60 THE MICROSCOPICAL NEWS. 
passing with apparently equal facility through the soft tissues and 
the hard spicules. Some of these slices—stained and unstained— 
Mr. Sollas mounted in glycerine, others in Canada balsam, after 
successive treatment with absolute alcohol and carbolic acid and 
turpentine. Before preserving sponges in spirit, he recommends a 
preliminary soaking in a .o2 or .o3 per cent. solution of osmic 
acid, as the histological characters of the specimens are thus less 
injured. 
THE Inpico CARMINE SoLuTiIoN of Tiersch is a good and 
useful blue stain for sections of brain and spinal cord after they 
have been hardened in chromic acid ; it possesses one convenient 
quality—viz., that if the sections are too deeply stained, any excess 
of colour may be removed by the action of a saturated solution of 
oxalic acid in alcohol. ‘This reducing process should be used with 
caution. ‘Tiersch’s fluid consists of :—Oxalic acid, 1 part; distilled 
water, 22 to 30 parts; indigo carmine, as much as the solution 
will take up. A further dilution with alcohol may be necessary ; 
the sections should be immersed in it from 12 to 48 hours; the 
colour will determine the time.— ogg. 
Borax CARMINE.—(1) carmine, ddr.; (2) borax, 2dr.; (3) 
distilled water, 40z. Rub 1 and 2 together in a mortar and 
gradually add the water; let them stand in a warm place for 24 
hours, after which pour off the supernatant fluid, and the solution 
is ready for use.—/ogg. 
