460 Biology in America 



fiat over a grocery store in the residence section. Being 

 annoyed for some days by a foul odor the doctor caused the 

 waniscoting around the plumbing to be removed. One or 

 two rat cadavers v^^ere found in tne hollow wall. In two or 

 three days the two membeis of the family who used the room 

 hickened, one dying on the fifth day of cervical bubonic 

 plague. It is probable that infected rat Heas were set free 

 by the removal of the wainscoting. Dead rats were frequently 

 touncl in or near houses waere plague had occurred." "- 



An outbreak of plague in rats occurred in New Orleans 

 in 1914. As the result of prompt measures for the destruction 

 of rats and the fumigation and rat-proohug of the infected 

 premises the disease was suppressed with but a snigle case 

 occurring in man. 



An eftective piece of plague control work is that conducted 

 by the Bureau of Health in the Philippines. The method of 

 plague control piactised m ivianila is (_t interest as showing 

 how it is possible practically to suppress the disease even 

 though it may be impossible to completely exterminate the rat. 



"A list of the places at which plague-infected rats were 

 found was made. Each was regarded as a center of infec- 

 tion. Radiating lines, usually five in number, were pro- 

 longed from this center, evenly spaced like the spokes of a 

 wheel. Rats were caught along these lines and examined. 

 Plague rats were seldom found more than a few blocks away. 

 The furthermost points at which infected rats were found 

 were then connected with a line (and) the space inclosed by 

 the dotted line was regarded as the section of infection. The 

 entire rat-catching force, which had heretofore been employed 

 throughout tlie eity, was then concentrated along the border 

 of the infected section; that is, along the dotted line. They 

 then commenced to move toward the center, catching the rats 

 as they closed in. Behind them thorough rat proofing was 

 carried out. One section after another was treated in this 

 way until they had all been wiped out. Once weekly there- 

 after rats were caught in the previously infected sections and 

 at other places which were insanitary and which had been in- 

 fected i!i years gone by. This was coutinned for one year." ^^ 



But not alone is the rat responsible for the spread of plague. 

 At least two species of ground squirrels as well as the tree 

 squirrel have been shown to be susceptible to the plague ba- 

 cillus, and the occurrence of plague in the first of these has 

 been shown in nature, as well as its probable relation to the 



""The Knt :uul Its Relation to the Public Health," p. 147. The U. S. 

 Public Health Service. 

 "Locus citatus, pp. 205-G. 



