Rabbit leucocytes, injected into the basal meninges of dogs, in doses from 0.7 to one cubic centimeter apparently invariably cause death. Horse leucocytes, injected in the same amounts, cause death in about 25 per cent. of the dogs.
The injection of foreign leucocytes into the meninges of monkeys causes few if any symptoms.
The injection of from one to three cubic centimeters of horse leucocytes into the meningeal cavities of dogs, simultaneously with the inoculation of the meninges with tubercle bacilli, causes a slight delay in the development of the paralytic symptoms in about half the treated animals. This delay, however, is very slight when compared with the remarkable prolongation of the latent period previously observed after treatment with dog leucocytes.
The injection of foreign leucocytes into the meningeal cavities of monkeys has thus far given almost uniformly negative results. In one small group of monkeys, however, inoculated by the method of lumbar puncture, the injection of rabbit leucocytes has been associated with a prolongation of the latent period in one of the treated monkeys, and with a complete prevention of the subsequent tuberculosis in a second monkey.