THE RELATIONS OF BACTERIA TO DISEASE 49 



Character of Infections. " In the production 

 of disease by microorganisms there are two main 

 factors involved, namely, (a) the multiplication of the 

 living organisms after they have entered the body, 

 and (b) the production by them of poisons which 

 may act both upon the tissues around, and upon the 

 body generally. The former corresponds to infec- 

 tion, and the latter is of the nature of intoxication 

 or poisoning. In different diseases one of these is 

 usually the more prominent feature, but both are al- 

 ways more or less concerned." (Muir and Ritchie.) 



Infections vary widely in the effects produced in 

 the body, both in the local and general or constitu- 

 tional symptoms. 



Certain diseases are known as toxcemic, that is, 

 the blood contains the poisonous products (toxins) 

 of the invading bacteria. Tetanus is notably a 

 toxsemic disease, the local symptoms being almost 

 entirely absent, and no bacteria are found in the 

 blood, while the constitutional effects are profound 

 and nearly always fatal. 



Diphtheria is also a characteristic toxsemic in- 

 fection, although the local symptoms are pronounced 

 as well. 



Septicaemia, or bacteremia as it is sometimes called, 

 denotes the presence and multiplication of bacteria 



