THE GERM THEORY OF CARIES. 155 



the underlying facts that have so long enshrouded the cause 

 of caries of the teeth in mystery. 



But in this we are anticipating. There is another work 

 which demands examination before we pass to this. The 

 views of Dr. Watt have received much commendation in this 

 country, but not so in the old. There, other men have been 

 prominent, and we find that while they have agreed in the 

 main, there are important differences between them. As we 

 have said, Dr. Watt has maintained that decay is caused by 

 the acids, nitric, hydrochloric and sulphuric, with possibly 

 others. In Europe the influence of these particular acids 

 has been very generally denied ; and the results attributed to 

 other acids, as the lactic, acetic, and the group known as the 

 organic acids. Among those that have examined this subject, 

 none, perhaps, have attained a wider hearing than Magitot, 

 of Paris. This gentleman published a work on this subject 

 in 1868, in which he makes an extended examination of the 

 subject, arriving at the conclusion that decay is caused by 

 acids. These acids, however, are derived from the saliva 

 through the process of fermentation. Dr. Magitot instituted 

 a long series of experiments to determine the effects of the 

 suspected acids on the teeth. This series of experiments show 

 that most of the organic acids act very feebly on the teeth 

 in the proportion of one to one thousand of water; and that 

 in the proportion of one to one hundred they act quite 

 energetically ; so that the teeth submitted to their action will 

 be completely decalcified within a few weeks or months. 

 Most of this series of experiments were continued, however, 

 for two years. The conclusion seems to be that caries may be 

 produced by any of the group of acids that may be developed 

 by the fermentation of the saliva ; these are the lactic, acetic, 

 butyric, etc. 



Dr. Magitot states distinctly, that the agency of micro- 



