The Feulgen Reaction Applied to Clinical Haematology.

The Feulgen reaction is a cytochemical test for the detection of desoxyribonucleic (tliymonucleic) acid. After acid hydrolysis, desoxyribonucleic acid in the presence of sulphurous acid gives a characteristic red-purple colour with basic fuchsin, and the depth of the colour roughly reflects the concentration of the compound. The detailed chemistry of the reaction has been fully described by Baker (1942). The reaction has been known for fifteen years and is much used in biology, especially in genetics, but it has only recently been applied to the problems of clinical haematology: La Cour in 1944 used the reaction to study mitotic abnormalities that occur in the bone marrow cells in pernicious anaemia; Thorell working in Caspersson's laboratory in Stockholm used the Feulgen reaction together with ultra-violet absorption techniques for studying the intimate metabolism of nucleoproteins in blood-forming cells (Thorell, 1944, 1947). We have utilized the Feulgen reaction to give help in classifying blood and bone-marrow cells when the differentiation is of clinical importance and when the routine methods fail to show really clear separation between the different types of cells.