The most natural explanation of the general correspondence between the highest rat catch and the highest incidence of human plague would be upon grounds of greater activity in rat catching effort at times of greatest plague prevalence, but from the inauguration of general systematic rat catching there was no cessation of effort, even during the abatement of plague, and in consequence this explanation does not apply strictly. It is true, however, that whenever plague occurred in districts theretofore free from the disease, rat catching was pushed vigorously in the surrounding localities. Making due allowance for all the factors mentioned I am impressed with the probability, amounting almost to certainty, that the catch of more than 79,676 rats definitely affected and checked the spread of plague in Manila in 1913; and I am of the opinion that systematic and wholesale rat catching, carried out in the most economical manner possible, should be persisted in indefinitely, at least until plague disappears, wherever the disease occurs. Efforts to prevent the spread of plague to the provinces of Luzon, by way of the railways, were successful and the present measures employed, freight inspection, the fumigation of packages suspected or likely to contain rats, and the similar treatment of freight cars showing signs of rats, should be continued. In a few cases these measures have driven rats out of both packages and cars and the animals have been killed by the sanitarians on duty at the station. The matter of water transportation was entirely within the control of the authorities in charge of inter-island quarantine affairs. Rat catching in Manila was systematically performed and all rats captured were turned over to the Bureau of Science for examination for plague. [Illustration: MATERIALS MUST BE MOVED ABOUT IN THE SEARCH FOR RATS (MANILA PLAGUE CAMPAIGN)] When plague foci were discovered the localities were trapped and poisoned both circumferentially and centrally, with a view to preventing the diffusion of infected rats throughout the city. RAT-PROOFING.--The theoretic desirability and superiority of "out building" the rat, over all other methods of rat suppression, is admitted. The apparent impracticability of actually rat-proofing Manila at the present time and our inability to starve the animals out, justify the other and less permanent measure, viz.: rat catching. However, I heartily favor and urge the most complete and thorough-going rat-proofing of buildings actually infected with human or animal plague, in all cases. The building ordinances of Manila already provide for rat-proof construction in all new buildings erected. With a view to cutting off the food supply of the rat, more than 1100 orders upon householders, to provide covered garbage cans, were served in the district of Tondo alone. The open ends of bamboo timbers in more than 2300 houses were closed, either by cement or tin cans, during 1913.