IMMUNITY. 105 



The Use of Local Treatment in Inhibiting Bacterial In- 

 vasion. The total extirpation of the infected area by 

 surgical means, if thoroughly carried out, removes the 

 disease entirely; but, unfortunately, this procedure is 

 rarely possible. When incomplete it is frequently 

 helpful; but it may be harmful, for by creating and 

 exposing fresh wounded surfaces to infection it may 

 lead to the further development of the disease. Again, 

 it may be useless, for by removing only a portion of 

 the bacteria it may leave those which have already 

 reached the deeper tissues or blood to go on devel- 

 oping. In some cases, like anthrax and infection 

 from bites of rabid animals, total removal of the 

 virus is possible, either by the knife or thorough cauter- 

 ization, and will prevent a general infection. So also 

 in tetanus, the invasion being limited, surgical inter- 

 ference may be of great use by removing not only the 

 bacilli themselves but also that portion of their poison 

 which has not as yet been absorbed from the tissues. 

 The beneficial effects of opening an abscess, incising a 

 cellulitis, or cleansing and drainage of the uterine 

 cavity are well known. The retention of the poisonous 

 products of the bacteria and altered tissue substance 

 leads to their absorption, and thus lowers the tone of 

 the neighboring, and to a less extent of the general, 

 tissues in consequence of the poisoning. This enables 

 the bacteria to penetrate into tissues which would other- 

 wise resist them. The mechanical effect of pressure on 

 the walls of an abscess by its contents also aids the bac- 

 terial progress. Local bleeding and the application of 

 cold probably act by lessening tension. The application 

 of warmth hastens absorption, and so, when the infec- 

 tion is one which tends to localize, it acts favorably by 



