New grid-replica for precise localization in slide cultures.

This report describes a simple technique for the production and use of Formvar film replicas of rulings, such as counting grids, etched on glass slides. The resulting thin, transparent films, when dried on cover slips, are an excellent tool for counting and for orientation in slide cultures (Taubeneck, 1957). The method is similar to that of Powell (1956) who employs a lattice-like ruled area on cellophane, obtained by engraving type of matrix is manufactured by Feinoptische Werkstatten, Jena. Type II also bears four ruled areas each consisting of ten thousand numbered 60-, squares (figure 3). This type of matrix has been produced with the aid of photographic techniques, and is manufactured by the Zeiss Works, Jena. Using the above-mentioned types of matrices, the following technique has proved particularly efficient in the preparation