XVI. 



THE TEETH. 



EVERY tooth, in the socket of the jaw is in close connection 

 with the surrounding structures and is composed of living 

 tissues. Morbid processes, especially caries, produce more or less 

 painful sensations in the tooth, even before the pulp- cavity has 

 been invaded. The cutting with dental instruments of healthy 

 portions of the tooth is an unpleasant and even painful process 

 to the patient, and especially so at the boundary between the 

 enamel and the dentine, and in the neck of the tooth. For- 

 eign bodies, such as fillings of any description, if brought in 

 contact vwith dental tissues, set up an inflammatory condition, 

 resulting in the so-called " consolidation" of dentine a process 

 which, a century ago, was observed by G-othe in the dentine of 

 the elephant's tusk after a bullet had been accidentally driven 

 into this tissue. The sensation called " putting the teeth on 

 edge," caused by eating sour fruits, is another proof of the pres- 

 ence of life in the tooth. All former observers, however, though 

 some of them have maintained the presence of nerves in the 

 dentine, failed in demonstrating the living matter in its most 

 intricate distribution, partly owing to the faulty method applied 

 for microscopic research, and partly to the lack of knowledge in 

 the arrangement of living matter in other and kindred tissues of 

 the body. Dry specimens, formerly resorted to, are only mum- 

 mies in which a frame of lime-salts is left, but the soft parts the 

 seats of life have disappeared. Our present knowledge of the 

 minute anatomy of the teeth, as displayed in the following arti- 

 cles, is largely due to the improved methods applied for research. 



