As links in attempts to establish the diagnosis of cancer at the earliest possible moment, cytological examinations are being increasingly utilized. In 1847, POUCHET (16) examined unstained smears of vaginal fluid and described the cytological changes throughout the cycle and their relation to ovulation and conception. It is a pioneer work of high quality but was not designed to be an aid in the diagnosis of cancer. Approximately at the same time as well as in the subsequent half century WALSHE (22), LANCEREAUX (lo), HAMPELN (7) and HUBER (8) found cancer tissue and cancer cells in expectorates. LUCKE & KLEBS (ll), QUINCKE (18), BOEGEHOLD (2), SCHWALBE (21) and RIEDER (19) discovered cancer cells in peritoneal and pleural fluid, while SANDERS (20), FERGUSON (5) and QUENSEL (17) found them in urine and vaginal fluid. It was only after the time of PAUL EHRLICH (4) - the great father of differential staining - that it was possible to improve cytological examinations and consequently make them more extensively used. In about 1876, after having studied for some time in Europe, the American WILLIAM HENRY WELCH, brought the scientific laboratory system to America where, after the turn of the century, cytological studies began to be carried out. Among the great cytological names of our time are PAPANICOLAOU