THE GERM THEORY OF CARIES. 165 



action on either acidity or alkalinity. They seem to be con- 

 trolled by some other than the known chemical laws, and 

 their action is not yet understood. We have no means of ex- 

 plaining them. If a piece of ivory thrust into the flesh is 

 attacked and burrowed out in holes by a secretion thrown out 

 by virtue of the irritation induced, as asserted by Krause, 

 Kolliker and other of the most capable observers of the 

 world, why may not a tooth be attacked in the same way, by 

 virtue of an irritation of the tissues about its neck or during 

 the irritation consequent upon its eruption when this is 

 unusually prolonged? As a matter of fact, it has been ob- 

 served that decays are very prone to occur in just such situa- 

 tions as tend to confirm this hypothesis. Thirteen years ago 

 we drew attention to this in a paper before the Illinois State 

 Dental Society. Both before and since that time I have 

 given much attention to this point, and I am more than ever 

 convinced that it has much to do with the beginnings of de- 

 cay. I do not wish to be misunderstood in my view of this 

 matter. It is not my notion that decays are initiated by this 

 cause alone. It is only one of the first steps by which other 

 forces which come later are rendered operative. The means, 

 if you please, by which the surface of the tooth is first broken, 

 and by which organisms are permitted to find a lodgment. 

 Not a means by which a decay is carried on to the complete 

 destruction of the tooth. This effect cannot be produced ex- 

 cept while the tissues are in contact, or in very close proximity 

 to the part in process of solution, for the reason that the 

 secretion from the tissues would be dissipated in the fluids of 

 the mouth before they could have time to produce their 

 effects upon the tooth structure. 



The positions at which these results are seen are wisdom 

 teeth, that come through very slowly ; on the buccal surfaces 

 of the molars generally ; and sometimes on the labial surfaces 



