POLIOMYELITIS IN FAMILIES ATTACKED BY THE DISEASE. II. The Presence, Appearance, and Persistence of Neutralizing Antibodies: August, p. 193, 1. 9 should read: The appearance of paralysis, and the presence of typical lesions in the CNS of inoculated monkeys indicates that virus was not neutralized. Conversely, no evidence of illness in a monkey indicates neutralization of virus in the serumvirus mixture, particularly if the animal (a) has no demonstrable lesions in the CNS or (b) succumbs to a challenge inoculation with the same strain.