HOUSEHOLD BACTERIOLOGY 



Effect of 

 Poisoning 



Immunity 



ger of a second attack. There seems to be great dif- 

 ferences also between the susceptibility of children and 

 adults to certain diseases. 



The different ways in which bacteria are known or 

 supposed to bring about diseased conditions more or 

 less severe have been described. Whether these 

 causes are the poisonous excretions during the nor- 

 mal life of the bacteria, or are the result of chemical 

 change produced by some ferment which they secrete, 

 the effects upon the blood and tissues are shown by 

 several common symptoms a high temperature or 

 fever ; quickened circulation or rapid pulse ; perhaps 

 difficulty in breathing, and pain. There may be local 

 redness, swelling, and finally the formation of pus, or 

 a "gathering" of the protective phagocytes and the 

 broken-down cells of the diseased portion. These local 

 effects may be entirely within the body or they may be 

 show themselves on the outside under or in the skin. 

 In the latter case a prompt discharge of the pus is 

 usually followed by relief. If there be no-discharge 

 and the dead and poisonous matter be reabsorbed into 

 the tissues, there follows a general poisoning of the 

 whole system. 



Whenever partial or entire immunity seems to be 

 present, we are interested to know in what this im- 

 munity consists. Great as is the protective force of 

 the "white guardians" their presence or numbers are 

 not the only factors in immunity. 



Metchnikoff, the father of the theory of phagocy- 



