Many physicians who have treated patients with poliomyelitis have come to believe that there is scarcely anything to be gained by using serum from either convalescent human beings or experimental animals, once the patient has contracted the disease. It may be that the antigen used to produce experimental antiserums is not strong enough and that a more effective serum could be obtained by fortifying the specific antigen in some way, or it may be that specific antiserums have not been used to the best advantage, i. e., not in large enough quantities. It was decided to administer injections of a "fortified" antigen to animals to determine the efficacy of the serum thus obtained.
Experiment 1.—The blood serums of three horses, 3732, 3733 and 3757, were tested for natural neutralizing antibodies. The dose for the test was an injection of 0.2 cc. given intracerebrally to Macacus rhesus monkeys and it contained