[Problem of choosing radiation for x-ray analysis of biological objects in their native form (for instance collagen treated within the substance of the dermis)].

Some authors report that collagen in derma after industrial treating by the salts of chrom imply rather diffuse X-ray patterns. At the same time our X-ray photographs of these samples using Cr Ka-irradiation rather then Cu Ka-irradiation are all of fine quality. Therefore the collagen in derma is not distroed after salt treatment. In fact Ka-seria of Cu (using in all other investigations) cause transitions in Cr-atoms implying as diffuse phone on the film.