CHAPTER XXXII. 



SEPTIC BLOOD DISEASES. 



Diseases due to ordinarily non-contagious facultative parasites, 

 but which become infective by inoculation in suitable soils. 



The most deadly microbes are Vibrio septicits of Pasteur, the 

 pyogenic bacteria, especially the streptococci, and some are suffi- 

 ciently virulent to poison the most healthy ; but generally the 

 animal body whilst in a state of health is not affected by their 

 presence, unless, indeed, they are very numerous. 



Septic diseases are induced in two ways : — -^rst, by the 

 entrance of the microbes themselves into the general circulation 

 (septiccc7nia), in which case the symptoms and results are not pro- 

 portionate to the dose, — i.e., fatal results may follow a very small 

 dose; and second, by the entrance of microbic products — ptomaines 

 only (sajjvccmia) — in which case the symptoms are proportionate to 

 the dose, — i.e., if large, the results may be immediately fatal, if 

 small, it is soon excreted, and, having no reproductive powers, the 

 effects soon pass off. 



These microbes in their normal condition exist in external 

 media, and only induce disease under circumstances which have 

 rendered the animal body susceptible to the morbific effects of 

 themselves or their ptomaines. For example, the body whilst 

 in a state of health can generally resist the bacteria, unless very 

 numerous ; but when an organ or tissue injured — as in a wound 

 — or diseased is exposed to the influence of such germs, they or 

 their products overcome the resistance of the injured or diseased 

 structures, penetrate the blood-stream, and give rise to grave 

 disturbances, and even death. In proof of this I may refer to 

 the experiments of Burdon Sanderson, who found that putrefac- 

 tive fluids injected into the healthy peritoneal cavity of guinea- 

 pigs produced no ill effects, but when the peritoneum had been 

 irritated by an injection of some irritant, such as mustard and 

 water, the virus penetrated the irritated membrane, inducing a 

 general septicemia, with rapidly fatal results. 



