92 
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, of 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- 
