TABLE OF CONTENTS. 



Page. 



Introduction (Walter Wyman) 9 



Natural History of the Rat (David E. Lantz) 15 



Classification of rats 15 



Distribution of the genus Miis in America 17 



History of the brown rat 19 



General description of the species in America and key to the species 20 



Habits of rats '. 22 



Breeding habits 22 



Abundance 23 



Migrations and invasions 24 



Food 26 



Feeding habits 26 



Ferocity 27 



Plague Infection in Rats (George W. McCoy) 29 



Mode of examination 30 



Gross lesions of natural rat plague, acute 32 



Subcutaneous injection 32 



The bubo 33 



The granular liver 34 



The spleen 35 



Pleural effusion 35 



Gross lesions of natural rat plague, chronic 36 



Rat plague without gross lesions 37 . 



Microscopical examinations 37 



Bacteriological diagnosis of rat plague 38 



Pest-like bacteria found in rats 41 



Artificial infection of rats with plague 41 



Modes of infection 42 



Local reaction 43 



The bubo 44 



The liver and spleen 44 



Chronic plague due to artificial inoculation 44 



The histology of rat plague 45 



Natural rat plague 46 



Immunity of rats to plague 46 



References 48 



Rat Leprosy (Walter R. Brinckerhoff) 49 



Introduction 49 



Review of literature 49 



Description of disease 50 



Etiology 52 



Summary 52 



Bibliography 53 



(3) 



