In previous reports (vol. vi. p. 470 and vol. vii. p. 421), we described several series of experiments the results of which went to show that fleas and fleas alone were the transmitting agents of the infection of plague. It will be remembered that these experiments were carried out in a series of small godowns, the construction of which has been described in detail. The animals employed in the majority of previous experiments were guinea-pigs, though a limited number of experiments were carried out with monkeys. Gottschlich (Kolle and Wassermann's Handbuch der Pathogenen Mikroorganismen, Suppl. vol. ii., 1907, p. 52) considers that the results obtained with guineapigs cannot be applied to rats as the latter animals, unlike guineapigs, feed on the carcases of their dead companions. Gottschlich while admitting that fleas may transmit the disease from rat to rat considers this method of spread to be of only subsidiary importance. He is of opinion that, among rats, plague is chiefly spread by the healthy animals feeding on the carcases of the plague infected. In order to examine the validity of these criticisms we decided to repeat the godown experiments using wild Bombay rats instead of guinea-pigs.