Abstract
P. californicus, P. eremicus and P. polionotus contracted acute infections, dying within 10 days, while in various forms of P. maniculatus the infection was subacute, with an av. duration of over 80 days. In P. leucopus noveboracensis the infection was often of a chronic type with apparent recovery in about half of the individuals, some of which were alive 471-553 days after the original inoculation.