ABBOTT'S PERTINENT QUESTIONS. 303 



filled, as some observers claim, with organisms of decomposition? 

 It certainly looks to me a little unreasonable, to say the least. 



Before closing, Mr. President, I would like to ask a few questions 

 of those who hold to the u septic theory." 1. Why is it that the 

 teeth of all persons do not decay the same ? 2. Why is it that in 

 99 cases out of a hundred the lower front teeth, on which may be 

 found the greatest number of organisms of any in the mouth, do not 

 decay, while all others do ? 3. Why is it that teeth with the great- 

 est amount of lime-salts, and consequently the smallest amount of 

 organic substance that upon which, it is claimed, the organisms 

 subsist do not decay sooner and more rapidly than the reverse? 



4. Why is it that a pulp canal which has held a dead and putrifying 

 pulp for many years, on being opened is found to be as solid and 

 free from decay as it was before the pulp died ? 



FUNGI OF TOOTH CARIES. 



DR. W. D. MILLER says: In the microscopical section of the 

 Physiological Institute investigations have been made by me on the 

 fungi of tooth caries, with the following results : 1. The acids which 

 are generated in the mouth through fermentation, withdraw the 

 the lime-salts from the teeth. 2. In the tissues of teeth from which 

 the lime-salts have been withdrawn by the action of acids, a prolific 

 growth of fungi is found. 3. Leptothrix are found, with rare ex- 

 ceptions, only on the surface and in the superficial layers of the tis- 

 sue ; bacilli penetrate deeper, and micrpcocci furthest of all. 4. Ii 

 the tooth tubuli we often find an undoubted gradual transition of 

 the long bacteria into shorter ones, and these again into micrococci. 



5. The invasion of fungi is always preceded by the action of acids. 



6. The fungi are not able to withdraw the lime-salts from the teeth ; 

 therefore a true infection of a thoroughly healthy tooth by a carious 

 one is impossible. 7. Fungi cause decay of the external portions 

 and pathological changes of the internal layers of the living tissue. 



THE greater the nutritive supply of a tooth the less liability will 

 there be to caries; hence diminished nutrition increases the liability 

 of caries. In old animals, and especially horses, the teeth receive 

 but little nourishment, so that in them we oftener find decayed teeth, 

 than in young animals. The decayed portion of the tooth varies in 

 color according to the hardness of the teeth. In some it is black, 

 in others brown, while in some it is nearly white, varying but little 



