THE PLAGUE BACILLUS 393 



particular two organs, the spleen and the lymph glands {huhonic 

 plague). The latter become inflamed in groups, commencing gener- 

 ally with the inguinal (60 per cent.) followed by the axillary (17 per 

 cent.). The buboes consist usually of masses of inflamed and enlarged 

 lymph glands, attended with haemorrhage and often with necrotic 

 softening. The spleen suffers from inflammatory swelling, which 

 may affect other organs also. In both places the bacilli occur in 

 enormous numbers. In the pulmonary form the lung is affected with 

 broncho-pneumonia. This form of plague is said to be always fatal. 

 Kitasato considers that the bacillus may enter the body by the three 

 channels adopted by anthrax, namely, (a) the skin, (6) alimentary 

 canal, and (c) respiratory tract. But the vast majority of cases arise 

 from infection through the skin. Infection through the alimentary 

 canal is still doubtful. Soil, clothes, and contaminated articles gener- 

 ally are the agencies of infection. As stated already, rats play an 

 important part in the propagation of the disease. The Indian Com- 

 mission hold that suctorial insects are practically of no importance 

 as transmitters of infection. 



Haffkine has prepared a vaccine to be used as a prophylactic (see 

 p. 424), and the Indian Plague Commissioners have recently reported 

 on its effects. Inoculation with this vaccine appears sensibly to 

 diminish the incidence of the plague attacks on the inoculated popu- 

 lation, although the degree of protection is not perfect. The disease 

 is four times more numerous among the uninoculated than among 

 the inoculated. The fatality of the attacks is also diminished in the 

 inoculated. Protection does not begin till a few days after the 

 inoculation, but it lasts many weeks and even months. It may here 

 be added that the means of stamping out plague are the ordinary 

 methods of notification, isolation, and disinfection. The latter should 

 include destruction of the patient's clothes, and the scraping of the 

 walls, and, in India, burning of the earthen floor of his dwelling. 

 The soil and dwellings are among the chief sources of infection, 

 and therefore require most attention. 



As to the infectivity of plague, it is now generally held that the 

 bubonic form is, as a rule, dangerous from the excretions, and only 

 in the last stages of the disease ; that the primary pneumonic form 

 is highly infective ; that houses in which plague patients or plague 

 rats have died, and in which clothing has been soiled by excretions, 

 are infective ; and that there is much more danger from living in an 

 infected house than from coming into contact with a plague patient. 

 Plague is a disease which is specially favoured by insanitation within 

 the walls of houses as contrasted with insanitation outside houses, 

 relating, for example, to drainage, removal of refuse, etc. Eats, 

 merchandise, clothing, etc., may each and all play a part in the con- 

 veyance of plague from one village to another, or one country to 



