122 THE PLAGUE 



mots die in great numbers and are eaten by dogs and wolves. It is 

 not known whether these animals are infected from such food or not. 

 It is not supposed that they play an important role in the transmission 

 to man. In man the pneumonic form of the plague is most in evi- 

 dence, and the bacillus is disseminated by droplets in talking, sneez- 

 ing and coughing. The cervical glands are often involved, the inguinal 

 less frequently. The fourth Asiatic focus lies in the mountains on the 

 southwest coast of Arabia in the region of Assir on the Red Sea. 

 This region has not been closely studied. The African nursery is 

 found in Uganda near the source of the White Nile. It is supposed 

 that this region is the breeding place of the pestilence which has given 

 Egypt an evil reputation for so many centuries. 



The distribution from these centers and from secondary foci fol- 

 lows lines of traffic, penetrating distant lands and traversing the widest 

 seas. 



The infection in man may be transferred directly from one to the 

 other. This is the chief method of spread in the pneumonic form. 

 The sputum is full of the bacilli and in crowded families droplet infec- 

 tion is most common. Among the more civilized and the better housed 

 peoples, this method of transmission is rapidly becoming less potent. 

 In 1900 out of 276 cases in Sydney there were only ten houses in 

 which more than one case developed. While "carriers" play an unim- 

 portant role in the transmission of the plague, it is known that those 

 recovering from the pneumonic form may suffer from a more or less 

 chronic bronchitis in which the sputum remains infective. The 

 bubonic form does not favor direct transmission, but in this form the 

 transfer may be indirect, by soiled clothing and infected houses. It 

 has long been known that poverty and hunger favor the spread of 

 this disease. Undoubtedly ignorance and filthy habits are also impor- 

 tant factors. The figures from Bombay show the following distribu- 

 tion per million among the several classes : Low caste Hindoos, 53.7 ; 

 Brahmins, 20.7; Mohammedans, 13.7; Eurasians, 6.1; Jews, 5.2; 

 Parsees, 4.6 ; Europeans 0.8. 



The rat has long been suspected as playing a part in the distribu- 

 tion of this disease. In the great epidemics of the middle ages it was 

 observed that rats come from their holes, lose all fear of man, become 

 uncertain in movement and die in great numbers. The most ignorant 



