156 THE GERM THEORY OF DISEASE. 



organisms in the production of these acids is admitted by 

 him, but discusses this phase of the subject no farther. He 

 makes no effort to determine to what extent these acids may 

 be formed in the mouth. All of his experiments were tried 

 out of the mouth, and no provision whatever was made to 

 ascertain the effect that fermentation may have had on his 

 solutions in the progress of his experimentation. This being 

 the case, the only result of the experiments is the determina- 

 tion of the strength of the solutions of these different acids 

 necessary to decalcify a tooth. 



This, together with the facts obtained from other sources, 

 showing that most of these acids are the products of certain 

 fermentations that may go on in the mouth, gives much force 

 to Dr. Magi tot's conclusions. 



Very soon after Dr. Magitot's work, in the same year, 

 indeed, came the work of Lieber and Rottenstein, to which 

 we have referred. The work seems to have been written for 

 the express purpose of showing that decay of the teeth is 

 caused by the life and development of the fungus known as 

 leptothrix buccalis. In this the authors seem to have signally 

 failed. They certainly make but little advance toward the 

 demonstration of the parasitic theory of this affection. Indeed, 

 they do not seem to have endeavored to show that this fungus 

 does more than promote decay that has already become 

 established. 



They say, after having made an extensive examination of 

 the life and growth of the leptothrix, " from what has been 

 said, it results that two principal phenomena manifest them- 

 selves in the formation of dental caries, viz., the action of 

 acids, and the rapid development of a parasitic plant, the 

 leptothrix buccalis." They do not suppose the leptothrix 

 buccalis capable in itself of attacking the teeth, if their con- 

 dition be normal, but when their surfaces are once softened 



