114 The Philippine Journal of Science i9i8 



the cans and throwing the contents into the street, thus furnish- 

 ing rats with food. 



In any house in which a case of rat or human plague occurred, 

 in addition to the measures mentioned above, all hollow walls 

 and ceilings were ordered removed and other rat proofing done. 



In infected districts, wherever necessary, ground surfaces 

 were ordered cemented, rat runs destroyed, and other rat proof- 

 ing was carried out. 



Wherever possible, the sewers were fumigated with sulphur 

 dioxide, but, on account of the many openings in the sewers at 

 unknown places, it is impossible to state whether rats were 

 killed in them or whether they escaped upon the gas being applied. 

 It was noted, however, that whenever the fumigation of the 

 sewers was going on, the number of rats caught in traps or 

 by poison always increased. 



On account of the experience had in Java, special attention 

 was directed toward bamboos which were large enough to harbor 

 a rat, but, on account of the fact that human and rat cases nearly 

 all occurred in houses which were built of strong materials, there 

 was not much opportunity to make observations on this point. 



At first, reliance was placed largely upon wire-cage and spring 

 traps, but the results were not very encouraging. The usual 

 formulas for rat poisons : Mixtures of bacon, various grains with 

 powdered glass and strychnine sulphate or arsenous acid, and 

 phosphorus pastes and preparations were tried, but none of 

 these proved very successful. The poison then adopted consisted 

 of arsenous acid and rice boiled together in the proportions of 

 1 to 5. This bait has been more successful than all of the others 

 combined. It has proved especially satisfactory because it can 

 be used day after day without the rats becoming suspicious of it. 



A persistent campaign of education was carried on by means 

 of the newspapers and by printed circulars which explained the 

 method of transmission of the disease. The contents of these 

 circulars were later taught in the public schools. 



PROBABLE FACTORS CONCERNED IN THE INTRODUCTION OF PLAGUE 

 INTO THE PHILIPPINES 



Immediately after plague made its appearance in Manila, large 

 numbers of rats were caught along the water front and around 

 the wharves, but none of these were found to be plague-infected. 

 On account of the fact that the first cases occurred among per- 

 manent residents, among persons who had not been out of Manila 

 in many months, among persons who did not associate with 



