164 THE GERM THEORY OF DISEASE. 



about by the life force, as manifested in the form of micro- 

 organisms? Does anyone pretend that all of the toxic bodies 

 elaborated by micro-organisms have been found, and their 

 effects on the animal economy made out? Certainly not. 

 Then we may expect to find others, if we make the search. 

 It seems certain that every organism that is hurtful to man, 

 is so by the elaboration of some substance that has toxic or 

 irritant properties. 



As we have said, we have no doubt that there are other 

 micro-organisms than the bacterium lactis that may be instru- 

 mental in the production of dental caries. Nor do we think 

 that it is necessarily only acid-producing organisms that may 

 produce caries or some of its phenomena. This, however, 

 need not be discussed now. 



I wish now to turn your attention for a moment to another 

 class of phenomena, and make some inquiry into their possible 

 participation in the production of caries. I have already 

 spoken of the strong probability that the otherwise normal 

 tissues, when under the influence of certain qualities of inflam- 

 mation, emit a fluid of acrid and very irritating properties. 

 About the necks and other parts of children we sometimes 

 see this fluid excoriating the skin wherever it touches it, 

 seemingly acting the part of a caustic. I have already 

 referred to the fact that dead bone, ivory driven into the flesh, 

 sponge, catgut ligatures, etc., are dissolved and removed. This 

 causes us to inquire whether or not a substance may be 

 elaborated in the same manner in the mouth, that may have 

 its quota of effect in the production of the phenomena of 

 caries. 



I was thoroughly convinced that this was the case years 

 ago, though I endeavored to explain the results by the 

 assumption that an acid was formed. This is entirely un- 

 necessary. Soluble ferments do not seem to depend for their 



