In a previous article1 wc referred to Nicolle's experiment, in which he apparently succeeded in transmitting the typhus fever of Tunis from the chimpanzee to the macacus monkey, through the bite of the louse. Nicolle used twenty-nine lice in his experiment; after feeding on the chimpanzee they were allowed to feed on the monkey for several successive days. Also, Anderson and Goldberger2 report two attempts to transmit the typhus fever of Mexico City to the macacus by means of the louse. Their first experiment seemed to be without result, and although the second showed a slight rise in temperature, their inability to give an immunity test to the animal makes it imposible to interpret the result. This test is essential, as will be manifest from considerations which follow.
Since January 1 we have performed a series of experiments bearing on the relation of Pediculus vestamenti