Seminal stains on clothes can best be visualised by

Woods lamp using ultraviolet rays can be used . When examined under ultraviolet light, seminal stains exhibit strong bluish-white fluorescence. Stains mixed with blood may not fluoresce. Fluorescence depends upon the choline of the semen. Substances such as food stains, vaginal secretions, urine, pus, etc. may also show fluorescence. Stains on aificial silk do not show fluorescence. The residues of modern detergents on clothes also fluoresce strongly. Ref : Krishnan vij Textbook of Forensic medicine and Toxicology 5th edtion ; pg no - 324