RELATION OP BACTERIA TO DISEASE 157 



2. ''Where toxin-producing bacteria have become adapted 

 to a definite species, as in diphtheria, the toxin itself acts 

 upon a number of different species. In other words, the 

 parasitic relation is far more specialized than the chief 

 pathogenic product. 



3. "No strictly invasive bacteria have yet been found 

 producing diffusible toxins which appear to be of any real 

 significance in the disease process. 



4. ''Those which produce such toxins are not strictly 

 invasive bacteria. 



5. "The injury due to invasive bacteria is known to be 

 due to the disintegration of bacteria and the setting free of 

 poisons locked up in the bodies of the microbes. 



6. "Pathogenic bacteria manifest less biochemic activity 

 than the related saprophytic forms. 



7. "The hemolytic and leukocidic toxins of bacterial fil- 

 trates may be due to autolysis of the bacteria. Jordan has 

 shown that hemolysis is at least in part due to a change in the 

 reaction of the culture fluid." 



Three possible fates await the invaders. 1. They are 

 largely destroyed within the body. 2. They are excreted, or 

 discharged through various channels. 3. They remain in- 

 definitely in the body after the disease is over to be eventually 

 destroyed or eliminated. 



Theoretically, the blood and organs of healthy animals 

 are free from bacteria. It has been found, however, that often 

 solitary streptococci, tubercle bacteria, etc., are present in 

 the healthy body, circulating in the lymph and blood stream 

 or localized in the lymph glands. These may and often do 

 become fixed at points of least resistance from which places 

 they multiply and extend further into the body. Perez found, 

 in a systematic examination of healthy bodies, that the lymph 

 glands only contain bacteria, but here the bacterial flora was 

 very rich. In dead animals, after sixteen to twenty hours at 

 room temperature or after five to six hours in the incubator, 

 bacteria are found in the blood and organs (Trombetta), 

 having for the greater part wandered from the intestine. In 



