- 

 sion first in methylated spirit and then in absolute alcohol. 

 The alcohol is then driven away by floating the tissue 

 upon oil of turpentine or oil of cloves, and then the balsam 

 or Dammar is added, and the covering glass put on. I 

 prepare the Canada balsam in this way : — a, Take pure 

 Canada balsam and place it in a saucer or other shallow 

 vessel, b, Cover the vessel with bibulous paper, to ex- 

 clude dust, c, Dry it in an oven at a temperature not 

 above 150° Fahr., until, when it cools, ii becomes as hard 

 as ice. d, Dissolve this crystalline balsam in chloroform 

 or oil of turpentine. A solution in the former medium 

 dries most rapidly, but a solution in turpentine is gene- 

 rally preferable for mounting sections of tissues. Now, 

 balsam is being replaced by Dammar. I am indebted to 

 Dr. Klein for the following receipt for this fluid. A, Gum 

 Dammar \ oz., oil of turpentine 1 oz. ; dissolve and filter 

 B, Gum mastic 5 oz., chloroform 2 oz. ; dissolve and filter 

 Add solution A to solution B. This, if rendered thicker by 

 drying, may be used as a luting. Dammar or balsam, suitable 

 for mounting. Unsoftened bone, tooth, hair, and most tissues 

 which have been hardened in alcohol or chromic acid. 

 3. Glycerine suitable for all tissues that are not rendered 

 too transparent by it ; well adapted for tissues which 

 are to be examined by very high powers. (Consult Beale, 

 ' How to work With the Microscope.') Liver, lung, alimentary 

 canal, and skin, after having been hardened in chromic acid or 

 alcohul, show better in glycerine than in balsam or Dammar. 

 The latter is apt to render them too transparent. For speci- 

 mens containing carmine or Prussian blue add 2 drops of 

 hydrochloric acid to 1 oz. of glycerine. Glycerine should not 

 be used for mounting things hardened in osmic acid. 4. Satu- 

 rated solution of potassium acetate, for mounting osmic acid 

 preparations. 5. Glycerine jelly, good for connective tissue, 

 softened bone and tooth, cartilage, blood-vessels, lung, &c. 

 Steep tissue in weak spirit previous to mounting. Heat a 

 lump of jelly upon the slide, gently place the tissue in it, and 

 then put on the covering glass. 6. Weak spirit (methylated 

 •spirit 1 part, distilled water 3 parts), adapted for connec- 

 tive tissue, muscle, and blood-vessels. 7. Naphtha and 



