MICROSCOPICAL TECHNIQUE. 97 



hoi of greater strength, and finally mounted in an anhydrous 

 medium. This alcoholic borax-carmine tincture answers equally 

 well for double-staining, using iodine green or methylene violet for 

 the complementary s\.Vi\n.^/our?i. de Pharm. in Pharin. Journ. 



Reagent for the Detection of Mucilage in Plant-Cells.— 

 Guiraud* employs a saturated solution of almost colourless hsema- 

 toxylin in absolute alcohol, mixed with too times its volume in 

 hot saturated solution of ammonia alum, as a reagent for the 

 detection of mucilage in plant cells. The rose-coloured liquid 

 deposits alum and becomes violet ; it is then filtered and mixed 

 with 30 per cent, of glycerine by measure. This reagent has the 

 advantage of staining only the contents of the mucilage cells, and 

 not their v.'2i\\?,.— Pharmaceutical Journal. 



Preparation of Clear Nutritive Agar, —In preparing a nutri- 

 tive medium for agar-agar, difficulty is often experienced in 

 obtaining a clear product, filtration being very tedious. A simple 

 apparatus, devised by Dr. M. Bleish ( Centralb. fur Bakt. und 

 Parazii., xvii., 403) obviates the necessity of filtration, and yet 

 enables a clear preparation to be obtained. A cylindrical glass 

 vessel, of about two litres capacity, has openings at top and 

 bottom. A perforated rubber cork closes the lower opening, and 

 through it slides a glass tube, long enough to reach the top of the 

 cylinder. Fix the latter in a retort-stand clamp and pour in the 

 prepared agar until it nearly reaches the top of the sliding-tube ; 

 then place the whole apparatus in an oven at 50*^ — 60" C, until 

 all the solid particles have been deposited. The apparatus is now 

 removed, a rubber tube with a clamp is fixed to the lower extre- 

 mity of the glass tube, and the latter then drawn down a few cen- 

 timetres below the surface of the agar. On opening the clamp the 

 clear agar runs through and is collected in a suitable vessel, and 

 the glass tube is gradually lowered from time to time until the 

 whole of the clear fluid is removed. It is stated that precipitation 

 of the solid particles may be facilitated by substituting sodium 

 phosphate for the carbonate generally used. — Pharm. Jotirnal. 



Varnish for Finishing Slides.— In selecting a varnish for finish- 

 ing slides on which microscopic objects are mounted, it is well to 



* Repert de Pharm., 1895, p. 71. 



International Journal of Microscopy and Natural Science. 

 Third Series. Vol. VI. h 



