At Socola, Rumania, 1, 198 patients were inoculated with a routine benign tertian strain; only 50 per cent, showed fever; 16 per cent, became temporary carriers, and 34 per cent, were immune. The immunity was increased by further inoculations; after 3 of them, it rose to 86.7 per cent. After 4 inoculations, it rose to 100 per cent, and withstood the transfusion of 200 cc. of virulent blood and the bites of 25 mosquitoes infected with the same strain. In quartan malaria, the process of immunization was slower; 35 per cent, resisted the first inoculation and 81 per cent, resisted the sixth. In subtertian, immunization took place still more slowly; 39 per cent, were immune to the first inoculation; 75 per cent, immune to the fourth, and 97 per cent, immune to the fifth. A latent infection after only one inoculation does not generally guarantee immunity. Acquired immunity in malaria is sometimes due to latent infection (premunition), but in some cases of immunity the authors were unable to find any evidence of this. W. F..