THE TEETH. 669 



bioplasson. Still nearer to the decay the canaliculi are enlarged to ten or fif- 

 teen times their original diameter, and the cavities thus produced are all 

 filled with a partly nucleated bioplasson. Between the roundish cavities we 

 meet with longitudinal cavities, arising from the confluence of several cavi- 

 ties in one main direction. The cavities continue increasing in size, and form 

 large spaces, with rounded, bay-like boundaries, between which only scanty 

 traces of unchanged basis-substance are left. Lastly, the basis-substance has 

 entirely disappeared, and only bioplasson is visible in its place, either in the 

 shape of multinuclear layers or of irregular so-called medullary elements, 

 with rather faint marks of division. Nearest to the periphery the bioplasson 

 does not exhibit any form-elements, but looks like a disintegrated granular 

 mass, probably intermixed with or replaced by micrococci. 



In less acute caries a relatively small number of dentinal canaliculi are 

 enlarged and filled with bioplasson. The center of the bioplasson bodies is 

 occupied by one or two nuclei, which look as if they originated from the 

 former dentinal fiber. On the periphery of the dentine there are regular 

 nests filled with bioplasson formations of the above description, partly broken 

 down into medullary elements. On other parts, on the contrary, the transfor- 

 mation of the basis-substance into bioplasson has even preceded the changes 

 of the dentinal fibers. The canaliculi are not noticeably enlarged ; the den- 

 tinal fibers are either unchanged or slightly swollen, and more granular than 

 in the normal condition ; while outside these we have a thoroughly decalcified 

 and liquefied basis-substance, which means a reappearance of the net-work 

 of the living matter before the stage of disintegration. (See Fig. 294.) 



Caries of Cement. So long as the gums are in their normal condition and 

 position caries does not begin in the cement ; but, if the gums have receded 

 from any cause, thus exposing the cement which covers the necks of the 

 teeth, it may then begin to decay. The microscope reveals a more or less 

 advanced decay, which, in its essential features, is fully analogous to caries 

 of the dentine when in a live condition. On the boundary of the caries we 

 see, besides unchanged cement-corpuscles, those which have been enlarged 

 and transformed into medullary or inflammatory elements. Nay, I have 

 observed that the lacunae holding the bioplasson body were partly unchanged 

 while a part participated in the inflammatory process. (See Fig. 295.) 



The enlargement of the cement-corpuscles is evidently not due to their 

 direct swelling, but to a liquefaction of the surrounding basis-substance, in 

 which the bioplasson condition, and with this also the medullary elements 

 which have participated in the formation of the basis-substance, reappear. 

 The inflamed portions of the cement look granular with lower powers of the 

 microscope, but high powers reveal the net-like structure of the living matter 

 and the formation of irregular polyhedral elements, which are separated from 

 each other by a light, narrow seam, this being traversed by extremely delicate 

 uniting threads. 



Virchow's view that the bone-corpuscles swell and divide into inflammatory 

 elements by being converted into proliferating mother-cells, is in my opinion 

 wrong. No proliferation is demonstrable in the earliest stages of inflamma- 

 tion of the cement. Nothing but a decalcification, and thereafter a liquefac- 

 tion, of the glue-yielding basis-substance takes place in order to bring to view 

 the very same medullary elements which once have shared in the formation 

 of the cement. The inflammatory reaction in the cement-corpuscle itself may 

 be so slight that a part of this bioplasson may look almost unchanged, while 



