“…Crosby also stated that in two patients personally studied who had been ill for more than 10 years the disease had become milder and that their erythrocytes were more resistant to haemolysis in vitvo than formerly. Wagley and Rumsfeld (1958) reported an even more striking case; their patient, 32 years after the onset of the disease, was normal clinically and had a completely normal blood picture. The acidified-serum test was, however, still positive (no figures for per cent haemolysis were given).…”