THE RELATIONS OF BACTERIA TO DISEASE 47 



At the present time the principal diseases known 

 to be due to specific microorganisms are : 



Class I. Septicaemia, gonorrhoea, Asiatic cholera, 

 leprosy, pyaBmia, syphilis, influenza, bubonic plague, 

 pneumonia, diphtheria, tetanus, relapsing fever, 

 meningitis, typhoid fever, tuberculosis, glanders, 

 anthrax, malaria, sleeping-sickness. 



Class II. To this class belong those diseases 

 caused by organisms which are yet unknown : small- 

 pox, foot-and-mouth disease, yellow fever, chicken 

 pox, hydrophobia (rabies), measles, mumps, scarlet 

 fever, Rocky Mountain spotted fever, typhus fever, 

 epidemic infantile paralysis. 



The sources of the communicable diseases in 

 man are man himself and the lower animals ; the 

 majority are peculiar to human beings, although 

 we contract anthrax from cattle, plague from rats, 

 tuberculosis in part from cattle, etc. Formerly it 

 was thought that the main sources of infection in 

 man were in water, air, soil, and food ; and while 

 these may serve as vehicles for conveying infectious 

 materials, the source is usually in man himself. 



No single species of pathogenic bacteria can pro- 

 duce disease in all animals, nor are the disease- 

 producing bacteria for animals the cause of disease 

 in plants. A bacterium may produce disease in 



