zit3 STAIN TECHSOLOGY

RESTORATION OF DETERIORATED TEMPORARY ACETO-CARMINE PREPARATIOXS

\Vhen sealed temporary aceto-carmine preparations are stored, the dye frequently precipitates as dark crystals which obscure the specimen (Fig. 1, A). The formation of such crystals often takes place after a few days of storage or when the preparation dries out. In either case it is no longer suitable for study. Heating the prepara- tion after 45% acetic acid has been added is not sufficient to remove these crystals, particularly from within the cells. Therefore, a spe- cial technic is required.

To restore such preparations, the seal is first carefully removed, then a drop of 2N HC1 is placed at one edge of the cover slip and

FIG. 1 , A, A dry deteriorated preparation of an oat pollen mother cell. Crystals of the dye are deposited in the cell. B, The same preparation after restoration.

drawn under it by applying a blotter to the opposite edge. After 3-5 minutes, the HCl is replaced entirely with aceto-carmine stain- ing solution b y the same procedure. The preparation is then heated as usual for staining. The combination of treatment with HC1 and heating with aceto-carmine dissolves the crystals and restains the specimen (Fig. 1, B).

This technic has been used with success in restoring deteriorated preparations of oat and wheat pollen mother cells.-MAxiM D. PERSIDSKY, Department of Botany, University of Wisconsin, Madison, TVisc.-From the Program in Cytology, Department of Botany, Uni- versity of Wisconsin, supported by grants to the late Dr. C. Leonard Huskins.

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