178 MICROBES, FEEMENTS, AND MOULDS. 



supposed to be the cause of the early decay of teeth, 

 especially in children who eat them in excess. 



The microbe which MiUer has 

 found to be most common in de- 

 cayed teeth is very polymorphic. 

 Microccocus, bacterium, chains and 

 filaments, are only different phases 

 of the same plant, which also pro- 

 duces acid fermentation in the 

 mouth, and the formation of lactic 

 acid. Within the dentine tubules, 

 a section examined under the 

 microscope shows aU the inter- 

 mediate stages between the isolated 

 micrococcus and the filaments 

 (Figs. 81, 82). Miller succeeded 

 in producing this disease in sound teeth artificially. 



Fir. 81. — Bncterium of dental 

 caries in the dentine tu- 

 bules : a, artilicial caries ; 

 b, spontaneous caries. 



I 









 







o 



8 



I 



• 



%*• • 



a 



a 



7 I ^S 



t) 



t^i^ 





'Co 



Fig. 82. ^Bacterium of dental caries : a, b, different forms obtained in gelatine 



culture. 



According to his experiments, the best dentifrice for 



