MICROSCOPICAL TECHNIQUE. 91 



Staining cover-glass preparations of blood. Its composition is as 

 follows : — Saturated aqueous solutions of orange, G., 120 grm.; acid 

 rubin, 80 grm. ; methyl green, loo grm. ; H^O (water), 300 grm. ; 

 absolute alcohol, 180 grm. ; glycerin, 50 grm. The aqueous solu- 

 tions must be saturated. The mixture is not to be shaken, but 

 the necessary quantity should be pipetted'ofif. The fixed cover- 

 glass film is treated with the solution for five to ten minutes ; the 

 superfluous stain is washed off with distilled water, the surface 

 dried with blotting paper, and the preparation mounted in balsam. 



New Staining Process.*— Dr. O. Zacharias recommends the 

 following process for both animal and vegetable preparations. The 

 material is laid in 70 per cent, alcohol, and then, for from sixteen 

 to fifty-four hours, in acetic carmine, prepared by boiling i gr. 

 powdered carmine for twenty minutes in 150 — 200 gr. dilute acetic 

 acid, and filtering when it has become cold. The preparation is 

 washed in dilute acetic acid, and then placed for from two to three 

 hours in ferric-oxide-ammonium-citrate. 



New Fixing Material.t— Under the name "chrome-potash- 

 sublimate-glacial-acetic-acid," Herr Zenker recommends a fixing 

 material for vegetable tissues, which has the advantage of pene- 

 trating the tissue readily, without producing any shrinking. Its 

 composition is as follows : — 100 parts distilled water, 5 sublimate, 

 2-5 double potassium chromate, i sodium sulphate, 5 glacial 

 acetic acid. It may also be used for preparations of the nervous 

 system. 



Cytotropism of Cleavage Cells.J— The following is Professor 

 Wilhelm Roux's method for demonstrating the phenomena of 

 cytotropism : — The eggs of Rana fusca, obtained from newly 

 captured animals at the beginning of the normal period of spawn- 

 ing, furnished the best material for observation. . . . The 

 phenomena of cytotropism are seen most readily between cells 

 separated from the egg in the morula or blastula stage. The 

 separation is effected by cutting or tearing the egg in an indifferent 

 * For schungober Biol. Stat. Plon., vide Journ. R.M.S., 1895, p. 127. 



\ Munch. Med. Wochenschr., xxvii., vide Journ. R.AI.S., 1895, p. 130. 



XAmerican Naturalist, xxix., 1895, PP- 5'' — '2, from Arch. f. Entw'mech. 

 d. Orgamsmen, II., pp. 44 — 48. 



