Ultra-Violet Absorption of Living Cells

ULTRA-VIOLET light has been used in microscopy mainly because it makes possible the study of the distribution in cells of absorbing substances, such as nucleic acids, proteins and organic iodine compounds. There has, however, been controversy about the ultra-violet absorption of living cells since Brumberg and Larionow¹ questioned the findings of earlier workers² and suggested that living cells have only a very low absorption around 2600 A., which increases markedly after a few minutes irradiation. The elegant photographs of Ludford, Smiles and Welch³, on the other hand, indicate that fresh cells of the Rb tumour show marked nuclear and cytoplasmic absorption when first observed at 2570 A. and 2750 A.