SOURCES OF INFECTION 41 



still send out a few organisms or small quantities of poison which 

 can attack other parts. Thus from a root abscess, germs may 

 sneak into the blood stream and settle in the kidneys or joint 

 membranes; this is focal infection and is usually subacute or 

 chronic in character. General inffection is self explanatory. 



Bacteria may become accustomed to the fluids of the body by a 

 similar process and may elaborate free receptors or their own 

 protection, i.e., anti-bacteriolysins (Welch's theory). 



In the aged, and in chronic disease of the liver and kidneys, 

 the complement existing in the blood may become reduced in 

 quantity, and the individual may succumb to an infection, which 

 ordinarily would be mild. 



Soluble products of bacterial activity which are alkaloidal 

 (basic), crystalline in character, and mostly poisonous, are known 

 as ptomaines, or putrefaction alkaloids. They are highly com- 

 plex in chemical structure, and are difficult to isolate. 



The foregoing processes are due to the toxic products of bac- 

 teria during their growth in the tissues, substances mentioned 

 before but now deserving a more detailed study from the stand- 

 point of the diseased tissue. 



Bacterial endotoxins are poisonous substances liberated only 

 upon the death and disintegration of the germ cells. They are 

 moderately active in attacking wandering and special tissue 

 cells; they are more resistant to heat and ferments than toxins. 

 The identity of these toxins has given rise to considerable dispute 

 and there will be given the two principle ideas concerning them. 

 The older theory considered them integral parts of the cell, peculiar 

 to each virus and calling forth specific responses because of the 

 individuality of each toxin. Recent work has shown that the 

 chemical and immunological response to bacterial injection is 

 similar to that obtained by the use of serum, or egg white or 

 animal cells. For this and more minute reasons it is believed by 

 some that there is in every protein (bacterium, cell, serum) a 

 toxic part with a common construction. Another and peculiar 



