Abstract
A potent hyperimmune antipoliomyelitic horse serum was developed, which may be increased in strength by conc. as demonstrated by in-vitro neutralization test. Conc. serum was without effect if given therapeutically during the prodromal stage after intracerebral injection of monkeys, but was apparently of value if administered prophylactically. This was demonstrated mainly after intranasal infection and only in part after intracerebral inoculation of monkeys.