Complete the dehydration in 100 per cent alcohol. 10 per cent Venetian turpentine in an exsiccator until the turpentine becomes thick enough for mounting. Mount in the Venetian turpentine. Even after the method became established, there occurred a period of several years during which it was practically impossible to get a Venetian turpentine suitable for histological use. There are probably other good turpentines and still others are likely to appear.
Venetian turpentine is made from the resin of Larix europea.
Since this resin is soluble in absolute alcohol, material can be transferred directly from absolute alcohol to a thin solution of the mounting medium, without the intervention of xylol or any other oil, thus eliminating the most dangerous stage in the preparation of filamentous algae and fungi and any forms which are to be mounted whole. The general outline, just given, is not sufficiently definite for a working introduction. The following concrete examples, describing the use of Venetian turpentine with an aqueous stain, with an alcoholic stain, and with a combination of aqueous and alcoholic stains, will be more practical than general directions. The steps from fixing to mounting, as used with an aqueous stain, will be described first, since this will introduce the method in its least complicated form. Fix 24 hours in chromo-acetic acid.