THE CAUSE OF INFECTIOUS DISEASE. 263 



era bacteria can incite diarrhoea ; the bacteria 

 of tuberculosis, of typhoid fever and pneumonia 

 may produce inflammation of the pia mater ; 

 tubercle, typhoid, and pneumonia bacteria, 

 gonococci, staphylococci, and streptococci, may 

 cause endocarditis ; the phenomena of blood- 

 poisoning are caused by a whole series of bac- 

 teria. In these cases, therefore, the determin- 

 ing cause resides in the tissues and their 

 disposition, not in entirely distinct kinds of 

 bacteria. 



The second group of facts, belonging with 

 these but obtained in another way, demonstrate 

 that one and the same " specific " disease germ 

 may produce very different affections. Diph- 

 theria bacilli, for example, may occasion local 

 diphtheria or paralysis or acute blood-poison- 

 ing ; the bacteria of erysipelas may bring about 

 erysipelas in the skin, but are able also to pro- 

 duce suppuration or inflammation of the lungs ; 

 the pneumonia germs may cause typical pneu- 

 monia, blood-poisoning, inflammation of the 

 cerebral membranes, or inflammation and sup- 

 puration of the middle ear ; tubercle bacilli 

 excite tubercle formation in connective tissue, 

 inflammation of the cerebral membranes, sup- 

 puration and true consumption or phthisis. 

 The preceding sections contain still other ex- 

 amples. 



