1899J MICROSCOPICAL JOURNAL. 311 



Miscellaneous Notes on Microscopy. 



J. H. COOKE, F. L. S., F. G. S. 



To Neutralize Balsam. — Canada balsam, one of the 

 most useful of resinous media, is usually slightly acid. In 

 some cases this is a drawback, but for mounting- sections 

 stained with carmine, or injected with carmine gelatine, or 

 Berlin blue gelatine, it is advantageous. The balsam may 

 be neutralized by mixing a little carbonate of soda with the 

 thinned solution before it is thickened. The soda settles 

 after a few days and leaves the balsam clear and neutral. 

 Carmine will diffuse, and blue willfadeintheneutral balsam 



Covers. — Thin mica plates are suggested as making good 

 covers for such objects as fish's eggs, frog's eggs,&c. On 

 account of the flexibility of the mica, the egg is less liable 

 to be crushed than with a glass cover, and if the effects of 

 pressure on the development of the egg are to be studied, 

 the mica cover may be easily manipulated. 



Bone Section. — The preparation of a bone section so as 

 to show the lacunae, canaliculi and deep seated cells, may 

 be quickly effected by the following method :— Take afresh 

 bone, and with a strong, sharp knife cut off a thin shaving. 

 Immerse the section in carmine dissolved in ammonia, the 

 ammonia being first neutralized by acetic acid. The walls 

 of the vessels which penetrate the lacunae and canaliculi 

 are by this means stained crimson, and the true structure 

 of the bone is thus rendered visible. 



Rock Sections. — A solution of gum-dammar in xylol is 

 more suitable than Canada balsam as a mounting medium 

 for rock sections. 



Luminous. — To render micro-photographs self-luminous 

 soak them in castor-oil to make them transparent, and dust 

 them over with powdered sulphate of baryta or sulphite of 

 lime. When dry mount them on cardboard of a suitable 

 size with starch paste. The phosphorescence of the salt 

 lights up the photograph. 



Drying. — Drying oils in every form, such as gold size, 



