CHAPTEE II. 



DO PATHOGENIC MICROORGANISMS EXIST IN THE 

 HEALTHY BODY? 



IT still remains a disputed question whether pathogenic micro- 

 organisms can exist in the body without giving rise to disease. It 

 has been definitely ascertained by experimental research that many 

 of the pathogenic germs are harmless as long as they remain in the 

 circulating blood, and that their specific pathogenic action only 

 becomes evident after localization takes place in some part of the 

 body, in a soil prepared by injury, or disease, for their arrest and mul- 

 tiplication. It has also been definitely settled by clinical experience 

 that pathogenic spores may remain in the healthy body, in a latent 

 condition, for an indefinite period of time, until by some accidental 

 pathological changes the tissues in which they may exist have been 

 prepared for their growth. Numerous experiments will be cited 

 elsewhere, in which injections of pure cultures directly into the 

 circulation produced no ill effects in healthy animals, but when 

 previous to the injection, or soon after, an injury was inflicted in 

 some part of the body, localization occurred at the seat of trauma, 

 and in the culture soil thus prepared the microbes produced their 

 specific pathogenic effects. From these remarks it is reasonable to 

 assume that pathogenic germs may exist in the healthy body with- 

 out necessarily giving rise to disease, especially if, as is well known, 

 they are being constantly eliminated through the excretory organs. 

 Some of the arguments for and against this theory will now be 

 introduced. 



Fodor ( u Bacterien im Blute lebeuder Thiere," Arohivf. Hygiene, 

 B. iv. p. 129) introduced directly into the circulation of rabbits 

 pathogenic bacteria, in order to study their effects on the tissues 

 and manner of elimination. As a rule, he found that they had 

 completely disappeared from the blood after twenty-four hours. 

 No culture experiments were made less than four hours after inocu- 

 lation. He believes that the microbes are removed by the red cor- 

 puscles, or that they are digested by the leucocytes. He affirms 

 that, as a rule, pathogenic germs are not present in the healthy 

 organism, as he found the blood of healthy rabbits, without excep- 

 tion, sterile ; and only in exceptional cases was he able to demon- 

 strate the presence of bacteria in animals killed, even where the 

 examination was postponed until putrefaction had set in. 



