1. The technique adopted for the feeding of ticks on guinea-pigs in investigations into the tick transmission of South African tick-bite fever is described.
2. Since the reactions produced in guinea-pigs by the intraperitoneal injection of guinea-pig passage brain material are irregular, the host guinea-pigs were infected with egg membrane cultures rich in rickettsias.
3. The criteria for positive transmission were the microscopic
demonstration of rickettsias in smears from the tunica vaginalis, and the production of a well-defined febrile reaction with scrotal enlargement on passage, or the development of a solid immunity in the guinea-pig.
4. It was shown that in the case of R. sanguineus infection was picked up by larvae and transmitted as nymphae, picked up by nymphae and transmitted as adults, and passed through the eggs to larvae of the next generation.
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