The Flea and Its Relation to Plague Continued. Page. 



Results of identification of fleas in California 135 



Synopsis of fleas commonly found on rats 136 



Ceratophyllus Fasciatus, Bosc 136 



Loemopsylla Cheopis, Rothschild 138 



Ctenopsyllus Musculi, Duges _ 140 



Pulex Irritans, Linnaeus 142 



Ctenocephalus Canis, Curtis 143 



References 144 



R orients in Relation to the Transmission of Bubonic riuunc ( Rupert Blue) 145 



Epidemiological observations in San Francisco 147 



Theories as to the cause of seasonal prevalence 149 



The occurrence of plague in the marmot of Asia and ground squirrel of 



California 150 



Plague infection in ground squirrels 150 



The natural habitat of plague 151 



References 152 



Rodent Extermination (Wm. Colby Rucker) 153 



Trapping 154 



Poisoning 156 



Natural enemies 159 



Cutting off of the rat's food supply 160 



Building the rat out of existence 161 



Natural Enemies of the Rat (David E. Lantz) 163 



Animals that destroy rats 163 



Hawks 163 



Owls 164 



Wild mammals 166 



Skunks 166 



Weasels 166 



Minks 167 



Domestic animals 167 



Dogs 167 



Cats . 167 



Ferrets 168 



Other animals 168 



Mongoose 168 



Alligators 168 



Snakes. 169 



Bounties on predatory animals .' 169 



Rat-Proofing as an Antiplague Measure (Richard H. Creel) , . . . 171 



Rat-proofing of primary importance 173 



Rat-proofing is expensive 174 



Methods of rat-proofing 175 



Rat-proofing ordinances should be specific 177 



Choice of architecture and building materials 178 



Inefficiency of Bacterial Viruses in the Extermination of Rats (Milton J. Rosenau). 179 



Introduction 179 



Experiments upon rat virus in the Hygienic Laboratory 183 



Experiments with micro-organisms for destroying rats by the U. S. Biolog- 

 ical Survey 186 



Experiments during the San Francisco plague outbreak 188 



Opinions of others 190 



Pathogenicity for man 193 



References f<> the literature 201 



Resume' 204 



