ABSTRACT
Materials needed (Fig. 9a)- 1) Slides, measuring 76 x 26 x 1 mm,
are usually used. The thickness should be about one miJlimeter, but slight variations can be tolerated. The slide must not be scratched. To obtain the best possible im-
age, the slide must be clean and greasefree, especially for phase-contrast or photomicroscopy. Slides that are sufficiently clean, cannot always be supplied. If this is the case, the slides need to be washed under running water whi! wiping them with one's fingers, a sponge or laboratory paper toweling. Then they must be rinsed and
dried with an absorbent paper that does not leave residual fibers. Slides are checked for cleanliness by holding the slide up to the light and, if necessary, repeat the cleaning procedure using ethyl alcohol and other solvents or degrl'asing detergents.
