Feulgen's test

A test used to detect DNA in nuclei, especially during cell division. A section of tissue is first placed in dilute hydrochloric acid for ten minutes at 60°C to hydrolyse DNA, removing the purine bases and exposing the aldehyde groups of deoxyribose. When the tissue is soaked in *Schiff's reagent the location of the DNA is shown by the development of a magenta colour.