DISEASES, HOW PRODUCED 205 



Not all the bacteria which secrete poisons are disease 

 germs. Some saprophytes may produce deadly poisons, 

 but since they are not able to grow in the living body 

 they are never in a proper sense the causes of disease. 

 They might, however, grow in our food and render that 

 poisonous, so that if it were subsequently eaten it would 

 give rise to cases of food poisoning such as already 

 noticed. Such troubles are cases of toxic poisoning but 

 not true diseases. A true germ disease is caused by 

 the germs themselves entering and multiplying within 

 the body. When the poisons and not the bacteria are 

 absorbed by the body, the sickness comes on very quickly 

 and violently, — a few hours after the poisonous food is 

 consumed. But it is also of short duration, for, if the 

 amount of poison absorbed is not sufificient to produce 

 death, it is quickly excreted from the body, and a day or 

 two afterward the person will have perfectly recovered, 

 except for the weakening effects of the poisoning. This 

 is the general history of- cases of poisoning from ice cream, 

 etc. A true disease acts very differently. It is slow in 

 appearing, gradual in its development, and very slow in 

 disappearing. 



' The Course of Bacterial Diseases. The diseases pro- 

 duced by bacteria have different histories in the body ; 

 but a considerable number of them, with many of which 

 the housewife is intimately concerned, have a course some- 

 what as follows. For some days after the bacteria enter 

 the body they have difficulty in maintaining a foothold. 

 Sometimes, indeed, even though they succeed in entering, 

 they are driven out by resisting powers which the body 

 possesses but which we cannot here particularly consider. 



