The rat usually gains entrance by gnawing through the natural partitions between the bamboo sections near the outer end of the pole. Our Manila photographs show both the natural open ends of such timbers and the rat-gnawed perforations in the partitions. In Java, rats also nest in the thatched roofs, as they occasionally do in the Philippines. NEST MATERIALS.--The materials utilized for nests by rats in Manila and Java seem to be identical also. Straw, dry leaves and pieces of cotton are mentioned in the Java reports. The same materials and additional ones will be found mentioned in our reports upon nests. [Illustration: BAMBOO HOUSE SUPPORTS NOT SEALED WITH CEMENT. NOTE HOLES GNAWED IN BAMBOO ENDS. RATS FREQUENTLY MAKE NESTS IN THESE HOLLOW BAMBOO RAFTERS.] The presence of food was also noted in the bamboo nests in Java and we often find articles of food in our Manila nests. Dr. Korn, P. H. Service, and the writer (T. W. J.) investigated a good many of these bamboo house-timbers and we not only found such evidences of rats as food, rat fæces and nest materials, but in one case a rat was actually driven out of a bamboo nest by introducing a long thin strip of wood. The evidence of similar conditions then is complete. We also duplicated the experiences of the Java workers in finding dead rats inside of the bamboo house timbers in close proximity to patients sick (or dead) with plague (see memoranda in the case of Esteban Masabik, of 140 Calle Perla, March 22, 1913). Very extensive rat destruction and cleaning operations, covering a large portion of the city of Manila and including all sections where cases of rat plague or human plague developed, were undertaken and this work was carried on without interruption for about two (2) years. City laborers to the number of 60 to 150 were used and the work was supervised by Sanitary Inspectors Brantigan and Searcy, of the Bureau of Health. During a part of the time a flying column of 50 men, under Sanitary Inspector Hunniecutt, was detached from the main party and employed at placing rat poison. The total amount of accumulated dirt removed from houses and yards approximated 5250 tons (for 17 months ending November 1, 1913). Without doubt this general cleaning campaign and the removal of this enormous accumulation of dirt and rubbish was of great value as an antiplague measure. The rat catch will always be found to depend upon several factors, viz.: the number of persons employed; the number of traps and portions of poison placed; the location of the operations and the length of time a given locality is trapped, poisoned and cleaned. The variety of baits and poisons will also affect the results. In addition to these factors certain others are found to operate in reducing the rat catch, as, for example, weather conditions and the occurrence of Sundays, holidays and the days just preceding and following holidays.