I 3 2 HOUSEHOLD BACTERIOLOGY 



We are likely to think that because bacteria are so 

 small and lowly they cannot do much. But in fact 

 they do a great deal. Their life processes are ex- 

 tremely complex. They are chemical engines of great 

 potency. Out of the food which they assimilate they 

 manufacture a host of subtle poisons, some of which 

 are stored up in their tiny bodies, some set free into 

 the fluids of their hosts. This, in fact, is the front of 

 their offending: the poisons which they elaborate and 

 set free damage the cells. 



Sometimes these poisons interfere with the neces- 

 sary performances of the cells close about them, or they 

 harm them, but not irretrievably; or they may kill 

 them forthwith. Again, they are carried far and wide 

 throughout the body, and the heart is enfeebled, the 

 brain palsied, or fever dominates the scene. 



This is the situation, then, when disease-producing 

 bacteria get in among the living body cells and begin 

 to grow, setting free their powerful poisons. It is 

 cell against cell the well-bred, highly differentiated 

 cell of the body against the crude, prolific spark of 

 matter way down upon her borderland of life, potent 

 only to eat, to multiply, to shed abroad its poison. But 

 the weapons of both the combatants are poisonous. 

 For we should not permit our sympathetic viewpoint 

 to obscure the fact that the fluids and the digestive 

 juices which our own cells elaborate are poisons for 

 bacteria, quite as much as is their stuff for us. It is 

 the old story of the survival of the fittest here in this 



